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Chapter 9 - Cell Cycle
What are the different stages of the cell cycle?
Interphase, prophase, prometaphase, metaphase, anaphase telophase and cytokinesis
What are the different things that occur during interphase?
DNA exists as chromatin, G1, S, G2 phase occur
Explain what happens during the different stages of mitosis and cytokinesis:
Mitosis:
Prophase: (separates the duplicated genetic material) Chromatin condenses into two sister chromatids, nuclear envelope breaks, mitotic spindle begins to form.
Prometaphase: Fragments of the nuclear envelope, spindle microtubules attach to chromosomes
Metaphase: Replicated chromosomes line up at the center of the cell
Anaphase: sister chromatids separate and are pulled apart by spindle fibers
Telophase: Nuclear membrane forms around each set of chromosomes, chromosomes begin to decondense, spindle fibers disappear.
Cytokinesis: Cleavage furrow, two daughter cells form
What is the basic structure of a chromosome? How is chromatin organized?
Chromosomes: Wound up chromatin (Dna not active). Each chromosome has two sister chromatids
Chromatin: Tightly coiled DNA around proteins called histones
Compare/contrast cell plate formation with a cleavage furrow?
Cell plate formation:
occurs during cytokinesis in plant cells
Vesicles containing cell wall materials fuse in the center of the cell forming a cell plate which eventually creates a new cell wall, separating the two daughter cells
Cleavage Furrow formation:
Occurs during cytokinesis in animal cells
Actin filaments contract at the center of the cell forming a furrow that pinches the cell into two daughter cells
How is the cell cycle regulated?
Cell cycle checkpoints:
G1: are the new cells with the proper DNA
G2: did DNA duplicate properly in S phase
If things aren't working correctly: apoptosis
What is cancer’s relationship to mitosis? What is metastasis?
Cancer ignores the mitosis controls like hayflick limit. Cancer cells continue to divide
Metastasis: process by which cancer cells spread. Ex. Cancer cells break free from the primary tumor and travel through the bloodstream and grow in new locations.
What does the mitotic spindle do, and what is its origin?
A structure made of microtubules that forms during mitosis to separate chromosomes into two daughter cells
The origin is the centrosome which contains centrioles (animal cells)
What is the Hayflick limit?
A built in limit to the number of mitotic divisions
Due to the shortening of telomeres
Approx. 50 divisions
Chapter 11 - Mendel and the Gene Idea
Why was Mendel’s approach to biology unique for his time?
He used math and ratios to describe heredity
Became a monk
Disproved the ‘Blending Hypothesis’
Be able to solve problems of dominant/recessive traits, codominance, incomplete dominance, and understand examples of various genetic conditions.
Recessive Conditions: Inherited conditions (individuals must be homozygous recessive)
Sickle Cell: Blood related, affects many african americans, deformed red blood cells that do not transport oxygen well
Cystic Fibrosis: Results in death due to overproduction of mucus in lungs, when transport protein cannot move chloride ions
Tay- Sachs: Fatal condition of young children, bursting of lysosomes
PKU
Dominant Conditions (usually only heterozygous individuals)
Achondroplasia
Huntington's Disease: Symptoms don't usually begin until adulthood
Sex-Linked Disorders
Red-Green Colorblindness
Hemophilia: Sex linked condition when blood doesn’t clot, passed from mother to son b/c only women can be carriers
Muscular Dystrophy
Codominance: Two alleles are expressed separately (no dominant or recessive)
You can see both traits (cow with black and white)
Incomplete dominance: Alleles are expressed equally
Red + white flower: pink flowers
Understand what phenotype is vs genotype. Homozygous v Heterozygus
Phenotype: observable characteristics (brown hair, blue eyes)
Genotype: Genetic composition (Pp)
Homozygous: Two identical alleles (both dominant or both recessive)
AA (homozygous dominant) aa (homozygous recessive)
Heterozygous: Two different alleles for a particular gene
Aa
What is a test cross? A dihybrid cross?
Test Cross: When you cross a homozygous recessive individual with another individual to determine the genotype of the second parent.
Dihybrid Cross: the 16 grid punnett square (using FOIL)
What is ‘heterozygote advantage’ and give an example
When someone with a heterozygous genotype has a survival advantage compared to homozygous individuals.
Ex. People who are heterozygous for sickle cell are resistant to malaria
Chapter 12 - Chromosomal basis of inheritance
How are sex-linked characteristics passed to the next generation
Sex linked characteristics are carried on sex chromosomes X and Y
Males (XY) only have one X chromosome so they are more likely to express sex linked traits if they inherit the recessive allele on their single X chromosome
Females (XX) have two X chromosomes so they can carry a recessive allele for a sex linked trait without expressing it.
What are some examples of sex-linked conditions
Hemophilia: Blood doesn’t clot (bleeder's disease) carried on the X chromosome
Color Blindness: carried on the X chromosome
What is meant by ‘X inactivation’ and Barr bodies
In females one of the two X chromosome is randomly inactivated
Barr Body: The inactivated X chromosome
What is nondisjunction and aneuploidy
Nondisjunction: Chromosomes fail to separate properly. This leads to egg or sperm (gametes) with an abnormal number of chromosomes
Aneuploidy: Condition where an individual has an abnormal number of chromosomes (often as a result of nondisjunction)
ex. Down syndrome: three copies of chromosome 21
Ex. turner syndrome: a female only has one X chromosome
What does a karyotype indicate?
Karyotype: a profile of an individual's chromosomes arranged by size shape and number
It indicates chromosomal abnormalities
What is polyploidy?
The cells of an organism have more than two complete sets of chromosomes
Chapter 13 - Molecular basis of inheritance
Historical perspectives - what did the following researchers do to contribute to the discover of form and function of DNA
Griffith: Transformation of DNA. Mice experiment to show how bacteria can transfer genetic information
Hershey/Chase: Used the blender to determine if DNA or proteins contained genetic info
Watson/Crick: Using photo 51 determined the structure of DNA
Franklin: Photo 51. Using X-ray crystallography.
Together this showed that DNA was a double helix and the distance between atoms
Meselson/Stahl: Determined which method DNA replicated by: conservative, semi conservative
What is the semi-conservative model of DNA replication
A new DNA double helix is made up of 1 original strand and 1 new strand
What is meant by antiparallel strands? What is the implication of that for DNA replication and transcription
The orientation of two strands of DNA
One runs in the 5’ to 3’ direction and the other 3’ to 5’
Replication: DNA polymerase can only add nucleotides to the 3’ end of a strand. So one strand is replicated continuously in the 5’ to 3’ direction and the other strand (lagging) is replicated in fragments (okazaki fragments)
Transcription:
Know which enzymes are involved with DNA replication
Helicase: unwinds the double helix
Polymerase: Adds new nucleotides to the DNA strand
Primase: Provides a starting point for DNA polymerase
Ligase: Joins the Okazaki fragments on the lagging strand, creates covalent bonds
Topoisomerase: Reduces kinks that DNA forms while unzipping
What is a leading strand? Lagging strand? Okazaki fragments? Primers?
Leading strand: Strand that is replicated continuously 5’ to 3’
Lagging strand: Strand that is replicated discontinuously in the 3’ to 5’ direction forming Okazaki fragments
Okazaki fragments: short segments of DNA on the lagging strand
Primers: RNA sequences created by Primase that provide a starting point for DNA polymerase
How is a chromosome packed?
FINISH THIS PART
DNA is wrapped around histone proteins
Further coiled to form chromatin
What are telomeres (and what is their relationship to the Hayflick limit)
Repetitive non coding DNA sequences at the end of chromosomes that help protect DNA from degradation during cell division
The Hayflick limit refers to the number of times a cell will divide before telomeres shorten too much
How are plasmids used in bioengineering?
What are restriction enzymes and “sticky ends” CRISPR Cas 9
Restriction Enzymes: Cut DNA at specific sequences
Sticky ends: Unpaired ends of DNA after being cut by restriction enzymes. Unpaired hydrogen bonds
CRISPR: A gene editing tool that uses guide RNA to target specific DNA sequences and the Cas 9 protein to cut the DNA.
What is PCR and what is it used for? How is PCR related to Covid?
Polymerase Chain Reaction: technique used to amplify small amounts of DNA into larger quantities
Covid: Used in Covid 19 testing to amplify viral RNA and detect the virus
What does reverse transcriptase do, and why is that useful? How is it related to covid testing?
Enzyme that converts RNA into DNA
Covid Testing: Reverse transcriptase is used to convert the viral RNA into DNA
What is a transgenic organism (GMO) Recombinant DNA?
GMO: Organism that has been genetically modified to contain genes from another species
Recombinant DNA; DNA that has been artificially combined from different sources
How is DNA technology used in medicine? In agriculture? In forensics?
What was the goal and outcome of the Human Genome Project?
The goal was to map the entire sequence of the human genome and identify all the genes and theory functions (decode all 46 chromosomes)
The outcome
What role do antibiotics serve when transforming bacteria with new genes?
When bacteria are exposed to an antibiotic the most susceptible will die quickly leaving any surviving bacteria to pass on the resistance to future generations
Chapter 14 - Gene expression: From Gene to Protein
What happens during transcription - what molecules, organelles and enzymes?
Transcription: DNA is copied into mRNA
DNA, RNA, RNA polymerase, Nucleus (where it occurs)
RNA polymerase: binds to DNA at the promoter region and starts synthesizing the mRNA
Transcription factors: help RNA polymerase bind to the promoter region
Stages of transcription:
Initiation: RNa polymerase binds to promoter and begins unwinding DNA
Elongation: RNA polymerase moves along the DNA synthesizing mRNA
Termination: RNA polymerase reaches the termination sequence and is released
What are triplets? Codons? Anticodons?
Triplets: 3 nucleotides that refer to an amino acid
Codon: 3 mRNA nucleotides that refer to an amino acid
Anticodon: 3 tRnA nucleotides that refer to an amino acid
What happens during translation? What molecules and organelles?
Translation: mRNA is used to create proteins
mRNA, tRNA, ribosomes
Stages of translation:
Initiation: The ribosomal unit binds to mRNA. The tRNA molecule carrying an amino acid binds to the start codon
Elongation: the ribosome moves along the mRNA, tRNA molecules bring the amino acid that match
Termination: a stop codon is reached and the ribosome releases the new protein
What are introns and exons?
Introns: non coding regions that are removed before translation
Exons: coding regions that are spliced together
Mutations - know the differences (and the potential consequences of base -pair substitutions, insertions and deletions (what is a frameshift mutation)
Point mutation: change in single nucleotide pair
Ex. Sickle cell/cardiomyopathy
Silent mutation: Change in nucleotide sequence that results in a codon that creates the same amino acid (no consequences)
Missense mutation: A nucleotide pair substitution that codes for another amino acid (different amino acid is inserted, altering protein function)
Nonsense mutation: A mutation that changes an amino acid to a stop codon (premature stopping of a sequence, incomplete protein)
Frameshift mutation: Nucleotides are either added or removed from a gene (not in a multiple of 3) causing improper grouping for subsequent nucleotides (changes every future codon)
Why is it a big deal about proteins anyway?
100,000 diff proteins in humans
Tissue
Enzymes
Some hormones
Neurotransmitters
Transport proteins
Receptor proteins
Antibodies
What is the detailed structure of a ribosome and how does that relate to protein synthesis?
What is the significance of cytosol in transcription and translation?
After transcription the mRNA is transported into the cytosol
Translation occurs in the cytosol
What is ‘alternative gene splicing’
Exons are joined in different combinations
How does the mRNA vaccine work? What is the reason for the lipid nano-particles?
Introduces a small piece of mRNA that codes for a protein from the virus (spike proteins in Covid) into the body. The body’s cells then use the mRNA to produce the protein prompting the immune system to recognize and respond to it
Lipid nano -particles: Encapsulate and protect the mRNA and help deliver it into cells
What are antigens and which antigen on the SARS Cov 2 is recognized by your immune system?
Foreign molecules that trigger immune response
The Spike Protein is an antigen
Chapter 15 - Regulation of Gene Expression
Operons! What is the deal with repressible operon? Inducible operons? What do repressors do?
Repressible operon: typically on and can be turned off when a corepressor binds to the repressor and activates it. Preventing further transcription
Example: Trp Operon makes tryptophan unless an excess amount is present
Inducible operon: Typically off and can be turned on by an inducer molecule
Example: Lac operon. When lactose is present it binds to the repressor (making the operon inactive) allowing the production of enzymes needed to metabolise lactose
Repressor: Proteins that bind to the operator region of an operon and prevent transcription by blocking RNA polymerase from binding to the promoter.
Promoters, regulatory genes, structural genes, operators?
Promoter: Sequence of DNA where RNA polymerase binds to begin transcription
Regulatory Genes: Produce regulatory proteins (ex. Repressors) that control the expression of structural genes
Structural Genes: Encode proteins that are involved in metabolic pathways. Genes expressed under the control of the operon.
Operators: DNA sequence that acts as a switch, where the repressor or activator binds to control the transcription of the operon.
What is the role of a promoter on a eukaryotic chromosome?
Promoter on a eukaryotic chromosome is the DNA sequence where RNA polymerase and other transcription factors bind to initiate transcription
What are histones and what do they do?
Proteins that DNA wraps around to form nucleosomes
Help compact and organize DNA in the nucleus
What is epigenetics? How does this affect gene expression (methylation, acetylation)
Epigenetics: changes in gene expression that do not involve changes to the DNA sequence
Involves modifications to DNA or histones that affect how genes are turned on and off
Methylation: The addition of a methyl group to DNA (usually cytosine bases) Silences gene expression because it makes the DNA more tightly wound
Acetylation: Addition of an acetyl group to histone proteins. Loosening the DNA histone interaction, making the DNA more accessible. Increasing gene expression.
What is repetitive DNA? RNA interference?
Repetitive DNA: sequences that are repeated multiple times
Ex. telomeres
Rna interference: Small RNA molecules (micro RNA, small interfering RNA) bind to and degrade specific RNA molecules preventing translation
What are telomeres and telomerase?
Telomeres: Non coding DNA sequences that protect the ends of chromosomes from degradation
Telomerase: Enzyme that adds telomeres to the ends of chromosomes
Chapter 16 - Development, stem cells, cancer
Cloning - what is the simple definition
Creating an identical copy of an organism cell or piece of DNA
What is gene cloning, therapeutic cloning, reproductive cloning?
Gene cloning: Creating copies of a specific gene or DNA segment (gene is usually inserted into a plasmid which is introduced to a host cell for replication)
Therapeutic cloning: Cloning cells or tissues for a medical treatment (embryonic stem cells)
Reproductive cloning: Creating a genetically identical organism, an entire organism (Dolly the sheep)
Stem cells - embryonic and adult, induced pluripotent stem cells
Embryonic: Cells from zygote to blastocyst (5 day old) all DNA is on - pluripotent (can develop into all tissue.
Adult: Partially differentiated that can become a variety of tissue (not all) multipotent (used in bone marrow transplants
IPS: Normal cells where the DNA is treated to re-awaken all the DNA to act like an embryonic cell
Oncogenes - what is the role between proto-oncogenes, tumor suppressor genes, triggers?
Proto-oncogenes: Normal genes that regulate cell growth and division. When mutated or overexpressed they become oncogenes and can lead to uncontrolled cell growth (contributing to cancer)
Tumor suppressor genes: genes that act as a brake on cell division and prevent the formation of tumors.
Triggers: Environmental factors (uv radiation, chemicals, viruses) can trigger mutations in proto-oncogenes or tumor suppressor genes, leading to cancer development.
What is chemotherapy and how does it target cancerous cells?
Chemotherapy: treatment that attempts to inhibit growth of cancer cells. Targeting cells that divide rapidly and interfering with their ability to replicate DNA
Targeting cancer cells: It targets rapidly dividing cells (usually cancer). It also targets other rapidly dividing cells like hair cells, bone marrow, etc.
What happens with apoptosis?
Programmed cell death. Occurs as a response to signals inside or outside the cells. It eliminates damaged or dysfunctional cells.
Relation to cancer: It removes cells with damaged DNA. Disruption of apoptosis is common in cancer cells allowing them to survive despite mutations.
Chapter 18 - Genomes and their evolution
Human Genome Project
Research project that determines the sequence of 3 billion base pairs of DNA
Coding v Non Coding DNA
Coding: 1-2% of the human genome. Information to produce the proteins that carry out various bodily functions
Noncoding: Regulatory roles (introns, microRNA, promoters)
Role of polyploidy in evolution
Allows for rapid genetic diversification
Chapter 19 Descent with modification
Compare and contrast religious ideas with evolutionary theory
Religious ideas: Believed life was perfect and unchanging
Evolution: Species change over time through natural selection
Who was Couvier and how did he explain extinction via fossil evidence
Father of paleontology
He proposed that a catastrophic event wiped out dinos
Fossils abruptly disappeared
Compare and contrast Lamarck’s approach to evolution with Darwin’s
Lamarck: Evolution occurs through inheritance of acquired traits, organism can change rapidly in response to environment (focused on individual changes)
Darwin: Evolution occurs as a result of natural selection. Species can change over a long period of time due to the reproduction of individuals with advantageous traits (focused on population changes)
What was the impact of Mathus’ and Lyell’s work on Darwin’s interpretation of the how and why species change?
Mathus: Economist that believed as human population increases disease and poverty does too
Lyell: Geologist that believed earth’s landforms change slowly over time
Impact: Mathus helped Darwin understand the role of competition in natural selection, Lyell reinforced the idea of gradual changes over time
What is artificial selection?
Humans selectively breed organisms with desired traits. Choosing particular characteristics to breed. Usually plants (ex. Breeding dogs)
What is natural selection?
Process by which organisms with traits that provide advantages in an environment are more likely to survive and reproduce. Over time, the more favorable traits become popular in a population
What are the steps that Darwin outlined to explain evolutionary processes?
Populations overproduce
Variations exist
Environment - struggle for existence (survival of fittest)
Most fit = most offspring
Change in a population occurs over time
Explain the following evidence to support evolution: fossil record, homologous structures, comparative biochemistry, comparative embryology, vestigial structures?
Fossil record: Sedimentary rock is the only kind of rock that forms fossils. It preserves bones and imprints of past life. It is laid down in layers that can indicate time.
Homologous structures: Similarities in bone structure across species suggest a common ancestor
Comparative biochemistry: Analyzing DNA for similarities in genomes shows common ancestor (ex. Chimps and humans share 98% of DNA)
Comparative embryology: Embryos across species suggest common ancestry (all have gill and tails)
Vestigial structures: Reduced or no longer functional organs suggest evolution (ex. Snake hip bones)
Chapter 21 - The Evolution of Populations
What is a gene pool?
A total collection of genes and their alleles in a population
What is the role of mutations in evolution?
They are the source of genetic variation
Mutations create new alleles which may give a survival advantage
Over time favorable mutations may spread through natural selection
What is microevolution
Small scale changes in a population over time
Driven by mutation, genetic drift, natural selection
Macroevolution: creating new species
How does the bottleneck effect impact genetic drift? The founder effect?
Bottleneck: A population undergoes a reduction in size due to a catastrophic event. This reduces genetic diversity
Founder: A small group from a population establishes in a different location
Impact: Bottleneck - genetic drift (changes in allele frequencies) becomes more pronounced in the surviving population and the genetic variation of the gene pool is reduced
Founder: Loss of genetic diversity compared to original population. Genetic drift can have a strong effect in small populations
What is stabilizing selection? Diversifying selection? Directional selection?
Stabilizing: Something happens in the environment to weed out extremes, reducing variation
Diversifying: Shifted to one extreme or another, shift towards one phenotype over the other
Directional: Favors both extremes not middle, losing the intermediate - can lead to speciation
What is the ‘peppered moth’ and explain how “Industrial melanism is an example of natural selection?
A species of moth found in England
Traditionally existed as light colored and dark colored
Light colored were well camouflage while dark colored were not
Industrial Revolution: pollution cause tree bark to darked with soot which made light colored moths more visible to predators, and dark colored became better camouflage
Natural selection favored the dark colored moths
Chapter 22 - The Origin of Species
What is the current definition of a species?
Members of a population that reproduce and create fertile offspring
Identify various prezygotic and postzygotic barriers
Prezygotic: Zygote fertilizing egg
Geographical isolation: Physical barriers (mountains)
Behavioral isolation: Species are isolated because of differences in behavior
Temporal isolation: Species reproducing at different times
Gametic isolation: Sperm of one species cannot fertilize egg of another species
Postzygotic:
Reduced hybrid viability: Genes of a different parent species may interact in ways that impair the hybrids development (reduced ability to survive)
Reduced hybrid fertility: Hybrids may be sterile (mules)
Compare and contrast allopatric and sympatric speciation
Allopatric: A population is geographically isolated into two or more groups. Over time these isolated populations evolve independently leading to formation of new species (more common among animals)
Example: a river splits a population of squirrels into two groups which each evolve into a different species
Sympatric: New species arise within the same area as its parent population. This can happen due to polyploidy or behavioral changes that lead to reproductive isolation without geographic isolation. Sudden speciation as a result of a chromosomal mutation, leading to reproductive isolation. (more common among plants)
How does geographical isolation lead to allopatric speciation?
Geographical isolation occurs when there is a geographical barrier that separates groups. They are then subject to different environmental factors (food, climate, predators) and they accumulate genetic differences. Causing new species to form
What is adaptive radiation?
The emergence of numerous and diverse species from a common ancestor
Rapid evolution of a diverse set of species from a common ancestor
Example: Finches on the Galapagos: A single species of finch arrived on the island and diversified into several species.
Chapters 23&24 Broad Patterns of evolution and early life
Why were conditions on pre-life Earth more conducive to chemical evolution than today?
Lack of oxygen: No ozone, reduced atmosphere, no free oxygen. (lack of O2 helped preserve and form early organic compounds
UV radiation: lightning, volcanic activity (immense amount of energy)
Water and Atmosphere: Abundant water, creating the conditions for chemical reactions to form basic molecules (amino acids)
Primordial soup: oceans were hot thin soup containing organic molecules
Explain the following researchers and their work with protobionts:
Miller-Urey: Experiment simulating early Earth conditions. Resulted in the formation of amino acids, suggesting that basic organic molecules were formed during this time.
Fox: Formation of protobionts. He demonstrated that amino acids could form simple membrane bound structures (proteinoid microspheres) which could be precursors to more complex cell life.
Why was RNA likely the first genetic material
Because it is more tough
More functional and used more often that DNA
How did the first ozone form?
Oxygen produced by early photosynthetic organisms began to accumulate in the atmosphere
One of the byproducts of photosynthesis is oxygen.
What is the heterotroph hypothesis?
Suggests that the first living organisms were heterotrophs (relied on organic molecules for nutrition - primordial soup)
These organisms consume amino acids, lipids, sugars, leading into more complex autotrophic organisms
What is the endosymbiont hypothesis?
Mitochondria and chloroplasts were once their own prokaryotic cells that were engulfed by a eukaryotic cell. They developed a symbiotic relationship.
Evidence: mitochondria and chloroplasts have their own DNA and reproduce independently
Explain the formation of various types of sedimentary rocks and petrification
Sedimentary rocks form because of compacted sediments. They get compacted into rock layers: sandstone, limestone
Petrification: organic material (wood) is turned into rock when minerals replace the organic material
Explain plate tectonics and Pangea
Earth's outer shell is divided into plates that float on the asthenosphere below. These plates move due to convection currents in the mantle leading to the formation of mountains, volcanoes, earthquakes.
Pangea: Supercontinent that existed during the Paleozoic era. Broke apart due to plate tectonic movements, forming the continents
What is the Alvarez Hypothesis and how/why is iridium implicated in that?
A massive asteroid was responsible for the extinction of dinosaurs.
High levels of iridium found
Iridium is rare on earth but common in asteroids suggesting that an asteroid was responsible
What is convergent evolution and give some examples
When unrelated species evolve similar traits due to similar environmental pressures
Example: Dolphins and fish both have fins for swimming but are from different evolutionary lineages.
What is the molecular clock and genetic drift? Gene flow?
Molecular clock: Method that uses genetic data to estimate how long ago a species diverged. Based on the number of mutations in DNA and protein sequences over time
Genetic Drift: Random changes in allele frequencies
Gene flow: Movement of genetic material in populations due to migration
What are R plasmids? F plasmids? Sex pili?
R plasmids: DNA molecules that carry genes conferring resistance to antibiotics
F plasmids: contain genetic information necessary for the transfer of genetic material to other bacteria.
Sex Pili: Found on some bacteria that facilitate conjugation (cell sex)
:
What are obligate vs facultative anaerobes?
Obligate: Cannot survive in the presence of oxygen. Anaerobic respiration
Facultative: Can survive with oxygen or without. Switch between aerobic and anaerobic processes.
How are archaea similar to, and different from other ‘modern’ bacteria?
Similar:
Both prokaryotic (no nucleus)
Cell walls, plasma membrane, circular DNA
Different
Archaea are more closely related to eukaryotes
Archaea have cells walls based on pseudomurein, bacteria have peptidoglycan cell walls
Archaea are found in extreme environments (like hot springs) Chapter 9 - Cell Cycle
What are the different stages of the cell cycle?
Interphase, prophase, prometaphase, metaphase, anaphase telophase and cytokinesis
What are the different things that occur during interphase?
DNA exists as chromatin, G1, S, G2 phase occur
Explain what happens during the different stages of mitosis and cytokinesis:
Mitosis:
Prophase: (separates the duplicated genetic material) Chromatin condenses into two sister chromatids, nuclear envelope breaks, mitotic spindle begins to form.
Prometaphase: Fragments of the nuclear envelope, spindle microtubules attach to chromosomes
Metaphase: Replicated chromosomes line up at the center of the cell
Anaphase: sister chromatids separate and are pulled apart by spindle fibers
Telophase: Nuclear membrane forms around each set of chromosomes, chromosomes begin to decondense, spindle fibers disappear.
Cytokinesis: Cleavage furrow, two daughter cells form
What is the basic structure of a chromosome? How is chromatin organized?
Chromosomes: Wound up chromatin (Dna not active). Each chromosome has two sister chromatids
Chromatin: Tightly coiled DNA around proteins called histones
Compare/contrast cell plate formation with a cleavage furrow?
Cell plate formation:
occurs during cytokinesis in plant cells
Vesicles containing cell wall materials fuse in the center of the cell forming a cell plate which eventually creates a new cell wall, separating the two daughter cells
Cleavage Furrow formation:
Occurs during cytokinesis in animal cells
Actin filaments contract at the center of the cell forming a furrow that pinches the cell into two daughter cells
How is the cell cycle regulated?
Cell cycle checkpoints:
G1: are the new cells with the proper DNA
G2: did DNA duplicate properly in S phase
If things aren't working correctly: apoptosis
What is cancer’s relationship to mitosis? What is metastasis?
Cancer ignores the mitosis controls like hayflick limit. Cancer cells continue to divide
Metastasis: process by which cancer cells spread. Ex. Cancer cells break free from the primary tumor and travel through the bloodstream and grow in new locations.
What does the mitotic spindle do, and what is its origin?
A structure made of microtubules that forms during mitosis to separate chromosomes into two daughter cells
The origin is the centrosome which contains centrioles (animal cells)
What is the Hayflick limit?
A built in limit to the number of mitotic divisions
Due to the shortening of telomeres
Approx. 50 divisions
Chapter 11 - Mendel and the Gene Idea
Why was Mendel’s approach to biology unique for his time?
He used math and ratios to describe heredity
Became a monk
Disproved the ‘Blending Hypothesis’
Be able to solve problems of dominant/recessive traits, codominance, incomplete dominance, and understand examples of various genetic conditions.
Recessive Conditions: Inherited conditions (individuals must be homozygous recessive)
Sickle Cell: Blood related, affects many african americans, deformed red blood cells that do not transport oxygen well
Cystic Fibrosis: Results in death due to overproduction of mucus in lungs, when transport protein cannot move chloride ions
Tay- Sachs: Fatal condition of young children, bursting of lysosomes
PKU
Dominant Conditions (usually only heterozygous individuals)
Achondroplasia
Huntington's Disease: Symptoms don't usually begin until adulthood
Sex-Linked Disorders
Red-Green Colorblindness
Hemophilia: Sex linked condition when blood doesn’t clot, passed from mother to son b/c only women can be carriers
Muscular Dystrophy
Codominance: Two alleles are expressed separately (no dominant or recessive)
You can see both traits (cow with black and white)
Incomplete dominance: Alleles are expressed equally
Red + white flower: pink flowers
Understand what phenotype is vs genotype. Homozygous v Heterozygus
Phenotype: observable characteristics (brown hair, blue eyes)
Genotype: Genetic composition (Pp)
Homozygous: Two identical alleles (both dominant or both recessive)
AA (homozygous dominant) aa (homozygous recessive)
Heterozygous: Two different alleles for a particular gene
Aa
What is a test cross? A dihybrid cross?
Test Cross: When you cross a homozygous recessive individual with another individual to determine the genotype of the second parent.
Dihybrid Cross: the 16 grid punnett square (using FOIL)
What is ‘heterozygote advantage’ and give an example
When someone with a heterozygous genotype has a survival advantage compared to homozygous individuals.
Ex. People who are heterozygous for sickle cell are resistant to malaria
Chapter 12 - Chromosomal basis of inheritance
How are sex-linked characteristics passed to the next generation
Sex linked characteristics are carried on sex chromosomes X and Y
Males (XY) only have one X chromosome so they are more likely to express sex linked traits if they inherit the recessive allele on their single X chromosome
Females (XX) have two X chromosomes so they can carry a recessive allele for a sex linked trait without expressing it.
What are some examples of sex-linked conditions
Hemophilia: Blood doesn’t clot (bleeder's disease) carried on the X chromosome
Color Blindness: carried on the X chromosome
What is meant by ‘X inactivation’ and Barr bodies
In females one of the two X chromosome is randomly inactivated
Barr Body: The inactivated X chromosome
What is nondisjunction and aneuploidy
Nondisjunction: Chromosomes fail to separate properly. This leads to egg or sperm (gametes) with an abnormal number of chromosomes
Aneuploidy: Condition where an individual has an abnormal number of chromosomes (often as a result of nondisjunction)
ex. Down syndrome: three copies of chromosome 21
Ex. turner syndrome: a female only has one X chromosome
What does a karyotype indicate?
Karyotype: a profile of an individual's chromosomes arranged by size shape and number
It indicates chromosomal abnormalities
What is polyploidy?
The cells of an organism have more than two complete sets of chromosomes
Chapter 13 - Molecular basis of inheritance
Historical perspectives - what did the following researchers do to contribute to the discover of form and function of DNA
Griffith: Transformation of DNA. Mice experiment to show how bacteria can transfer genetic information
Hershey/Chase: Used the blender to determine if DNA or proteins contained genetic info
Watson/Crick: Using photo 51 determined the structure of DNA
Franklin: Photo 51. Using X-ray crystallography.
Together this showed that DNA was a double helix and the distance between atoms
Meselson/Stahl: Determined which method DNA replicated by: conservative, semi conservative
What is the semi-conservative model of DNA replication
A new DNA double helix is made up of 1 original strand and 1 new strand
What is meant by antiparallel strands? What is the implication of that for DNA replication and transcription
The orientation of two strands of DNA
One runs in the 5’ to 3’ direction and the other 3’ to 5’
Replication: DNA polymerase can only add nucleotides to the 3’ end of a strand. So one strand is replicated continuously in the 5’ to 3’ direction and the other strand (lagging) is replicated in fragments (okazaki fragments)
Transcription:
Know which enzymes are involved with DNA replication
Helicase: unwinds the double helix
Polymerase: Adds new nucleotides to the DNA strand
Primase: Provides a starting point for DNA polymerase
Ligase: Joins the Okazaki fragments on the lagging strand, creates covalent bonds
Topoisomerase: Reduces kinks that DNA forms while unzipping
What is a leading strand? Lagging strand? Okazaki fragments? Primers?
Leading strand: Strand that is replicated continuously 5’ to 3’
Lagging strand: Strand that is replicated discontinuously in the 3’ to 5’ direction forming Okazaki fragments
Okazaki fragments: short segments of DNA on the lagging strand
Primers: RNA sequences created by Primase that provide a starting point for DNA polymerase
How is a chromosome packed?
FINISH THIS PART
DNA is wrapped around histone proteins
Further coiled to form chromatin
What are telomeres (and what is their relationship to the Hayflick limit)
Repetitive non coding DNA sequences at the end of chromosomes that help protect DNA from degradation during cell division
The Hayflick limit refers to the number of times a cell will divide before telomeres shorten too much
How are plasmids used in bioengineering?
What are restriction enzymes and “sticky ends” CRISPR Cas 9
Restriction Enzymes: Cut DNA at specific sequences
Sticky ends: Unpaired ends of DNA after being cut by restriction enzymes. Unpaired hydrogen bonds
CRISPR: A gene editing tool that uses guide RNA to target specific DNA sequences and the Cas 9 protein to cut the DNA.
What is PCR and what is it used for? How is PCR related to Covid?
Polymerase Chain Reaction: technique used to amplify small amounts of DNA into larger quantities
Covid: Used in Covid 19 testing to amplify viral RNA and detect the virus
What does reverse transcriptase do, and why is that useful? How is it related to covid testing?
Enzyme that converts RNA into DNA
Covid Testing: Reverse transcriptase is used to convert the viral RNA into DNA
What is a transgenic organism (GMO) Recombinant DNA?
GMO: Organism that has been genetically modified to contain genes from another species
Recombinant DNA; DNA that has been artificially combined from different sources
How is DNA technology used in medicine? In agriculture? In forensics?
What was the goal and outcome of the Human Genome Project?
The goal was to map the entire sequence of the human genome and identify all the genes and theory functions (decode all 46 chromosomes)
The outcome
What role do antibiotics serve when transforming bacteria with new genes?
When bacteria are exposed to an antibiotic the most susceptible will die quickly leaving any surviving bacteria to pass on the resistance to future generations
Chapter 14 - Gene expression: From Gene to Protein
What happens during transcription - what molecules, organelles and enzymes?
Transcription: DNA is copied into mRNA
DNA, RNA, RNA polymerase, Nucleus (where it occurs)
RNA polymerase: binds to DNA at the promoter region and starts synthesizing the mRNA
Transcription factors: help RNA polymerase bind to the promoter region
Stages of transcription:
Initiation: RNa polymerase binds to promoter and begins unwinding DNA
Elongation: RNA polymerase moves along the DNA synthesizing mRNA
Termination: RNA polymerase reaches the termination sequence and is released
What are triplets? Codons? Anticodons?
Triplets: 3 nucleotides that refer to an amino acid
Codon: 3 mRNA nucleotides that refer to an amino acid
Anticodon: 3 tRnA nucleotides that refer to an amino acid
What happens during translation? What molecules and organelles?
Translation: mRNA is used to create proteins
mRNA, tRNA, ribosomes
Stages of translation:
Initiation: The ribosomal unit binds to mRNA. The tRNA molecule carrying an amino acid binds to the start codon
Elongation: the ribosome moves along the mRNA, tRNA molecules bring the amino acid that match
Termination: a stop codon is reached and the ribosome releases the new protein
What are introns and exons?
Introns: non coding regions that are removed before translation
Exons: coding regions that are spliced together
Mutations - know the differences (and the potential consequences of base -pair substitutions, insertions and deletions (what is a frameshift mutation)
Point mutation: change in single nucleotide pair
Ex. Sickle cell/cardiomyopathy
Silent mutation: Change in nucleotide sequence that results in a codon that creates the same amino acid (no consequences)
Missense mutation: A nucleotide pair substitution that codes for another amino acid (different amino acid is inserted, altering protein function)
Nonsense mutation: A mutation that changes an amino acid to a stop codon (premature stopping of a sequence, incomplete protein)
Frameshift mutation: Nucleotides are either added or removed from a gene (not in a multiple of 3) causing improper grouping for subsequent nucleotides (changes every future codon)
Why is it a big deal about proteins anyway?
100,000 diff proteins in humans
Tissue
Enzymes
Some hormones
Neurotransmitters
Transport proteins
Receptor proteins
Antibodies
What is the detailed structure of a ribosome and how does that relate to protein synthesis?
What is the significance of cytosol in transcription and translation?
After transcription the mRNA is transported into the cytosol
Translation occurs in the cytosol
What is ‘alternative gene splicing’
Exons are joined in different combinations
How does the mRNA vaccine work? What is the reason for the lipid nano-particles?
Introduces a small piece of mRNA that codes for a protein from the virus (spike proteins in Covid) into the body. The body’s cells then use the mRNA to produce the protein prompting the immune system to recognize and respond to it
Lipid nano -particles: Encapsulate and protect the mRNA and help deliver it into cells
What are antigens and which antigen on the SARS Cov 2 is recognized by your immune system?
Foreign molecules that trigger immune response
The Spike Protein is an antigen
Chapter 15 - Regulation of Gene Expression
Operons! What is the deal with repressible operon? Inducible operons? What do repressors do?
Repressible operon: typically on and can be turned off when a corepressor binds to the repressor and activates it. Preventing further transcription
Example: Trp Operon makes tryptophan unless an excess amount is present
Inducible operon: Typically off and can be turned on by an inducer molecule
Example: Lac operon. When lactose is present it binds to the repressor (making the operon inactive) allowing the production of enzymes needed to metabolise lactose
Repressor: Proteins that bind to the operator region of an operon and prevent transcription by blocking RNA polymerase from binding to the promoter.
Promoters, regulatory genes, structural genes, operators?
Promoter: Sequence of DNA where RNA polymerase binds to begin transcription
Regulatory Genes: Produce regulatory proteins (ex. Repressors) that control the expression of structural genes
Structural Genes: Encode proteins that are involved in metabolic pathways. Genes expressed under the control of the operon.
Operators: DNA sequence that acts as a switch, where the repressor or activator binds to control the transcription of the operon.
What is the role of a promoter on a eukaryotic chromosome?
Promoter on a eukaryotic chromosome is the DNA sequence where RNA polymerase and other transcription factors bind to initiate transcription
What are histones and what do they do?
Proteins that DNA wraps around to form nucleosomes
Help compact and organize DNA in the nucleus
What is epigenetics? How does this affect gene expression (methylation, acetylation)
Epigenetics: changes in gene expression that do not involve changes to the DNA sequence
Involves modifications to DNA or histones that affect how genes are turned on and off
Methylation: The addition of a methyl group to DNA (usually cytosine bases) Silences gene expression because it makes the DNA more tightly wound
Acetylation: Addition of an acetyl group to histone proteins. Loosening the DNA histone interaction, making the DNA more accessible. Increasing gene expression.
What is repetitive DNA? RNA interference?
Repetitive DNA: sequences that are repeated multiple times
Ex. telomeres
Rna interference: Small RNA molecules (micro RNA, small interfering RNA) bind to and degrade specific RNA molecules preventing translation
What are telomeres and telomerase?
Telomeres: Non coding DNA sequences that protect the ends of chromosomes from degradation
Telomerase: Enzyme that adds telomeres to the ends of chromosomes
Chapter 16 - Development, stem cells, cancer
Cloning - what is the simple definition
Creating an identical copy of an organism cell or piece of DNA
What is gene cloning, therapeutic cloning, reproductive cloning?
Gene cloning: Creating copies of a specific gene or DNA segment (gene is usually inserted into a plasmid which is introduced to a host cell for replication)
Therapeutic cloning: Cloning cells or tissues for a medical treatment (embryonic stem cells)
Reproductive cloning: Creating a genetically identical organism, an entire organism (Dolly the sheep)
Stem cells - embryonic and adult, induced pluripotent stem cells
Embryonic: Cells from zygote to blastocyst (5 day old) all DNA is on - pluripotent (can develop into all tissue.
Adult: Partially differentiated that can become a variety of tissue (not all) multipotent (used in bone marrow transplants
IPS: Normal cells where the DNA is treated to re-awaken all the DNA to act like an embryonic cell
Oncogenes - what is the role between proto-oncogenes, tumor suppressor genes, triggers?
Proto-oncogenes: Normal genes that regulate cell growth and division. When mutated or overexpressed they become oncogenes and can lead to uncontrolled cell growth (contributing to cancer)
Tumor suppressor genes: genes that act as a brake on cell division and prevent the formation of tumors.
Triggers: Environmental factors (uv radiation, chemicals, viruses) can trigger mutations in proto-oncogenes or tumor suppressor genes, leading to cancer development.
What is chemotherapy and how does it target cancerous cells?
Chemotherapy: treatment that attempts to inhibit growth of cancer cells. Targeting cells that divide rapidly and interfering with their ability to replicate DNA
Targeting cancer cells: It targets rapidly dividing cells (usually cancer). It also targets other rapidly dividing cells like hair cells, bone marrow, etc.
What happens with apoptosis?
Programmed cell death. Occurs as a response to signals inside or outside the cells. It eliminates damaged or dysfunctional cells.
Relation to cancer: It removes cells with damaged DNA. Disruption of apoptosis is common in cancer cells allowing them to survive despite mutations.
Chapter 18 - Genomes and their evolution
Human Genome Project
Research project that determines the sequence of 3 billion base pairs of DNA
Coding v Non Coding DNA
Coding: 1-2% of the human genome. Information to produce the proteins that carry out various bodily functions
Noncoding: Regulatory roles (introns, microRNA, promoters)
Role of polyploidy in evolution
Allows for rapid genetic diversification
Chapter 19 Descent with modification
Compare and contrast religious ideas with evolutionary theory
Religious ideas: Believed life was perfect and unchanging
Evolution: Species change over time through natural selection
Who was Couvier and how did he explain extinction via fossil evidence
Father of paleontology
He proposed that a catastrophic event wiped out dinos
Fossils abruptly disappeared
Compare and contrast Lamarck’s approach to evolution with Darwin’s
Lamarck: Evolution occurs through inheritance of acquired traits, organism can change rapidly in response to environment (focused on individual changes)
Darwin: Evolution occurs as a result of natural selection. Species can change over a long period of time due to the reproduction of individuals with advantageous traits (focused on population changes)
What was the impact of Mathus’ and Lyell’s work on Darwin’s interpretation of the how and why species change?
Mathus: Economist that believed as human population increases disease and poverty does too
Lyell: Geologist that believed earth’s landforms change slowly over time
Impact: Mathus helped Darwin understand the role of competition in natural selection, Lyell reinforced the idea of gradual changes over time
What is artificial selection?
Humans selectively breed organisms with desired traits. Choosing particular characteristics to breed. Usually plants (ex. Breeding dogs)
What is natural selection?
Process by which organisms with traits that provide advantages in an environment are more likely to survive and reproduce. Over time, the more favorable traits become popular in a population
What are the steps that Darwin outlined to explain evolutionary processes?
Populations overproduce
Variations exist
Environment - struggle for existence (survival of fittest)
Most fit = most offspring
Change in a population occurs over time
Explain the following evidence to support evolution: fossil record, homologous structures, comparative biochemistry, comparative embryology, vestigial structures?
Fossil record: Sedimentary rock is the only kind of rock that forms fossils. It preserves bones and imprints of past life. It is laid down in layers that can indicate time.
Homologous structures: Similarities in bone structure across species suggest a common ancestor
Comparative biochemistry: Analyzing DNA for similarities in genomes shows common ancestor (ex. Chimps and humans share 98% of DNA)
Comparative embryology: Embryos across species suggest common ancestry (all have gill and tails)
Vestigial structures: Reduced or no longer functional organs suggest evolution (ex. Snake hip bones)
Chapter 21 - The Evolution of Populations
What is a gene pool?
A total collection of genes and their alleles in a population
What is the role of mutations in evolution?
They are the source of genetic variation
Mutations create new alleles which may give a survival advantage
Over time favorable mutations may spread through natural selection
What is microevolution
Small scale changes in a population over time
Driven by mutation, genetic drift, natural selection
Macroevolution: creating new species
How does the bottleneck effect impact genetic drift? The founder effect?
Bottleneck: A population undergoes a reduction in size due to a catastrophic event. This reduces genetic diversity
Founder: A small group from a population establishes in a different location
Impact: Bottleneck - genetic drift (changes in allele frequencies) becomes more pronounced in the surviving population and the genetic variation of the gene pool is reduced
Founder: Loss of genetic diversity compared to original population. Genetic drift can have a strong effect in small populations
What is stabilizing selection? Diversifying selection? Directional selection?
Stabilizing: Something happens in the environment to weed out extremes, reducing variation
Diversifying: Shifted to one extreme or another, shift towards one phenotype over the other
Directional: Favors both extremes not middle, losing the intermediate - can lead to speciation
What is the ‘peppered moth’ and explain how “Industrial melanism is an example of natural selection?
A species of moth found in England
Traditionally existed as light colored and dark colored
Light colored were well camouflage while dark colored were not
Industrial Revolution: pollution cause tree bark to darked with soot which made light colored moths more visible to predators, and dark colored became better camouflage
Natural selection favored the dark colored moths
Chapter 22 - The Origin of Species
What is the current definition of a species?
Members of a population that reproduce and create fertile offspring
Identify various prezygotic and postzygotic barriers
Prezygotic: Zygote fertilizing egg
Geographical isolation: Physical barriers (mountains)
Behavioral isolation: Species are isolated because of differences in behavior
Temporal isolation: Species reproducing at different times
Gametic isolation: Sperm of one species cannot fertilize egg of another species
Postzygotic:
Reduced hybrid viability: Genes of a different parent species may interact in ways that impair the hybrids development (reduced ability to survive)
Reduced hybrid fertility: Hybrids may be sterile (mules)
Compare and contrast allopatric and sympatric speciation
Allopatric: A population is geographically isolated into two or more groups. Over time these isolated populations evolve independently leading to formation of new species (more common among animals)
Example: a river splits a population of squirrels into two groups which each evolve into a different species
Sympatric: New species arise within the same area as its parent population. This can happen due to polyploidy or behavioral changes that lead to reproductive isolation without geographic isolation. Sudden speciation as a result of a chromosomal mutation, leading to reproductive isolation. (more common among plants)
How does geographical isolation lead to allopatric speciation?
Geographical isolation occurs when there is a geographical barrier that separates groups. They are then subject to different environmental factors (food, climate, predators) and they accumulate genetic differences. Causing new species to form
What is adaptive radiation?
The emergence of numerous and diverse species from a common ancestor
Rapid evolution of a diverse set of species from a common ancestor
Example: Finches on the Galapagos: A single species of finch arrived on the island and diversified into several species.
Chapters 23&24 Broad Patterns of evolution and early life
Why were conditions on pre-life Earth more conducive to chemical evolution than today?
Lack of oxygen: No ozone, reduced atmosphere, no free oxygen. (lack of O2 helped preserve and form early organic compounds
UV radiation: lightning, volcanic activity (immense amount of energy)
Water and Atmosphere: Abundant water, creating the conditions for chemical reactions to form basic molecules (amino acids)
Primordial soup: oceans were hot thin soup containing organic molecules
Explain the following researchers and their work with protobionts:
Miller-Urey: Experiment simulating early Earth conditions. Resulted in the formation of amino acids, suggesting that basic organic molecules were formed during this time.
Fox: Formation of protobionts. He demonstrated that amino acids could form simple membrane bound structures (proteinoid microspheres) which could be precursors to more complex cell life.
Why was RNA likely the first genetic material
Because it is more tough
More functional and used more often that DNA
How did the first ozone form?
Oxygen produced by early photosynthetic organisms began to accumulate in the atmosphere
One of the byproducts of photosynthesis is oxygen.
What is the heterotroph hypothesis?Suggests that the first living organisms were heterotrophs (relied on organic molecules for nutrition - primordial soup)
These organisms consume amino acids, lipids, sugars, leading into more complex autotrophic organisms
What is the endosymbiont hypothesis?
Mitochondria and chloroplasts were once their own prokaryotic cells that were engulfed by a eukaryotic cell. They developed a symbiotic relationship.
Evidence: mitochondria and chloroplasts have their own DNA and reproduce independently
Explain the formation of various types of sedimentary rocks and petrification
Sedimentary rocks form because of compacted sediments. They get compacted into rock layers: sandstone, limestone
Petrification: organic material (wood) is turned into rock when minerals replace the organic material
Explain plate tectonics and Pangea
Earth's outer shell is divided into plates that float on the asthenosphere below. These plates move due to convection currents in the mantle leading to the formation of mountains, volcanoes, earthquakes.
Pangea: Supercontinent that existed during the Paleozoic era. Broke apart due to plate tectonic movements, forming the continents
What is the Alvarez Hypothesis and how/why is iridium implicated in that?
A massive asteroid was responsible for the extinction of dinosaurs.
High levels of iridium found
Iridium is rare on earth but common in asteroids suggesting that an asteroid was responsible
What is convergent evolution and give some examples
When unrelated species evolve similar traits due to similar environmental pressures
Example: Dolphins and fish both have fins for swimming but are from different evolutionary lineages.
What is the molecular clock and genetic drift? Gene flow?
Molecular clock: Method that uses genetic data to estimate how long ago a species diverged. Based on the number of mutations in DNA and protein sequences over time
Genetic Drift: Random changes in allele frequencies
Gene flow: Movement of genetic material in populations due to migration
What are R plasmids? F plasmids? Sex pili?
R plasmids: DNA molecules that carry genes conferring resistance to antibiotics
F plasmids: contain genetic information necessary for the transfer of genetic material to other bacteria.
Sex Pili: Found on some bacteria that facilitate conjugation (cell sex)
:
What are obligate vs facultative anaerobes?
Obligate: Cannot survive in the presence of oxygen. Anaerobic respiration
Facultative: Can survive with oxygen or without. Switch between aerobic and anaerobic processes.
How are archaea similar to, and different from other ‘modern’ bacteria?
Similar:
Both prokaryotic (no nucleus)
Cell walls, plasma membrane, circular DNA
Different
Archaea are more closely related to eukaryotes
Archaea have cells walls based on pseudomurein, bacteria have peptidoglycan cell walls
Archaea are found in extreme environments (like hot springs)
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