Untitled Flashcards Set

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)