Bio Final

Counting chromosomes

Number of chromosomes = Number of centromeres

Number of DNA molecules = Number of chromatids

Diploid cell - 2 copies of each chromosome

Haploid cell - one copy of each chromosome

G1 phase (cell cycle/interphase)

Cell grows physically larger, copies organelles, and makes the molecular building blocks it will need in later steps

S phase (cell cycle/interphase)

Cell undergoes DNA replication, creating duplicated chromosomes (sister chromatids)

G2 phase (cell cycle/interphase)

During the 2nd gap phase, the cell grows more, makes proteins and organelles, and begin to reorganize its contents in preparation for mitosis

M phase (cell cycle/mitosis)

Cell divides into two daughter cells

Checkpoints (cell cycle)

G2 checkpoint- checks for cell size, DNA replication

Metaphase checkpoint - checks for chromosome spindle attachment

G1 checkpoint - checks for nutrients, growth factors, DNA damage

Law of Independent Assortment (Mendel’s laws on inheritance)

The allele that a parent gives to its offspring for one characteristic will not affect which allele is given for another characteristic

Law of Dominance (Mendel’s laws on inheritance)

When 2 organisms that are true breeding for different traits are crossed, only one trait will appear in the next generation .That trait is dominant, the one that is covered up is recessive

Law of Segregation (Mendel’s laws on inheritance)

Each trait is controlled by 2 genes on homologous chromosomes, but only one is distributed into a gamete. The 2 genes for the same traits are called alleles.

Genotypes

Genetic makeup of an organism

Homozygous dominant - AA

Homozygous recessive - aa

Heterozygous - Aa

Phenotype

Physical trait of an organism

Ex. hair color, eye color, height

Meiosis - description

Production of egg/sperm cells via sexual reproduction, starts with one diploid parent cell and ends up with 4 different daughter cells that are haploid

Meiosis I

Similar to mitosis. During prophase I, homologous chromosome “cross over” (exchange genetic info) and form a tetrad. During anaphase I, the tetrads are pulled apart by spindle fibers. Meiosis I ends with two haploid daughter cells.

Meiosis II

The sister chromatids in each of the two cells are pulled apart by spindle fibers during anaphase II. In cytokinesis II, the cytoplasm and organelles are divided in half, and meiosis ii ends with four haploid daughter cells (gametes).

Genetic variety

The law of independent assortment, crossing over of tetrads, and random distribution of chromatids into daughter cells during meiosis results in an abundance of genetic variation in offspring

Dominant and Recessive Alleles (Pedigrees)

Dominant if affected child has one parent with trait

Recessive if affected child has no parent with trait

Small population (5 fingers of evolution/pinky)

If population shrinks, then chance will take over (genes of survivors)

Non-random mating (5 fingers of evolution/ring finger)

If individuals choose a mate based on appearance or location, the frequency of genes may change

Mutations (5 fingers of evolution/middle finger)

If a new gene is added through mutation, it can affect the frequency

Gene flow (5 fingers of evolution/pointer finger)

If individuals flow in/out of an area, then frequency of genes will change

Natural selection/adaptation (5 fingers of evolution/thumb)

Natural selection is the only process that creates organisms better adapted to their environment - If a mutation with an advantage is present, the organisms with the mutations will survive and reproduce better than the organisms without the mutation, and thus the next generations will have a prevalence of the advantageous mutation.

Producers (Energy in Ecosystems)

Producers are autotrophs, are the base of the food web, and support all life

Consumers (Energy in Ecosystems)

Consumers are heterotrophs, and must eat producers or other consumers, meaning they are herbivores, carnivores, omnivores, detritivores, or decomposers

Autotrophs (Energy in Ecosystems)

Autotrophs create their own food, either by trapping energy from the sun or converting chemicals into organic substances

Heterotrophs (Energy in Ecosystems)

Heterotrophs cannot produce their own food and therefore are consumers

Detritivores and Decomposers (Energy in Ecosystems)

Detritivore - eats waste material (lobsters, worms)

Decomposers - break down organic material (fungi, worms, larvae, bacteria)

Herbivores, Carnivores, and Omnivores (Energy in Ecosystems)

Herbivores - animals that eat plants

Carnivores - animals that eat other animals

Omnivores - animals that eat both plants and animals

Trophic Levels (Energy in Ecosystems)

Primary producers (plants, algae, some bacteria), primary consumers (herbivores), secondary consumers (carnivores), higher level consumers (eats secondary consumers), detritivores, decomposers

Cas9 (CRISPR Gene Editing)

Protein that scans and cuts target DNA three bases (a codon) down from the PAM site

PAM Site (CRISPR Gene Editing)

Site near the area where target DNA is cut. Must contain the bases NGG (where N is a placeholder for any nucleotide)

Single guide RNA (CRISPR Gene Editing)

Binds to Cas9 and guides it to locate the PAM site, where it attaches to target DNA

Positive Feedback Loop (Homeostasis and Feedback Loops)

The final outcome of a series of reactions increases the whole cycle

Negative Feedback Loop (Homeostasis and Feedback Loops)

The final outcome stops the whole cycle from continuing

Blood Glucose Control - Glucagon (Glucose Feedback Loop)

Blood sugar gets low ; pancreas notices, releases more glucagon ; glucagon travels to skeletal muscle, liver, fat cells ; glucagon breaks down glycogen to produce glucose ; glucose goes up, so pancreas stops making glucagon

Blood Glucose Control - Insulin (Glucose Feedback Loop)

Blood glucose gets too high ; pancreas notices and releases more insulin ; insulin travels to skeletal muscle, liver, fat cells ; insulin makes these cells store glucose as glycogen ; blood glucose goes down, so pancreas stops making insulin

Digestive System

Nutrients leave through the small intestine ; glucose produced from lactose leaves through the small intestine and enters the bloodstream ; waste leaves through large intestine (colon)

Enzymes - defintion

Name ends in -ase

Proteins that speed up metabolism, aid in digestion, and build or break down substances

Enzymes and Substrates

A substrate (substance an enzyme works on), enters via the active site of the enzyme. The substrate then binds to and interacts with the enzyme

Lactose and Lactase

Lactose (substrate) reaches the active site of lactase, and is converted into two smaller sugars, galactose and glucose, which then leave the small intestine and enter the bloodstream

Substitution (DNA and mutations)

A letter (nucleotide) in a codon sequence is replaced

Ex. ATT ACC GCG to ATT AGC GCG

The most “harmless” type of mutation

Insertion (DNA and Mutations)

A new letter (nucleotide) is inserted into a codon sequence

Ex. ATT ACC GCG to ATT AGC CGC

Deletion (DNA and Mutations)

A letter (nucleotide) in a codon sequence is deleted

Ex. ATT ACC GCG to ATT ACG CGA

Frameshift (DNA and Mutations)

Mutation that affects the entire DNA sequence - insertion and deletion

The more dangerous mutations, as they can produce entirely different proteins than the intended result

Silent (DNA and Mutations)

Mutated codons that code for the same amino acid as the original codon

Missense (DNA and Mutations)

Mutated codons that code for a different amino acid than the original codon

Nonsense (DNA and Mutations)

Mutated codons that code for a premature stop

Transcription - DNA to mRNA

When a gene is switched on , an enzyme called RNA polymerase binds to the promoter region of a gene, unwinding the DNA. It then moves along the DNA, making a strand of RNA out of the free bases in the nucleus according to the DNA code. The mRNA (messenger RNA) template is complete once the polymerase reaches the terminator portion of the gene, where everything disassociates and DNA goes back to normal. Before the mRNA can be used in translation, introns (non-coding regions of the gene) need to be removed.

Translation - mRNA to protein

mRNA moves out of the nucleus via nuclear pores and enters the cytoplasm, where it binds to ribosomes. Transfer RNA carries the amino acid to the ribosome, where it delivers the right AA for each codon. Amino acids then bind and form a long chain of protein, which folds into a complex 3d shape once the last amino acid has been added. When tRNA is done, it leaves the mRNA.

Helicase, DNA Polymerase, Ligase (DNA Replication )

Helicase separates a double helix into 2 strands ; polymerase matches free-floating bases to make complementary strands ; ligase joins the backbones of each strand to create new double helices

Conservative model (DNA Replication)

One old chromatid, one new chromatid in each chromosome

Semi-conservative model (DNA Replication)

Half new, half old DNA strands in each sister chromatid

Dispersive model (DNA Replication)

Mix of old and new DNA randomly distributed between sister chromatids

Mitosis - description

Somatic cell division, starts with a diploid parent cell and ends up with 2 identical daughter cells that are diploid

Mitosis - Interphase to Metaphase

Cell lives and grows, preps for cell division (interphase) ; chromatin condenses, spindle fibers appear, nuclear membrane breaks down (prophase) ; spindle fibers attach to centromeres of chromosomes, which line up across the middle of the cell (metaphase)

Mitosis - Anaphase to Cytokinesis

Sister chromatids are pulled apart by spindle fibers (anaphase) ; chromosomes uncoil into chromatin, new nuclei form, cell wall or cleavage furrow appear become visible (telophase) ; cell’s cytoplasm is divided and there are two new daughter cells (cytokinesis)