Mendelian Genetics
What do P, F1, and F2 mean in terms of mendelian genetics?
P generation: parents of the first cross
F1 generation: offspring of the first cross
F2 generation: offspring of the F1 gen
in a monohybrid cross, what trait is lost and what trait remains in the F1 gen?
the trait that remained is the dominant trait, and the one that was lost the recessive trait
What are somatic and germ line mutations?
Somatic mutation: occurs in body cells; not passed to offspring
Germ line mutation: occurs in gametes; offspring receives
What is the difference between autocrine, juxtracrine, and paracrine signal distances?
Autocrine: signal affects the cells that made them
Juxtracrine: signals affect adjacent cells that are connected
Paracrine: signals that affect nearby cells
What is the difference between a trait and character?
Character: observable physical feature (like flower color)
Trait: form of a character (purple flowers or white flowers)
If A= purple and a=white,
AA x Aa
what is the ratio of purple to white flowers?
3:1 purple to white
A mutation occurs that causes an enzyme to lose the ability to phosphorylate its target. would this be dominant or recessive mutation?
recessive
how do inhibitors work?
Inhibitors can also bind to receptor proteins, inhibiting ligand binding
Over ⅔ of drugs that alter human behavior function as inhibitors that bind to receptors of brain cells
Ex: adenosine and caffeine
What alleles code for functional and nonfunctional proteins?
Dominant alleles code for functional proteins
What is a dihybrid? What results in the F2 generation?
dihybrids: a hybrid that is heterozygous for alleles of two different genes
F2 gen: 9:3:3:1 ratio
What affect do mutations 1) outside the protein coding region, 2) at the promoter region, 3) to introns, have?
Mutations outside the protein coding regions may or may not have significant effects
Mutations at the promoter regions can radically change the rate of gene expression (switches)
Mutations to intron have no effect
Explain the different types of cytoplasmic and plasma membrane receptors and how they work.
cytoplasmic: ligand + receptor = gene regulator
plasma membrane:
Ion channels
channel proteins that allow ions to enter or leave a cell when interacting with the ligand.
Ex: facilitated diffusion
Enzyme-linked receptors
transmembrane integral protein with three parts (extracellular receptor, transmembrane region, intracellular enzyme).
When the signal is received, enzyme is activated
G protein-linked receptors
Receptor receives the signal, activated G protein, G protein activates an effector protein (enzyme)
explain the difference between mendels laws
Mendel’s first law: when gametes are made, the 2 gene versions (homologues or “particles”) separate, and gametes get one
What cross do you do to figure out if the genotype of a dominant phenotype is homozygous or heterozygous? how can you tell which it is?
a test cross - cross with recessive phenotype
If all offspring have the dominant trait, the dominant parent’s genotype is homozygous
If offspring include some with the recessive traits, the dominant parent’s genotype is heterozygous
List and describe the types of point mutations and chromosomal mutations
point mutations
Silent: Do not affect AA sequence. AKA the wobble effect
Missense: Base substitution results in a different AA
Nonsense: Base substitution results in a stop codon
Frameshift: Single bases are inserted or deleted
chromosomal
Deletions: Missing loci
Duplications: Repeated loci
Inversion: Break and rejoin during crossing over, but a segment is flipped
Translocation: Segment of DNA breaks off and is inserted into another chromosome.
Explain the difference between cytoplasmic receptors and plasma membrane receptors? include signal type & examples/types.
(for examples you can just name them)
1. Cytoplasmic receptors: receive nonpolar signals that can diffuse actress the plasma membrane
Ex estrogen
Ligand activates the receptor, Activated receptor functions as a gene regulator that turns transcription on or off
2. Plasma membrane receptors: receive polar signals that cannot diffuse across the membrane
Ex insulin
Ion channels: channel proteins that allow ions to enter or leave a cell when interacting with the ligand.
Ex: facilitated diffusion
Enzyme-linked receptors: transmembrane integral protein with three parts (extracellular receptor, transmembrane region, intracellular enzyme). When the signal is received, enzyme is activated
G protein-linked receptors: Receptor receives the signal, activated G protein, G protein activates an effector protein (enzyme)
explain the 4 alternatives to dominant and recessive allele relationships.
Incomplete dominance
“Blending”
Ex: red x white = pink
Concentration determines the straight of the trait
Codominance
Both phenotypes are present, but not blended
White + red = patches
Multiple alleles
Ex: rabbits
4 different alleles exist for the rabbit coat color gene (C )
C is dominant to Cch, Cch is dominant to Ch, Ch is dominant to c
Multiple alleles provide different dominance
Epistasis
If A= purple and a=white,
Aa X aa
what is the ratio of purple to white flowers?
3:1 white:purple
What is PKU, what happens because of it, and what 2 things result from it?
PKU = PAH is bad
PAH cant convert phenylalanine to tyrosine
phenylalanine builds up and damages neurons
mental retardation + pale skin and hair
Explain the signal transduction pathway in terms of signal < receptor protein < transduction < cellular response
be as specific as possible
1. signals can be polar/nonpolar & travel short distance or long distance
2. receptor proteins (cytoplasmic or plasma membrane) on cells will interact with a signal and change shape once bound
3. secondary messengers (cAMP, Ca ions) will amplify the signal inside of the cell by binding to enzymes and activating them
4. cell will respond accordingly (opening ion channels, changing enzyme activity, gene regulation)