Exam #3 Study Guide

2

How many genes are in a dihybrid cross?

dihybrid cross

What is this an example of?

RrYy x RrYy

9:3:3:1

When doing a dihybrid cross, what ratio do we get in a heterozygous state?

phenotype

in a dihybrid cross multiple genotypes can give us the same __________

the genes are on two different chromosomes (homologous)

What would A “/” indicate?

that there are two separate genes

What would A “;” indicate? (Ex. separating two different colors that are both shown in the phenotype)

2 mutant parents producing wild type children

What is an example of complementation?

complementation

____________ can occur when one parent has a mutation on the “B” gene and a normal “A” gene, and the other parent has a mutation on the “A” gene and a normal “B” gene

the allele of one gene masks the expression of another gene

What is epistasis?

how far apart two genes are on the same chromosome

What do map units represent?

add the recombinants then divide by total offspring

How do you find map units?

short

Would the distance be short or long if the map units number was low?

less likely to be separated during crossover

What is less likely when the map unit number is low (short distance)?

long

Would the distance be short or long if the map units number was high?

more likely to be separated during crossover

What is more likely when the map unit number is high (long distance)?

recombinants

When crossover occurs, what is the result?

parentals

When crossover doesn’t occur what is the result?

genes are located on the same chromosome, so they are sorted together

What is linkage?

cis configuration

____ __________ - both dominant alleles (or both mutant alleles) are on the same chromosome, and both recessive alleles (or wild type alleles) are on the homologous chromosome

same, homologous

in cis configuration, both dominant alleles (or both mutant alleles) are on the _____ chromosome, and both recessive alleles (or wild type alleles) are on the ________ chromosome

trans configuration

_____ _________ - each chromosome carries one dominant and one recessive allele

recombination

___________ (crossing over) can change cis to trans and vice versa

population genetics

________ ________ focuses on the whole population instead of the genetics of one specific individual

environmental factors

population genetics must take in to account ________ _______

quantitative, categorical

population genetics focuses more on _________ (continuous traits) over _________ (discrete traits)

continuous traits, discrete traits

population genetics focuses more on quantitative (numbers; ________ ______) over qualitative (categorical; _______ _____)

height, weight

What are 2 examples of continuous traits?

the graphs are symmetrical around the mean (half above the mean, half below the mean)

How can we tell if it is a normal distribution?

mean, median, and mode

______, ________, and ______ are all equal in normal distribution

norm of reaction

each genotype does not have a simple phenotypic expression; instead there is a ______ ___ _______

case specific

the norm of reaction is often complicated and _______ _______

situations where genotypes are the same but we are seeing multiple different phenotypes

What types of situations does the norm of reaction apply to?

environment

if there is a norm of reaction, it means the __________ has some effect

the environment

What will have an effect in quantitative genetics?

loci

in quantitative genetics the will be many ______ per phenotype

additive genetics

What is this an example of?

Ex. if you have one allele (+), you’ll have a certain height, but if you have the (-) allele, there will be no additive that adds to your height

yes

Is quantitative genetics distributed normally?

lower than actual mutation rate due to error-checking systems and mutations that lead to cell death

What is apparent mutation rate lower than, and why?

larger than nonsynonymous mutations because those mutations are more likely to kill the cell

What do synonymous mutation rates appear larger than, and why?

deterministic

mutation rates are _________, meaning they can be predicted/a number can be assigned to it

individuals that have it

mutation frequency = ?

how likely the mutation is to occur

mutation rate = ?

number of cells affected/total # of cells

How do you find the mutation frequency?

environment, genetics

What 2 things can cause variation?

environmental variance + genetic variance

max variance = ?

0-1

What is the heritability range?

not genetic

What does 0 mean in the heritability range?

completely genetic

What does 1 mean in the heritability range?

longitudinal studies

What is this an example of?

Ex. a study of identical twins (100% the same genetics) who were separated and raised in different environments to see the differences in their traits to determine which traits are determined more by genetics vs. environment

F(A) = # of A alleles/# of total alleles

How do you find out the frequency of dominant alleles in population genetics?

F(a) = # of a alleles/# of total alleles

How do you find out the frequency of recessive alleles in population genetics?

F(AA) + F(Aa) + F(aa) = 1

What is the Hardy-Weinberg equilibrium using only alleles?

P² + 2pq + q² = 1

What is the Hardy-Weinberg equilibrium using P and Q?

null model, meaning assumptions need to be made

What kind of model is the Hardy-Weinberg equilibrium equation, and what does that mean?

random mating

What is the 1st assumption that can be made with the null model of the Hardy-Weinberg equilibrium?

alleles can’t change into other alleles

What is the 2nd assumption that can be made with the null model of the Hardy-Weinberg equilibrium?

alleles can’t be better than others at being copied into the next generation

What is the 3rd assumption that can be made with the null model of the Hardy-Weinberg equilibrium?

alleles can’t leave or join the bucket

What is the 4th assumption that can be made with the null model of the Hardy-Weinberg equilibrium?

there is an infinitely large population

What is the 5th assumption that can be made with the null model of the Hardy-Weinberg equilibrium?

sexual selection

What is the evolutionary force behind random mating?

mutation

What is the evolutionary force behind alleles not being able to change into other alleles?

natural selection

What is the evolutionary force behind allele not being able to be better than others at being copied into the next generation?

migration

What is the evolutionary force behind alleles not being able to leave or join the bucket?

genetic drift

What is the evolutionary force behind there being an infinitely large population?

founder effect

_______ ______ - when a few individuals become isolated from a larger population, this smaller group may establish a new population whose gene pool is not reflective of the source population; people tend to move from a larger population to a small one

allele frequencies

What does evolutionary force change?

mutations

What is the source of all alleles?

mutations

___________ accumulate once they appear in populations

forward mutation rate

µ = ?

reverse mutation rate

v = ?

the probability of a forward mutation rate is greater

Is the probability of a forward mutation rate much greater than the probability of a reverse mutation rate, or vice versa?

likelihood of making an error and that error being incorporated in that DNA molecule

What is mutation rate?

evolutionary forces (current and/or ancient)

What can allele frequency be based on?

lethal, conditional, resistant, nutritional, morphological, behavioral

What are the 6 mutation categories?

lethal mutations

What type of mutation will simply kill the individual?

only under certain conditions

When will conditional mutations show up?

environmental

conditional mutations are usually __________

conditional mutaiton

What type of mutation is this an example of?

Ex. heat-sensitive mutation in fruit flies

• <30 degrees = good; >30 degrees = death

• must have the mutation and be in the correct condition for the mutation to show

antibiotics, insecticides, pathogens

What are 3 examples of resistant mutations?

resistant mutation

What type of mutation is this an example of?

Ex. people with the CCR5-delta 32 gene are resistant to HIV, smallpox, and bubonic plague

the precursor, intermediate, or final product in a pathway

What can’t be made in nutritional mutations?

on external of organisms

Where are morphological mutations apparent?

organism behaves differently

What happens because of behavioral mutations?

genetics, environment

What are 2 sources of mutations?

genetic mutations

________ _______ can be purposeful or accidental

meiosis

What is an example of a purposeful genetic mutation?

DNA replication, mispairing, insertions, deletions

What are examples of accidental genetic mutations?

electromagnetic radiation (light), radioactivity, chemicals

What 3 environmental factors can cause mutations?

UV-C, UV-B, UV-A

What 3 ways is ultraviolet light divided?

UV-C

What type of UV does the ozone block?

UV-A, UV-B

What 2 types of UV do we get a little of?

DNA

ultraviolet light can cause mutations in _______

short wavelengths (less than 400nm)

What type of wavelengths does UV light have? (Give a number too)

thymine and cytosine are chemically bonded to each other on the same DNA strand

What occurs in thymine/cytosine dimer mutation?

causes base pairs to bind differently

What does the thymine/cytosine dimer mutation cause?

thymine/cytosine dimer

What type of DNA mutation is this an example of?

Ex. G may bind to T instead of C

only cells undergoing division

What types of cells are sensitive to UV light?

by stripping off electrons, causing the hydrogen bond holding base pairs together to be broken

How can ionizing radiation destroy DNA?

ionizing radiation

What has the shortest wavelength?

x-rays and gamma rays

What does ionizing radiation include?