Bio 184 Study Guide

Question 1

what is the law of segregation

Answer 1

it describes how alleles for a particular gene will segregate independently of one another into separate gametes

Question 2

what is the law of independent assortment

Answer 2

chromosome pairs will assort independently of other homologs

Question 3

what is “crossing over” when does it occur

Answer 3

“crossing over” is when nonsister chromatids exchange DNA from the two parents.

it occurs during prophase 1, when homologs synapse

Question 4

how is the distance separating 2 genes relayed tp the amount of crossing over?

Answer 4

when genes are further apart, they are more likely to recombine

Question 5

if 2 genes are located far enough apart that the recombination frequency is 50%, how will the genes behave?

Answer 5

they will assort independently and give equal ratios of genotypes

Question 6

what is the life cycle of a fly

Answer 6

eggs hatch into larvae, the larvae age from first to third instar stages, at third instar they emerge from the food and form pupal cases where they undergo metamorphosis and hatch as adults

Question 7

what does the ap mutation mean?

Answer 7

the fly has apterous wings

Question 8

what does w mean

Answer 8

the fly has white eyes

Question 9

what does eb mean

Answer 9

the fly has an ebony body

Question 10

what does ey mean

Answer 10

the fly has no eyes

Question 11

how can a male and female drosophila be distinguished

Answer 11

males have sex combs, male genitalia, and abdominal structures/pigmentations

Question 12

what is a “pure breeding” strain

Answer 12

they are homozygous for the traits of interest

Question 13

what is a “tester” strain

Answer 13

it is a homozygous recessive organism. They are used to identify whether the parents genes will assort independently or if they are linked

Question 14

if two genes are loctaed on different chromosomes, what will the outcome of the parent generations be?

Answer 14

all offspring will be diheterozygotes with wild-type phenotypes

Question 15

if two genes are located on different chromosomes, what will the F1 generation in a test cross produce

Answer 15

they will have four phenotypes in equal proportions

Question 16

if two genes are so close together that they are 100% linked, what is the parental cross outcome?

Answer 16

it will result in 100% wild type dominant heterozygotes

Question 17

if two genes are so close together that they are 100% linked, what is the f1 tester cross outcome

Answer 17

it will produce 50% wildtype and 50% homozygous mutants

Question 18

if genes are far enough to allow some crossing over, what phenotypes will be observed?

Answer 18

there will be some recombinant phenotypes

Question 19

how do you calculate the probability of an event occurring?

Answer 19

of events of A/ total # of events

Question 20

when determining the probability of getting heads and heads twice in a row, what rule do you use?

Answer 20

product rule defines the probability of A and B occuring in a defined order

(1/2)(1/2) the probability is 1/4

Question 21

when determining the probability of getting heads or tails, what rule do you use?

Answer 21

the sum rule defines the probability of A or B occuring

(1/2+1/2)=1

Question 22

to calculate the probability of an unordered sequence of events, what must be used?

Answer 22

the binomial expansion equation

Question 23

what is the general null hypothesis for any chi-squared test?

Answer 23

there is no statistical difference between expected and observed results

Question 24

what is the null hypothesis for the coin toss experiment

Answer 24

the coins are equally weighted and have equal chance of landing on heads or tails

Question 25

what is the null hypothesis for sn experiment testing the phenotypic ratio for one gene (apterous wings vs no apterous wings)?

Answer 25

the alleles are segregating randomly and there is an equal chance of having wild type or apterous wings according to mendels law of segregation

Question 26

what is the null hypothesis for assessing two genes in flies

Answer 26

there are equal proportions of the phenotypic ratios, so the genes are unlinked and assort independently. There is no difference been the observed and expected values.

Question 27

what is the p value in statistics?

Answer 27

the probability is the probability of obtaining results as extreme as the observed results.

Question 28

how do we calculate degrees of freedom for a Chi-Squared test?

Answer 28

number of categories minus 1

Question 29

how do you figure out the expected outcomes for the chi square test

Answer 29

the fraction expected x the total number of offspring

Question 30

if the X^2 is less than or equal to the X^2 critical

Answer 30

you fail to reject the null hypothesis, there is no statistical difference

Question 31

if the X^2 is greater than the X^2 critical

Answer 31

the null hypothesis can be rejcted, there is a statistical difference

Question 32

if there is no crossing over/recombination, what is the off spring in the F2 genertion for 100% linked genes

Answer 32

only wildtype and double mutant flies

Question 33

what is the null hypothesis when phenotypic ratios are tested for independent assortment

Answer 33

there is no difference between the observed and expected phenotypic ratios in the progeny. There are equal proportions of the 4 phenotypic classes so the genes are unlinked and assort independently.