Genetics

Question 1

What is Mendel’s first hypothesis?

Answer 1

genes in genetic characters occur in pairs (one from mom and one from dad)

Question 2

What is Mendel’s second hypothesis?

Answer 2

if two alleles of a gene are different, one allele is dominant over the other

Question 3

What is Mendel’s third hypothesis?

Answer 3

two alleles of a gene segregate (seperate) and each enter a different gamete

Question 4

What is homozygous vs heterozygous?

Answer 4

two of the same allele, one of each allele

Question 5

Are both alleles expressed in heterozygotes? What happens in complete dominance?

Answer 5

yes, the trait associated with the dominant allele will appear in character and the recessive allele will not

Question 6

What is a monohybrid cross used for?

Answer 6

examining a single trait

Question 7

What is the result of a monohybrid cross? (both homozygous)

Answer 7

all heterozygous

Question 8

What is the result of a monohybrid cross? (both heterozygous)

Answer 8

1/4 homozygous dominant, 1/4 homozygous recessive, 1/2 heterozygous

Question 9

What is the product rule?

Answer 9

individual probabilities of two or more independent events occur are multiplied together

Question 10

What is the sum rule?

Answer 10

individual probabilities of two or more different events producing the same outcome are added together

Question 11

What is the range of probability?

Answer 11

0-1, 0 is not going to happen, 1 is going to happen

Question 12

What is the probability calculation for a monohybrid cross with heterozygotes?

Answer 12

RR: 1/2 x 1/2 = 1/4
rr: 1/2 x 1/2 = 1/4
Rr or rR: 1/2 x 1/2 + 1/2 x 1/2 = 1/4 + 1/4 =1/2

Question 13

What is a testcross?

Answer 13

determines if an individual with a dominant phenotype is a heterozygote or homozygote

other parent that is crossed must be homozygous recessive

Question 14

When doing a test cross all of the offspring have the dominant phenotype, what does this mean?

Answer 14

individual with an unknown genotype is homozygous dominant

Question 15

When doing a test cross half of the offspring are purple the other half are white, what does this mean?

Answer 15

individual with an unknown genotype is heterozygous

Question 16

What is a dihybrid cross used for?

Answer 16

examining two characters that are associated with different genes, they assort independently

Question 17

What is the principle of independent assortment?

Answer 17

different genes independently separate from each other because they are located at different chromosomes

Question 18

What is Mendel’s fourth hypothesis?

Answer 18

alleles of genes that govern two different characters segregate independently during the formation of gametes (principal of independent assortment)

Question 19

How can you figure out the potential gamete combinations in a dihybrid cross? Example?

Answer 19

foil (first, outside, inside, last)

First generation is RrYy, gametes can be RY, Ry, rY, ry

Question 20

If you cross RRYY and rryy all the gametes will have the genotype?

Answer 20

RY and ry, RrYy

Question 21

If two RrYy heterozygotes are crossed what are the genotypes of the gametes? What is the phenotypic ratio

Answer 21

RY, Ry, rY, ry

9:3:3:1
(9 dominant alleles for both, 3 with dominant and recessive, 3 with dominant and recessive, and 1 with recessive for both)

Question 22

AaBbCc is an allele combination what is the probability of a gamete with ABC?

Answer 22

probability of A is 1/2, probability of B is 1/2, probability of C is 1/2

1/2 x 1/2 x 1/2 = 1/8

Question 23

What is an example of multiple alleles?

Answer 23

blood type

Ia, Ib, i

Question 24

What combinations of alleles give A, B, AB, and O blood type?

Answer 24

A: IaIa, Iai
B: IbIb, Ibi
AB: IaIb
O: ii

Question 25

What happens in incomplete dominance? Example?

Answer 25

dominant alleles do not completely mask recessive alleles, red is dominant and white is recessive so heterozygote is pink

Question 26

What happens in codominance? Example?

Answer 26

both alleles are expressed seperately, red is dominant white is recessive so heterozygote has red and white leaves or AB blood type

Question 27

How many sex/autosomal chromosomes do we have?

Answer 27

1 pair of sex chromosomes and 22 paris of autosomes

Question 28

What are the types of sex linked inheritance?

Answer 28

x-linked dominant, x-linked recessive, y-linked

Question 29

What are the types of autosomal inheritance?

Answer 29

autosomal dominant, autosomal recessive

Question 30

Is the x or y chromosome bigger?

Answer 30

x is bigger

Question 31

What does the y chromosome contain? Why is it important?

Answer 31

SRY gene

codes for male phenotype

Question 32

What is true of sex-linked inheritance?

Answer 32

traits that are determined by genes on x or y chromosomes, traits do not appear equally on men and women

Question 33

What does x-linked recessive inheritance mean?

Answer 33

recessive allele that is carried on the x chromosome

Question 34

For x-linked recessive allele in males what are the possible options?

Answer 34

recessive allele on x means they show symptoms or dominant allele on x means they have no symptoms

Question 35

For x-linked recessive allele in females what are the possible options?

Answer 35

heterozygous means carrier, homozygous recessive means they show symptoms, and homozygous dominant means no symptoms

Question 36

What does a carrier mean?

Answer 36

they have no symptoms but can have children that have symptoms

Question 37

What is x-linked dominant inheritance?

Answer 37

dominant allele carried on x chromosome

Question 38

For x-linked dominant allele in males what are the possible options?

Answer 38

dominant allele of x chromosome means symptoms and recessive allele on x chromosome means no symptoms

Question 39

For x-linked dominant allele in females what are the possible options?

Answer 39

heterozygous means they show symptoms, homozygous dominant means they show symptoms, and homozygous recessive means no symptoms

Question 40

Who do y-linked disorders affect?

Answer 40

men

Question 41

In autosomal recessive inheritance who are carriers, affected, and unaffected?

Answer 41

heterozygotes are carriers, homozygous recessive are affected, and homozygous dominant are unaffected

Question 42

In autosomal dominant inheritance who are carriers, affected, and unaffected?

Answer 42

heterozygotes and homozygous dominant are affected, and homozygous recessive are unaffected

Question 43

If two parents are carriers for an autosomal recessive inheritance what are the possibilities for their children?

Answer 43

50% chance of carrier child
25% of unaffected child
25% of affected child