C3: Mendelian Genetics

Question 1

what is a gene?

Answer 1

a unit of heredity passed on from parent to offspring, length of DNA that codes for a gene product

Question 2

what is an allele?

Answer 2

different forms of a gene

Question 3

what is a genotype?

Answer 3

genetic constitution of an individual organism

Question 4

what is a phenotype?

Answer 4

set of observable characteristics of an individual resulting from the interaction of its genotype with the enviornment

Question 5

what is a trait?

Answer 5

expressed characteristic or quality, genetically determined

Question 6

what is a locus?

Answer 6

genetic address or location

Question 7

what is incomplete dominance?

Answer 7

if the phenotype of a heterozygote is a blended mix of both alleles and the alleles for that trait are different
ex: R for red, W for white

Question 8

what is codominance?

Answer 8

2 alleles are both expressed but not blended (blood types)

Question 9

• what is the P generation?
• F1 generation?
• F2 generation?

Answer 9

• parental generation
• offspring of P generation
• offspring of F1 generation, grandchildren of P generation

Question 10

what is a monohybrid cross?
- example?

Answer 10

a mating between 2 individuals at one gene locus (1 gene)
- Aa x Aa

Question 11

what is a dihybrid cross?
- example?

Answer 11

a mating between 2 individuals involving 2 genetic loci (2 genes)
- AaBb x AaBb

Question 12

what is a testcross?
- example?

Answer 12

crossing to a homozygous recessive individual
- AaBbCc x aabbcc

Question 13

what is a backcross?
- example?

Answer 13

crossing to a previous generation
- F1 x P

Question 14

for the following cross, AA x AA

• what is the genotypic ratio?
• phenotypic ratio?

Answer 14

• 100% AA
• 100% A

Question 15

for the following cross, aa x aa

• what is the genotypic ratio?
• phenotypic ratio?

Answer 15

• 100% aa
• 100% a

Question 16

for the following cross, AA x aa

• what is the genotypic ratio?
• phenotypic ratio?

Answer 16

• 100% Aa
• 100% A

Question 17

for the following cross, Aa x AA

• what is the genotypic ratio?
• phenotypic ratio?

Answer 17

• 50% AA, 50% Aa
• 100% A

Question 18

for the following cross, Aa x aa

• what is the genotypic ratio?
• phenotypic ratio?

Answer 18

• 50% Aa, 50% aa
• 50% A, 50% a

Question 19

for the following cross, Aa x Aa

• what is the genotypic ratio?
• phenotypic ratio?

Answer 19

• 25% AA, 50% Aa, 25% aa
• 75% A, 25% a

Question 20

for the following cross,
AaBb x aabb

• what is its description?
• what is the genotypic ratio?
• phenotypic ratio?

Answer 20

• testcross a dihybrid heterozygote
• 25% AaBB, 25% Aabb, 25% aaBB, 25% aabb
• 25% AB, 25% Ab, 25% aB, 25% ab

Question 21

for the following cross,
AbBb x AaBb

• what is its description?
• what is the genotypic ratio?
• phenotypic ratio?

Answer 21

• cross 2 dihybrid heterozygotes
• n/a, rules of probability must be used to determine
• 9AB, 3Ab, 3aB, 1ab

Question 22

what is the formula for the rule of multiplication?
- when do you use it?

Answer 22

• probability (A and B)=
  prob(A) * prob(B)
• if you see the word “and”

Question 23

what is the formula for the rule of addition?
- when do you use it?
- what is something important to mention about using this rule?

Answer 23

probability (A or B)=
prob(A) + prob(B) - prob(A and B)
- if you see the word “or”
- you only use the last part of the formula, “prob (A and B)” if A and B can occur together

Question 24

what is the law of dominance?

Answer 24

one trait can mask the effects of another trait

Question 25

what is the law of segregation?

Answer 25

alleles segregate and recombine

Question 26

what is the law of independent assortment?

Answer 26

traits can segregate and recombine independently of other traits