Inheritance

Question 1

Gene

Answer 1

a fundamental unit of heredity that is passed from parent to offspring. Genes are made up of DNA and are located on chromosomes in the nucleus of cells. They contain information for making proteins, which are responsible for specific traits or functions in the body

Question 2

Allele

Answer 2

alternate forms of a gene that code for different proteins

Question 3

Wild type

Answer 3

allele present in most of the population

Question 4

Mutation

Answer 4

stable, inherited change in genetic material, where new alleles arise

Question 5

True breeding

Answer 5

a term used in genetics and selective animal breeding to describe organisms or animals that pass on the same traits to their offspring

Question 6

Phenotype vs genotype

Answer 6

• Phenotype: physical appearance of an organism
• Genotype: genetic constitution of an organism

Question 7

Dominant vs recessive

Answer 7

• Dominant alleles: are expressed; exert their effects whenever they’re present
• Recessive alleles: effect is masked if dominant allele also present; may be mutated and no longer expressed, or encode non‐functional proteins

Question 8

Homozygous vs heterozygous

Answer 8

• Homozygous: two alleles are the same
• Heterozygous: two different alleles; one may be dominant and the other recessive

Question 9

P vs. F1 vs. F2

Answer 9

The parent or P generation refers to the individuals being crossed; the offspring are the filial or F generation. F₁ or the first filial represents the children of the parents; F₂ represents children of the F₁ or grandchildren of the parents

Question 10

Gregor Mendel’s 1st law

Answer 10

Law of segregation: the two copies of a gene separate during gamete formation; each gamete receives only one copy

Question 11

Mendel’s 2nd law

Answer 11

Law of independent assortment: copies of different genes assort independently

Question 12

Who do offspring inherit alleles from

Answer 12

Offspring inherit alleles from both of their parents; each parent contributes one allele for every gene, meaning the offspring receives a pair of alleles for each trait, one from the mother and one from the father

Question 13

Multiplication rule

Answer 13

probability of two independent events
happening together –multiply by probabilities of the individual events
– Tossing two coins: probability that both will come up heads = ½ x ½ = 1/4

Question 14

Addition rule

Answer 14

the probability of an event that can occur in two different ways is the sum of the individual probabilities
– In F2, there are two ways to get Rr, thus ¼ + ¼ = ½

Question 15

Codominant vs incomplete dominance

Answer 15

Codominance: more than one allele
encodes a functional protein
Incomplete dominance: alleles are neither dominant nor recessive – heterozygotes have an intermediate phenotype

Question 16

Locus

Answer 16

specific position on a chromosome

Question 17

Linked genes

Answer 17

genes that are located close together on a chromosome and are often inherited together

Question 18

Pleiotropic vs. epistatic

Answer 18

Pleiotropic: one allele has multiple phenotypic effects
Epistasis: phenotypic expression of one gene influenced by another gene

Question 19

What environmental conditions can affect expression of genotype

Answer 19

Light, temperature, nutrition, etc., can affect expression of the genotype

Question 20

Coat patterns of Siamese cats and rabbits

Answer 20

Point restriction coat patterns in Siamese cats and rabbits
- Enzyme that produces dark fur inactive at higher temps.
- Nose, ears, etc., are cooler, thus darker in color

Question 21

How can prokaryotes exchange genes

Answer 21

horizontal gene transfer” which primarily occurs through three mechanisms: conjugation (direct cell-to-cell contact via a pilus), transformation (taking up free DNA from the environment), and transduction (transfer of DNA by a virus)