Ch. 5

Question 1

What information does a pedigree provide?

Question 2

What is the inheritance pattern of autosomal dominant traits and do they skip generations?”

Answer 2

Autosomal dominant traits have a pattern that does not skip generations

Question 3

What are the three types of mutations commonly seen in genetic studies?

Answer 3

loss of function, gain of function, wild type

Question 4

The three main components of genetic inheritance are?

Answer 4

alleles, genotypes, phenotypes (alleles form genotypes, which determine phenotypes)

Question 5

What is the relationship between heterozygous and homozygous phenotypes in incomplete dominance?

Answer 5

intermediate phenotype

Question 6

When a single gene locus affects more than one trait, this is called

Answer 6

Pleiotropy

Question 7

When a single gene locus has more than two possible alleles, this is called

Answer 7

multiple alleles

Question 8

When the phenotype of heterozygotes is intermediate between the homozygotes, this is called

Answer 8

incomplete dominance

Question 9

When the phenotype of heterozygotes shows some aspects of both homozygotes, this is called

Answer 9

codominance

Question 10

When alleles at one gene locus can mask the expression of alleles at another gene locus, this is called

Answer 10

epistasis

Question 11

When different genes produce the same phenotype, this is called

Answer 11

genetic heterogeneity

Question 12

Mitochondrial Inheritance

Answer 12

Mitochondrial genes are inherited from the mother only, mutates faster than DNA in nucleus, not wrapped in proteins, not “interrupted” by DNA sequences that do not encode protein

Question 13

Epistasis and multiple alleles differ in that

Answer 13

epistasis is an interaction between two genes, and multiple alleles are variants of the same gene.

Question 14

A couple have been trying to have a second child for 10 years. They have one healthy child, but the woman has had four early, spontaneous abortions. The most likely explanation for the many pregnancy losses is that both parents

Answer 14

are each heterozygous for lethal alleles of the same gene. (When both parents carry a recessive lethal allele for the same gene, each pregnancy the couple has has a 25% chance of spontaneously aborting. Being heterozygous for the same lethal alleles is the most likely explanation for the pregnancy losses.)

Question 15

Multiple alleles are common because

Answer 15

a gene sequence can vary in different ways and still encode a functional protein.

Question 16

Different alleles that are both expressed in a heterozygote are

Answer 16

codominant

Question 17

Autosomal Dominant Trait

Answer 17

does not skip generations, can affect both sexes, “gain of function”
ex. polydactyly

Question 18

Autosomal Recessive Trait

Answer 18

parents are inferred to be heterozygotes, “loss of function”
ex. albinism

Question 19

Lethal Alleles

Answer 19

A phenotypic class does not survive to reproduce

Question 20

Multiple Alleles

Answer 20

Many variants or degrees of a phenotype are possible

Question 21

Incomplete dominance

Answer 21

A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.

Question 22

Codominance

Answer 22

A heterozygote’s phenotype is distinct from and not intermediate between those of the two homozygotes

Question 23

Epistasis

Answer 23

One gene masks or otherwise affects another’s phenotype

Question 24

Linkage

Answer 24

expresses 2 genes at the same time

Question 25

Haplotype

Answer 25

groups of linked genes that are inherited together because they are located close to each other on the same chromosome