Genetics I and II

Question 1

Mendel’s first law

Answer 1

The principle of segregation, meaning two members of a gene pair segregate from each other in the formation of gametes> Half of the gametes carry one allele and the other half carry the other allele.

Question 2

Mendel’s second law

Answer 2

The principle of independent assortment meaning genes for different traits assort independently of one another in the formation of gametes.

Question 3

What is a compound heterozygote?

Answer 3

A genotype in which two different mutant alleles of the same gene are present rather than one mutant and one normal

Question 4

What is hemizygosity?

Answer 4

A male that has an abnormal alleles for a gene located on the X-chromosome and there is not other copy of the gene

Question 5

In pedigrees, what does kindred mean?

Answer 5

Extended family depicted in pedigrees

Question 6

What is a pro band?

Answer 6

The member through whom a family with a genetic disorder is first brought to the attention of a geneticist

Question 7

What is the consultand?

Answer 7

The person who brings the family to the attention of the geneticist

Question 8

Who is the first degree of a pedigree?

Answer 8

Parents and sibs of offspring and proband

Question 9

Who is the second degree of a pedigree?

Answer 9

Grandparents and grandchildren, uncles and aunts, nephew and nieces and half sibs

Question 10

Who is the third degree of a pedigree?

Answer 10

First cousins

Question 11

Most recessive disorders are due to ________

Answer 11

Loss of function

Question 12

What is penetrance?

Answer 12

Percentage of people with a predispositioning genotype who are actually affected, at least to some degree; can be age dependent

Question 13

What is expressivity?

Answer 13

Severity of expression of the phenotypes among individuals with the same disease causing genotypes.

Question 14

There are three types of heterogeneity, what are they?

Answer 14

Allelic heterogeneity, Locus heterogeneity, and phenotypic heterogeneity

Question 15

Genome mutations produce _________ and are the most common mutations in humans

Answer 15

Chromosomal aneuploidy

Question 16

Chromosomal mutations are usually ___________

Answer 16

Not compatible with life

Question 17

Gene mutations can be caused by two mechanisms, _________ or ____________

Answer 17

1. Errors introduced during the normal process of DNA replication 2. Mutation arising from a failure to repair DNA

Question 18

Dynamic mutations such as Huntington disease or fragile X syndrome involve ___________

Answer 18

Amplification of trinucleotide repeats sequence

Question 19

The longer oocytes remain in meiosis I, the greater the chance for _________ to occur when the cells finally complete meiosis.

Answer 19

Nondisjunction error

Question 20

_______________ are common in sperm

Answer 20

Point mutations that usually cause missense mutations

Question 21

Huntington’s disease is a _____________ of paternal order

Answer 21

Trinucleotide repeat disorder

Question 22

In _________, there are massive expands in the CGG repeat region and nearly always occurs during female gametogensis

Answer 22

Fragile X

Question 23

Genetic Polymorphism occurs when a variant is so common that it is found in ___________

Answer 23

1% of chromosomes

Question 24

Alleles with frequencies less than 1% are called _________

Answer 24

Rare Variants

Question 25

The Hardy-Weinberg Law is a relationship for calculating ________ from __________

Answer 25

Genotype frequencies from allele frequencies

Question 26

For x-linked genes, there are only two possible _______ but three ___________

Answer 26

Male genotypes; famale genotypes

Question 27

Assumptions of HW equilibrium (3)

Answer 27

1. Population in large 2. Mating is random 3. Allele frequencies are not changing over time

Question 28

Non-random mating could be due to three factors. What are they?

Answer 28

1. Stratification 2. Assortative mating 3. Consanguinity

Question 29

_________ occurs in small populations

Answer 29

Genetic drift

Question 30

Most deleterious recessive alleles are hidden in heterozygotes and ____________

Answer 30

Not subject to selection

Question 31

What is the founder effect?

Answer 31

When a small subpopulation breaks off from a larger population and may not have the same genetic frequencies as the parent group.

Question 32

For both hemophilia A and B, the level of _____ and _____ activity predict the clinical severity.

Answer 32

Factor VIII and IX

Question 33

Point mutations and the common F8 inversions almost always arise in male meiosis and therefore, mother carriers get it from a new mutation from their _________

Answer 33

Father