Mendelian Inheritance

Question 1

_____ _____ refers to the rather strict rules for inheritance of monogenic traits as first recognized by Gregor Mendel in the 19th century.

Answer 1

Mendelian inheritance

Question 2

A _____ or single gene trait is one in which the expression is determined by the input of the two alleles of a single gene.

Answer 2

monogenic

Question 3

Traits or structures that involve the input of more than one gene known as _____ traits.

Answer 3

polygenic

Question 4

In _____ expression, the two gene alleles are expressed equally.

Answer 4

codominant

Question 5

In _____ inheritance, the phenotype accurately expresses the genotype. Red flowers must have 2 red gene alleles (homogenous), pink flowers must have one red gene allele and one white gene allele (heterogenous), and white flowers must have two white gene alleles.

Answer 5

codominant

Question 6

Specific inheritance patterns of a monogenic trait can be assessed without knowing a person’s genotype based on _____ _____.

Answer 6

family history

Question 7

_____ is the term used to describe how a trait is inherited or passed from one human generation to the next.

Answer 7

Transmission

Question 8

A _____ (sometimes termed a kinship) is the extended family relationships over several generations.

Answer 8

kindred

Question 9

A _____ is a pictorial or graphic illustration of family members’ places within a kindred and their history for a specific trait or health problem over several generations.

Answer 9

pedigree

Question 10

_____-_____ single gene traits have the controlling gene alleles located on an autosomal chromosome.

Answer 10

Autosomal-dominant

Question 11

Autosomal-dominant traits are found in approximate _____ distribution between male and female family members.

Answer 11

equal

Question 12

True or false:

An autosomal-dominant trait has a carrier status.

Answer 12

False

the person with even one dominant allele expresses the trait

Question 13

The autosomal-dominant trait appears in _____ generation with clear transmission from _____ to child.

Answer 13

1. every

2. parent

Question 14

The risk for an affected person with an autosomal-dominant trait who is heterozygous for the dominant allele to pass the trait to his or her child is _____%.

Answer 14

50

Question 15

The risk for an affected person with an autosomal-dominant trait who is homozygous for the dominant allele to pass the trait to his or her child is _____%.

Answer 15

100

Question 16

Unaffected people do _____ have the autosomal-dominant allele and have essentially _____ (#) risk for transmitting the trait to their children.

Answer 16

1. not

2. zero

Question 17

A person can be homozygous for the dominant alleles of a normal trait, but not for health disorders because with these disorders, the homozygous autosomal-dominant genotype appears _____, with loss at the embryonic or fetal pregnancy stages or within the first _____ (#) months after birth. This distinction slightly changes the predictability of the disorder.

Answer 17

1. lethal

2. 12

Question 18

Two factors that affect the expression of some autosomal-dominant single gene traits are _____ and _____.

Answer 18

1. penetrance

2. expressivity

Question 19

_____ is how often a gene is expressed within a population when it is present.

Answer 19

Penetrance

Question 20

The higher degree of _____ of an AD trait, the higher the risk for a person to develop the disease.

Answer 20

penetrance

Question 21

_____ is a personal issue (rather than a population issue) in which the degree of gene expression varies by the person who has the dominant gene for a health problem.

Answer 21

Expressivity

Question 22

The gene is _____ expressed, but some people have more severe problems than do other people.

Answer 22

always

Question 23

A person with low expression of a gene trait can transmit the gene to his or her child who then may have _____ expression of the disorder. The reverse is also true.

Answer 23

high

Question 24

_____-_____ (AR) traits have the controlling gene alleles on an autosomal chromosome are are expressed _____ when both alleles are present.

Answer 24

1. Autosomal-recessive

2. only

Question 25

An AR trait is found in approximate _____ distribution between male and female family members.

Answer 25

equal

Question 26

An AR trait often appears first in _____ rather than in the _____ of affected children.

Answer 26

1. siblings

2. parents

Question 27

An AR trait my not appear in _____ generations of any one branch of a family.

Answer 27

all

Question 28

The risk for children of two affected parents with an AR trait to also be affected is close to _____%.

Answer 28

100

Question 29

About _____% of the members of a family with an AR trait will express the trait or disorder.

Answer 29

25

Question 30

True or False:
AR traits do have a carrier status in which those individuals who have only one affected allele may not express any level of the trait.

Answer 30

True

Question 31

Unaffected carriers of AR traits _____ transmit the trait to their children if their partner is either a carrier or is affected.

Answer 31

can

Question 32

An AR allele may be present in a family for many generations without overt _____.

Answer 32

expression

Question 33

The phenotype and _____ are the same for expressed AR traits and disorders.

Answer 33

genotype

Question 34

A person who has one mutated allele for a recessive genetic disorder is a _____.

Answer 34

carrier

Question 35

An AR trait carrier is usually not affected and can pass the trait to his or her children. For some AR disorders, a carrier may have very _____ manifestations.

Answer 35

mild

Question 36

A person who has only one sickle cell gene allele and one normal gene allele for beta glob in usually has about _____% normal hemoglobin and rarely expresses sickle cell health problems.

Answer 36

50

Question 37

The unique genes on the Y chromosome are all ______ in origin and are expressed only in _____.

Answer 37

1. paternal

2. males

Question 38

_____ of the unique Y chromosome genes are important for male anatomic and sexual development and fertility.

Answer 38

Most

Question 39

Females have _____ the number of X chromosomes than males.

Answer 39

twice

Question 40

Because X-linked alleles in the male have no corresponding allele in the Y chromosome, any X-linked allele in a male is expressed as if it were a _____ allele, a condition known as _____.

Answer 40

1. dominant

2. hemizygosity

Question 41

X-linked recessive genes have _____ expression in males and _____ expression in females.

Answer 41

1. dominant

2. recessive

Question 42

X-linked recessive traits are also known as _____-_____ recessive traits.

Answer 42

sex-linked

Question 43

The incidence of a _____-_____ trait is much higher among males in a family than among females (and my be exclusive to males).

Answer 43

sex-linked

Question 44

A sex-linked recessive trait _____ be transmitted from father to son.

Answer 44

cannot

Question 45

Sex-linked recessive trait transmission occurs from an affected father to _____ daughters ( who will be obligate carriers) and from a carrier mother to _____ sons and daughters.

Answer 45

1. all

2. both

Question 46

Female carriers of a sex-linked recessive trait have a _____% risk of transmitting the gene to their children with each pregnancy.

Answer 46

50

Question 47

If no sons are born to carrier mothers, the sex-linked recessive trait may not be expressed _____ for many generations.

Answer 47

overtly

Question 48

If no _____ are born to affected fathers with a sex-linked recessive trait who have children with non carrier mothers, the trait is not transmitted further.

Answer 48

daughters

Question 49

Depending on the sex-linked recessive trait disorder, females who are _____ may not survive pregnancy or will have more severe disease.

Answer 49

homozygous

Question 50

X-linked dominant disorders are _____.

Answer 50

rare

Question 51

Females do express the X-linked dominant disorder in the heterozygous state and have a _____% chance of transmitting the trait with each pregnancy to children of either gender.

Answer 51

50

Question 52

Males who are homozygous for the X-linked dominant allele are _____ profoundly affected than heterozygous females.

Answer 52

more

Question 53

A father affected by an X-linked dominant disorder transmits the disorder to _____ of his daughters (who then express the disorder) and to _____ of his sons.

Answer 53

1. all

2. none

Question 54

A special genetic feature is present in the somatic cells of females related o the issue of unequal gene alleles for the approximate _____ (#) genes on the X chromosome.

Answer 54

1500

Question 55

Within the first week of embryonic life in females, these cells all randomly inactivate one _____ chromosome in every cell, to prevent XX females from having an excessive “dose” of the X chromosome genes coding for somatic cell function.

Answer 55

X

Question 56

As early embryonic cells commit to become a specific type of tissue or organ, the early organ contains only a few cells, and usually this small number of cells is not _____ in maternal-to-paternal percentage for X inactivation.

Answer 56

equal