EXTENSION OF MENDELIAN INHERITANCE(lesson 1) genetics

Question 1

Prevalent alleles in a
natural population.

Answer 1

Wild-type alleles

Question 2

more than one
wild-type allele may occur

Answer 2

Genetic polymorphism-

Question 3

promote the
reproductive success of organisms in
their native environments.

Answer 3

Wild-type alleles

Question 4

random mutations occur
in populations and alter preexisting
alleles. Called as such to distinguish
them from the more common wild-type
alleles

Answer 4

Mutant alleles-

Question 5

usually cause a substantial decrease in the
expression of a functional protein supported by the analysis of many human genetic diseases.

Answer 5

Recessive mutant alleles

Question 6

• much less common than recessive
  mutant alleles.

Answer 6

Dominant mutant allele

Question 7

is usually caused by a mutant
allele.

Answer 7

genetic disease

Question 8

Three explanations account for most dominant mutant
alleles:

Answer 8

Gain-of-function mutation
* Dominant-negative mutation
* Haploinsufficiency.

Question 9

*Change the gene or the protein encoded by a gene
so it gains a new or abnormal function.

Answer 9

Gain-of-function mutation

Question 10

*Change a protein such that the mutant protein acts
antagonistically to the normal protein.

Answer 10

Dominant-negative mutations

Question 11

The dominant mutant allele is a loss-of-function
allele.

Answer 11

Haploinsufficiency

Question 12

used to describe patterns of
inheritance in which a heterozygote

• An example in humans is polydactyly.

Answer 12

Haploinsufficiency

Question 13

which an allele that is expected to cause
a particular phenotype does not.

Answer 13

INCOMPLETE PENETRANCE

Question 14

Human pedigree for a dominant trait
known as

Answer 14

polydactyly

Question 15

due to an autosomal
dominant allele—

Answer 15

Polydactyly

Question 16

a single copy of this
allele is sufficient to cause this
condition.

Answer 16

autosomal
dominant allele

Question 17

term used to describe the outcome of traits is
the degree to which the trait is expressed

Answer 17

Expressivity-

Question 18

often due to environmental
influences and/or due to effects of modifier genes

Answer 18

INCOMPLETE PENETRANCE

Question 19

The
phenotypic effects are dependent on
the temperature

Answer 19

Temperature-sensitive allele.

Question 20

caused by a defect in
a gene that encodes the enzyme
phenylalanine hydroxylase.

Answer 20

Phenylketonuria (PKU)

Question 21

which is found in most protein-rich
foods,

Answer 21

phenylalanine,

Question 22

A condition in which the phenotype is
intermediate between the corresponding
homozygous individuals.

Answer 22

INCOMPLETE DOMINANCE

Question 23

German botanist ____ first
observed this phenomenon in the color of the
flowers of the four-o’clock plant (Mirabilis
jalapa)

Answer 23

Carl Correns

Question 24

lack of
a functional protein required for pigmentation.

Answer 24

Heterozygote Advantage/ OVERDOMINANCE

Question 25

which the affected individual produces an altered form of the protein hemoglobin, which carries oxygen within red blood cells.

Answer 25

Sickle cell disease-

Question 26

This causes their red blood cells to deform into a

Answer 26

sickle shape under conditions of low oxygen concentration

Question 27

Individuals affected with sickle cell disease are

Answer 27

homozygous for the HbS allele

Question 28

high frequency among human populations that are exposed to malaria.

Answer 28

OVERDOMINANCE

Question 29

spends part of its life cycle within the Anopheles mosquito and another part within the red blood cells of humans who have been bitten by an infected mosquito.

Answer 29

malaria, Plasmodium,

Question 30

, are likely to rupture when infected by this parasite, thereby preventing the parasite from propagating.

Answer 30

HbA HbS

Question 31

two alleles are both expressed in the heterozygous individual

Answer 31

CODOMINANCE

Question 32

when a gene is located on the X chromosome but not on the Y chromosome.

Answer 32

X-linked inheritance

Question 33

to indicate that males have a single copy of an X-linked gene

Answer 33

Hemizygous

Question 34

is that males are more likely to be affected by rare, recessive X-linked disorders.

Answer 34

X-linked inheritance

Question 35

X-linked recessive, the allele causing the disease is recessive and located on the X chromosome

Answer 35

Duchenne muscular dystrophy-

Question 36

refers to a gene that is found on one of the two types of sex chromosomes but not on both.

Answer 36

Sex-linked gene-

Question 37

relatively few genes are located only on the Y chromosome.

Answer 37

Holandric genes

Question 38

found in mammals.

Answer 38

SRY gene

Question 39

Its expression is necessary for proper male development.

Answer 39

SRY gene

Question 40

which an allele is dominant in one sex but recessive in the opposite sex.

Answer 40

Sex-influenced inheritance-

Question 41

controlled by sex hormones or by the pathway that leads to male and female development

Answer 41

Sex-limited inheritance-

Question 42

The genes that affect sex-limited traits maybe

Answer 42

autosomal or X-linked

Question 43

are the presence of ovaries in females and the presence of testes in males.

Answer 43

sex-limited traits

Question 44

which members of the opposite sex have different morphological features.

Answer 44

Sexual dimorphism

Question 45

has the potential to cause the death of an organism.

Answer 45

LETHAL ALLELES

Question 46

one that must be present for survival

Answer 46

Essential gene-

Question 47

not absolutely required for survival, although they are likely to be beneficial to the organism.

Answer 47

Nonessential genes-

Question 48

some lethal alleles may kill an organism only when certain environmental conditions prevail

Answer 48

Conditional lethal alleles-

Question 49

conditional lethal alleles cause an organism to die only in a particular temperature range.

Answer 49

Temperature-sensitive (ts) lethal alleles-

Question 50

may also be identified when an individual is exposed to a particular agent in the environment.

Answer 50

lethal alleles-

Question 51

People with a defect in the gene that encodes the ____ have a negative reaction to the ingestion of ____.

Answer 51

enzyme glucose-6-phosphate dehydrogenase (G-6-PD) fava beans

Question 52

lethal alleles act only in some individuals.

Answer 52

Semilethal alleles-

Question 53

multiple effects of a single gene

Answer 53

PLEIOTROPY

Question 54

all traits are affected by the contributions of many genes.

Answer 54

GENE INTERACTIONS