midterm - modification of mendelian genetcs

Question 1

___ is the joint expression of both alleles in a heterozygote

Answer 1

Codominance

Question 2

If two alleles of a single gene are responsible for producing two distinct, detectable gene products, a situation called ___ occurs

Answer 2

codominance

Question 3

The MN blood group in human illustrates this codominance and is characterized by an antigen called a
___ found in the surface of RBCs

Answer 3

glycoprotein

Question 4

The ___ is under the control of an autosomal locus on chromosome 4 and two alleles
designated LM and LN

Answer 4

MN system

Question 5

Three combinations are possible, each resulting in a distinct blood type

Answer 5

CODOMINANCE

Question 6

Mutations can modify the information stored in a gene, and each change produces a different allele

Answer 6

MULTIPLE ALLELES

Question 7

When three or more alleles of the same gene are found, ____ are present that create a
unique mode of inheritance

Answer 7

multiple alleles

Question 8

The ___ have 3 alternative alleles

Answer 8

ABO blood group

Question 9

It is characterized by the presence of antigens on the surface of RBCs

Answer 9

ABO blood group

Question 10

Mutations resulting in the synthesis of a gene product that is nonfunctional can be often tolerated in
the heterozygous state; one wild-type allele may be sufficient to produce essential product to allow
survival

Answer 10

LETHAL GENES

Question 11

However, such mutations behaves as a recessive lethal allele and homozygous recessive individuals will
not survive

Answer 11

LETHAL GENES

Question 12

In mammals, this might occur during development, early childhood, or even adulthood

Answer 12

LETHAL GENES

Question 13

The presence of just one copy of the allele results in the death of the individual

Answer 13

dominant lethal allele

Question 14

The effects of two or more genes on a single characteristic, the converse situation, where expression of
a single gene has multiple phenotypic effects, is also quite common

Answer 14

PLEIOTROPY

Question 15

pleiotropy

EXAMPLE is ___ an autosomal dominant mutation in the gene encoding the connective
tissue protein fibrillin

Answer 15

Marfan syndrome,

Question 16

Phenotypes associated with __ includes lens dislocation, increased risk of aortic
aneurism, and lengthened long bones in limbs

Answer 16

Marfan syndrome

Question 17

Males cannot be homozygous or heterozygous for X linked genes, and this condition is referred to as
being ___

Answer 17

hemizygous

Question 18

Gene expression may be affected by the gender of an individual even when genes are not on the X
chromosom

Answer 18

SEX LIMITED AND SEX-INFLUENCED

Question 19

*_____ –expression of a specific phenotype is absolutely limited to one gender

Answer 19

Sex-limited

Question 20

—-–the gender of an individual influences the expression of a phenotype but the
phenotype is expressed in both gender

Answer 20

Sex-influenced

Question 21

in both cases, ___ are responsible for the existence of contrasting phenotypes, but the
expression of such genes is dependent on the hormone constitution of the individual

Answer 21

autosomal genes

Question 22

Hen feathering is due to dominant allele, iss an examle of

Answer 22

SEX-LIMITED INHERITANCE

Question 23

*___ inheritance include pattern baldness in humans

Answer 23

Sex-influenced

Question 24

utosomal genes are responsible for the phenotypes, but the expression of the genes is dependent on
the hormonal constitution of the individua

Answer 24

SEX-INFLUENCED INHERITANCE

Question 25

The heterozygous genotype exhibits one phenotype in one sex and the contrasting one in the other

Answer 25

sEX-INFLUENCED INHERITANCE

Question 26

____ –phenotype is determined by the genetic information expressed in the gamete of the
mother; following fertilization, the developing zygote’s phenotype is influenced not by the individual’s
genotype, but by gene products directed by the genotype of the mother.

Answer 26

Maternal effect

Question 27

___–the phenotype is affected by the expression of genes contained in the DNA of
mitochondria rather than the nucleus

Answer 27

Organelle heredity

Question 28

Gene interaction are those that reveal the phenomenon of ___

Answer 28

epistasis

Question 29

*___ –the expression of one gene or gene pair masks or modifies the expression of another gene
or gene pair (can be antagonistic or complementary)

Answer 29

Epistasis

Question 30

For example, the homozygous presence of a recessive allele prevents or overrides the expression of
other alleles at a second locus

Answer 30

epistasis

Question 31

Another example, a single dominant allele at the first locus influences the expression of the alleles at as
second gene locus

Answer 31

epistasis

Question 32

When the alleles masking another gene on another locus is recessive, this is called ___
▪ *

Answer 32

recessive epistasis

Question 33

___ occurs when a dominant allele at one genetic locus masks the expression of the
alleles at a second locus

Answer 33

Dominant epistasis