Chapter 4: Non Mendelian Genetics (Modifications in the Mendelian Ratios)

Question 1

A mutation in a genes that causes diminution or the loss of the specific wild-type function.

Answer 1

Loss-of-function mutation

Question 2

When a mutation causes a complete loss of function in the genes, the resulting mutated gene si called?

Answer 2

Null allele

Question 3

Total loss of function mutation causes the gene product to lose?

Answer 3

affinity to its substrate

Question 4

A mutation that enhances the function of the wild-type product.

Answer 4

Gain-of-function mutation

Question 5

What effect does a gain-of-function mutation confer?

Answer 5

Increased gene product. In such a case, the mutation may be affecting the regulation of the transcription of the gene under study.

Question 6

Gain-of-function mutation generally results to?

Answer 6

Dominant allele. Since one copy of in a diploid organism is sufficient to alter the normal phenotype.

Question 7

A mutation in the genes where no change in function can be detected.

Answer 7

Neutral mutation

Question 8

This happens when neither of the alleles for a specific trait comes dominant (both of alleles are expressed resulting in intermediate expression of the overt phenotype).

Answer 8

Incomplete dominance

Question 9

True or False. Even when complete dominance seems apparent, careful examination of the gene product, rather than the phenotype, often reveals an intermediate level of gene expression

Answer 9

True. For example is Tay-Sachs disease

Question 10

This happens when two contrasting alleles are phenotypically expressed. It is characterized by distinct expression of the gene products of both alleles.

Answer 10

Codominance

Question 11

Two forms of glycoprotein that exist in MN blood group.

Answer 11

1. M glycoprotein

2. N glycoprotein

Question 12

Examples of codominance:

Answer 12

1. MN blood group

2. ABO blood group

Question 13

True or False. In the ABO blood group, the presence of the A and B antigens are codominant and the absence of either of them results in O type.

Answer 13

True

Question 14

Specificity of the A and B antigens is based on?

Answer 14

Terminal sugar of the carbohydrate group.

Question 15

Both the A and B antigens are derived from a precursor molecule called?

Answer 15

H substance

Question 16

The incompleteness of the H substance leads to?

Answer 16

Blood type O because an incompletely formed H substance will not be enough substrate for the enzyme that normally adds the terminal sugar.

Question 17

Individuals that are homozygous for this mutated gene cannot synthesize the complete H substance.

Answer 17

Fucosyltransferase 1 gene

Question 18

FUT1 gene encodes what enzyme?

Answer 18

Fucosyl transferase

Question 19

A mutation resulting in the synthesis of an essential gene product that is nonfunctional.

Answer 19

Lethal allele

Question 20

A mutation resulting in the synthesis of a gene product that is nonfunctional can be often tolerated in the heterozygous state.

Answer 20

Recessive lethal allele

Question 21

True or False. For an individual heterozygous for a lethal allele, one wildtype allele is not sufficient to produce enough of the essential product to allow survival.

Answer 21

False.

Question 22

True or False. In some cases, recessive lethal allele may take on the form of a dominant trait when present heterozygously.

Answer 22

True. Yellow allele in mice is dominant to the wild-type agouti allele. The yellow allele is also a recessive lethal allele because the presence of two copies of the yellow allele kills a mouse before birth.

Question 23

Presence of just one copy of this allele results in the death of an individual.

Answer 23

Dominant lethal allele

Question 24

Huntington’s disease is caused by?

Answer 24

Dominant autosomal allele H

Question 25

True or False. The onset of the Huntington’s disease in heterozygotes (Hh) is delayed usually well into adulthood

Answer 25

True

Question 26

The cellular function of numerous gene products contributes to the development of a common phenotype.

Answer 26

Gene interaction

Question 27

Is often used to describe the idea that several genes influence a particular characteristic.

Answer 27

Gene interaction

Question 28

Each step of development increases the complexity of a sensory organ and is under the control and influence of one or more genes. This is an example of what phenomenon.

Answer 28

Epigenesis

Question 29

Mutations that interrupt many of the steps of ear development lead to a common phenotype causes what condition?

Answer 29

Hereditary deafness

Question 30

A mutated phenotype where multiple genes are involved.

Answer 30

Heterogenous trait

Question 31

A phenomenon where the expression of one gene or gene pair masks or modifies the expression of another gene.

Answer 31

Epistasis

Question 32

True or False. In epistasis, genes involved control the expression of the same general phenotypic characteristic in a constructive manner.

Answer 32

False.

Question 33

Homozygous presence of a recessive allele prevents or overrides the expression of other alleles at a second locus (or several other loci) such that of the Bombay phenotype. This is an example of?

Answer 33

Epistasis

Question 34

One of the epistasis-participating genes that is expressed.

Answer 34

Epistatic allele

Question 35

One of the epistasis-participating alleles that is masked.

Answer 35

Hypostatic allele

Question 36

True or False. ABO blood type is an example of recessive epistasis where the presence of two wild-type FUT1 gene is needed to phenotypically express either A or B blood types.

Answer 36

True

Question 37

A presence of homologous recessive trait masks the expression of another gene.

Answer 37

Recessive Epistasis

Question 38

Occurs when a dominant allele at one genetic locus masks the expression of the alleles at a second locus.

Answer 38

Dominant Epistasis

Question 39

At least one of the dominant allele must be present to produce pigmentation because the homozygous nature of any of the two recessive allele masks the dominant trait.

Answer 39

Complementary Epistasis

Question 40

Fruit shape in Cucurbita pepo is a novel phenotype, a dominant allele at any one of the loci gives what fruit?

Answer 40

Sphere-shaped fruit

Question 41

Fruit shape in Cucurbita pepo is a novel phenotype, absence of a dominant allele on both of the loci gives what fruit?

Answer 41

Long-shade fruit

Question 42

Fruit shape in Cucurbita pepo is a novel phenotype, the presence of a dominant allele on both of the loci gives what fruit?

Answer 42

Disc-shaped fruit

Question 43

This technique allows for the determination of whether two alleles are of the same gene or whether they represent mutations in separate genes.

Answer 43

Complementation Analysis

Question 44

True or False. In complementation analysis, if the F1 progeny developed the normal phenotype, then two recessive mutations are in separate genes and are not alleles of one another.

Answer 44

True

Question 45

True or False. In complementation analysis, if the F1 progeny developed the mutated phenotype, then two recessive mutations affect the same gene and are alleles of one another.

Answer 45

True

Question 46

The expression of a single gene has multiple phenotypic effects.

Answer 46

Pleiotropy

Question 47

Human malady resulting from an autosomal dominant mutation in the gene encoding the connective tissue protein fibrillin.

Answer 47

Marfan Syndrome

Question 48

Afflicted individuals cannot adequately metabolize the porphyrin component of hemoglobin when this respiratory pigment is broken down as red blood cells are replaced.

Answer 48

Porphyria variagata

Question 49

Marfan Syndrome and Porphyria variagata are examples of what?

Answer 49

Genes having multiple phenotypic effects

Question 50

A condition of having only one possible locus for a specific gene.

Answer 50

hemizygous

Question 51

White eye mutation in Drosophila is an example of?

Answer 51

X-linkage

Question 52

An inheritance pattern where phenotypic traits controlled by recessive X-linked genes are passed from homozygous mothers to all sons

Answer 52

Crisscross pattern of inheritance

Question 53

Crisscross pattern occurs because?

Answer 53

Females exhibiting a recessive trait carry the mutant allele on both X chromosome

Question 54

Colorblindness in humans is an example of?

Answer 54

X-linked disease

Question 55

Duchenne muscular dystrophy in humans is an example of?

Answer 55

X-linked disease

Question 56

The expression of a specific phenotype is absolutely limited to one sex.

Answer 56

Sex-limited

Question 57

Hen and cock feathering in fowl is an example of?

Answer 57

Sex-limited trait

Question 58

True or False. In both sex-limited and sex-influenced inheritance, autosomal genes
are responsible for the existence of contrasting phenotypes, but the expression of these genes is dependent on hor-
mone constitution of the individual.

Answer 58

True.

Question 59

Pattern baldness in humans is an example of?

Answer 59

Sex-influenced trait

Question 60

Autosomal genes are responsible for the contrasting phenotypes displayed by both males and females, but the expression of these genes is dependent on the hormonal constitution of the individual.

Answer 60

Sex-influenced

Question 61

The percentage of individuals who show at least some degree of expression of a mutant genotype.

Answer 61

Penetrance

Question 62

Reflects the range of expression of the mutant genotype.

Answer 62

Expressivity

Question 63

True or False. The physical location of a gene in relation to other genetic material may influence its expression.

Answer 63

True

Question 64

Mutations whose expression is affected by temperature

Answer 64

Temperature-sensitive mutations

Question 65

True or False. All genetic traits become apparent at the same time during an organism’s life span.

Answer 65

False

Question 66

Only one or a few of the organelles contain a mutant gene in a cell among a population of mostly normal mitochondria, the corresponding mutant phenotype may not be revealed.

Answer 66

Heteroplasmy

Question 67

Strain of Saccharomyces cerevisiae a deficiency in cellular respiration involving abnormal electron transport..

Answer 67

Poky strain