Non-Mendelian Genetics

Question 1

Transmission patterns of a visible trait are not consistent with a mode of inheritance (dominant or recessive)

Mendel’s Laws operate, underlying genotypic ratios persist, but
Either nature of the phenotype or influences from other genes or environment alter the phenotypic ratios.

Answer 1

Gene Expression Alters Mendel Ratio

Question 2

Modifications to Mendelian Ratios

Answer 2

1. Incomplete Dominance
2. Codominance
3. Multiple Alleles
4. Epistasis/ Gene Interaction
5. Sex Related

Question 3

Modification of gene expression by another gene

Answer 3

Epistasis/ Gene Interaction

Question 4

For example, if plants such as four-o’clocks or snapdragons with red flowers are crossed with white-flowered plants, the offspring have pink flowers.

Answer 4

Incomplete Dominance

Question 5

a type of inheritance pattern where neither allele for a trait is fully dominant, resulting in an intermediate phenotype in heterozygous individuals

Answer 5

Incomplete Dominance

Question 6

A condition where the heterozygote shows the phenotypic effects of both alleles equally

Answer 6

Codominance

Question 6

For example, In certain blood types, the A and B alleles are codominant, so an individual with genotype AB expresses both A and B antigens on their red blood cells. The resulting phenotypic ratio differs from the usual dominance ratios.

Answer 6

Codominance

Question 7

example: human ABO blood types

Answer 7

Multiple Alleles

Question 8

the main blood type is determined by a single locus with three known alleles

Answer 8

IA, IB, and i (also known as IO)

Question 9

alleles in blood are codominant with respect to each other

Answer 9

IA, IB,

Question 9

the alleles in blood that leads to the expression of type A antigen on the surface of red blood cells

Answer 9

IA

Question 9

the alleles in blood that leads to the expression of type B antigen on the surface of red blood cells

Answer 9

IB

Question 10

is a recessive allele in blood; allele does not lead to expression of a cell surface antigen

Answer 10

IO

Question 11

The expression of one gene or gene pair masks or modifies the expression of another gene or gene pair

Answer 11

Epistasis/ Gene Interaction

Question 12

For example:
In Labrador Retrievers, coat color is influenced by two genes: the B gene controls the black/brown color, while the E gene determines whether any pigment will be deposited. The interaction between these genes results in a 9:34 ratio instead of the expected Mendelian ratio.

Answer 12

Epistasis/ Gene Interaction

Question 13

Example of epistasis in coat color genetics: If no pigments can be produced the other coat color genes have no effect on the phenotype, no matter if they are dominant or if the individual is homozygous. Here the genotype “cc” for no pigmentation is epistatic over the other genes

Answer 13

Epistasis

Question 14

H normal allele encodes an enzyme that inserts a sugar molecule antigen H, onto a particular glycoprotein on the surface of immature RBC.

Recessive allele h produces an inactive form of the enzyme that cannot insert the sugar

Answer 14

EPISTASIS: BOMBAY PHENOTYPE

Question 15

gene that produces fucosyl transferase 1

Answer 15

H gene

Question 16

a gene whose phenotype is masked or suppressed by the expression of another gene at a different locus, known as an epistatic gene.

Answer 16

hypostases

Question 17

is the precursor of the ABO blood group antigens, if it is not produced, the ABO blood group antigens are also not produced.

Answer 17

H antigen

Question 18

Blood group

Antigens
A, H

Antibodies
B

Answer 18

A

Question 19

Blood group

Antigens
B, H

Antibodies
A

Answer 19

B

Question 20

Blood group

Antigens
H

Antibodies
A,B

Answer 20

O

Question 20

Blood group

Antigens
A, B, H

Answer 20

AB

Question 21

Blood group Antigens - Antibodies A,B, H

Answer 21

Bombay Blood group

Question 21

For example the interaction between hair color and baldness. A gene for total baldness would be epistatic to one for blond hair or red hair. The hair-color genes are hypostatic to the baldness gene. The baldness phenotype supersedes genes for hair color, and so the effects are non-additive.

Answer 21

Epistasis

Question 22

is a trait controlled by a pair of alleles found on the autosomal chromosomes (pairs 1 through 22) but it's phenotypic expression is influenced by the presence of certain hormones.

Answer 22

What is a sex-influenced trait?

Question 23

can be seen in BOTH sexes, but will vary in frequency between the sexes, or in the degree of the phenotypic expression.

Answer 23

Sex-influenced traits

Question 24

An autosomal trait where the expression of baldness is dominant in males but recessive in females. Thus, men are more likely to express baldness than women if they inherit the gene.

Answer 24

Pattern baldness:

Question 25

Sex-Influenced Traits Pattern Baldness can occur in both males and females, however it is much more common in males. Why is this?

Answer 25

Because the pattern baldness trait is influenced by the hormone testosterone.

Question 26

is encoded by autosomal genes that are expressed in only one sex. The trait has zero penetrance in the other sex.

Answer 26

Sex-limited characteristics

Question 26

Example: In domestic chicken, some males display a pattern called cock feathering: other display a pattern called hen feathering. Cock feathering is an autosomal recessive trait that is sex limited to males.

Answer 26

Sex-limited characteristics

Question 27

the inheritance patterns of genes located on the sex chromosomes (X and Y).

Answer 27

Sex Related Diseases/Conditions

Question 28

Since males have only one X chromosome, how many of the mutated hemophilia gene result in the expression of hemophilia?

Answer 28

one

Question 28

Sex Related Diseases/Conditions

Answer 28

1.Hemophilia 2.Color blindness 3.Duchenne muscular dystrophy (DMD). 4.X-linked agammaglobulinemia:

Question 29

a bleeding characterized by the inability of the blood to clot properly.

Answer 29

Hemophilia

Question 30

The gene mutations responsible for hemophilia are located on the _chromosome.

Answer 30

X

Question 31

Females, on the other hand, need to inherit ________ copies of the mutated gene to exhibit the hemophilia disorder.

Answer 31

two

Question 32

Red-green color blindness is another example of a

Answer 32

sex-linked trait.

Question 33

It is more commonly observed in males because the genes responsible for perceiving ________ colors are located on the X chromosome.

Answer 33

red and green

Question 34

Males have only one X chromosome, so if it carries the color blindness gene, they are more likely to be color blind.

Answer 34

true

Question 35

(long wavelengths-red light)

Answer 35

L-cones

Question 35

Females, on the other hand, need to inherit the gene mutation on how many X chromosomes to be color blind?

Answer 35

two

Question 35

(short wavelengths-blue light)

Answer 35

S-cones

Question 36

Mutation in photoreceptors

Answer 36

Color blindness

Question 37

(medium wavelengths-green light)

Answer 37

M-cones

Question 38

The gene mutation responsible for DMD is located on the X chromosome called the

Answer 38

(Dystrophin gene).

Question 39

is a progressive muscle-wasting disorder.

Answer 39

Duchenne muscular dystrophy

Question 40

X-linked agammaglobulinemia is caused by a mutation in the gene located on the X chromosome, resulting in

Answer 40

impaired B-cell development and reduced antibody production

Question 40

Females typically remain carriers of DMD unless they inherit the mutation on both X chromosomes.

Answer 40

true

Question 40

is a critical structural protein that helps stabilize and protect muscle fibers during contraction by linking the internal cytoskeleton of muscle cells to the extracellular matrix

Answer 40

Dystrophin

Question 41

This is an immunodeficiency disorder characterized by the inability to produce normal levels of antibodies.

Answer 41

X-linked agammaglobulinemia

Question 42

Males with the mutation typically exhibit the X-linked agammaglobulinemia , while females are usually carriers unless they inherit the mutation on both X chromosomes

Answer 42

true

Question 43

is crucial for B cell maturation and development. Mutations in this gene lead to X-linked agammaglobulinemia (XLA), a severe immunodeficiency characterized by the absence of B cells and consequently, a lack of antibody production

Answer 43

BTK gene-Bruton's tyrosine kinase -B cell maturation

Question 44

A genetic trait becomes more strongly expressed or is expressed at an earlier stage as it is passed from generation to generation.

Answer 44

Anticipation

Question 44

Is the Stronger or Earlier Expression of Traits in Succeeding Generations

Answer 44

Genetic Anticipation

Question 45

Example of what?: The mutation causing myotonic dystrophy consists of an unstable region of DNA that can increase or decrease in size as the gene is passed from generation to generation.

Answer 45

Anticipation

Question 46

some characteristics are encoded by genes located in the cytoplasm. .

Answer 46

Cytoplasmic inheritance

Question 47

Mitochondria in humans have

Answer 47

15,000 nucleotides that encode 37 genes

Question 48

For most organisms, all the cytoplasm is inherited from the ______.

Answer 48

egg

Question 49

example of Cytoplasmic inheritance

Answer 49

Example: Chloroplasts and mitochondria

Question 50

the phenotype of the offspring is determined by the genotype of the mother. The genes are inherited from both parents but the offspring's phenotype is determined not by its own phenotype but by the genotype of the mother. The substances present in the cytoplasm of an egg are pivotal in early development.

Answer 50

Genetic maternal effect

Question 50

example Genetic maternal effect

Answer 50

shell coiling of the snail Limnaea peregra.

Question 51

shell coiling of the snail lymnaea peregra results from a genetic maternal effect?

Answer 51

This means that the direction the snail’s shell coils — either dextral (right-handed) or sinistral (left-handed) — is not determined by the snail’s own genes. Instead, it's determined by the genotype of its mother. The offspring’s own genotype won’t affect their shell coiling — but it will affect the shell coiling of their own offspring later on.

Question 52

mutation appears or not

Answer 52

Penetrance

Question 53

severity of phenotype for those with mutation

Answer 53

Expressivity

Question 54

reflects the range of expression of the mutant genotype

Answer 54

expressivity

Question 54

For example, the phenotypic expression of many mutant alleles in Drosophila can overlap with wild type. If 15 percent of mutant flies show the wild-type appearance, the mutant gene is said to have a penetrance of _____ percent.

Answer 54

85

Question 54

For example, if a region of a chromosome is relocated or rearranged normal expression of genes in that chromosomal region may be modified.

Answer 54

true

Question 54

percentage of individuals who show at least some degree of expression of a mutant genotype defines the _________ of the mutation

Answer 54

penetrance

Question 54

expressivity example in flies

Answer 54

Flies homozygous for the recessive mutant eyeless gene yield phenotypes that range from the presence of normal eyes to a partial reduction in size to the complete absence of one or both eyes

Question 55

(a) a Himalayan rabbit. (b) a Siamese cat. Both species show dark fur color on the snout, ears, and paws. the patches are due to the ___________ responsible for pigment production

Answer 55

temperature-sensitive allele

Question 55

The physical location of a gene in relation to other genetic material may influence the expression of a gene.

Answer 55

true

Question 55

(a) a Himalayan rabbit. (b) a Siamese cat. is an example of ?

Answer 55

Temperature Effects-Conditional Mutations

Question 55

if a region of a chromosome is relocated or rearranged

Answer 55

(called a translocatio or an inversion event),

Question 55

how does the enzyme for pigment work on the (a) a Himalayan rabbit. (b) a Siamese cat.

Answer 55

The enzyme normally responsible for pigment production is functional only at the lower temperatures present in the extremities, but it loses its catalytic function at the slightly higher temperatures found throughout the rest of the body.

Question 55

Tay-Sachs disease, inherited as an autosomal recessive, is a lethal lipid metabolism disease involving an abnormal enzyme,

Answer 55

hexosaminidase

Question 56

the age at which a mutant gene exerts a noticeable phenotype depends on events during the normal sequence of growth and development

Answer 56

Onset of Genetic Expression

Question 56

inherited as an autosomal recessive, is a lethal lipid metabolism disease involving an abnormal enzyme. A Newborns appear to be phenotypically normal for the first few months. Then developmental disability paralysis, and blindness ensue, and most affected children die around the age of 3.

Answer 56

Tay-Sachs disease

Question 57

inherited as an X-linked recessive disease, is characterized by abnormal nucleic acid metabolism (biochemical salvage of nitrogenous purine bases), leading to the accumulation of uric acid in blood and tissues, intellectual disability, palsy, and self- mutilation of the lips and fingers. Newborns are normal for six to eight months prior to the onset of the first symptoms

Answer 57

Lesch-Nyhan syndrome

Question 58

Lesch-Nyhan syndrome is due to a mutation in the gene encoding hypoxanthine-guanine ___________

Answer 58

phosphoribosyltransferase (HGPRT)

Question 59

an X- Inked recessive disorder associated with progressive muscular wasting it is not usually dagnosed until the child is 3 to 5 years old Even with modem medical intervention, the disease is often fatal in the early 20s.

Answer 59

Duchenne muscular dystrophy (DMD)

Question 60

Phenotypic expression is not always the direct reflection of the

Answer 60

genotype

Question 61

A percentage of organisms may not express the expected phenotype at all, the basis of the _________ of a mutant gene.

Answer 61

penetrance

Question 62

The phenotype can be modified by genetic background, temperature, and nutrition.

Answer 62

true