extensions of Mendelian Inheritance

Question 1

wild type alleles

Answer 1

most prevalent version of a gene in wild populations in which the proteins function normally and promote reproductive success of an organism

Question 2

in large populations, there may be more than 1 common allele considered wild-type

Answer 2

polymorphism- inheritance of a trait controlled by a single genetic locus with 2 alleles

Question 3

mutant alleles

Answer 3

are less common version of a gene that can be due to random mutations that occur in DNA or due to mutations induced by scientists

Question 4

difference between wild-type and mutant alleles

Answer 4

Wild-type is the normal phenotype of an organism found in natural populations, whereas mutant alleles have an abnormal phenotype that differs from the normal.

Question 5

3 types of dominant alleles

Answer 5

gain of function, dominant negative, and haplo-insufficiency

Question 6

penetrance

Answer 6

proportion of individuals that have a specific allele as well as the associated phenotype

Question 7

incomplete penetrance

Answer 7

when an allele does not completely penetrate into the population
Ex: 40% penetrant allele = 40% of pop. with allele will show phenotype, where are the other 60% will NOT show phenotype but will carry allele

Question 8

incomplete dominance

Answer 8

form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele, results in a third phenotype of a combination of the phenotypes
Ex: red flower (R1R1 ) x white flower (R2R2) = pink flower (R1R2)

Question 9

codominance

Answer 9

multiple alleles being expressed, each allele encodes a functional protein but in a different sequence
Ex: ABO blood type in humans

Question 10

overdominance

Answer 10

where a heterozygote produces a phenotype more extreme/better adapted than that of the homozygote
Ex: sickle cell anemia, heterozygotes have a higher resistance to malaria and sickle cell than their homozygous counterpart

Question 11

incomplete dom. vs. codominance vs. over dominance

Answer 11

incomplete is a mixture of the 2 alleles, codominance when both alleles are expressed together in offspring, and overdominance is when the heterozygote phenotype is better than their homozygous counterpart.

Question 12

how can the 2 protein variants produce a favorable phenotype in the heterozygote?

Answer 12

disease resistance, homodimer formation, variation in functional activity

Question 13

sex-influenced traits

Answer 13

when an allele is dominant in 1 sex, but recessive in the next
Ex: male patterned baldness

Question 14

sex limited traits

Answer 14

are traits that occur in only one 1/2 of the sexes, both sexes have genes. Is responsible for sexual dimorphism

Question 15

lethal alleles

Answer 15

is a mutation in an essential gene leading to a non-function protein product leading to a lethal phenotype

Question 16

essential genes

Answer 16

are genes that are necessary for an organism

Question 17

conditional lethal alleles

Answer 17

exert effects only under certain conditions

Ex: drosophila are temperature sensitive, large will not survive under certain temp

Question 18

semi-letal alleles

Answer 18

can cause death of individuals with the affected genotype, however not all will die

Question 19

pleiotropy

Answer 19

when single gene has multiple effects on the phenotype of an organism

Question 20

why does pleiotropy happen?

Answer 20

gene product has multiple uses in cellular function, gene is expressed in different cell types, or the gene is expressed during different stages of development

Question 21

epistasis

Answer 21

inheritance pattern in which allele of 1 gene masks the phenotypic effects of the alleles of a different gene
Ex: Lab coat color

Question 22

complementation

Answer 22

2 different parents that express the same or similar recessive phenotypes produce offspring with a wild-type genotype

Question 23

modifying genes

Answer 23

phenomenon in which an allele of 1 gene modifies the phenotypic outcome of the alleles of a different gene

Question 24

gene redundancy

Answer 24

pattern in which the loss of function in a single gene has no phenotypic effect, but loss of function of 2 genes has an effect

Question 25

extranuclear inheritance

Answer 25

inheritance pattern of traits not in nuclear genes (genes where DNA is located in the cell nucleus)

Question 26

how are chloroplasts and mitochondria inherited

Answer 26

are commonly inherited from the female parent (via edge cells)

Question 27

genomic imprinting

Answer 27

imprinted genes express one allele (maternal or paternal), the other is silenced.

Question 28

recessive alleles

Answer 28

typically produce less function proteins, proteins tend to be defective and the organism produces lower levels of that functional protein

Question 29

dominant alleles

Answer 29

effect phenotype with just one copy, they are less common in natural systems