Topic 10 - Non-Mendelian Genetics

Question 1

A

Answer 1

Blood type with A surface antigens. Possible genotypes IAIA or IAi.

Question 2

AB

Answer 2

Blood type with A and B surface antigens. Possible genotype IAIB.

Question 3

Addition Rule

Answer 3

(“or” rule)The probability that any of several mutually exclusive events will occur is equal to the SUM of the events’ individual probabilities. E.g. Having wrinkled seeds or yellow seeds - add up the probabilities of being wrinkled and of being yellow.

Question 3

Autosome

Answer 3

Any chromosome other than a sex chromosome (i.e., any chromosome other than the X or Y in mammals).

Question 4

B

Answer 4

Blood type with B surface antigens. Possible genotypes IBIB or IBi.

Question 5

Codominance

Answer 5

An inheritance pattern in which heterozygotes exhibit both of the traits seen in each type of homozygous individual.

Question 6

Incomplete dominance

Answer 6

An inheritance pattern in which the phenotype of a heterozygote is in between the phenotypes of the homozygotes.

Question 7

Linked genes

Answer 7

Genes located on the same chromosome, so that inheritance patterns show dependent assortment of the alleles involved in this association, with genotypic ratios different from 9:3:3:1, in the case of a dihybrid cross.

Question 8

Multiple alleles

Answer 8

Type of inheritance which happens when there are more than two common alleles for a locus in a given population.

Question 9

O

Answer 9

Blood type lacking A or B surface antigens. Possible genotype ii.

Question 10

Pleiotropy

Answer 10

The ability of a single gene to affect more than one trait.

Question 10

Product rule

Answer 10

(“and” rule)The probability of two (or more) independent events occurring together can be calculated by MULTIPLYING the individual probabilities of the events. E.g. Having wrinkled AND yellow seeds - multiply each of the probabilities.

Question 11

Quantitative trait

Answer 11

A trait that exhibits continuous phenotypic variation (as in human height) rather than the clearly separated phenotypes of a discrete trait.

Question 11

Sex chromosome

Answer 11

Chromosomes that differ in shape or in number in males and females. For example, the X and Y chromosomes of many animals.

Question 12

Epistasis

Answer 12

The phenomenon in which the effect of one gene (locus) is dependent on the presence of one or more modifier genes.

Question 13

Polygenic inheritance

Answer 13

When many genes influence one trait. This leads to continuous variation rather than coming in distinct phenotype.

Question 14

Qualitative trait

Answer 14

Also called discrete trait, it exists in discrete categories, such as green or yellow seed coat colour in peas, without intermediate colors.

Question 15

x-linked inheritance

Answer 15

Inheritance pattern observed in genes carried on sex chromosomes. In this case, females and males have different numbers of alleles of a gene. Often creates situations in which a trait appears more often in one sex.