Mendelian Genetics

Question 1

heredity

Answer 1

The transmission of traits from parents to offspring via genetic information.

Question 2

model organism

Answer 2

An organism selected for intensive scientific study based on features that make it easy to work with (e.g., body size, life span), in the hope that findings will apply to other species.

Question 3

pollen grains

Answer 3

In flowering plants, a male gametophyte enclosed within a protective coat.

Question 4

pure line

Answer 4

In animal or plant breeding, a strain of individuals that produce offspring identical to themselves when self-pollinated or crossed to another member of the same population. Pure lines are homozygous for most, if not all, genetic loci.

Question 5

F1 Generation

Answer 5

First filial generation. The first generation of offspring produced from a mating (i.e., the offspring of the parental generation).

Question 6

monohybrid cross

Answer 6

A mating between two parents that are both heterozygous for a given gene.

Question 7

When do the terms dominant and recessive apply to genetics?

Answer 7

When a distinct phenotype is shown when the individual carries two different genetic determinants for each trait.

Question 8

reciprocal cross

Answer 8

A breeding experiment in which the mother’s and father’s phenotypes are the reverse of that examined in a previous breeding experiment.

Question 9

particulate inheritance

Answer 9

The observation that genes from two parents do not blend together to form a new physical entity in offspring, but instead remain separate or particle-like.

Question 10

dihybrid cross

Answer 10

A mating between two parents that are heterozygous for both of the two genes being studied.

Question 11

principle of independent assortment

Answer 11

The concept that each pair of hereditary elements (alleles of the same gene) behaves independently of other genes during meiosis.

Question 12

test cross

Answer 12

The breeding of an individual of unknown genotype with an individual having only recessive alleles for the traits of interest in order to infer the unknown genotype from the phenotypic ratios seen in offspring.

Question 13

locus

Answer 13

A gene’s physical location on a chromosome.

Question 14

Which genetic process is responsible for Mendel’s principle of segregation?

Answer 14

Anaphase Meiosis 1

Question 15

chromosome theory of inheritance

Answer 15

The principle that genes are located on chromosomes and that patterns of inheritance are determined by the behavior of chromosomes during meiosis.

Question 16

wild type

Answer 16

The most common phenotype seen in a population; especially the most common phenotype in wild populations compared with inbred strains of the same species.

Question 17

mutation

Answer 17

Any change in the hereditary material of an organism (DNA in most organisms, RNA in some viruses).

Question 18

x-linked inheritance

Answer 18

Inheritance patterns for genes located on the mammalian X chromosome. Also called X-linkage.

Question 19

y-linked inheritance

Answer 19

Inheritance patterns for genes located on the mammalian Y chromosome. Also called Y-linkage.

Question 20

sex-linked inheritance

Answer 20

Inheritance patterns observed in genes carried on sex chromosomes, so females and males have different numbers of alleles of a gene and may pass its trait only to one sex of offspring. Also called sex-linkage.

Question 21

autosomal inheritance

Answer 21

The inheritance patterns that occur when genes are located on autosomes rather than on sex chromosomes.

Question 22

linkage

Answer 22

In genetics, a physical association between two genes because they are on the same chromosome; the inheritance patterns resulting from this association.

Question 23

recombinant

Answer 23

Possessing a new combination of alleles. May refer to a single chromosome or DNA molecule, or to an entire organism.

Question 24

genetic map

Answer 24

An ordered list of genes on a chromosome that indicates their relative distances from each other. Also called a linkage map or meiotic map.

Question 25

incomplete dominance

Answer 25

An inheritance pattern in which the heterozygote phenotype is a blend or combination of both homozygote phenotypes.

Question 26

codominance

Answer 26

An inheritance pattern in which heterozygotes exhibit both of the traits seen in either kind of homozygous individual.

Question 27

multiple allelism

Answer 27

In a population, the existence of more than two alleles of the same gene.

Question 28

polymorphic

Answer 28

(1) The occurrence of more than one allele at a certain genetic locus in a population. (2) The occurrence of more than two distinct phenotypes of a trait in a population.

Question 29

pleiotropic

Answer 29

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

Question 30

discrete traits

Answer 30

An inherited trait that exhibits distinct phenotypic forms rather than the continuous variation characteristic of quantitative traits such as body height.

Question 31

quantitative traits

Answer 31

A heritable feature that exhibits phenotypic variation along a smooth, continuous scale of measurement (e.g., human height), rather than the distinct forms characteristic of discrete traits (e.g., eye color).

Question 32

polygenic inheritance

Answer 32

The inheritance patterns that result when many genes influence one trait.