Topic 9 -Mendelian Genetics

Question 1

Peas

Answer 1

Model organism used by Mendel. It has individuals with easily recognizable traits (seed colour and texture, for example) in a polymorphic state (appearing commonly in two or more forms within a population), and it is easy to grow and mate.

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, reproductive characteristics, genome size) in the hope that findings will apply to other species.

Question 3

P generation

Answer 3

The adults used in the first experimental cross of a breeding experiment (parental).

Question 4

F1 generation

Answer 4

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

Question 5

F2 generation

Answer 5

Second filial generation, resulting from the cross between individuals of an F1 generation.

Question 6

Segregation

Answer 6

The fact that characteristics inherited from each of the parents don’t blend together, but are instead passed on as independent units that separate (segregate) during gamete formation (which today we know are the homologous chromosomes)

Question 7

Independent assortment

Answer 7

The fact that alleles of different genes located at different chromosomes are transmitted to gametes independently of one another.

Question 8

Dominant allele

Answer 8

Referring to an allele that determines the same phenotype when it is present in a homozygous or heterozygous form.

Question 9

Gametes

Answer 9

What is represented by the letters (or sets of letters) we write at the sides of a punnet square.

Question 10

Hybrid

Answer 10

The offspring of parents who have different sets of alleles for a given gene, or from two different strains, populations, or species.

Question 11

Linked genes

Answer 11

Genes located on the same chromosome that tend to be inherited together in genetic crosses.

Question 12

True-breeding

Answer 12

Also known as pure line. Individuals of the same phenotype that, when crossed, always produce offspring with the same phenotype.

Question 13

Monohybrid cross

Answer 13

A mating between two parents that differ in alleles (are heterozygous) at the one gene being studied.

Question 14

Dihybrid cross

Answer 14

A mating between two parents that differ in alleles (are heterozygous) at the two genes being studied.

Question 15

Recessive

Answer 15

Referring to an allele whose phenotypic effect is observed only in homozygous individuals.

Question 16

1:2:1

Answer 16

Genotypic ratios resulting from a monohybrid cross (involving one pair of different alleles).

Question 17

3:1

Answer 17

Phenotypic ratios resulting from a monohybrid cross involving a dominant and a recessive allele.

Question 18

9:3:3:1

Answer 18

Phenotypic ratios resulting from a dihybrid (double hybrid) cross involving two pairs of dominant/recessive alleles.