Chapter 5 - Genetics

Question 1

Monohybrid

Answer 1

Organism that is heterozygous with respect to a single gene

Question 2

Monohybrid cross

Answer 2

cross between two monohybrids. Only one gene is involved, and the cross is between two organisms that are heterozygous at one gene locus for a dominant and recessive allele

Question 3

Test cross

Answer 3

a technique used in which an individual whose genotype is unknown for a dominant phenotype (could be homozygous or heterozygous dominant) is crossed with an individual that is homozygous recessive.

Question 4

Dihybrid cross

Answer 4

cross between two organisms that are heterozygous at two gene loci

Question 5

Independent assortment

Answer 5

random orientation of maternal and paternal homologous chromosomes at the equator during metaphase, resulting in random combinations of alleles in the gametes at the conclusion of meiosis

Question 6

incomplete dominance

Answer 6

the state in which a heterozygous individual has a phenotype that is intermediate between those of the corresponding homozygous individuals

Question 7

Polygenetic inheritance

Answer 7

The inheritance of more than one gene that affects the inheritance of single characteristic

Question 8

Polygenes

Answer 8

genes that have a small additive effect on a phenotype, and each gene consists of multiple alleles

Question 9

Allele

Answer 9

Stored set of instructions for a protein, found on a specific locus (position) on a chromosome. Different forms of a gene. A set of alleles (one from each parent) is called a genotype

Question 10

Autosomal inheritance

Answer 10

The passing on of a trait for a gene located on an autosome

Question 11

Parental generation

Answer 11

To individuals or lines that represent the start of a breeding experiment. The offspring are the F1 generation

Question 12

first filial generation (F1)

Answer 12

The generation of offspring produced from a cross between two parents

Question 13

second filial generation (F2)

Answer 13

Offspring of the F1 generation, the second generation produced from a cross between two homozygous parents

Question 14

Multiple alleles

Answer 14

The term given when three or more alleles of a gene exist among members of a population

Question 15

Discontinuous variation

Answer 15

Variation in a characteristic that shows two or just a few clearly distinct phenotypes

Question 16

Continuous variation

Answer 16

Variation in a phenotype characteristic that shows a smooth range, this occurs when a treat is controlled by many genes

Question 17

For modes of inheritance

Answer 17

• Autosomal dominant: The allele cannot be recessive as two affected parents could not have an infected offspring (must be heterozygous)
• Autosomal recessive: The allele cannot be dominant as two unaffected parents could not have an infected offspring (Must be heterozygous)
• X-linked dominant: 100% incidence of affected daughters from affected father suggests X-linked dominant
• X-linked recessive: 100% incidence of affected sons from the affected mother suggests excellent recessive