Ch 5 Extensions and Modifications of Basic Principles

Question 1

heterozygote has the same phenotype as one homozygote

Answer 1

complete dominance

Question 2

heterozygote has phenotype intermediate between those of two parental homozygotes

Answer 2

incomplete dominance

Question 3

heterozygote exhibits traits of both parental homozygotes simultaneously

Answer 3

codominance

Question 4

phenomenon where the genotype does not always produce the expected phenotype

Answer 4

incomplete penetrance

Question 5

the percentage of individual organisms having a particular genotype that express the expected phenotype

Answer 5

penetrance

Question 6

the degree to which a trait is expressed

Answer 6

expressivity

Question 7

allele that causes death at an early stage of development

Answer 7

lethal allele

Question 8

what ratio is produced by a recessive lethal allele

Answer 8

2:1 ratio (heterozygote:homozygous recessive)

Question 9

loci where more than two alleles are present

Answer 9

multiple alleles

Question 10

how do you determine the number of possible genotypes in a locus with multiple alleles

Answer 10

[n(n+1)/2]; n = # of different alleles at a locus

Question 11

what is gene interaction?

Answer 11

interaction between effects of genes at different loci

Question 12

interaction of gene that hides the effect of another gene at a different locus

Answer 12

epistasis

Question 13

the gene who does the masking

Answer 13

epistatic gene

Question 14

the gene whose effect is masked

Answer 14

hypostatic gene

Question 15

describe recessive epistasis; what’s the ratio?

Answer 15

recessive allele at a second locus masks the effect of alleles at the first locus; two recessive alleles must be present
9:3:4

Question 16

describe dominant epistasis; what’s the ratio?

Answer 16

dominant allele at a second locus masks the effect of alleles at the first locus; only one allele required to be present

Question 17

describe duplicate recessive epistasis; what’s the ratio?

Answer 17

two recessive alleles at either of two different loci are capable of suppressing a phenotype
9:7

Question 18

what is the ratio for duplicate dominant epistasis?

Answer 18

15:1

Question 19

what is the ratio for duplicate interaction epistasis?

Answer 19

9:6:1

Question 20

characteristics determined by autosomal genes, but are expressed differently in males and females

Answer 20

sex-influenced characteristics

Question 21

characteristics encoded by autosomal genes but expressed only in one sex

Answer 21

sex-limited characteristics

Question 22

characteristics encoded by genes located in the cytoplasm

Answer 22

cytoplasmic inheritance

Question 23

how are cytoplasmic inherited traits usually passed down

Answer 23

they are usually passed from mother to offspring

Question 24

describe the genetic maternal effect

Answer 24

the phenotype of offspring are determined by the genotype of the mother

Question 25

what is genomic imprinting

Answer 25

differential expression of genetic material depending on whether it is inherited from the male or female parent

Question 26

describe anticipation

Answer 26

a genetic trait becomes more strongly expressed or expressed earlier as it is passed down from generation to generation

Question 27

an allele whose product is functional only at certain temperatures

Answer 27

temperature-sensitive allele