Ch. 5 Extensions on Mendel

Question 1

Lethal alleles

Answer 1

causes death at an early stage of development (often before birth) so that some genotype do not appear among the progeny

Question 2

incomplete dominance

Answer 2

heterozygote is intermediate (phenotype is between the homozygotes)

Question 3

codominance

Answer 3

heterozygote exhibits both phenotypes

Question 4

Penetrance

Answer 4

the percentage of individuals with a particular genotype that express the expected phenotype

Question 5

True or false: in incomplete dominance the phenotypic ratio with match the genotypic ratio

Answer 5

true
(both are 1:2:1)

Question 6

Genes at multiple loci determine

Answer 6

a single phenotype (products of different loci combine to produce a phenotype)

Question 7

Epistasis

Answer 7

One gene hides/masks the effect of another gene at a different locus

Question 8

Cystic fibrosis is an example of

Answer 8

a compound heterozygote

Question 9

What is a compound heterozygote

Answer 9

an individual who carries 2 different alleles at a locus that result in a recessive phenotype (cystic fibrosis)

Question 10

recessive epistasis

Answer 10

the presence of 2 recessive alleles inhibits the expression of an allele at a different locus

Question 11

dominant epistasis

Answer 11

the presence of a single copy of an allele can inhibit the expression of an allele at a different locus

Question 12

epistatic gene

Answer 12

the gene that does the masking

Question 13

hypostatic gene

Answer 13

the gene whose effect is masked

Question 14

incomplete penetrance

Answer 14

describes individuals with the same genotype that do not exhibit the same phenotype (genotype does not produce expected phenotype)

Question 15

How do you calculate penetrance

Answer 15

number of individuals with phenotype/ total number of individuals

Question 16

Sex influence trait

Answer 16

a trait determined by an autosomal gene that is more prominently expressed in one sex

Question 17

sex limited trait

Answer 17

a trait determined by an autosomal gene that is expressed in only one sex

Question 18

pleiotrophy

Answer 18

a gene that affects more than one phenotype

Question 19

polygenic trait

Answer 19

a trait that is determined by multiple genes

Question 20

Imprinting

Answer 20

a trait that is at least partially determined by the sex of the parent of origin

Question 21

In lethal alleles when you cross 2 individuals with a lethal allele what is the pheno ratio you get

Answer 21

2:1 (instead of our normal 3:1); 2 show what the parents had shown, the 1 shows the recessive (there is another 1/4 but they are dead so they are not included)

Question 22

true or false: phenotypes are not preductable from single-locus effect alone

Answer 22

true: interaction among genes at 2, 3, 4 or more loci is common

Question 23

expressivity

Answer 23

the degree to which a character is expressed

Question 24

sex-linked

Answer 24

genes on X or Y chromosomes

Question 25

continuous characteristics

Answer 25

polygenic and influenced by the environment= multifactoral