Topic 5: Mendelian Extensions

Question 1

Mendel’s experiments looked at traits that exhibited ___________ over the other form (recessive phenotype)

Answer 1

complete dominance

Question 2

in incomplete dominance, the phenotype of the heterozygote is ______ from the phenotypes of homozygous dom/rec individuals

Answer 2

distinct, different!

Question 3

we use _____ on letters to display incomplete dominance during punnet square crosses

Answer 3

subscripts

Question 4

incomplete dominance leads to ______, instead of the shared mixing of codominace

Answer 4

blending

Question 5

codominance leads to ______, instead of the blending of incomplete dominance

Answer 5

shared mix (ex: blood type)

Question 6

_______: dominance decreases as we continue along the series

Answer 6

allelic series

Question 7

_______: mutations in essential genes cause death if homozygous

Answer 7

lethal alleles (difficult to detect because they’re often masked by the dominant phenotype, creating carriers)

Question 8

____: genotype always produces the same phenotype, organism carrying the dominant allele will always produce the dominant trait

Answer 8

complete penetrance

Question 9

____: phenotypic variance due to environmental/genetic influence, so the same genotype doesn’t always produce the same phenotype

Answer 9

incomplete penetrance (a genotype fails to produce the expected phenotype)

Question 10

_______: same genotype produces variable phenotypes due to varying expression of the alleles

Answer 10

variable expressivity

Question 11

what are some examples of gene-environment interactions?

Answer 11

sex, age, temperature, chemicals and diet, pathogens and parasites

Question 12

______: alters multiple features in the phenotype due to a single mutation in the genotype

Answer 12

pleiotropy (one gene->multiple phenotypic effects)

Question 13

true/false: mendelian ratios can be modified from gene interactions

Answer 13

true1

Question 14

true/false: genes can’t produce multiple proteins/various RNA

Answer 14

false, genes affect eachother and influence eachother! it’s not just “one gene=one enzyme”

Question 15

_____: the effect of a particular genetic variant is masked by a variant at another locus

Answer 15

epistatic interactions

Question 16

complementary gene interaction has a _____ ratio

Answer 16

9:7 ratio

Question 17

duplicate gene action has a _______ ratio

Answer 17

15:1 (only homozygous recessive at both loci produce the recessive phenotype)

Question 18

dominant gene interaction produces _____ ratio

Answer 18

9:6:1 ratio (heterozygotes are added together)

Question 19

recessive epistasis produces _____ ratio

Answer 19

9:3:4 ratio (being homozygous at one locus masks the expression of the second locus) (ex: fur colour in dogs)

Question 20

dominant epistasis produces _____ ratio

Answer 20

12:3:1 ratio (dominant gene MASKS expression of second locus)

Question 21

dominant suppression produces _____ ratio

Answer 21

13:3 ratio, (dominant allele of one gene SUPPRESSES expression of the second locus)