Unit 05: Mendelian Extentions

Question 1

what is haplosufficient?

Answer 1

when only one copy of the allele is enough to produce the product

Question 2

in dominant mutations, heterozygotes are ______

Answer 2

haploinsufficient

Question 3

what are null mutations?

Answer 3

dominant mutations resulting in a non-functional protein

Question 4

what type of dominance do snapdragon flower colours follow?

Answer 4

incomplete dominance

Question 5

what does the F1 of a red true breeding snap dragon x a white true breeding snap dragon look likfe? if an F1 plant is selfed, what does the F2 look like?

Answer 5

f1: all pink

f2: 1 red: 2 pink: 1 white

Question 6

do we see incomplete dominance in humans?

Answer 6

meh kinda but not rly

Question 7

what are some simplified examples of incomplete dominance in humans?

Answer 7

• dark colouration in eye colour (polygenic)
• height (polygenic)
• skin colour (single gene)
• wavy hair
• tay sachs
• hypercholesterolemia

Question 8

which genotypes can give each blood type?

Answer 8

A - I^A/i or I^A/I^A

B - I^B/i or I^B/I^B

AB - I^A/I^B

O - ii

Question 9

A type blood has ___ antigen and ____ antibodies

Answer 9

A, B

Question 10

B type blood has ___ antigen and ____ antibodies

Answer 10

B, A

Question 11

AB type blood has ___ antigen and ____ antibodies

Answer 11

A and B antigens, no antibodies

Question 12

O type blood has ___ antigen and ____ antibodies

Answer 12

no antigens, A and B antibodies

Question 13

the M and N alleles display what type of dominance?

Answer 13

autosomal codominance

Question 14

what is the formula for number of genotypes in an allelic series?

Answer 14

n(n+1)/2

Question 15

what is the formula for number of homozygotes in an allelic series?

Answer 15

n

Question 16

what is the formula for number of heterozygotes in an allelic series?

Answer 16

n(n-1)/2

Question 17

what are lethal alleles?

Answer 17

mutations in essential genes resulting in death in a homozygote condition

Question 18

what does the phenotypic ratio look like in the F1 when considering a lethal allele? why?

Answer 18

all dominant bc homozygous for lethal allele is deadly

Question 19

what does the phenotypic ratio look like in the F1 when considering a lethal allele for a codominant trait?

Answer 19

2 displaying the heterozygote condition and 1 displaying the dominant condition

Question 20

what is the difference between complete and incomplete penetrance?

Answer 20

complete: when a genotype always produces the same phenotype

incomplete: when a genotype does not always produce the same phenotype due to environmental influences

Question 21

what is variable expressivity?

Answer 21

when one genotype can produce different phenotypes due to varying expression of alleles

Question 22

describe the polydactyly trait and how it presents.

Answer 22

autosomal dominant trait with incomplete penetrance coding for extra fingers

Question 23

what happens when the polydactyly trait is displaying incomplete penetrance. how often does this happen?

Answer 23

normal fingers about 20-30% of the time even tho there is at least 1 dominant allele

Question 24

what is incomplete penetrance?

Answer 24

when a genotype doesn’t produced its expected phenotype

Question 25

what are some gene environment interactions that can affect gene expression?

Answer 25

- sex - age - temperature - chemicals and diet - pathogens and parasite exposure