Modification of Mendelian Ratios Flashcards Preview

Genetics- Exam 2 > Modification of Mendelian Ratios > Flashcards

Flashcards in Modification of Mendelian Ratios Deck (12)
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1
Q

intra-allelic gene interactions

A

interaction between alleles of a locus

types: complete dominance, incomplete dominance, codominance, overdominance

2
Q

incomplete dominance

A

heterozygous genotype exhibits an intermediate phenotype between the phenotypes of the 2 homozygous genotypes
neither allele is dominant
single gene, 2 alleles
(same ratio as codominance)

3
Q

codominance

A

both alleles are expressed in a heterozygote
F2= 1:2:1
can exhibit either one or both alleles
heterozygotes are codominant
- distinct expression of both gene products (alleles)
(same ratio as incomplete dominance)

ex: MN blood groups

4
Q

complete dominance

A

one allele dominates

5
Q

simple dominance hierarchy

multiple allelic series-relationship

A
each allele is dominant to the remaining alleles in a series
alleles can be arranged in order of dominance
# of phenotypes= # of alleles
ex: coat color in rabbits
6
Q

Multiple allelic series relationship

A
incomplete dominance or codominance
# of possible phenotypes= # of possible genoypes
ex: A,B,O blood groups
7
Q

Inter-allelic interactions

A

gene interactions between non-allelic genes

type: epistasis
- duplicate recessive
- duplicate dominant
- recessive
- dominant

8
Q

epistasis

A

expression of one gene or gene a pair masks or modifies the expression of another gene/gene pair; modified F2 ratio (9:3:3:1 ratio)
occurs in sixteenths (clue that 2 genes are involved in controlling the observed phenotype)
principles of segregation & independent assortment hold true (not dominance/recessiveness)
*more than one phenotype –> clue that it’s epistasis

9
Q

Recessive Epistasis

A

9:3:4

ex: color pigment & pigment distribution
one gene produces pigment
on gene reduces pigment
A/a and B/b
when b is homozygous, color effects Gene A are masked

10
Q

Dominant Epistasis

A

12:3:1

dominant allele at one gene locus masks the expression of alleles at a second locus

11
Q

Duplicate Recessive Epistasis

A

9:7

ex: flower color
A/a and B/b
presence of a dominant allele of each gene is required for the production of purple flower color
all other allele combos= white flower color
(homozygous condition of either recessive allele masks the expression of the dominant allele at the other locus)

12
Q

Duplicate Dominant Epistasis

A

15:1
2 genes provide an alternative genetic determination of a specific genotype
the presence of a dominant allele of either gene= dominant phenotype