Advanced Mendelian Flashcards
Incomplete dominance
- one allele contributes to the phenotype
- other allele does not
-dose makes a difference
Co-dominance
-each of two different alleles contributes equally to the phenotype
Monohybrid Cross Aa X Aa
Will always produce a
1:2:1 phenotypic ratio
ABO Blood Genotypes
I^A I^A or I^A i
I^B I^B or I^B i
I^A I^B
ii
A
B
AB
O
2:1
- Lethal gene
- alleles that control more than one aspect of the phenotype are pleiotropic
- dominant with respect to one aspect of the phenotype (tail or no tail)
- recessive with respect to another aspect of the phenotype (viability)
Gene interaction
- two or more genes interact to control the same aspect of the phenotype
- do not use the terms DOMINANT or RECESSIVE for interactions between genes
Epistasis
-gene masking
-e.g. RR or Rr genotype masks or is epistatic to pp
Pp or Pp genotype masks or is epistatic to rr
Genetic explanation for 15:1 heart-shaped:narrow
9/16, 3/16, 3/16 = heart-shaped
1/16 = narrow
- must have either a dominant allele at gene A/a or a dominant allele at gene B/b to be heart shaped
- homozygous recessive at BOTH results in the narrow phenotype
Genetic explanation for blue flowered plants selfed
9:3:4 blue:pink:white
9/16 = blue, 3/16 = pink, 3/16 & 1/16 = white
- homozygous recessive at the A/a gene results in white regardless of genotype at B/b gene
- if dominant allele at A, then allele B results in blue, homozygous recessive at bb results in pink
Genetic explanation for 9:3:4 black:chocolate:yellow lab
9/16 = black, 3/16 = chocolate, 3/16 & 1/16 = yellow
- homozygous recessive at the A/a gene results in yellow regardless of genotype at the B/b gene
- if dominant allele at A, then allele B results in black, homozygous recessive bb results in chocolate
Modified 9:3:3:1 ratios
9: 7
15: 1
9: 3:4
12: 3:1
9: 6:1
13: 3
10: 3:3
10: 6
