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Genetic 342 A&B

Kenneth G Wilson

Professory of Botany

Modified Phenotypic Ratios

Imprinting is Aa the same as aA?

Result is called gene imprinting - in some cases it is important which parent the gene came from.

Some Modified Phenotypic Ratios Produced by Gene Interaction

Type of gene interaction 9 A_B_ 3 A_bb 3 aaB_ 1 aabb Phenotypic ratio Example
None - simple dominance 9 3 3 1 9:3:3:1

Pea seeds
wrinkled-round
green-yellow
Pepper fruit color

Complementary gene action 9 7 9:7

Cyanide in Clover
High vs Low
color in snail pigmented vs albino

Recessive suppression by aa acting on bb 9 3 4 9:3:4 ???
Recessive epistasis of aa acting on B and b alleles 9 3 4 9:3:4 Coat Color
Black:Brown:Albino
Dominant epistasis of A acting on B and b alleles 12 3 1 12:3:1 Summer Squash
white:yellow:green
Dominant epistasis of A acting on B and b alleles 12 3 1 13:3 Chickens
white:colored
Duplicate genes (tetraploidy) 15 1 15:1 Shepherd's Purse
Round : Narrow

How would you explain 9:6:1? Can you give an example?

Cytoplasmically inherited characters.

  1. mitochondrial trait - segregate during mitosis
    1. cytoplasmic sterility -
    2. color in fungi
  2. chloroplast traits
    1. Leaf Characters
    2. Correns or Bauer
    3. organelle destruction

Cytoplasmically influenced characters ie maternal effect

  1. snail coiling

 

oliver

This is our friend Oliver the parrotlet,

Oliver is a true parrot,

the smallest in the world.