Hey, it's not that difficult. But a screwed up vocabulary screws up everyone. Start off with this:

Homozygous = two copies of the same gene in a gene pair. Examples: AA, aa.

Heterozygous = two different genes in a gene pair. Example: Aa.

Recessive mutant gene = Shows its effect only when homozygous. Symbolized with a lower case letter and fits the following pattern:
AA = homozygous normal, looks normal.
Aa = heterozygous because has a mutant gene paired with a normal gene, looks like an AA individual.
aa = homozygous mutant gene, shows the mutant appearance.

Dominant mutant gene = Shows its effect when either heterozygous or homozygous. Symbolized with an upper case letter and fits the following pattern, which is the mirror image of a recessive mutant gene:
AA = homozygous mutant gene, shows the mutant appearance.
Aa = heterozygous because has a mutant gene paired with a normal gene, looks like an AA individual.
aa = homozygous normal, looks normal.

Codominant mutant gene = Shows a different effect when heterozygous than when homozygous. Symbolized with an upper case letter and fits the following pattern:
AA = homozygous mutant gene, shows the full mutant appearance.
Aa = heterozygous because has a mutant gene paired with a normal gene, does not have the appearance of either an AA or an aa individual.
aa = homozygous normal, looks normal.

The codominant symbolism used here stinks. This forum won't show the plus sign, which is the standard symbol for a wild type or normal gene.

Paul Hollander

[ Hide Replies ]

• boa genetics - carpetguy, Mon Sep 11 09:33:38 2006
• RE: boa genetics - Paul Hollander, Mon Sep 11 13:29:57 2006
• RE: boa genetics - Paradigmboas, Mon Sep 11 15:30:38 2006
• RE: boa genetics - jayf, Mon Sep 11 15:53:42 2006
• And is much more difficult to..... - rainbowsrus, Mon Sep 11 16:25:49 2006
• RE: okay... now I'm really confused - snakehorse, Mon Sep 11 17:00:06 2006
• RE: okay... now I'm really confused - rainbowsrus, Mon Sep 11 17:54:53 2006
• RE: okay... now I'm really confused - Paul Hollander, Mon Sep 11 18:06:01 2006
• RE: okay... now I'm really confused - carpetguy, Mon Sep 11 18:16:33 2006
• RE: okay... now I'm really confused - carpetguy, Mon Sep 11 18:48:00 2006
• RE: okay... now I'm really confused - Paul Hollander, Mon Sep 11 19:46:53 2006
• RE: okay... now I'm really confused - Paul Hollander, Mon Sep 11 19:09:30 2006
• RE: okay... now I'm really confused - carpetguy, Tue Sep 12 03:48:12 2006
• RE: okay... now I'm really confused - rainbowsrus, Tue Sep 12 09:41:03 2006
• RE: okay... now I'm really confused - Paul Hollander, Tue Sep 12 18:14:24 2006
• RE: okay... now I'm really confused - carpetguy, Tue Sep 12 19:07:25 2006
• Are you sure............................ - vcaruso15, Tue Sep 12 19:22:12 2006
• RE: Are you sure........................ - Paradigmboas, Wed Sep 13 03:05:26 2006
• Couldn't have said it better myself. n/p - Paul Hollander, Wed Sep 13 13:16:25 2006