GENETIC PRINCIPLES

Lounging around the

house

Two heads are better than one

Look before you leap

GENETIC PRINCIPLES

•If the genes are on the same chromosome, they will not follow the law of Independent Assortment.

Polygenic Inheritance: When more than one gene affects the phenotype of a trait.

Target: I will be able to identify the phenotype given a genotype in incomplete dominance, co-dominance, and multiple alleles.

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Exceptions to Simple Dominance: 1. Incomplete Dominance: when the two alleles in a heterozygous genotype contribute to the individual phenotype that isn’t like either parent

Neither allele is completely dominant; there is a blend of the two.R

RW

W

RW RW

RW RW

Genotype Ratio: 4 (100%) RW

Phenotype Ratio: 4 (100%) Pink

2. Co-Dominance: When two dominant alleles are expressed at the same time

Represented in Punnett squares by capital letters with superscripts- ex: CB, CW.

CB CB

CW

CW

CB

CW

Genotype Ratio: 4 (100%) CBCW

Phenotype Ratio: 4 (100%) black and white (CB, CW)

CB

CW

CB

CW

CB

CW

3. Multiple Alleles: When there are more than two alleles for a trait Ex: There are three types of blood alleles in humans- A, B, and O

A and B are Dominant over OO is RecessiveA and B are Co-Dominant

  Caucasians African American

Hispanic Asian

O +

37% 47% 53% 39%

O - 8% 4% 4% 1%

A + 33% 24% 29% 27%

A - 7% 2% 2% 0.5%

B + 9% 18% 9% 25%

B - 2% 1% 1% 0.4%

AB +

3% 4% 2% 7%

AB -

1% 0.3% 0.2% 0.1%

Human Blood Types

Summary:

Genotype Blood Type (Phenotype)A

IB IB or IB i

Bii OIA IB AB

IA

iIA

IB

IA IA or IA i

IA IA

IA i

IA IB

IB i

Genotype Ratio: 1 IA IA : 1IA i : IA I B : IB I

Phenotype Ratio: 2 Type A: 1 Type AB: 1 Type B

WHEN MENDEL WAS WRONG

Divide paper into 3 sections. Draw pictures to represent Incomplete Dominance, Co-Dominance, and Multiple Alleles *Use a minimum of 4 colors

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