The gametes produced by critters with 2 genes:

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How many different gametes will the following genotype make? (AA, BB, CC, DD). This genotype will only produce 1 kind of gamete; it will produce: ABCD. Since each gene only has 1 kind of allele, the product of each allele is 1. See below:

 

 

 

 

 

 

 

 

 

AA

 

BB

 

CC

 

DD

 

 

 

 

 

1 allele

X

1 allele

X

1 allele

X

1 allele

=

1 Kind of gamete

 

 

 

 

 

 

 

 

(ABCD)

 

 

 

 

 

 

 

 

 

Aa

 

Bb

 

CC

 

DD

 

 

2 alleles

X

2 alleles

X

1 allele

X

1 allele

=

4 Kinds of gametes

 

 

 

 

 

 

 

 

(ABCD, AbCD, aBCD, abCD)

 

 

 

 

 

 

 

 

 

Aa

 

Bb

 

CC

 

Dd

 

 

2 alleles

X

2 alleles

X

1 allele

X

2 alleles

=

8 Kinds of gametes

 

 

 

 

 

 

 

 

 

If the genotype is "Aa, Bb", then 4 different kinds of gametes can be made: (aB, AB, ab, and Ab) A creature with 2 heterozygous genes is called a "dihybrid."

The following phrase may also help you determine the gametes of a dihybrid:

BIG BIG

BIG small

small BIG

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In comparison, a creature with this genotype: "Aa, BB" will have these sex cells: (AB and aB)

In comparison, a creature with this genotype: "AA, BB" will have only have this: (AB)

 

Use this equation to determine how many different kinds of gamete will be produced: 2n Where n= number of gene pairs

A "tri-hybrid", a beast with 3 hybrid genes, would produce 8 different kinds of sperm/egg.

A "tetra-hybrid", a beast with 4 hybrid genes, would produce 16 different kinds of sperm/egg.

A "penta-hybrid", a beast with 5 hybrid genes, would produce 32 different kinds of sperm/egg.

Click this link to see some children of a penta-hybrid cross

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