The gametes produced by critters with 2
genes:
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:
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AA |
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BB |
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CC |
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DD |
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1 allele |
X |
1 allele |
X |
1 allele |
X |
1 allele |
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1 Kind of gamete |
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(ABCD) |
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Aa |
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Bb |
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CC |
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DD |
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2 alleles |
X |
2 alleles |
X |
1 allele |
X |
1 allele |
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4 Kinds of gametes |
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(ABCD, AbCD, aBCD, abCD) |
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Aa |
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Bb |
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CC |
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Dd |
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2 alleles |
X |
2 alleles |
X |
1 allele |
X |
2 alleles |
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8 Kinds of gametes |
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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."
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The
following phrase may also help you determine the gametes of a dihybrid: BIG à BIG BIG à small small à BIG small à small |
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