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Inheritance Part 3, MMP - Coggle Diagram
Inheritance Part 3, MMP
Terminologies:
The genes that occupy corresponding positions on homologous chromosomes and control the same characteristic are called allelomorphic genes, or alleles.
There are often more than two alleles of a gene. The human ABO blood groups are controlled by three alleles.
Patterns of inheritance:
The allele in a mother’s body cells that causes her to have brown eyes may be present on one of the chromosomes in each ovum she produces.
If the father’s sperm cell contains an allele for brown eyes on the corresponding chromosome, the zygote will receive an allele for brown eyes from each parent.
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Breeding true:
A black rabbit, on the other hand, could be either BB or Bb and, by just looking at the rabbit, you could not tell the difference.
When a male black rabbit BB produces sperm, each one of the pair of chromosomes carrying the B alleles will end up in different sperm cells. Since the alleles are the same, all the sperm will have the B allele for black fur.
A black rabbit BB is called a true-breeding black and is said to be homozygous for black coat colour.
If this rabbit mates with another black (BB) rabbit, all the babies will be black because all will receive a dominant allele for black fur.
When all the offspring have the same characteristic as the parents, this is called ‘breeding true’ for this characteristic.
Genotype and phenotype::
The two kinds of black rabbit BB and Bb are said to have the same phenotype. This is because their coat colours look exactly the same.
However, because they have different allele pairs for coat colour they are said to have different genotypes, i.e. different combinations of alleles.
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