Human beings have 23 pairs of chromosomes, one pair being the sex chromosomes which determine if you are female (**) or male (XY).
Some characteristics are controlled by a single gene.
Genes can have different forms called alleles.
Some alleles are dominant and some are recessive.
We can construct genetic diagrams (i.e. a punnett square) to predict characteristics.
Phenotype: physical appearance of the characteristc i.e. dimples
Genotype: the genetic make up - which alleles does the individual inherit - DD, Dd or dd?
Homozygous: both alleles are the same - DD (homozygous dominant) or dd (homozygous recessive)
Heterozygous: the two alleles are different Dd.
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