The language of genetics

你需要知道的

• A gene is a section of DNA on a chromosome that codes for a characteristic; humans have 23 pairs of chromosomes, one of each pair from each parent.
• An allele is a different version of a gene, and you inherit one allele of each gene from each parent.
• A dominant allele (capital letter) shows its effect even with one copy; a recessive allele (lower-case letter) only shows when there are two copies.
• Genotype is the pair of alleles, such as TT, Tt or tt; phenotype is the characteristic that results.
• Two parents who both carry a recessive allele can have a child who shows the recessive trait.

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