Page 14 - My FlipBook

Glossary

allele: a variant or alternative sequence of a gene, which usually arises
by mutation
amino acid: a building block for a protein
autosomal: located on an autosome
autosome: any chromosome that is not a sex chromosome
base pair: a set of two nucleotides that form the links between the
sugar-phosphate backbones of DNA and RNA. In DNA the pairs are
adenine (A) and thymine (T), and guanine (G) and cytosine (C).
carrier: a person who possesses a disease-causing allele from one parent
and a normal allele from the other parent. Carriers are usually unaffected by
the disease.
chromosome: a threadlike structure of DNA and proteins found in the nucleus of
most living cells
codon: a sequence of three nucleotides that together form a unit of genetic code
in a DNA or RNA molecule
crossing over: the exchange of genes between chromosomes that results in a
mixture of parental characteristics in offspring
de novo mutation: a genetic alteration that is present in a gamete of one of
the parents but not present in either parent. It can also arise as an embryo
begins to develop.
deoxyribonucleic acid (DNA): a self-replicating material present in nearly all
living organisms that carries heritable genetic information

diploid: containing two complete sets of chromosomes, one from each parent
DNA polymerase: a type of enzyme that helps form new copies of DNA, in the
form of nucleic acid molecules during DNA replication
DNA sequencing: determining the order of nucleotides in a piece of DNA
dominant: expressed when only one copy of the allele is present
enzyme: a protein that triggers a chemical reaction in a living organism

eugenics: the discredited idea of improving the human population by controlled
breeding or by selecting desired heritable traits
eukaryote cell: any cell or organism that possesses a clearly defined nucleus
exome: the part of the genome consisting of exons

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