||Different copies of the ame gene. You inherit one allele from your mother and one from your father.
|Autosome||Any chromosome other than the sex chromosomes.|
|| Structures found in the cell which contain a package of the cell's DNA.
|| Chromosomes come in pairs and a normal human cell has 46 chromosomes: 22 pairs of autosomes and two sex chromosomes.
|| Sub-unit of DNA which codes for a specific protein. The translated protein performs a unique function in the cell.
||The entire group of genes possessed by an organism.
|| The actual genes carried by the individual, not necessarily what is expressed (as opposed to phenotype).
|| Organism carrying two different alleles of the same gene (adjective is heterozygous).
|| Organism carrying two of the same allele of a gene (adjective is homozygous).
| Incomplete penetrance
|| Occurs when a gene only sometimes results in disease.
|Mutation|| A change in the nucleotide sequence of a gene.
||A sub-unit of DNA or RNA, consisting of one chemical base plus a phosphate molecule and a sugar molecule. There are four different chemical bases: adenine, guanine, cytosine, and thymine. Nucleotides pair up via hydrogen bonds in the DNA strand to form the double helix.
||When a gene is inherited in a recessive fashion, the mutated allele will not be expressed if there is a normal copy. You must possess two recessive alleles to show the mutated phenotype. eg. cystic fibrosis (opposite of dominant).
|Penetrance||The likelihood that a given gene will actually result in disease.|
|Phenotype||The physical characteristics into which genes are translated (eg. a carrier of the CF gene and a non-carrier have the same phenotype).|
|Polymorphism||Different forms of the same gene or allele.|
|Sex chromosome||Chromosomes that contain the genes that distinguish the sexes. In humans, females have two "X" chromosomes, and males have one "X" and one "Y" chromosome.
| Tumour-suppressor gene
||A gene that normally suppresses cell growth but, if missing or mutated, a cell is allowed to divide uncontrolled.|