Genetics Definitions

Define DNA

Deoxyribonucleic acid contained in nucleus and contains all necessary instructions for making specific proteins required by the body/cell.

Describe structure of DNA

Long molecule shaped into double stranded helix.

Sugar-phosphate backbone with nucleotide “rungs”

Name nucleotides

Adenine, thymine, guanine, cytosine

State complementary nucleotide bases

Adenine and thymine, guanine and cytosine

Name components of sugar-phosphate backbone

Phosphate group + deoxyribo sugar (DNA)

Phosphate group + ribo sugar (RNA)

Name bonds between nucleotide groups

Hydrogen bonds (2 for adenine and thymine, 3 for guanine and cytosine)

Define gene

Unit of heredity that is a code for a specific protein/enzyme at a specific location on a chromosome

Define allele

Alternate DNA sequences for a gene, leads to different versions of the same gene (located on same position on a chromosome)

Define autosome

Chromosome pairs 1-22, same in males and females (ordered biggest to smaller)

Define sex chromosome

Chromosome pair 23 (XX in females, XY in males)

Define gene locus/loci

Location of one gene/location of multiple genes

Define homozygous alleles

Identical alleles (maternal and paternal inherited alleles are same)

Define heterozygous alleles

Different alleles (maternal and paternal inherited alleles are different)

Define genotype

The two alleles for a gene (genetic makeup)

Define phenotype

Physical characteristic inherited from gene due to alleles (depends on which allele is dominant). Can also be influenced by the environment (e.g. tanner skin due to sun exposure)