UNIT 4 -- Genetics

DNA (Deoxyribonucleic Acid)

The double-helix molecule that stores genetic information in the sequence of its nitrogenous bases.

Nitrogenous Bases of DNA

Adenine (A), Thymine (T), Cytosine (C), and Guanine (G); A pairs with T, and C pairs with G.

RNA (Ribonucleic Acid)

A single-stranded nucleic acid that carries genetic messages from DNA to the ribosome; contains Uracil (U) instead of Thymine (T).

Codon

A sequence of three bases on mRNA that codes for a specific amino acid.

Gene

A section of DNA that contains the instructions to produce one specific protein.

Chromosome

A tightly coiled structure of DNA and proteins that carries genetic information.

Mutation

A change in the base sequence of DNA, which can alter the resulting protein.

Inheritance of Mutations

Mutations can only be passed to offspring if they occur in gametes (sperm or egg cells); somatic (body) cell mutations are not inherited.

Mutagen

An environmental agent that increases the frequency of mutations (ex: UV radiation, X-rays, toxic chemicals).

Selective Breeding

The process of breeding organisms with desired traits to produce offspring with those traits (artificial selection).

Genetic Engineering

Technology used to alter the genetic instructions of an organism by inserting genes from another organism.

Restriction Enzymes

Enzymes used to cut DNA at specific base sequences for genetic engineering and gel electrophoresis.

Gel Electrophoresis

A laboratory technique used to separate DNA fragments by size using an electric current, producing a DNA fingerprint to show evolutionary or hereditary relationships.

Cloning

Creating an organism that is genetically identical to another by inserting the nucleus of a somatic cell into an enucleated egg cell.