Biology 225 (Perry)- Unit 2

Define a gene and explain how it codes for a protein.

A gene is not just a segment of DNA, a gene is a specific sequence of nucleotides that codes for a functional product, usually a protein. When a gene is expressed (gene expression) the DNA is transcribed to produce mRNA. The mRNA is then translated into proteins. The DNA in a cell is duplicated (DNA replication) before the cell divides so each daughter cell receives the same genetic information.

Genotype

The genetic composition of an organism - all of its DNA and the genes contained in the DNA.

Phenotype

The result of expression of the genes - the proteins of the cell and the properties they confer on the organism.

Define genetics.

The study of what genes are, how they carry information, how their information is expressed, and how they are replicated and passed to subsequent generations or other organisms.