BIOL 103 - Chapter 8 Gene Expression

Genes

Sections of DNA that contain a nucleotide sequence with instructions to make a protein.

Regulatory Sequences

On/off switches for genes that determine when a protein is made and how much is made.

Coding Sequences

Determine the amino acid sequence of the protein, which determines its shape and function.

Gene Expression

The two-step process of converting DNA instructions into proteins (transcription and translation).

Transcription

Copies DNA into complementary messenger RNA (mRNA); occurs in the nucleus in eukaryotes.

Translation

Converts the mRNA sequence into an amino acid sequence; occurs on ribosomes.

Codon

A group of three nucleotides on mRNA that specifies one amino acid.

Start Codon

AUG, which specifies methionine and initiates translation.

Stop Codons

UAA, UAG, and UGA, which signal the end of translation.

Primary Protein Structure

The linear sequence of amino acids.

Secondary Protein Structure

Bonding between non-neighboring amino acids forming corkscrew twists or zig-zag folds.

Tertiary Protein Structure

The overall 3D folding and bending of the secondary structure.

Quaternary Protein Structure

The structure formed when two or more polypeptide chains are held together.

Recombinant DNA (rDNA)

A gene containing parts of different genes combined from two or more organisms.

Transgenic Organism

An organism genetically modified to contain genes from another species.