Unit 6: Gene Expression and Regulation (copy)

DNA

Deoxyribonucleic acid, the molecule that carries the genetic instructions for life.

Nucleotide

The basic building block of DNA, consisting of a five-carbon sugar, a phosphate group, and a nitrogenous base.

Deoxyribose

The pentagon-shaped sugar component of DNA.

Double helix

The shape of DNA, consisting of two strands twisted around each other.

Base pairing

The specific pairing of nitrogenous bases in DNA: adenine with thymine (A–T) and cytosine with guanine (G–C).

Euchromatin

Loose form of DNA found in the nucleus, genes are active and available for transcription.

Heterochromatin

Condensed form of DNA that is generally inactive in gene expression.

DNA replication

The process of copying DNA to produce two identical molecules.

Helicase

The enzyme that unwinds the DNA double helix during replication.

Template

A DNA strand that serves as a guide for the synthesis of a complementary strand.

Okazaki fragments

Short segments of DNA synthesized on the lagging strand during DNA replication.

RNA polymerase

The enzyme that synthesizes RNA from a DNA template during transcription.

mRNA

Messenger RNA, a temporary RNA copy of a gene that is translated into a protein.

tRNA

Transfer RNA, the molecule that brings amino acids to the ribosome during protein synthesis.

Ribosome

The cellular machinery that synthesizes proteins by translating mRNA.

Codon

A sequence of three nucleotides in mRNA that codes for a specific amino acid.

Stop codon

Nucleotide triplet that signals the termination of protein synthesis.

Mutations

Errors in the genetic code that can alter gene function.

Base substitution

A type of mutation where one nucleotide is replaced with another.

Nonsense mutation

A mutation that creates a premature stop codon, truncating protein synthesis.

Gene rearrangements

Mutations involving the alteration of the structure of genes or chromosomes.

Biotechnology

The use of technology to manipulate biological systems for the purpose of developing products.

Recombinant DNA

DNA that has been artificially created by combining DNA from different sources.

Polymerase Chain Reaction (PCR)

A technique used to amplify specific DNA sequences to create millions of copies.

Transformation

The process of introducing foreign DNA into a bacterial cell.