BIO 215: DNA and Gene Expression

Comprehensive vocabulary flashcards covering the molecular biology of DNA, RNA, replication, protein synthesis, and bacterial gene regulation.

Gene

A region of DNA that codes for a single protein.

Genome

The complete set of genetic information, including the chromosome and plasmids.

Nucleotide

The building block of DNA composed of a pentose sugar (deoxyribose), a phosphate group, and a nitrogenous base.

Phosphodiester bond

The covalent bond that joins nucleotides to one another to create a strand.

Complementary base pairing

The joining of nucleotide strands via hydrogen bonds between specific nitrogenous bases: $A$ pairs with $T$ and $C$ pairs with $G$.

Antiparallel

The arrangement of DNA strands where the $5'$ end of one strand is bound to the $3'$ end of the other, and vice versa.

Semiconservative replication

A mode of replication where each new DNA molecule contains one original template strand and one newly synthesized strand.

DNA polymerases

Enzymes responsible for synthesizing DNA by adding nucleotides to the $3'$ end of the new molecule, proceeding in the $5' \rightarrow 3'$ direction.

Gene expression

The process in which a gene is used as a template from which a protein is synthesized.

Transcription

The synthesis of RNA from a DNA template.

Translation

The process where information encoded on an mRNA transcript is deciphered to synthesize a protein.

Messenger RNA (mRNA)

A strand of RNA that is complementary and antiparallel to a gene, serving as a "photocopy" of the genetic instructions.

Promoter

A specific sequence on the DNA where RNA polymerase binds to initiate transcription and designate which gene will be expressed.

Terminator

A DNA sequence that signals RNA polymerase to stop transcription and release the mRNA strand.

Codon

A series of three nucleotides on mRNA that correlates with one specific amino acid on the synthesized protein.

Anticodon

A series of three nucleotides on a tRNA molecule that are complementary to an mRNA codon.

Degenerate

A characteristic of the genetic code meaning that a single amino acid may be coded for by more than one codon.

Constitutive enzymes

Enzymes that are synthesized constantly because they are key to central metabolic pathways.

Inducible enzymes

Enzymes that are synthesized only when their specific substrate is present.

Repressible enzymes

Enzymes whose synthesis is turned off when their specific product is present.

lac Operon

A section of DNA including a promoter, operator, and three genes for lactose degradation, used as a model for understanding bacterial gene regulation.

Signal transduction

The mechanism through which bacterial cells sense environmental changes and adjust their metabolism in response.

Two-Component Regulatory System

A system involving a sensor protein that phosphorylates a response regulator to activate or repress gene expression.

Quorum Sensing

A process where organisms sense the density of their population and activate gene expression only when a critical mass is reached.

Antigenic variation

The random alteration of surface proteins (like flagella or pili) within a population to evade the immune system.

Phase variation

A process where the expression of specific genes is routinely switched on and off within a population of cells.