Chapter 8 2270 Key terms

Expression

The process by which genetic information is used to produce functional products like proteins or RNA.

Transcription

The synthesis of RNA under the direction of DNA.

Translation

The synthesis of proteins under the direction of RNA.

Reverse Transcription

The process of synthesizing DNA from an RNA template.

Origin of Replication

The specific sequence in DNA where replication begins.

Replication Bubble

A region where the DNA double helix is unwound, allowing replication to occur.

Replication Fork

The Y-shaped region where the DNA strands are being separated and replicated.

Primase

An enzyme that synthesizes short RNA primers to initiate DNA replication.

Primer

A short RNA sequence that provides a starting point for DNA synthesis.

DNA Polymerase

An enzyme that synthesizes DNA by adding nucleotides to a growing strand.

dNTP

Deoxyribonucleotide triphosphates, the building blocks for DNA synthesis.

Pyrophosphate

A byproduct of DNA synthesis, released when nucleotides are added to the growing DNA strand.

Leading Strand

The DNA strand that is synthesized continuously in the 5' to 3' direction.

Lagging Strand

The DNA strand that is synthesized discontinuously in short fragments called Okazaki fragments.

Proofreading

The ability of DNA polymerase to correct errors during DNA replication.

DNA Ligase

An enzyme that joins Okazaki fragments on the lagging strand.

DNA Helicase

An enzyme that unwinds the DNA double helix during replication.

Topoisomerase

An enzyme that relieves supercoiling in DNA during replication.

Constitutive Expression

Genes that are expressed at a constant rate and are not regulated.

Repression

The inhibition of gene expression, often by a repressor protein.

Activation

The process of turning on gene expression.

Operator

A DNA sequence that controls the transcription of adjacent genes.

Promoter

A DNA sequence where RNA polymerase binds to initiate transcription.

Induction

The process of turning on gene expression in response to an inducer.

Operon

A set of genes controlled by a single promoter and operator.

cAMP

Cyclic adenosine monophosphate, a signaling molecule involved in gene regulation.

Catabolite Repression

The inhibition of gene expression in the presence of a preferred carbon source like glucose.

CAP

Catabolite activator protein, which binds to cAMP to activate transcription.

Repressor

A protein that inhibits gene expression by binding to the operator.

Corepressor

A molecule that binds to a repressor, enabling it to inhibit gene expression.

Mutation

A permanent change in the DNA sequence.

Point Mutation

A mutation that affects a single nucleotide.

SNP

Single nucleotide polymorphism, a variation at a single position in a DNA sequence.

Transition

A point mutation where a purine is replaced by another purine or a pyrimidine by another pyrimidine.

Transversion

A point mutation where a purine is replaced by a pyrimidine or vice versa.

Indel

An insertion or deletion of nucleotides in a DNA sequence.

Insertion

The addition of one or more nucleotides into a DNA sequence.

Deletion

The removal of one or more nucleotides from a DNA sequence.

Inversion

A mutation where a segment of DNA is reversed in orientation.

Duplication

A mutation where a segment of DNA is copied and inserted elsewhere in the genome.

Transposition

The movement of a DNA segment from one location to another.

Genotype

The genetic makeup of an organism.

Phenotype

The physical expression of the genotype.

Wild-type

The typical form of a gene or organism as it occurs in nature.

Knockout

A mutation that completely inactivates a gene.

Loss of Function

A mutation that reduces or eliminates the function of a gene.

Gain of Function

A mutation that confers a new or enhanced function to a gene.

Reversion

A mutation that restores a gene to its original function.

Silent Mutation

A mutation that does not change the amino acid sequence of a protein.

Missense Mutation

A mutation that results in the substitution of one amino acid for another.

Nonsense Mutation

A mutation that introduces a premature stop codon.

Frame-shift Mutation

A mutation that shifts the reading frame of a gene, altering the amino acid sequence.

Pseudogene

A nonfunctional segment of DNA that resembles a functional gene.

Spontaneous Mutations

Mutations that occur without the influence of external factors.

Base Analog

A chemical that resembles a DNA base and can be incorporated into DNA, causing mutations.

Ionizing Radiation

High-energy radiation that can cause DNA damage and mutations.

Auxotroph

An organism that requires a specific nutrient for growth due to a mutation.

Ames Test

A test used to determine the mutagenic potential of chemicals.

Homologous Recombination

The exchange of genetic material between similar DNA sequences.

Vertical Gene Transfer

The transfer of genes from parent to offspring.

Horizontal Gene Transfer

The transfer of genes between organisms of the same generation.

Conjugation

The transfer of DNA between bacteria through direct cell-to-cell contact.

F-Plasmid

A plasmid that carries genes for bacterial conjugation.

Conjugation Pilus

A structure used by bacteria to transfer DNA during conjugation.

Generalized Transduction

The transfer of random bacterial DNA by a bacteriophage.

Specialized Transduction

The transfer of specific bacterial genes by a bacteriophage.

Transformation

The uptake and incorporation of free DNA by a bacterial cell.

Competence

The ability of a cell to take up DNA from the environment.

Transposon

A DNA segment that can move to different locations in the genome.