Chapters 11 & 12: Gene Regulation and Gene Mutation

A comprehensive set of vocabulary flashcards covering genetic switches, operons, mutation types, DNA repair mechanisms, and eukaryotic epigenetic regulation based on the lecture notes.

Genetic switch

A mechanism that controls whether a gene is turned on or off, composed of DNA regulatory sequences and regulatory proteins.

Promoter

A DNA region where RNA polymerase binds to start transcription.

Operator

A DNA sequence located near the promoter that controls the access of RNA polymerase to the genes.

Activator

A regulatory protein that increases transcription by helping RNA polymerase bind to the DNA.

Repressor

A regulatory protein that blocks transcription by preventing RNA polymerase from binding to the DNA.

DNA-binding domain

The specific part of a protein that recognizes and binds to specific DNA sequences.

Allosteric site

A region on a protein where small molecules bind, changing the protein's shape and controlling its ability to bind DNA.

Positive Regulation

A form of regulation that turns genes ON, often involving activator proteins that increase transcription.

Negative Regulation

A form of regulation that turns genes OFF, often involving repressor proteins that block transcription.

Operon

A group of genes controlled together by a single promoter and a single operator.

lacZ

A structural gene in the lac operon that produces beta-galactosidase to break down lactose.

lacY

A structural gene in the lac operon that produces permease to allow lactose into the cell.

lacA

A structural gene in the lac operon that produces transacetylase.

Inducer

A molecule, such as lactose in the lac operon, that binds to a repressor and changes its shape so it leaves the operator, turning genes ON.

cAMP

A molecule that increases when glucose levels are low, binding to the CAP protein to increase transcription of the lac operon.

CAP protein

A protein used in positive regulation that, when bound to cAMP, helps RNA polymerase bind to the promoter.

Cis-acting elements

DNA sequences, such as promoters, operators, and enhancers, that regulate genes located on the same DNA molecule.

Trans-acting elements

Proteins that can regulate multiple DNA copies, such as repressor proteins.

Mutation

A change in the DNA sequence.

Mutant

The organism, cell, or phenotype produced as a result of a mutation.

Polymorphism

A genetic variant found in more than $1\%$ of a population, such as SNPs.

SNPs

Single nucleotide polymorphisms; genetic variants that generally do not cause disease but may influence traits.

Germline mutation

A mutation occurring in egg or sperm cells that is passed to offspring and is present in every cell.

Somatic mutation

A mutation that occurs in body cells, is not inherited, and only affects certain cells, such as those in cancer.

Substitution

A single base mutation where one nucleotide replaces another.

Silent mutation

A type of substitution where the DNA sequence changes but the resulting protein remains the same.

Missense mutation

A type of substitution that changes one amino acid in the protein, such as in sickle cell disease.

Nonsense mutation

A type of substitution that creates an early stop codon, resulting in a shortened protein.

Frameshift Mutation

A mutation caused by the insertion or deletion of DNA bases, which shifts the reading frame and changes the entire protein sequence.

Splice-Site Mutation

A mutation that affects the removal of introns, resulting in incorrect mRNA and protein production.

Duplication

A large DNA change where a segment of DNA is copied multiple times.

Translocation

A large DNA change where a segment of DNA is moved to another location.

Pseudogenes

Inactive gene copies that have the potential to disrupt normal genes.

Transposons

Also known as 'jumping genes,' these are DNA sequences that move around the genome and can cause mutations.

Conditional Mutations

Mutations that produce different effects depending on environmental conditions, such as temperature.

DNA repair

The collective processes that protect the genome by fixing base changes, damaged nucleotides, and breaks in DNA strands.

Proofreading

A DNA repair mechanism where DNA polymerase checks the newly synthesized DNA for errors.

Mismatch Repair

A DNA repair process that fixes incorrect base pairing after replication has occurred.

Nucleotide Excision Repair

A DNA repair mechanism that removes damaged sections of DNA, such as those caused by UV damage.

Double-Strand Break Repair

A specialized DNA repair process that fixes physical breaks in both strands of the DNA.

Transcription Factors

Proteins that regulate transcription in eukaryotes, typically containing DNA-binding, activation/repression, dimerization, and ligand-binding domains.

Enhancers

DNA sequences that increase transcription; they can be proximal (close to the gene) or distal (far from the gene).

Coregulators

Proteins that assist transcription factors in controlling RNA polymerase, divided into coactivators and corepressors.

Mediator complex

An example of a coactivator that helps increase transcription.

Histones

Proteins that DNA is packaged around to form chromatin.

Nucleosomes

The basic repeating unit of chromatin, consisting of DNA wrapped around histones.

Euchromatin

A form of chromatin that is 'open' and accessible to proteins, characterized by active transcription.

Heterochromatin

A form of chromatin that is 'closed' and hard to access, characterized by low transcription levels.

Histone Acetylation

The addition of acetyl groups to histones, which loosens DNA and increases transcription.

Histone Methylation

The addition of methyl groups to histones that can either activate or repress genes depending on the specific location.

DNA Methylation

The addition of methyl groups to cytosine; high levels typically turn genes OFF, while low levels turn genes ON.

Chromatin Remodeling

The process of changing nucleosome arrangement to make DNA more or less accessible.

Epigenetics

Changes in gene expression that occur without changing the underlying DNA sequence.

Epigenome

The complete pattern of epigenetic modifications within an organism.

Genomic Imprinting

A phenomenon where gene expression depends on which parent contributed the allele.

X-Chromosome Inactivation

The process in females where one of the two X chromosomes becomes inactive.

Barr body

The inactive, condensed X chromosome found in female cells.

Xist RNA

The RNA molecule that controls the process of X-chromosome inactivation.

Position Effect Variegation

A change in gene expression that depends on where the DNA is located, such as being moved near heterochromatin and becoming silenced.