Chapter 18: 18.1 -18.2

Transcription

The process of synthesizing RNA from a DNA template.

Eukaryotic

Organisms whose cells have a nucleus and other membrane-bound organelles.

Noncoding RNAs

RNA molecules that do not code for proteins but play multiple roles in controlling gene expression.

Multicellular organism

An organism composed of multiple cells that have different functions and specialized roles.

Cancer

A disease caused by genetic changes that affect cell cycle control, leading to uncontrolled cell growth.

Enzyme

A protein that catalyzes specific chemical reactions in the cell.

Promoter

A site on DNA where RNA polymerase can bind to initiate transcription.

mRNA

Messenger RNA, a type of RNA molecule that carries the genetic information from DNA to the ribosome for protein synthesis.

Polypeptide

A chain of amino acids that makes up a protein.

Operator

A segment of DNA that controls the access of RNA polymerase to the genes it regulates.

Metabolic pathway

A series of chemical reactions that convert a starting molecule into a final product.

Tryptophan

An amino acid that is synthesized by cells and is essential for their survival.

Feedback inhibition

A regulatory mechanism in which the end product of a pathway inhibits the activity of an enzyme involved in its synthesis.

Operon

A group of genes that are transcribed together and regulated by a single promoter and operator.

Regulatory gene

A gene that encodes a protein that controls the expression of other genes.

Allosteric protein

A protein that can change its shape and activity in response to binding of a small molecule.

Corepressor

A small molecule that cooperates with a repressor protein to switch off an operon.

Tryptophan

An amino acid that acts as a corepressor in the trp operon, regulating its expression.

Transcription

The process of synthesizing RNA from a DNA template.

Genes

Segments of DNA that contain the instructions for making proteins.

Enzymes

Proteins that catalyze biochemical reactions in cells.

DNA

Deoxyribonucleic acid, the molecule that carries the genetic information in cells.

mRNA

Messenger RNA, the RNA molecule that carries the genetic information from DNA to the ribosomes for protein synthesis.

Repressor

A protein that binds to the operator region of an operon and prevents transcription of the structural genes.

cAMP

Cyclic adenosine monophosphate, a small organic molecule that accumulates when glucose is scarce and acts as a signaling molecule in gene regulation.

CRP

cAMP receptor protein, an activator protein that binds to DNA and stimulates transcription of a gene when cAMP is bound to it.

Lac Operon

An operon in E. coli that controls the expression of genes involved in lactose metabolism.

Glucose

A simple sugar that is the preferred energy source for E. coli. Its presence affects the regulation of the lac operon.

Allolactose

A small organic molecule that binds to the lac repressor and prevents it from binding to the operator, allowing transcription of the lac operon.

Positive Regulation

Gene regulation that occurs when a regulatory protein interacts directly with the genome to switch transcription on.

Negative Control

Gene regulation that occurs when a regulatory protein switches off transcription by binding to the operator region.

RNA Polymerase

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

Promoter

A region of DNA that initiates transcription by providing a binding site for RNA polymerase.

Transcription

The process by which genetic information from DNA is copied into RNA.

Enzymes

Proteins that catalyze biochemical reactions in cells.

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Repressor

A protein that binds to DNA and prevents transcription of a specific gene or set of genes.

Lac operon

A group of genes in bacteria that are involved in the metabolism of lactose.

RNA polymerase

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

Differential gene expression

The process by which different genes are expressed in different cell types or at different times.

Transcription factors

Proteins that bind to DNA and regulate the transcription of genes.

Chromatin

The complex of DNA and proteins that make up chromosomes.

Histone modifications

Chemical modifications to histone proteins that can affect gene expression.

DNA methylation

The addition of a methyl group to DNA, which can affect gene expression.

Control point

A stage in gene expression where regulation can occur, such as transcription or translation.

Chromatin structure

The organization and packaging of DNA and proteins in the nucleus.

Nucleosome

The basic unit of chromatin, consisting of DNA wrapped around histone proteins.

DNA methylation

Alterations in normal patterns of DNA methylation are seen in some cancers, where they are associated with inappropriate gene expression. Methylation patterns are passed on to daughter cells and can be reversed during gamete formation.

Chromatin-modifying enzymes

Enzymes that modify chromatin structure are integral parts of the eukaryotic cell's machinery for regulating transcription. They provide initial control of gene expression by making a region of DNA either more or less able to bind the transcription machinery.

Transcription initiation

The initiation of transcription is the next major step at which gene expression is regulated. Proteins that bind to DNA in eukaryotes either facilitate or inhibit binding of RNA polymerase, similar to bacteria.

Eukaryotic gene organization

A typical eukaryotic gene and its DNA elements (segments) are organized with a promoter sequence where a transcription initiation complex assembles. It also includes coding segments, untranslated regions (UTRs), introns, exons, and a poly-A tail.

Epigenetic inheritance

The chromatin modifications that do not change the DNA sequence but can be passed along to future generations of cells are called epigenetic inheritance. Epigenetic variations play a role in the regulation of gene expression and may explain differences in genetically identical individuals.

RNA polymerase II

An enzyme that transcribes genes by synthesizing a primary RNA transcript (pre-mRNA).

Pre-mRNA

The primary RNA transcript synthesized by RNA polymerase II, which undergoes RNA processing to become mature mRNA.

Control elements

Segments of noncoding DNA that serve as binding sites for transcription factors and regulate gene expression.

Transcription factors

Proteins that bind to control elements on DNA and regulate transcription.

General transcription factors

Proteins that are essential for the transcription of all protein-coding genes and bind to the promoter.

Specific transcription factors

Proteins that bind to control elements close to or farther away from the promoter and are required for the transcription of specific genes.

Enhancers

Control elements located thousands of nucleotides upstream or downstream of a gene, which can strongly increase or decrease the rate of gene expression.

Activators

Specific transcription factors that bind to enhancers and enhance transcription of a given gene.

Repressors

Specific transcription factors that bind to enhancers and inhibit gene expression.

Chromatin modification

The recruitment of proteins that acetylate or remove acetyl groups from histones, leading to either enhanced or reduced transcription, respectively.

Combinatorial control

The precise control of transcription that depends on the binding of multiple activators to DNA control elements.

Transcription initiation complex

The assembly of general transcription factors, mediator proteins, and RNA polymerase II on the promoter, which leads to the initiation of RNA synthesis.

Regulation of Gene Expression

The process by which a gene is turned on or off, resulting in the production or inhibition of a specific protein.

Control elements

DNA sequences that regulate the transcription of a gene by binding to specific transcription factors.

Transcription factors

Proteins that bind to control elements and regulate the initiation of transcription.

Enhancer

A DNA sequence that can increase the transcription of a gene when bound by specific activator proteins.

Activator proteins

Proteins that bind to enhancers and increase the transcription of a gene.

Promoter

A DNA sequence that initiates the transcription of a gene.

Reporter gene

A gene whose mRNA product can be easily measured experimentally to determine the level of gene expression.

Independent variable

The variable that is deliberately changed or manipulated in an experiment.

Dependent variable

The variable that is measured or observed in an experiment and is affected by the independent variable.

Control treatment

The treatment in an experiment that serves as a baseline or reference point and does not receive any experimental manipulation.

Biological explanation

A scientific explanation that relates to the functioning and processes of living organisms.

Steroid hormone

A hormone that can enter a cell and bind to a specific intracellular receptor protein, forming a hormone-receptor complex that serves as a transcription activator.

Signal transduction pathway

A series of molecular events that transmit a signal from the cell surface to the nucleus, resulting in changes in gene expression.

Coordinate regulation

The activation of genes with the same sets of control elements by the same chemical signals.

Nuclear architecture

The organization and spatial arrangement of chromosomes within the nucleus.

Operon

A cluster of coordinately controlled genes in bacteria that are regulated by a single promoter and transcribed into a single mRNA molecule.

Transcription factor

A protein that binds to specific control elements in DNA and regulates the transcription of genes.

Enhancer

A DNA sequence that can increase the transcription of a gene when bound by specific transcription factors.

Post-transcriptional regulation

Mechanisms that operate after transcription to regulate gene expression, such as RNA processing and mRNA degradation.

Alternative RNA splicing

A process in which different mRNA molecules are produced from the same primary transcript by including or excluding different RNA segments.

Chromatin loop

Loops of chromatin that extend from individual chromosomal territories into specific sites in the nucleus, where transcription factories are located.

Nucleotide sequences

Sequences of nucleotides that make up DNA or RNA molecules.

mRNA

Messenger RNA, a type of RNA molecule that carries genetic information from DNA to the ribosomes for protein synthesis.

Untranslated region

The region of an mRNA molecule that does not code for protein and is not translated into amino acids.

3' end

The end of an mRNA molecule where nucleotides are added during transcription.

Short-lived mRNA

mRNA molecules that have a short lifespan and are quickly degraded.

Growth factor

A substance that stimulates cell growth and division.

Globin mRNA

mRNA that codes for globin proteins, which are components of hemoglobin.

RNA molecules

Molecules made up of nucleotides that play various roles in gene expression and regulation.

Protein processing

The modification and maturation of polypeptides into functional protein molecules.

Protein degradation

The breakdown and removal of proteins from the cell.

Insulin polypeptide

A polypeptide that is processed to form the active hormone insulin.

Chemical modifications

Changes made to proteins through the addition or removal of chemical groups.

Regulatory proteins

Proteins that control the activity of other proteins or genes.

Phosphate groups

Chemical groups consisting of phosphorus and oxygen that can be added or removed from proteins to regulate their activity.

Ubiquitin

A small protein that marks other proteins for degradation.