Cell Bio Chapter 8 Exam 2

Gene expression

the process by which a gene makes a product that is useful to the cell or organism by directing the synthesis of a protein or an RNA molecule with a characteristic activity

Differentiation

process by which a pluripotent cell undergoes a progressive, coordinated change to a more specialized cell type, brought about by large scale changes in gene expression

Housekeeping proteins

proteins common to all cells; includes RNA polymerases, DNA repair enzymes, ribosomal proteins, enzymes involved in glycolysis and other basic metabolic processes, and many of the proteins that form the cytoskeleton

Transcription regulation

determines which genes a cell transcribes into RNA

RNA sequencing

the most comprehensive method for analyzing gene expression

Transcription regulators/factors

proteins that bind to specific DNA sequences and control gene transcription

Promoter

DNA sequence that initiates gene transcription; includes sequences recognized by RNA polymerase and its accessory proteins

Transcription initiation site

where RNA synthesis begins

Recognition sites

sequences nearby transcription initiation sites that associate with RNA polymerase; sigma factor in bacteria or general transcription factors in eukaryotes

Regulatory DNA sequences

DNA sequence to which a transcription regulator binds to determine when, where, and in what quantities a gene is to be transcribed into RNA

Transcription regulators

protein that binds specifically to a regulatory DNA sequences to switch a gene either on or off

Transcription factor binding

factors tightly bind to the DNA double helix recognizing specific nucleotide sequences usually inserting itself into the major groove of DNA forming noncovalent molecular contacts with the nucleotide pairs in the groove

Operons

a cluster of genes on a chromosome that are transcribed from a single promoter as one long mRNA molecule

Operator

short DNa sequence that a transcription regulator recognizes

Transcriptional repressor

a protein that binds to a specific regulatory region of DNA to prevent transcription of an adjacent gene

Transcriptional activator

a protein that binds to a specific region of DNA to stimulate transcription of an adjacent gene

Enhancers

eukaryotic gene activators’ site that dramatically enhance the rate of transcription

Mediator

large complex of additional proteins that serve as adaptors to close the DNA loop between the enhancer and promoter

Eukaryotic repressor proteins

decrease transcription by blocking the assembly of the transcription initiation complex or by keeping the formed complex locked in place so RNA polymerase cannot move forward

Combinatorial control

describes the way in which groups of transcription regulators work together to regulate the expression of a single gene

Reporter gene

gene encoding a protein whose activity is easy to monitor experimentally; used to study the expression pattern of a target gene or the localization of its protein product

Induced pluripotent stem (iPS) cells

somatic cell that has been reprogrammed to resemble and behave like a pluripotent embryonic stem (ES) cell through the artificial introduction of a set of genes encoding particular transcription regulators

Cell memory

the ability of differentiated cells and their descendants to maintain their identity

Positive feedback loop

an important form of regulation in which the end product of a reaction or pathway stimulates continued production or activity; can control a variety of biological processes, including enzyme activity, cell signaling, and gene expression

DNA methylation

the enzymatic addition of methyl groups to cytosine bases in DNA; this covalent modification generally turns off genes by attracting proteins that block gene expression

Epigenetic inheritance

the transmission of a heritable pattern of gene expression from one cell to its progeny that doesn’t involve altering the nucleotide sequence of the DNA

Post transcriptional controls

regulation of gene expression that occurs after transcription of the gene has begun; examples include RNA splicing and translational control

Regulatory RNA

RNA molecule that plays a role in controlling gene expression

MicroRNAs (miRNAs)

small noncoding RNA that control gene expression by base pairing with a specific mRNA to regulate its stability and its translation

RNA interference (RNAi)

cellular mechanism activated by double stranded RNA molecules that results int he destruction of RNAs containing a similar nucleotide sequence; widely exploited as an experimental tool for preventing the expression of selected genes (gene silencing)

Small interfering RNA (siRNA)

short length of RNA produced from double stranded RNA during the process of RNA interference; it base pairs with complementary sequences in other RNAs, leading tot he inactivation or destruction of the target RNA

CRISPR

system for gene editing based on a bacterial enzyme that uses a guide RNA molecule to search for and modify specific nucleotide sequences in the genome

Long noncoding RNAs

class of RNA molecules more than 300 nucleotides in length that doesn’t encode proteins; often used to regulate gene expression