Smart book 9

Indirect repressors are regulatory proteins that prevent transcription by ____

Interfering with the function off activators

coactivators acetylate amino acid

histone acetyl transferase enzyme

Positively charged ____________ on the N-terminal tails of core histone proteins can be acetylated by the enzyme ______________ ____________

lysines histone acetyltransferase

core-pressers can inhibit transcription by

preventing the RNA polymerase II basal complex from binding to the promoter modifying amino acids in histone tails

Eukaryotic repressors inhibit transcription by _________

recruiting corepressor proteins to enhancers

To initiate translation, ribosomes attach to the mRNA at a site called the ___________-________ site

ribosome binding

In prokaryotes, the RNA polymerase holoenzyme is composed of the core enzyme plus the __________ ______________

sigma factor

Coactivators

Chromatin remodeling complexes

The two protein domains that are found in all activator proteins are the _______-binding domain and the ___________ domain

DNA activation

A repressor protein typically has a(n) ____________ -binding domain, a(n) _________ domain that allows it to interact with corepressors, and a(n) ___________ domain that allows two protein subunits to interact.

DNA bind repression dimer

Two DNA-binding domains that are commonly found in transcription factors are the _______ finger and the ______-turn-______ domains

zinc helix helix

Protein domains found in repressors

DNA binding domain repression dimerization

who proposed the operon theory of gene regulation

François Jacob and Jacques Monod

enzymes that can repress transcription

Histone deacetylase Histone methyltransferase

The enzyme that transcribes a gene's DNA into RNA is called ________ ________

RNA polymerase

basal comple or with coactivatiors

activation domain

Transcription factors that, when bound to an enhancer element, increase transcription of a gene above the basal level, are called transcriptional _________

activators

Enzymes called histone acetyltransferases _____

add acetyl groups to specific lysine residues in a histone

The dimerisation domain of an activator enables the activator to bind to

another transcription factor subunit

if a segment of chromatin is subjected to histone deacetylation, it will likely

become more condensed which will repress gene expression

Pathways that break down complex molecules into smaller units are termed ____________ while pathways that construct end product molecules from simpler units are called ___________

catabolic anabolic

breakdown of sugars occurs via _________ pathways, whereas the synthesis of amino acids occurs via _________ pathways

catabolic anabolic

Histone acetyltransferases can act as transcription factor _______ because they can favor gene expression by acetylating certain lysine residues in histones.

coactivators

Eukaryotic repressors recruit _______ proteins to enhancers

corepressor

Some corepressors are enzymes that modify amino acids in histone tails. Such enzymes may be histone ____________ or histone _________.

deacetylase methyltransferase

Many activators are composed of two protein subunits. To form a complete activator, each protein subunit must have a(n) ______ domain

dimerized

The zinc finger motif is typically found in transcription factors in ______ cells, while the helix-turn-helix domain also occurs in transcription factors in ______ cells

eukaryotic prokaryotic

Core ________ proteins contain a globular domain and a flexible amino-terminal tail. DNA wraps around the globular domains, and the amino-terminal tails protrude from the chromatin.

histone

Some corepressors inhibit transcription by modifying amino acids in the tails of _____________ proteins. Other corepressors interact directly with the RNA pol II basal complex and prevent it from binding to the _____________.

histone promoter

A regulatory protein that prevents transcription by interfering with the function of activators instead of by recruiting corepressors is called a(n) ___________ repressor.

indirect

A molecule that can stimulate production of a protein is called an

inducer

The process by which a specific molecule stimulates synthesis of a given protein is called __________

induction

Enhancer sequences can function at a distance from the promoter because the DNA between the enhancer and promoter will _________ to allow basal factors, Mediator, and activators to interact with one another.

loop

The protein complex that serves as a bridge between RNA polymerase II bound at the promoter and activator or repressor proteins bound at an enhancer is called _________

mediator

An enzyme that adds methyl groups to a histone N-terminal tail is called a histone __________ while an enzyme that removes methyl groups is a histone _________

methyltransferases demethylase

The inhibition of RNA polymerase activity is termed _______________ regulation, whereas the enhancement of RNA polymerase activity is known as ______________ regulation

negative positive

histone acetylation

prevents close packing of nucleosomes and therefore favours gene expression

Activators promote transcription by interacting with basal factors and RNA polymerase to recruit them to the _______ of a gene

promotor

Bacteria can adjust their behavior according to their population density by using a communication system called __________ ___________

quorum sensing

Histone proteins can be chemically modified by adding acetyl or methyl groups to _________ which extend outward from the nucleosome

their N-terminal tails

When bacterial cells are grown in a medium without lactose

there are vey low levels of proteins required for lactose utilisation

Two protein domain

trans binding cis domain

Basal factors, activators, and repressors are collectively known as ______ factors

transcriptional

the protein Lac permease is required for

transporting lactose into the bacterial cell