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