CH 12 Flashcards
The process in which the information in a gene is made into a functional gene product, such as an RNA molecule or a protein, is termed gene
expression
What are two major benefits of gene regulation?
Expression of genes at appropriate times
The conservation of energy
How can gene regulation conserve energy?
Proteins that metabolize molecules such as small sugars are produced only when those sugars are available in the environment.
Different cell types, such as skin cells and nerve cells, have different morphologies because ___________ are expressed and regulated in different ways in different cells.
genes
During mammalian development
different globin genes are expressed at different developmental stages
The production of the functional product of a gene is called
gene expression.
Most _ in all species are regulated so the proteins they specify are produced at appropriate times and in specific amounts.
gene
Regulation of prokaryotic gene expression typically involves all of the following mechanisms except
regulation of RNA processing
Living organisms benefit from gene regulation because it conserves energy; _____ that are encoded by genes will be produced only when they are______
Proteins; necessary
The morphologies of different cell types, such as skin cells and nerve cells, is strikingly different. This is due to the fact that the cells:
express different genes
Control of gene expression takes place at what levels in eukaryotes? Select all that apply.
Post-translation
Transcription
Processing of mRNA
Translation
Which of the following is an example of developmental gene regulation in mammals?
Different globin genes are expressed in the embryo, fetus, and adult.
Regulatory transcription factors influence the expression of genes by binding directly to DNA at or near the _____ site of a gene
promoter
The process in which the information in a gene is made into a functional gene product, such as an RNA molecule or a protein, is termed gene
expression
Match each mechanism for the regulation of gene expression with the proper description.
(a) Negative control
(b) Positive control
(c) Induction
(d) Repression
(a) A repressor protein binds to DNA and blocks transcription
(b) An activator protein binds to DNA and activates transcription
(c) A small effector molecules activates transcription
(d) A small effector molecules prevents transcription
At what levels does gene regulation occur in prokaryotes?
Post-translation
Transcription
Translation
What are small effector molecules?
Molecules that bind to transcription factors and change their conformation
What are regulatory transcription factors?
Proteins that bind to DNA and affect the transcription of one or more genes
A(n) ______________ is a cluster of genes that are part of a single transcription unit that is under the control of a single promoter.
Operon
Repressors are regulatory transcription ____.
factors
negative
activators
positive
Regulation of prokaryotic gene expression typically involves all of the following mechanisms except
regulation of RNA processing
Operons enable bacteria to
coordinate the regulation of genes with related functions
small effector molecules bind to regulatory _____ factors and cause conformational changes that influence their ability to bind to DNA
transcription
What are the basic components of the lac operon?
promoter
lacA
lacY
lacZ
What is an operon?
A cluster of genes under the transcriptional control of a single promoter
The lacO site of the lac operon is called the _____ and is the site where the repressor protein binds.
Operator
How does the presence of lactose in the cell influence the transcription of the lac operon?
When lactose is present, transcription of the lac operon is high.
When lactose is present, the lac repressor protein does not bind to the operator site and transcription can occur.
What is the CAP site for the lac operon?
The sequence of nucleotides that is recognized by an activator protein
What is the advantage of operon organization in bacteria?
Bacteria can coordinate the expression of multiple genes in the same biological pathway.
In the lac operon, the _______ is the DNA sequence at which the lac repressor binds.
operator
The lac repressor protein prevents the enzyme (1)_____ (2)_____ from transcribing the genes in the lac operon.
RNA polymerase
An activator protein recognizes the ______ of the lac operon.
CAP site
The lac operon is also under positive control by an activator protein called what?
CAP
When _____ binds to CAP, the resulting complex binds to the CAP site near the lac _____. This causes a bend in the DNA that enhances the ability of RNA polymerase to bind, and so the transcription rate is increased
cAMP; promoter
Under what conditions does the lac repressor bind to the operator of the lac operon and prevent transcription?
When the concentration of lactose is low in the cell
Which of the following factors help to increase transcription levels in eukaryotes?
- Binding of an activator protein to DNA
* Loosening of chromatin structure
What are the two components of the core promoter?
TATA box
transcriptional start site
The transcription of the lac operon genes is inhibited when the lac repressor protein binds to
the lac operator
Which of the following describe the TATA box?
- The TATA box is a sequence upstream of the transcriptional start site.
- The TATA box determines the precise starting point for transcription.
The catabolite activator protein (CAP) is involved in ______ control of the lac operon.
positive
Which of the following elements are DNA sequences that regulate gene transcription? Select all that apply.
enhancers
silencers
How do CAP and cAMP increase the transcription of the lac operon?
When CAP and cAMP bind to the CAP site, this enhances binding of RNA polymerase to the promoter site
In order to initiate transcription, RNA polymerase II must associate with proteins known as ______ ___ _____ at the TATA box of the core promoter.
general transcription factors
Proteins that use energy from ATP hydrolysis to change the locations and compositions of nucleosomes are called ATP____________-_______________dependent - complexes.
Chromatin-remodeling
An activator can affect the function of a GTF by
recruiting the GTF to the TATA box
The acetylation of _______ proteins can loosen chromatin packing
histone
A nucleosome-free region (NFR) is
a site on a chromosome that is missing nucleosomes
Which of the following elements are DNA sequences that regulate gene transcription? Select all that apply.
enhancers
silencers
True or false: Repressors can prevent TFIID from binding to the TATA box.
True
During transcription, evicted histones are then reassembled by _______ proteins and placed back on the DNA behind the moving RNA polymerase II. These histones may be _______ so they bind more tightly to the DNA.
chaperone ; deacetylated
What is the function of chromatin-remodeling complexes?
They cause a change in the locations and/or compositions of nucleosomes
Which of the following statements about histone acetylation is TRUE?
Acetylated histone proteins do not bind as tightly to the DNA, which aids in transcription.
True or false: Methylation of DNA near the promoter a eukaryotic gene activates transcription of the gene.
False
Many eukaryotic genes are flanked by a nucleosome- , which is a site that is missing nucleosomes.
free region
Which of the following is a form of gene regulation in which a eukaryotic pre-mRNA can be processed to produce more than one mature RNA?
Alternative splicing
When iron levels are low, the iron regulatory protein:
binds to the iron regulatory element and blocks translation of ferritin
The binding of general transcription factors and RNA polymerase II to the core promoter is facilitated by the actions of -remodeling complexes and -modifying enzymes. This allows the formation of a preinitiation complex.
Chromatin
histone
The protein IRP binds to a site within the ferritin mRNA known as the
Iron regulatory element
Proteins that use energy from ATP hydrolysis to change the locations and compositions of nucleosomes are called ATP-dependent
Chromatin - remodeling complexes
In eukaryotes, DNA methylation usually
inhibits
The process whereby different transcripts are made from a single gene is called
alternative splicing
When the IRP is bound to ______, translation is blocked; when the IRP is bound to ______, translation proceeds.
IRE; iron
The mRNA encoding ferritin is controlled by an RNA-binding protein called the
iron regulatory protein
