Biology 114- Chapter 13 Learnsmart
1. Cis 2. Acting
A (1)_____-(2)_____ element is a DNA segment that must be adjacent to the gene that it regulates.
1. Cis 2. Trans
A (1)_____-effect is mediated by a DNA element that binds regulator proteins, whereas a (2)_____-effect is mediated by genes that encode diffusible regulatory proteins.
Contains F` factor genes
A merozygote is a bacterium that
Inducer
A small effector molecule that increases the rate of transcription is called a(n) _____.
Their covalent modifications
According to the histone code hypothesis, proteins recognize histones based on:
Inducible
An operon that can be turned on in the presence of a small effector molecule is said to be a(n) _____ operon.
1. One or more repressor proteins may be involved in transcriptional regulation 2. One or more activator proteins may be involved in transcriptional regulation 3. DNA methylation usually inhibits transcription
At the level of transcription, there are several common factors that contribute to combinatorial control. What are they? (Check ALL that apply)
1. Post-translation 2. Transcription 3. Translation 4. Processing of mRNA
At what levels does gene regulation occur in eukaryotes? (Check ALL that apply)
1. Translation 2. Post-translation 3. Transcription
At what levels does gene regulation occur in prokaryotes? (Check ALL that apply)
Activator and repressor
Both prokaryotes and eukaryotes use _____ proteins to regulate the process of transcription.
The low level of transcription activated by the core promoter alone
What is basal transcription?
The process by which cells become specialized in different types
What is cell differentiation?
The sequence of nucleotides that is recognized by an activator protein
What is the CAP site for the lac operon?
High levels of tryptophan will result in low levels of transcription
What is the effect of high levels of tryptophan on the transcription of the trp operon?
GTFs and RNA polymerase come together at the core promoter for the initiation of transcription
What is the function of general transcription factors (GTFs) in the initiation of transcription?
The repressor protein binds to the operator site and prevents the transcription of the trp operon.
What is the role of the repressor protein in the transcription of the trp operon?
cAMP
What small effector molecule is involved in the activation of the lac operon when glucose is absent?
Chromatin
DNA and its associated proteins form a compact structure called:
Enhancer; chromatin
DNA methylation may prevent transcription by blocking a(n) _____ site or by converting _____ to a closed conformation.
Genes
Different cell types, such as skin cells and nerve cells, have different morphologies because _____ are expressed and regulated in different ways in different cells.
1. II 2. mediator
For initiation of eukaryotic transcription at the core promoter, three types of proteins are needed: RNA polymerase (1)_____, GTFs, and a large protein complex called (2)_____.
E. coli
Francois Jacob and Jacques Monod studied enzyme adaptation in:
The degree of chromatin compaction
Histone modifications primarily affect:
When CAP and cAMP bind to the CAP site, this enhances binding of RNA polymerase to the promoter site
How do CAP and cAMP increase the transcription of the lac operon?
Activators and repressors interact with GTFs or mediator proteins
How do activators and repressors regulate the function of RNA polymerase in eukaryotes?
1. Polymerase 2. Factors
In eukaryotic transcription, the two major components of the pre-initiation complex are RNA (1)_____ II and general transcription (2)_____.
Repressor
The lacl gene encodes the lac _____.
Catabolite repression
When glucose is present in a bacterial cell, it can act to repress the expression of the lac operon because it is preferentially used compared to other sugars. What form of transcriptional regulation is this?
The mediator protein controls interactions between the pre-initiation complex and other regulatory elements.
How does the mediator protein interact with RNA polymerase and the GTFs during the initiation of transcription?
1. When lactose is present, transcription of the lac operon is high 2. When lactose is present, the lac repressor protein does not bind to the operator site and transcription can occur
How does the presence of lactose in the cell influence the transcription of the lac operon? (Check ALL that apply)
1. Activators 2. Repressors
In eukaryotes, the rate of transcription of genes is influenced by regulatory transcription factors called (1)_____ and (2)_____. These proteins bind to regulatory elements and control the gene expression rate.
Enhancers
In eukaryotic DNA, regulatory elements known as _____ play a role in the ability of RNA polymerase to begin transcription, thereby increasing the rate of transcription.
Operator
In the lac operon, the _____ is the DNA sequence at which the lac repressor binds.
1. Regulation of RNA processing
Regulation of prokaryotic gene expression typically involves all of the following mechanisms EXCEPT:
1. Core Promoter 2. RNA polymerase II 3. GTFs
Select all of the following that form the pre-initiation complex in eukaryotic transcription, including the binding site. (Check ALL that apply)
Transcription
Small effector molecules bind to regulatory _____ factors and cause conformational changes that influence their ability to bind to DNA.
Genome
The _____ of a cell is the complete set of genes present.
The repressor binds to the operator and prevents transcription
The binding of the corepressor to the trp repressor results in what?
1. Genome 2. Proteomes
The different cell types of an individual contain the same (1)_____, meaning they carry the same set of genes. However, their (2)_____, which is the collection of proteins they make, is quite different.
1. Adenylyl 2. Cyclase
The effector molecule cyclic AMP (cAMP) is produced from ATP via an enzyme known as (1)_____ (2)_____.
1. DNA 2. methyltransferase
The enzyme (1)_____ (2)_____ is responsible for covalently attaching methyl groups to DNA.
to repress transcription of the lac operon
The function of the protein encoded by lacl is:
1. Fetal 2. Birth 3. Fetus
The hemoglobin produced during the embryonic and (1)_____ stages has a higher binding affinity for oxygen than does the hemoglobin produced after (2)_____. Therefore, the embryo and (3)_____ can remove oxygen from the mother's bloodstream and use that oxygen for their own needs.
CAP
The lac operon is also under positive control by an activator protein called what?
Breakdown of a substance
The lac operon is an example of an operon involved in:
Inducible
The lac operon is said to be a(n) _____ operon because the binding of an effector molecule increases the rate of transcription.
Absent; present
The lac repressor binds to the lac operon when lactose is _____, and the trp repressor binds to the trp operon when tryptophan is _____.
RNA polymerase
The lac repressor protein prevents the enzyme (1)_____ (2)_____ from transcribing the genes in the lac operon.
Operator
The lacO site of the lac operon is called the _____ and is the site where the repressor protein binds.
Lactose; glucose; CAP; lacO
Transcription rate of the lac operon is very high when _____ levels are high and _____ levels are low. This is because the protein _____ is bound to the DNA, and the lac repressor is not bound to the _____ site.
Proteins that bind to DNA and affect the transcription of one or more genes
What are regulatory transcription factors?
Regulatory elements that can prevent or decrease transcription
What are silencers?
1. Regulatory elements 2. Transcriptional start site 3. TATA box
What are the three features common to most promoters that are needed for the initiation of transcription of protein coding genes in eukaryotes? (Check ALL that apply)
Repressible
An operon in which a small effector molecule prevents transcription is called a(n) _____ operon.
Activators and repressors can bind to GTFs or mediator and can influence the level of DNA compaction at the promoter site
How do activator and repressor proteins regulate transcription in eukaryotes?
It binds to the repressor protein and prevents it from binding to the operator site of the lac operon
How does allolactose affect the lac repressor protein?
Transcription
Most gene regulation in both prokaryotes and eukaryotes occurs at the level of:
1. Post-translational regulation 2. Regulation of transcription 3. Regulation of translation
Which of the following are ways of regulating gene expression in BOTH prokaryotes and eukaryotes? (Check ALL that apply)
1. Binding of an activator protein to DNA 2. Loosening of chromatin structure
Which of the following factors help to increase transcription levels in eukaryotes? (Check ALL that apply)
lacl
Which of the following genes encodes the lac repressor protein?
Glucose inhibits the production of cAMP, thereby preventing the activation of the lac operon
How does glucose repress the expression of the lac operon?
By attracting proteins that affect gene transcription
How does the histone code play a key role in transcription?
Differentiation
In humans, a cell can become a muscle cell, kidney cell, skin cell, neuron, etc. This is an example of the process of cell _____.
1. Embryonic 2. Fetal
In humans, the (1)_____ stage lasts from fertilization to 8 weeks. This is followed by the (2)_____ stage, which lasts until birth.
Combinatorial control
In many multicellular species a combination of many different factors determines the regulation of gene expression. This is called:
1. RNA Polymerase- synthesis of RNA from a DNA template 2. General Transcription Factors- required for binding to the core promoter and initiating transcription 3. Activators- binding to enhancer sequences and interaction with other proteins
Match each protein or group of proteins with its role in transcription:
1. Transcription- The amount of RNA synthesized from a gene is regulated 2. RNA processing- Two or more different types of mRNA are created from a single gene 3. Translation- The amount of protein synthesized from a mRNA is regulated 4. Post-translation- Protein function is affected by feedback inhibition, covalent modifications, and degradation
Match each regulated step of eukaryotic gene expression with the appropriate description
1. The repressor proteins bind to the operator in the PRESENCE of the small effector molecule- trp operon 2. The repressor proteins binds to the operator in the ABSENCE of the small effector molecule- lac operon
Match the operon with the proper effect of the small effector molecule on the repressor protein.
Encodes more than one protein
Polycistronic mRNA:
Express different genes
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:
Prevent transcription of the lac operon
The protein encoded by the lacl gene functions to:
The lac operator
The transcription of the lac operon genes is inhibited when the lac repressor protein binds to:
Repressor
The trp operon is under negative control by a(n) _____ protein.
1. TATA 2. Site
The two components that make up the core promoter are the (1)_____ box and the transcriptional start (2)_____.
lac operon in the presence of lactose
This diagram is a representation of the: (Diagram is Figure 13.7b)
An operon that can be repressed by the presence of a small effector molecule
What is a repressible operon?
A cluster of genes under the transcriptional control of a single promoter
What is an operon?
The synthesis of the amino acid tryptophan
What is the function of the genes encoded by the trp operon?
Allolactose
What is the inducer molecule for the lac operon?
Repressor proteins bind to DNA and decrease the rate of transcription
What is the role of repressor proteins in the regulation of transcription?
It is expressed in the presence or absence of lactose
What statement about the lacl gene is TRUE?
Hemoglobin has four protein subunits, that are encoded by two different globin genes
What statement correctly describes the structure of the protein hemoglobin?
Activator
When _____ proteins bind to DNA, they increase the rate of transcription.
Enzyme adaptation
When an enzyme appears in a living cell only after the cell has been exposed to an environment in which the substrate for the enzyme is found, this is called:
CAP
When cAMP binds to a protein called _____, it enhances the transcription of the genes of the lac operon.
1. Closed 2. Open
When chromatin is tightly packed, this is called the (1)_____ conformation, and when it is loosely packed, this is called the (2)_____ conformation.
When no mRNA is transcribed from the gene
When is a gene "turned off"?
Negative control
When transcription is regulated by repressor proteins, this is called:
Positive
When transcription of a gene is regulated by activator proteins, the gene is under _____ control.
The merozygote strain in the presence of lactose
Which of the following E. coli strains in the Jacob, Monod, and Pardee experiment had the highest expression of the lac operon?
1. Loosely packed chromatin allows transcription factors and RNA polymerase to access the promoter site and transcription can take place 2. Tightly packed chromatin is difficult to transcribe
Which of the following accurately describe the role of chromatin packing in the expression of eukaryotic genes? (Check ALL that apply)
1. Combinatorial control of gene expression is more common in eukaryotes. 2. The majority of genes are organized individually in eukaryotes, but are organized as operons in prokaryotes. 3. The complexity of eukaryotic development requires that transcription be more coordinated and integrated than in prokaryotes.
Which of the following are key differences between eukaryotic and prokaryotic transcriptional regulation? (Check ALL that apply)
trpA, trpB, trpC, trpD, trpE
Which of the following are the structural genes found in the trp operon?
trp operon
Which of the following is an example of an operon that is involved in the biosynthesis of a substance?
Different globin genes are expressed in the embryo, fetus, and adult
Which of the following is an example of developmental gene regulation in mammals?
It has its own promoter and is not considered a part of the lac operon
Which of the following statements about the lacl gene is true?
When allolactose is produced, this causes the transcription of the lac operon
Why is the lac operon considered inducible?
Hemoglobin
_____ is the main protein that delivers oxygen to cells of a mammal's body.
