Gen BCH Final
The table below shows four possible mRNA products of this gene. Use the labels to explain what may have caused each mRNA. 1. exon 1, exon 2, intron 2, exon 3 2. no mRNA produce 3. exon 1, intron 1, exon 2, intron 2, exon 3 4. exon 1, exon 2, exon 3
1. mutation in a splicing signal sequence in intron 2 2. mutation in the gene's promoter sequence 3. mutations in splicing signal sequences in both intron 1 and intron 2 4. no mutation in any splicing signal sequence
The linker histone H! has a high proportion of the following amino acid residue. a. isoleucine b. lysine c. leucine d. asparagine e. histidine
b. lysine
Part A: Which of the following lists steps of mRNA production in eukaryotes in the correct order? a. Transcription, 5' cap addition, addition of poly-A tail, passage through nuclear membrane, exon splicing b. Transcription, addition of poly-A tail, 5' cap addition, exon splicing, passage through nuclear membrane c. Transcription, 5' cap addition, addition of poly-A tail, exon splicing, passage through nuclear membrane d. 5' cap addition, addition of poly-A tail, exon splicing, passage through nuclear membrane, transcription
c. transcription, 5' cap addition, additions of a poly-A tail, exon splicing, passage through nuclear membrane
translation
is the process of protein synthesis using mRNA produced during transcription
Part A: Arrange the steps of transcription of DNA to synthesize mRNA. Rank the steps of transcription of DNA to synthesize mRNA.
1. DNA double helix unwinds to expose the nucleotide bases 2. RNA polymerase identifies the start sequence 3. RNA polymerase adds bases that are complementary to the DNA template 4. RNA polymerase identifies the termination sequence 5. mRNA strand and RNA polymerase are released
Transcription in eukaryotes. Drag the labels into the flowchart to show the order of events as they are thought to occur during eukaryotic transcription involving RNA polymerase II (RNA pol II)
1. TFIID binds to the TATA box 2. TFIIB, TFIIF, and RNA pol II bind 3. TFIIE and TFIIH bind 4. Synthesis of the pre-mRNA begins at the +1 nucleotide 5. a 5' cap is added to the pre-mRNA 6. spliceosome complexes carry out intron splicing 7. a poly-A tail is added to the pre-mRNA
Part A - Operon vocabulary Can you match terms related to operons to their definitions? Drag the terms on the left to the appropriate blanks on the right to complete the sentences.
1. an OPERON is a scratch of DNA consisting of an operator, a promoter, and genes for a related set of proteins, usually making up an entire metabolic pathway 2. the GENES OF AN OPERON is/are arranged sequentially after the promoter 3. a(n) PROMOTER is a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place 4. A(n) REGULATORY GENE codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes. 5. regulatory proteins bind to the OPERATOR to control expression of the operon 6. a(n) REPRESSOR is a protein that inhibits gene transcription. In prokaryotes, this protein binds to the DNA in or near the promoter 7. a(n) INDUCER is a specific small molecules that binds to a bacterial regulatory protein and changes its shape so that it cannot bind to an operator, this switching an operon on
Part A - maintaining homeostasis 1. This heating system maintains room temperature at or near a particular value, known as the 2. You open the window, and a blast of icy air enters the room. The temperature drops to 17 degrees Celsius, which acts as a _____ to the heating system 3. The thermostat is a ______ that detects the stimulus and triggers a response. 4. The heater turns on, and the temperature in the room _______ until it returns to the original setting. 5. The response of the heating system reduces the stimulus. This is an example of _______ feedback 6. The way this heating system maintains a stable room temperature is similar to the way an animal's body controls many aspects of its internal environment. The maintenance of a relatively constant internal environment is known as _________
1. set point 2. stimulus 3. sensor 4. increases 5. negative 6. homeostasis
If each base pair has a mass of about 660 daltons and there are about 2 g of protein (histones plus nonhistones) per gram of DNA, how much does such a chromosome weigh (in grams)?
3.3⋅10−13 g
If the DNA were extended, how long would it be?
3.4 cm
An actual chromosome is about 5 μm long. What is the approximate compaction ratio?
6800
elongation
A new tRNA carrying an amino acid arrives at the ribosome, at the next codon. If its anticodon matches the mRNA codon, it base-pairs and the ribosome joins the two amino acids together by a peptide bond. The ribosome then moves one triplet forward and a new tRNA carrying an amino acid arrives at the ribosome and the procedure repeats.
Part A - tRNA interactions with mRNA and the ribosome Ribosomes provide the scaffolding on which tRNAs interact with mRNA during translation of an mRNA sequence to a chain of amino acids. A ribosome has three binding sites, each of which has a distinct function in the tRNA-mRNA interactions. Drag the appropriate tRNAs to the binding sites on the ribosome to show the configuration immediately before a new peptide bond forms.
E -- empty P -- AUA with 3 piece A -- UCC with 1 piece
formation of the new peptide bond
In the process, the polypeptide chain is transferred from the tRNA in the P site to the amino acid on the tRNA in the A site.
movement of the mRNA through the ribosome
In this step, the discharged tRNA shifts to the E site (where it is released) and the tRNA carrying the growing polypeptide shifts to the P site.
chain termination
Most bacterial genes have a pair of inverted repeats and a polyadenine sequence located downstream of the RNA-coding region. Transcription of the inverted repeats produces an RNA transcript that folds into a stem-loop structure. Transcription of the polyadenine sequence produces a poly-U sequence in the RNA transcript, which facilitates release of the transcript from the DNA.
Part C - protein targeting pathways For each protein, identify its targeting pathway: the sequence of cellular locations in which the protein is found from when translation is complete until it reaches its final (functional) destination. (Note that if an organelle is listed in a pathway, the location implied is inside the organelle, not in the membrane that surrounds the organelle.)
PFK -- cytoplasm only insulin -- ER -> Golgi -> outside cell
promoter recognition
RNA polymerase is a holoenzyme composed of a five-subunit core enzyme and a sigma ( σ ) subunit. Different types of σ subunits aid in the recognition of different forms of bacterial promoters. The bacterial promoter is located immediately upstream of the starting point of transcription (identified as the +1 nucleotide of the gene). The promoter includes two short sequences, the -10 and -35 consensus sequences, which are recognized by the σ subunit.
chain initiation
The RNA polymerase holoenzyme first binds loosely to the promoter sequence and then binds tightly to it to form the closed promoter complex. An open promoter complex is formed once approximately 18 bp of DNA around the -10 consensus sequence are unwound. The holoenzyme then initiates RNA synthesis at the +1 nucleotide of the template strand.
chain elongation
The RNA-coding region is the portion of the gene that is transcribed into RNA. RNA polymerase synthesizes RNA in the 5′ → 3′ direction as it moves along the template strand of DNA. The nucleotide sequence of the RNA transcript is complementary to that of the template strand and the same as that of the coding (nontemplate) strand, except that the transcript contains U instead of T.
binding of the charged tRNA to the A site
This step requires correct base-pairing between the codon on the mRNA and the anticodon on the tRNA
termination
When the ribosome reaches one of the three stop codons, for example, UGA, there is no corresponding tRNA to this codon and hence it does not code for any amino acid. Instead, termination proteins bind to the ribosome and stimulate the release of the polypeptide chain, and the large and small ribosomal subunits separate from the mRNA.
Arrange the following events for the synthesis of RNA in the correct order: 1) nucleophilic attack of the 3' OH group of the first nucleotide at the a-phosphate group of the second nucleotide 5' triphosphate occurs 2) Template specific rNTPs are bound. 3) Several DNA bases are unwound, forming a stable complex. 4) Polymerase finds a promoter region. 5) A Mg+2-dependent isomerization of DNA takes place. a. 4, 3, 5, 2, 1 b. 4, 3, 2, 5, 1 c. 4, 2, 3, 5, 1 d. 4, 1, 3, 2, 5
a. 4, 3, 5, 2, 1
Which of these is responsible for initiating a signal transduction pathway? a. A b. B c. C d. D e. E
a. A
Part A: Once elongation is underway, tRNAs involved in the process occupy a series of sites on the complexed ribosome. The occupation of sites occurs in the following order. a. A Site, P Site, E Site b. P Site, E Site, A Site c. A Site, P Site, E Site, S Site d. A Site, S Site, E Site
a. A Site, P Site, E Site
Which of the following choices represent mRNA molecules that could be produced from the primary RNA transcript by alternative RNA splicing? (In each choice, the yellow part on the left represents the 5' cap, and the yellow part on the right represents the poly-A tail.) a. ACEI b. BDEH c. BDFH d. ACGI e. ACEGI f. ACDI g. BFHI
a. ACEI d. ACGI e. ACEGI
Which of the following best describes the role of chaperone proteins in the regulation of gene expression by steroid hormones? a, Chaperone proteins maintain functionality of the receptor. b. Chaperone proteins activate receptor proteins. c. Chaperone proteins directly enhance transcription. d. Chaperone proteins enter the cell and bind receptor molecules.
a. Chaperone proteins maintain functionality of the receptor
What is the role of activated protein kinases? a. Phosphorylate proteins. b. Degrade cAMP to AMP. c. Activate adenylate cyclase. d. Convert ATP to cAMP by phosphorylation. e. Phosphorylate ADP to ATP
a. Phosphorylate proteins.
Which of the following events in transcription initiation likely occurs last? a. RNA polymerase binds to the promoter of the gene. b. Regulatory transcription factors bind to enhancers. c. Basal transcription factors form a basal transcription complex. d. TBP is recruited to the promoter
a. RNA polymerase binds to the promoter of the gene
Part C: What name is given to the process in which pre-mRNA is edited into mRNA? a. RNA processing b. gene expression c. polypeptide formation d. transcription e. translation
a. RNA processing
The diagram below shows a length of DNA containing a bacterial gene. Drag the labels to their appropriate locations in the diagram to describe the function or characteristics of each part of the gene.
a. RNA-coding region -- same sequence as RNA transcript (except for having T instead of U) b. inverted repeats -- produces stem loop structure in RNA transcript c. -35 consensus sequence/-10 consensus sequence -- recognize by σ subunit of RNA polymerase d. complementary to RNA transcript e. polyadenine sequence -- leads to an unstable RNA-DNA duplex
Part A: In prokaryotes, the methionine that initiates the formation of a polypeptide chain differs from subsequently added methionines in that _______. a. a formyl group is attached to the initiating methionine b. the initiating methionine is not an amino acid c. incorporation of the initial methionine does not require a tRNA d. its tRNA anticodon is not complementary to the AUG codon
a. a formyl group is attached to the initiating methionine
Part B - predicting the effect of a point mutation Based on the genetic code chart above, which of the following would be the result of this single base-pair substitution? a. a nonsense mutation resulting in early termination of translation b. a frameshift mutation causing a single amino acid change in the protein c. a missense mutation causing a single amino acid change in the protein d. a silent mutation (no change in the amino acid sequence of the protein) e. a frameshift mutation causing extensive change in the amino acid sequence of the protein
a. a nonsense mutation resulting in early termination of translation
Part B - controlling blood glucose levels In the animation, you saw that both high blood glucose levels and low blood glucose levels are stimuli that trigger specific responses by the body. These responses cause blood glucose levels to return to their normal range. In this activity, you will explore how this happens.
a. beta cells of pancreas release insulin b. body cells take up more glucose c. liver takes up glucose and build glycogen d. blood glucose levels fall e. alpha cells of pancreas release glucagon f. liver breaks down glycogen and releases glucose g. blood glucose levels rise
Part E: Translation occurs in the ______. a. cytoplasm b. lysosome c. nucleus d. mitochondrion e. nucleoplasm
a. cytoplasm
Part A - Locations of the processes involved in protein synthesis In eukaryotic cells, the processes of protein synthesis occur in different cellular locations. Drag the labels to the appropriate targets to identify where in the cell each process associated with protein synthesis takes place.
a. formation of ribosomal subunits b. attachment of an amino acid to tRNA c. translation of cytoplasmic proteins d. transcription and RNA processing e. translation of secreted proteins
Part B: When a peptide bond is formed between two amino acids, one is attached to the tRNA occupying the P site and the other _______. a. is attached to the tRNA occupying the A site b. is attached through hydrogen bonds to the mRNA c. is attached to the tRNA occupying the E site d. is free in the cytoplasm
a. is attached to the tRNA occupying the A site
Which of the following terms describes the DNA-protein complexes that look like beads on a string? a. Nucleosome b. Histones c. 30-nanometer fiber d. Chromatin
a. nucleosome
Which of the following is NOT correct when considering the initiation of transcription in E. coli? a. only the -10 region of the promoter is required b. DNA melting near the transcription start site is essential for promoter recognition c. the phosphodiester bonds that are formed are not stable until about 10 nucleotides have been incorporated d. the σ subunit of RNA polymerase makes strong contacts with he -10 region of promoters e. the RNA polymerase contacts about 50 bp of DNA
a. only the -10 region of the promoter is required
Part C: Spliceosomes are composed of _________. a. snRNPs and other proteins b. polymerases and ligases c. introns and exon d. the RNA transcript and protein e. snRNPs and snurps
a. snRNPs and other proteins
Part C: Which of the following best describes the first step in the formation of the translation initiation complex? a. The small ribosomal subunit binds to an mRNA sequence near the 5' end of the transcript b. The large ribosomal subunit binds to an mRNA sequence near the 5' end of the transcript c. The large ribosomal subunit binds to the small ribosomal subunit. d. The small ribosomal subunit binds to an mRNA sequence near the 3' end of the transcript.
a. the small ribosomal subunit binds to an mRNA sequence near the 5' end of the transcript
Part A: Label the components of the initiation step of protein synthesis.
amino acid tRNA anticodon mRNA strand start codon small ribosomal subunit
Which statements about the modification of chromatin structure in eukaryotes are true? a. Deacetylation of histone tails in chromatin loosens the association between nucleosomes and DNA. b. Acetylation of histone tails is a reversible process. c. DNA is not transcribed when chromatin is packaged tightly in a condensed form. d. Acetylation of histone tails in chromatin allows access to DNA for transcription. e. Methylation of histone tails in chromatin can promote condensation of the chromatin. f. Some forms of chromatin modification can be passed on to future generations of cells.
b. Acetylation of histone tails is a reversible process. c. DNA is not transcribed when chromatin is packaged tightly in a condensed form. d. Acetylation of histone tails in chromatin allows access to DNA for transcription. e. Methylation of histone tails in chromatin can promote condensation of the chromatin. f. Some forms of chromatin modification can be passed on to future generations of cells.
Which of these is a membrane receptor? a. A b. B c. C d. D e. E
b. B
_____ catalyzes the production of _____, which then opens an ion channel that releases _____ into the cell's cytoplasm. a. Protein kinase ... PIP2 ... Na+ b. Phospholipase C ... IP3 .... Ca2+ c. Adenylyl cyclase ... cyclic AMP ... Ca2+ d. Adenylyl cyclase ... IP3 .... Ca2+ e. Phospholipase C ... cyclic AMP ... Ca2+
b. Phospholipase C ... IP3 .... Ca2+
Eukaryotic cells produce three distinct RNA polymerases: pol I, pol II, and pol III. Which of the following statements is NOT true about eukaryotic RNA polymerases? a. Pol III is responsible for the transcription of ribosomal 5S rRNA. b. Pol II, with twelve subunits on its own, is capable of initiating transcription. c. Pol I carries out the transcription of the 45S pre-rRNA transcript. d. Pol III is responsible for the transcription of all tRNAs.
b. Pol II, with twelve subunits on its own, is capable of initiating transcription
Part B What molecule binds to promoters in bacteria and transcribes the coding regions of the genes? a. DNA ligase b. RNA polymerase c. a nucleotide d DNA polymerase
b. RNA polymerase
Part B: During RNA processing a(n) _____ is added to the 3' end of the RNA. a. 3' untranslated region b. a long string of adenine nucleotides c. 5' untranslated region d. coding segment e. modified guanine nucleotide
b. a long string of adenine nucleotides
Part G Which of the following enzymes converts ATP to cAMP? a. galactoside permeate b. adenylyl cyclase c. b-galactosidase e. ATP synthase
b. adenylyl cyclase
Calcium ions that act as second messengers are stored in _____. a. mitochondria b. endoplasmic reticula c. chloroplasts d. peroxisomes e. lysosomes
b. endoplasmic reticula
Which of the following regulatory DNA sequences might be located thousands of nucleotides away from the transcription start site of a gene? a. TATA box b. enhancer c. promoter d. promoter-proximal element
b. enhancer
Part D: The RNA segments joined to one another by spliceosomes are _____. a. caps b. exons c. snRNPs d. tails e. introns
b. exon
Part B: Which of the following is characteristic of transcription in eukaryotes but not in prokaryotes? a. A 3' untranslated trailer sequence b. Exon splicing c. A 5' untranslated leader sequence d. A single transcript may be transcribed and translated simultaneously.
b. exon splicing
Part D Under which conditions are the lac structural genes expressed most efficiently? a. high glucose, high lactose b. no glucose, high lactose c. no glucose, no lactose d. high glucose, no lactose
b. no glucose, high lactose
A bacterial genome is packaged into a nucleoid, which is organized mainly by: a. having many attachment points to the cell membrane. b. supercoiling of the DNA. c. being bound within a nuclear membrane. d. interactions with protein. e. being wrapped around histone proteins
b. supercoiling of the DNA.
initiation
begins when a small subunit of a ribosome combines with mRNA. The tRNA carrying the amino acid methionine forms a hydrogen bond with mRNA at the start codon, AUG. Then, the large ribosomal subunit and the small ribosomal subunit interlock around the mRNA to form a complete ribosome. With the first tRNA in place at the start codon, the protein synthesis initiates.
Part A Which of the following statements best defines the term operon? a. An operon is a region of RNA that consists of the coding regions of more than one gene. b. An operon is a region of DNA that codes for sugar-metabolizing enzymes. c. An operon is a region of DNA that codes for a series of functionally related genes under the control of the same promoter. d. An operon is a region of DNA that consists of a single gene regulated by more than one promoter. Submit
c. An operon is a region of DNA that codes for a series of functionally related genes under the control of the same promoter.
How do endocrine hormones reach their target cells? a. Hormones travel through the lymphatic system to target cells. b. Hormones are released at synapses adjacent to target cells. c. Hormones are transported through the blood stream to target cells. d. Ducts transport hormones directly to target cells. e. Hormones are produced by endocrine cells that are adjacent to target cells.
c. Hormones are transported through the blood stream to target cells.
Which statements about the regulation of transcription initiation in these genes are true? a. The fantasin gene and the imaginin gene have identical enhancers. b. Both the fantasin gene and the imaginin gene will be transcribed at high levels whenever general transcription factors are present in the cell. c. The fantasin gene will be transcribed at a high level when activators specific for control elements A, B, and C are present in the cell. d. The imaginin gene will be transcribed at a high level when repressors specific for the imaginin gene are present in the cell. e. Control elements C, D, and E are distal control elements for the imaginin gene. f. Both the fantasin gene and the imaginin gene will be transcribed at high levels when activators specific for control elements A, B, C, D, and E are present in the cell. g. Control elements A, B, and C are proximal control elements for the fantasin gene.
c. The fantasin gene will be transcribed at a high level when activators specific for control elements A, B, and C are present in the cell. e. Control elements C, D, and E are distal control elements for the imaginin gene. f. Both the fantasin gene and the imaginin gene will be transcribed at high levels when activators specific for control elements A, B, C, D, and E are present in the cell.
In addition to histones, chromatin contains other proteins. Which of the following are present in chromatin? 1) polymerases and nuclear receptor proteins 2) transcription factors 3) topoisomerases 4) cohesins and condemns a. Only 1 and 2 are chromatin proteins. b. Only 1, 3, and 4 are chromatin proteins. c. All of the listed choices are chromatin proteins. d. None of the listed choices are chromatin proteins.
c. all of the listed choices are chromatin proteins
Part B: Translation is directly dependent on all of the following associations except _______. a. complementary base pairing between mRNA and tRNA b. association of the 30S and the 50S ribosomal subunits c. complementary base pairing between mRNA and DNA d. complementary base pairing between mRNA and rRNA Submit
c. complementary base pairing between mRNA and DNA
Which of these acts as a second messenger? a. protein kinase b. G-protein-linked receptor c. cyclic AMP d. adenylyl kinase e. G protein
c. cyclic kinase
Part C: Which of the following statements concerning peptide bond formation is correct? a. it requires GTP b. it uses water c. it is catalyzed by peptide transferase d. it is catalyzed by an enzymatic protein
c. it is catalyzed by peptide transferase
The reason some cells respond to the presence of a steroid hormone while others do not is that _______. a. the specific HRE is present only in certain cells b. only certain cells contain the gene that is targeted by a given steroid hormone c. the receptors necessary for regulation differ among cells of various types d. chaperone proteins block the hormone response elements (HREs) in some cells
c. the receptors necessary for regulation differ among cells of various types
Part E What happens to the expression of the lacI gene if lactose is not available in the cell? a. the lacl gene turns on b. the lacl gene turns off c. there is no change--the lacl gene is constitutively expressed d. the lacl gene increases its rate of transcription
c. there is no change--the lacl gene is constitutively expressed
Part C - Codon size and the genetic code Life as we know it depends on the genetic code: a set of codons, each made up of three bases in a DNA sequence and corresponding mRNA sequence, that specifies which of the 20 amino acids will be added to the protein during translation. Imagine that a prokaryote-like organism has been discovered in the polar ice on Mars. Interestingly, these Martian organisms use the same DNA → RNA → protein system as life on Earth, except that there are only 2 bases (A and T) in the Martian DNA, and there are only 17 amino acids found in Martian proteins. Based on this information, what is the minimum size of a codon for these hypothetical Martian life-forms? a. 2 bases b. 3 bases c. 4 bases d. 5 bases e. 6 bases f. the answer cannot be determined from the information provided
d. 5 bases
What role does a transcription factor play in a signal transduction pathway? a. By binding to a plasma membrane receptor it initiates a cascade. b. It relays a signal from the cytoplasm to the plasma membrane. c. It activates relay proteins. d. By binding to DNA it triggers the transcription of a specific gene. e. It is a plasma membrane protein that binds signal molecules.
d. By binding to DNA it triggers the transcription of a specific gene.
Part C What is allosteric regulation? a. In allosteric regulation, a gene is turned off by a repressor protein. b. In allosteric regulation, a gene is turned on by an activator protein. c. In allosteric regulation, genes are expressed constitutively. d. In allosteric regulation, a small molecule binds to a large protein and causes it to change its shape and activity.
d. In allosteric regulation, a small molecule binds to a large protein and causes it to change its shape and activity.
Part C: Which of the following best describes the function of the 5'mRNA cap? a. To add a phosphate to the triphosphate moiety b. Termination of transcription c. To provide a binding site for poly(A) polymerase d. It provides a site for ribosome binding in the cytoplasm.
d. It provides a site for ribosome binding in the cytoplasm.
Which of the following is NOT true regarding the packing of nucleic acids into the nucleus? a. Packing is accomplished by different mechanisms between eukaryotes and prokaryotes. b. Packing must be organized so that when needed, processes like replication can take place. c. Packing allows very large molecules to be present in a very tight compartment. d. Packing is required for eukaryotes but not bacteria
d. Packing is required for eukaryotes but not bacteria
Which of the following best describes the mechanism by which steroid hormones control gene expression? a. Chaperone proteins transport steroid hormones into the cell and guide them to their target genes. b. Steroid hormones transport mRNA from the nucleus into the cytoplasm, where it is translated into protein. c. Steroid hormones enter a cell, bind directly to hormone response elements (HREs), and enhance transcription. d. Steroid hormones that enter the cell activate receptors. These hormone-receptor complexes then bind HREs and influence gene expression.
d. Steroid hormones that enter the cell activate receptors. These hormone-receptor complexes then bind HREs and influence gene expression.
Some viruses, such as SV40, contain closed circular DNAs carrying nucleosomes. If the SV40 viral chromosome is treated with topoisomerase, and the histone is then removed, it is still supercoiled. If histones are removed before topoisomerase treatment, however, the DNA is relaxed. a. Gaps produced by topoisomerase cannot move on DNA molecule, stopping in places of binding with nucleosomes, and are ligated at that position thereby not remove the supercoiling. b. Recognition and activity sites of topoisomerases are hidden by the binding of DNA nucleosomes. With the DNA release of the histones this sequences open and relax occurs. c. Topoisomerase turns whole sections of DNA-linkers and nucleosomes. With the removal of histones windings that was hidden under compactization are revealed and mimic the original twists. d. The DNA makes superhelical turns about each nucleosome. These turns are constrained by binding to histone octamers and cannot be unwound by topoisomerase action.
d. The DNA makes superhelical turns about each nucleosome. These turns are constrained by binding to histone octamers and cannot be unwound by topoisomerase action.
Part F What is the function of the lacZ gene ? a. This gene encodes an enzyme, galactoside permease, which transports lactose into the cell. b. This gene encodes an enzyme, b-galactosidase, that cleaves lactose into two glucose molecules. c. This gene encodes the repressor of the lac operon. d. This gene encodes an enzyme, b-galactosidase, which cleaves lactose into glucose and galactose.
d. This gene encodes an enzyme, b-galactosidase, which cleaves lactose into glucose and galactose.
Which of the following regulatory elements is not composed of DNA sequences? a. enhancers b. promoter-proximal elements c. silencers d. activators
d. activators
A protein kinase activating many other protein kinases is an example of _____. a. deactivation b. sensitization c. a cellular response d. amplification e. mutualism
d. amplification
Part E: RNA processing converts the RNA transcript into _____. a. a protein b. DNA c. a eukaryotic cell d. mRNA e. a polypeptide
d. mRNA
Water-soluble hormones affect target cells by binding to __________. a. cAMP b. protein kinases c. adenylate cyclase d. plasma membrane receptors e. cytoplasmic receptors
d. plasma membrane receptors
A signal transduction pathway is initiated when a _____ binds to a receptor. a. G protein b. tyrosine kinase c. calmodulin d. signal molecule e. cyclic AMP
d. signal molecule
Which of the following statements about E. coli RNA polymerase is INCORRECT? a. it has five different subunits b. the σ subunit can be dissociated easily from the rest of the enzyme c. the σ subunit has a role in regulation of transcription d. the σ subunit is responsible for accurate determination of transcription start sites e. without σ subunit the enzyme has no RNA polymerase activity
d. the σ subunit is responsible for accurate determination of transcription start sites
Part A: What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA? a. RNA processing b. gene expression c. polypeptide formation d. transcription e. translation
d. transcription
Which of these acts as a second messenger? a. A b. B c. E d. C E. D
e. D
miRNAS are used in gene regulation to: a. promote degradation of polyA tails b. target mRNA for degradation c. block translation d. cause ribosomes to stall e. all of the above
e. all of the above
Part D: Polypeptides are assembled from _____. a. hexoses b. glycerol c. nucleotides d. proteins e. amino acids
e. amino acids
The magnification of the signal from a water-soluble hormone is achieved through an increase in _______. a. phosphodiesterase in the cytoplasm b. adenylate cyclase in the plasma membrane c. plasma membrane receptors d. water-soluble hormone in the blood e. cAMP in the cytoplasm
e. cAMP in the cytoplasm
Part A: During RNA processing a(n) _____ is added to the 5' end of the RNA. a. 3' untranslated region b. a long string of adenine nucleotides c. 5' untranslated region d. coding segment e. modified guanine nucleotide
e. modified guanine nucleotide
Cyclic AMP is degraded by __________. a. AMP b. protein kinase c. G proteins d. adenylate cyclase e. phosphodiesterase
e. phosphodiesterase
Part B: What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein? a. RNA processing b. gene expression c. polypeptide formation d. transcription e. translation
e. translation
Part H True or false? The mechanism by which glucose inhibits expression of the lac structural genes is known as catabolite stimulation, whereas the mechanism by which lactose stimulates expression of the lac structural genes is known as allosteric regulation.
false
True of False: All processing of eukaryotic mRNAs takes place in the nucleus after transcription has been completed.
false
True or False: Regulatory and basal transcription factors regulate transcription by binding to the promoter.
false
Part B: Sort two features into each stage of translation they describe.
initiation -- the mRNA binds to the small subunit of a ribosome , a methionine-carrying tRNA has no anticodon UAC that occupies the AUG site of mRNA at the 5' end elongation -- the ribosome shifts exactly one codon to the right , the ribozyme present in the large ribosomal subunit catalyzes peptide bond formation termination -- the stop codon present on mRNA does not code for any amino acid , the ribosomal subunits, mRNA, and polypeptide chain separate
Part B - Regulation of model operons The trp and lac operons are regulated in various ways. How do bacteria regulate transcription of these operons? Sort the statements into the appropriate bins depending on whether or not each operon would be transcribed under the stated conditions.
operon is not transcribed -- lac operon: lactose absent , trp operon: tryptophan present operon is transcribed, nut not sped up through positive control -- lac operon: lactose present, glucose present , trp operon: tryptophan operon is transcribed quickly through positive control -- lac operon: lactose present, glucose absent
Part C - Regulation of a hypothetical operon You are studying a bacterium that utilizes a sugar called athelose. This sugar can be used as an energy source when necessary. Metabolism of athelose is controlled by the ath operon. The genes of the ath operon code for the enzymes necessary to use athelose as an energy source. You have found the following: The genes of the ath operon are expressed only when the concentration of athelose in the bacterium is high. When glucose is absent, the bacterium needs to metabolize athelose as an energy source as much as possible. The same catabolite activator protein (CAP) involved with the lac operon interacts with the ath operon. Based on this information, how is the ath operon most likely controlled?
positive control -- a. inactive activator (empty) , b. cAMP , c. active activator (block) negative control -- a. active repressor (empty), b. athelose, c. inactive repressor (block)
bacterial transcription is a four stage process
promoter recognition chain initiation chain elongation chain termination
Part B - The role of RNA in the flow of genetic informationIndicate at which step of the replication-transcription-translation process each type of RNA first plays a role.
replication -- empty transcription/RNA processing -- mRNA translation -- tRNA , rRNA
Part A - Properties of RNA Sort each description by the type of RNA it describes
tRNA -- has amino acids covalently attached , contains an anticodon mRNA -- contains exons, specifies the amino acid sequence for a protein rRNA -- is the most abundant form of RNA , is a component of ribosomes
Part B - Roles of RNA in protein synthesis in eukaryotes RNA plays important roles in many cellular processes, particularly those associated with protein synthesis: transcription, RNA processing, and translation. Drag the labels to the appropriate bins to identify the step in protein synthesis where each type of RNA first plays a role. If an RNA does not play a role in protein synthesis, drag it to the "not used in protein synthesis" bin.
transcription/RNA processing -- snRNA, pre-mRNA, mRNA translation -- rRNA, tRNA not used in protein synthesis -- RNA primers
True or False RNA interference can be a mechanism of defense against viral infection as well as for regulation of gene expression
true
True or False: In bacteria, mRNA, tRNA and rRNA are all transcribed by the same RNA polymerase.
true
True or false? One possible way to alter chromatin structure such that genes could be transcribed would be to make histone proteins more positively charged.
true
