cell biology module 2
6, 7, 2, 4, 5, 3, 1
The following steps must be performed to make a bacterium produce human protein X: 1-Translation; 2-Restriction enzyme; 3-Prokaryotic transcription; 4-DNA ligase; 5-Transformation; 6-Eukaryotic transcription; 7-Reverse transcription. Put the steps in the correct sequence. 5, 2, 3, 4, 7, 6, 1 1, 2, 3, 5, 4, 7, 6 6, 7, 2, 3, 4, 5, 1 6, 7, 2, 4, 5, 3, 1 6, 2, 1, 3, 4, 5, 7
to work as a sliding clamp
The function of PCNA is: polymerization of nucleotides to work as a sliding clamp to synthesize RNA primers to remove primers
Incorporate into newly replicated DNA strands and terminate their synthesis
The function of the dideoxy (dd) nucleotides that are used in the Sanger method of DNA sequencing is to Denature DNA into single strands Serve as primers Be a fluorescent tag Incorporate into newly replicated DNA strands and terminate their synthesis None of the choices are correct
A gene from an organism can theoretically be expressed by any other organism.
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following? A gene from an organism can theoretically be expressed by any other organism. All organisms have experienced convergent evolution. DNA was the first genetic material. The same codons in different organisms translate into the different amino acids. Different organisms have different numbers of different types of amino acids
it is heat stable and can withstand the temperature changes of the cycler.
The reason for using Taq polymerase for PCR is that it is heat stable and can withstand the temperature changes of the cycler. only minute amounts are needed for each cycle of PCR. it binds more readily than other polymerases to primer. it has regions that are complementary to primers. All of the above
8
You have a small gene that you wish replicated by PCR. After 3 replication cycles, how many double-stranded DNA molecules do you have? 2 4 8 16 Thousands
It leaves sticky ends of sequence AATT
The restriction enzyme EcoRI cuts between the G and the A of the sequence GAATTC. Which statement is true about this enzyme? It will cut this sequence only in bacteriophage DNA. It leaves sticky ends of sequence CTTA. It will cut this sequence only in bacterial DNA. It leaves sticky ends of sequence GAAT. It leaves sticky ends of sequence AATT.
The cell component that binds the antibiotic could be found by the incubation of a radiolabeled antibiotic with cell extracts followed by electrophoretic separation.
Many antibiotics, most of which have been isolated from fungi, act by inhibiting initiation, elongation, or termination of peptides during protein synthesis. These compounds have been very useful in the study of protein synthesis, mainly because an individual antibiotic usually interferes with protein synthesis at a single well-defined step in the complex process of translation. Assume that you have isolated a novel antibiotic from the fungus Pilobolus, this antibiotic inhibits bacterial growth and bacterial protein synthesis but does not affect growth or protein synthesis in eukaryotic cells. How could you identify the component of the translational machinery that is affected by this novel antibiotic?
RNA primers are synthesized by primase
At replication forks: DNA helicases make endonucleolytic cuts in DNA. DNA primers are degraded by ligase. DNA topoisomerases make endonucleolytic cuts in DNA. RNA primers are removed by primase. RNA primers are synthesized by primase.
contains a foreign gene
A "transgenic" animal is the offspring of a clone. has been amplified by PCR. contains a foreign gene. has had all its chromosomes removed. is infected with recombinant bacteria
The GCATGGCCACTACCG sequence has 10 CG base pairs compared to GAATGGTAACAACTG sequence having 6 CG base pairs making it more stable. The CG pairs have 3 hydrogen bonds compared to AT pairs having 2 hydrogen bonds. The more hydrogen bonds would make the 10 CG base pairs sequence more stable and therefore the Tm would be higher because it would take more energy to denature.
A double-stranded piece of DNA containing the sequence GCATGGCCACTACCG has a higher Tm than one containing the sequence GAATGGTAACAACTG. Describe the properties of DNA that make this true.
in all four types of broth
A eukaryotic gene has "sticky ends" produced by the restriction endonuclease BamHI. The gene is added to a mixture containing BamHI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for BamHI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics. Bacteria that contain the plasmid, but not the eukaryotic gene, would grow in the nutrient broth plus ampicillin, but not in the broth containing tetracycline. only in the broth containing both antibiotics. in the broth containing tetracycline, but not in the broth containing ampicillin. in all four types of broth. in the nutrient broth without antibiotics only
bonding of the anticodon to the codon and the attachment of amino acids to tRNAs.
Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the binding of ribosomes to mRNA. shape of the A and P sites of ribosomes. bonding of the anticodon to the codon. attachment of amino acids to tRNAs. bonding of the anticodon to the codon and the attachment of amino acids to tRNAs.
Descendants of the living cells are also phosphorescent.
After mixing a heat-killed, phosphorescent strain of bacteria with a living nonphosphorescent strain, you discover that some of the living cells are now phosphorescent. Which observations would provide the best evidence that the ability to fluoresce is a heritable trait? DNA passed from the heat-killed strain to the living strain. Protein passed from the heat-killed strain to the living strain. The phosphorescence in the living strain is especially bright. Descendants of the living cells are also phosphorescent. Both DNA and protein passed from the heat-killed strain to the living strain.
5' RNA nucleotides, DNA nucleotides 3'
An Okazaki fragment has which of the following arrangements? primase, polymerase, ligase 3' RNA nucleotides, DNA nucleotides 5' 5' RNA nucleotides, DNA nucleotides 3' DNA polymerase I, DNA polymerase III 5' DNA to 3'
4
An mRNA sequence is 5' AUG-GCC-ACU-CAU-ACU-UAA 3', where AUG is the start codon and UAA is the stop codon. How many distinct aminoacyl-tRNA synthetases are required to translate the mRNA sequence? 2 3 4 5 6
all of the above
Analysis of DNA fragments in gel electrophoresis involves Larger fragments move slowly and remain closer to the wells DNA has an overall negative charge and moves to the positive pole DNA fragments are stained with fluorescent dye ethidium bromide to see them An electric current through the gel causes DNA fragments to migrate all of the above
You could perform a Northern Blot test because it is done on RNA samples. The RNA sample is denatured by treatment which will release the hydrogen bonds between base pairs leaving the RNA in a linear conformation. The RNA is then separated by size on gel electrophoresis and then transferred to nitrocellulose filter which the denatured RNA will adhere to. The filter is exposed to a labeled DNA probe that is complementary to the gene we are looking for - in this case hepatitis A. It is then exposed to autoradiography. If the hepatitis A gene is present then the patient has hepatitis A.
As a physician, you have a patient with symptoms that suggest a hepatitis A infection, but you have not been able to detect viral proteins in the blood. Knowing that hepatitis A is an RNA virus, what lab test could you perform to support your diagnosis? Explain the results that would support your hypothesis.
E coli is prokaryotic cell that does not have organelles such as ER and golgi apparatus. The original RNA from translation goes through the ER and golgi to be edited and folded so a large scale production of genetically engineered hemoglobin from E. coli would not be possible.
Assembly of multi-subunit secretary proteins, such as hemoglobin, occurs within the ER and golgi apparatus of a eukaryotic cell. Discuss what limitations, if any, exist to the large scale production of genetically engineered hemoglobin from E. coli
the ampicillin broth and the nutrient broth
Bacteria containing a plasmid into which the eukaryotic gene has integrated would grow in the nutrient broth only. the nutrient broth and the tetracycline broth only. the nutrient broth, the ampicillin broth, and the tetracycline broth. all four types of broth. the ampicillin broth and the nutrient broth
nucleotide, DNA, gene, chromosome, genome
Beginning with the simplest level of structure, which order of organization of genetic material is CORRECT? DNA, nucleotide, gene, genome, chromosome nucleotide, DNA, gene, chromosome, genome DNA, nucleotide, gene, chromosome, genome nucleotide, DNA, gene, genome, chromosome nucleotide, DNA, chromosome, gene, genome
amino to carboxyl terminus
Cellular protein synthesis proceeds in which direction? carboxyl to amino terminus amino to carboxyl terminus 3´ to 5´ 5´ to 3´ Bidirection
DNA B form is right handed helix, the stacked bases are 3.4 to 3.6 nm and contain 10 to 10.5 base pairs per turn. This is the form of most DNA in the cells. This forms has major grooves and minor grooves which are binding sites. DNA A form is the crystallographic form were most of the water is removed. It is wider and shorter than form B, containing 11 base pairs per turn. The major grooves are wider and deeper and the minor grooves are narrower and shallower. DNA Z form is a left handed helix, it forms a zig zag pattern with 12 base pairs per turn. A small amount of DNA is naturally in this form
Compare and contrast B, A and Z forms of DNA.
In the 5' > 3' direction on both DNA strands
DNA is synthesized in which of the following directions? In the 5' > 3' direction on the leading strand and 3' > 5' direction in the lagging strand. The 3' > 5' direction on the leading strand and the 5' > 3' direction on the lagging strand. In the 5' > 3' direction on both DNA strands. The direction differs depending on the genes being duplicated. None of the above are correct.
5' and 3' mean prime and indicate the carbon numbers in the DNA backbone. 5' has a phosphate group attached and 3' has a hydroxyl group. The DNA polymerase adds deoxyribonucleotides to the hydroxyl group at the 3' end of the primer. A 3' to 5' chain growth would require energy as there would be no high energy bond cleaved, and the DNA polymerase has an exonuclease activity to correct errors in the 3' to 5' direction.
DNA replication is always 5' to 3'. Explain what 5' to 3' means with respect to nucleotide subunits. Explain what activity of DNA polymerase necessitates that replication be 5' to 3' rather than 3' to 5'? What problems do you envision with 3' to 5' direction of DNA chain growth?
The fidelity of DNA replication is the ability of DNA polymerase to avoid or correct errors in the process. Base excision repair - G-T mismatch which is recognized by glycosylase and flips the thymine base out of the helix and then hydrolyzes the bond that connects the sugar-phosphate DNA backbone. Mismatch excision repair - recognizes and repairs erroneous insertions, deletions, and mis-incorporation of bases using MutS, MutH, and MutL. Nucleotide excision repair - fix regions of chemically modified bases. 30 proteins involved, Slide down helix looking for bulges or irregularities
Describe all the processes that contribute to the high fidelity of DNA replication.
When the level of Trp concentration is high in the cytoplasm the trp repressor will repress the trp operon, which will decrease gene expression by altering initiation of transcription. Attenuation responds to the concentration to the concentration of charged tRNAtrp. It is the secondary mechanism of the negative feedback in the trp operon. Attenuation alters the process of transcription that is already in progress. With high concentrations of charged tRNAtrp the formation of 3 to 4 stem loops that are follwed by a series of U will cause the termination of the transcription.
Describe how levels of Trp control initiation of transcription at the trp operon. Also, describe attenuation and transcriptional control by regulation of RNA pol elongation and termination at this operon
Stigma factor is a protein that allows for the initiation of gene transcription. A change in the environment can initiate the binding of stigma factor to the genome so that needed RNA can be transcribed to produce proteins that will respond to the environmental change. For example, when temperatures are high bacteria need heat shot proteins to survive. Stigma 32 binds to the genome and prompts the transcription of a RNA to make the protein
Describe how sigma factor switching helps the bacteria adapt to its dynamic environment.
Southern blotting is a method that is used the detect DNA fragments Northern blotting is a method use to detect mRNA. Transient Transfection- DNA fragments are incorporated into host cell but not permanently into the genome Stable Transfection - DNA fragments are permanently incorporated into the host cells. Leading Strand - The strand of DNA that is continuously transcribed from the replication fork Lagging Strand - The strand of DNA that must be transcribed in fragments so it can be done in the 5' to 3' direction Watson-Clark Base - Are the base pairs in DNA A-T and C-G Wobble base pairs - is the pairing between mRNA condon and tRNA anticodon, can be atypical at the wobble position Peptidyl Transferase - is in the nascent polypeptide chain, causes tRNA to release amino acid and link it to the previous amino acid for chain growth Aminoacyl-tRNA synthetase - is the enzyme that links the tRNA to an amino acid
Describe the following terms and bring out the differences between them: A. Northern Blotting and Southern Blotting B. Transient Transfection and Stable Transfection C. Leading Strand and Lagging Strand D. Watson-Crick Base and Wobble base pair E. Roles of Peptidyl Transferase and Aminoacyl-tRNA Synthetase
the production of two distinct proteins from a single gene
Differential RNA processing may result in: a shift in the ratio of mRNA produced from two adjacent genes. attachment of the poly(A) tail to the 5' end of an mRNA. inversion of certain exons in the final mRNA. the production of the same protein from two different genes. the production of two distinct proteins from a single gene.
Rapidly dividing bacteria
During the DNA replication process, which of the following organisms would have the fewest origins of replication per cell? Rapidly dividing bacteria A yeast cell A human A young oak tree A fruit fly
Gaps left at the 5' end of the lagging strand
Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following? The evolution of telomerase enzyme DNA polymerase that cannot replicate the leading strand template to its 5' end Gaps left at the 5' end of the lagging strand Gaps left at the 3' end of the lagging strand because of the need for a primer The "no ends" of a circular chromosome
DNA template is used as a template for the synthesis of daughter strands by DNA polymerase. The daughter strands are labeled at one end and terminate at one of the four nucleotides. Daughter strands are separated by length by gel electrophoresis. The nucleotide sequence of the original DNA fragment can be determined from the different lengths of strands. If the ratio of ddNTPs to dNTPs were increased we would expect to see more ddNTPs incorporated instead of dNTPs with shorter fragments seen. If the ratio was decreased we would see more dNTPs incorporated and longer fragments produced.
Explain the process of DNA sequencing by controlled termination of DNA synthesis in vitro (Sangers dideoxy sequencing method). How would a DNA sequencing reaction be affected if the ratio of ddNTPs to dNTPs were increased? What would be the consequences if the ratio were decreased?
95 oC
For PCR, DNA is denatured at 37 oC 42 oC 60 oC 95 oC 120 oC
Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment work? There is no radioactive isotope of nitrogen. Radioactive nitrogen has a half-life of 100,000 years, and the material would be too dangerous for too long. Avery et al. have already concluded that this experiment showed inconclusive results. Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive. Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
3' → 5' along the template strand
In which direction does the RNA polymerase move? 3' → 5' along the template strand 5' → 3' along the template strand 3' → 5' along the non-template strand 5' → 3' along the non-template strand 5' → 3' along the double-stranded DNA
Type1- many subunits, require cofactors, cleave DNA far from recognition site, recognize sites that are not symmetric Type II - homodimers, cleave DNA closer to recognition site, require cofactor (Mg2+), recognize palindromic site Type III - more than one subunit, cleave further from recognition site, require cofactors, recognize 2 oppositely oriented sequences Type IV- target methylated DNA
Highlight the differences between different types of restriction endonucleases
DNA Polymerase works as a dimer, and the looped lagging strand allows the enzyme to proceed in the same direction with each strand.
How can the leading and lagging strands be synthesized in a coordinated fashion? Specific enzymes control the size of the DNA opening. Lagging-strand binding proteins inhibit leading-strand replication if the strands become disproportionate in size. DNA Polymerase works as a dimer, and the looped lagging strand allows the enzyme to proceed in the same direction with each strand. All of the above. None of the above.
Many amino acids have more than one tRNA that they can attach to, this would explain why the number of tRNA in most cells os more than the 20 amino acids used in protein synthesis. A single tRNA anticodon can recognize more than one coden corresponding to an amino acid would explain why some cells have less than the 61 expected tRNA. The wobble position with nonstandard pairing between bases allow this to happen.
If perfect Watson-Crick base pairing were demanded between codons and anticodons, cells would need 61 different tRNAs. If there are only 20 amino acids used in protein synthesis, how would you explain this excess number of tRNAs compared to amino acids? Conversely, how would you explain the fact that some cells contain fewer than 61 tRNAs?
an assembled ribosome with a polypeptide attached to the tRNA in the P site
If the translation reaction were to be experimentally stopped at the point when the ribosome reaches a stop codon on the mRNA and no molecule enters the A site, which of the following would you be able to isolate? an assembled ribosome with a polypeptide attached to the tRNA in the P site separated ribosomal subunits, a polypeptide, and free tRNA an assembled ribosome with a separated polypeptide separated ribosomal subunits with a polypeptide attached to the tRNA a cell with fewer ribosomes
No replication fork will be formed
In E. coli, there is a mutation in a gene called dnaB that compromises the helicase activity. Which of the following would you expect as a result of this mutation? No proofreading will occur. No replication fork will be formed. DNA replication will not be affected at all. Replication will occur via RNA polymerase alone. Replication will require a DNA template from another source.
Egg proteins are required for embryonic development
In animal cloning why is an egg cell required? Somatic cells will fuse only with egg cells. Egg chromosomes are required for embryonic development. Egg proteins are required for embryonic development. Surrogate mother animals will develop only embryos derived from their own eggs. Only egg cells can provide the DNA for reproductive clones
some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic
In his work with pneumonia-causing bacteria and mice, Griffith found that: the protein coat from pathogenic cells was able to transform nonpathogenic cells. heat-killed pathogenic cells caused pneumonia. some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic. the polysaccharide coat of bacteria caused pneumonia. bacteriophages injected DNA into bacteria
decrease in glucose and increase in cAMP
In positive control of several sugar-metabolism-related operons, the catabolite activator protein (CAP) binds to DNA to stimulate transcription. What causes an increase in CAP? increase in glucose and increase in cAMP decrease in glucose and increase in cAMP increase in glucose and decrease in cAMP decrease in glucose and increase in repressor decrease in glucose and decrease in repressor
to facilitate purification of the expressed protein though binding to an affinity column containing chelated nickel
In the large-scale production of a particular human protein in E. coli cells, the cDNA corresponding to the protein was modified so that the expressed protein would have six histidine residues at the C-terminus. The purpose of this modification was to facilitate transfer of the cDNA into the E. coli cells. to provide a promoter for the transcription of the cDNA in E. coli. to facilitate gene expression to facilitate purification of the expressed protein though binding to an affinity column containing chelated nickel. to prevent degradation of the expressed protein by E. coli proteases.
genes active within tissues are identified using a complementary DNA probe
Microarray technology is a process in which: A normal human egg has its nucleus removed and then is fused with a somatic (non-egg or sperm related) cell. genetically altered embryo is implanted into a recipient mother. genes active within tissues are identified using a complementary DNA probe. A hybrid vector is placed into a host cell. viral DNA is injected into a bacterial host
The bacteria would be unable to produce necessary enzymes to carry out basic metabolism.
New antibiotic is developed that interferes with the way tRNA fits into bacterial ribosomes. How would this kill? The bacteria would be unable to produce necessary enzymes to carry out basic metabolism. The tRNA would be unable to carry out transcription. Ribosomes will not be able to produce mRNA and cell functions will halt. tRNA would not unwind the DNA to allow DNA polymerase to copy it, thus cell division stops.
a DNA sequence that is expressed to form a functional product: either RNA or polypeptide
Of the following, which is the most current description of a gene? a unit of heredity that causes formation of a phenotypic characteristic a DNA subunit that codes for a single complete protein a DNA sequence that is expressed to form a functional product: either RNA or polypeptide a DNA—RNA sequence combination that results in an enzymatic product a discrete unit of hereditary information that consists of a sequence of amino acids
conversion of normal bases to modified bases, such as inosine and pseudouridine
Processing of a primary mRNA transcript in a eukaryotic cell does not normally involve: attachment of a long poly(A) sequence at the 3' end. conversion of normal bases to modified bases, such as inosine and pseudouridine. excision of intervening sequences (introns). joining of exons. methylation of one or more guanine nucleotides at the 5' end.
can synthesize RNA chains de novo (without a primer).
RNA polymerase: binds tightly to a region of DNA thousands of base pairs away from the DNA to be transcribed. can synthesize RNA chains de novo (without a primer). has a subunit called λ (lambda), which acts as a proofreading ribonuclease. separates DNA strands throughout a long region of DNA (up to thousands of base pairs), then copies one of them. synthesizes RNA chains in the 3' → 5' direction.
palindromes
Sequences of DNA that are identical when read from the 5' to 3' direction on one strand and the 3' to 5' direction on the other strand are palindromes reverse transcriptase restriction endonucleases Ligases DNA polymerases
release factor
The ___________________ recognizes a stop codon at the A site of the ribosome.
blunt
Some restriction enzymes cleave both DNA strands at the same point within the restriction site, generating fragments with ________________ ends in which all the nucleotides at the fragment ends are base-paired to nucleotides in the complementary strand.
DNA.
Southern blotting is used to detect a specific DNA. RNA. Protein. Carbohydrate. all of the above
DNA in both daughter cells would be radioactive
Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive adenine has been added. What would happen if a cell replicates once in the presence of this radioactive base? One of the daughter cells, but not the other, would have radioactive DNA. Neither of the two daughter cells would be radioactive. All four bases of the DNA would be radioactive. Radioactive adenine would pair with nonradioactive guanine. DNA in both daughter cells would be radioactive
I would first use restriction endonucleases to produce fragments of different sizes. The restriction endonucleases are enzymes that can cleave the DNA at specific sites and produce fragments of different sizes. Then use southern blotting to identify the different DNA fragments and piece together the peptide hormone gene. The southern blot test can separate DNA fragments based on length. PCR to amplify to DNA fragment and make many copies of the gene. Mixing the fragments with a primer and DNA polymerase we will use heat and cooling to allow DNA replication to occur. The replicated DNA can be inserted into cloning vectors and inserted into bacteria to produce large quantities of the peptide hormone.
Suppose you would like to study a gene that codes for a peptide hormone H secreted by human neurons. You know the primary sequence of this peptide hormone. Explain how you might be able to identify or isolate the gene that codes for this peptide hormone. How will you produce multiple copies of this gene for study? How will you produce large quantities of this hormone for evaluation as a potential therapeutic agent? Provide a detailed outline of steps you will use for each of these objectives explaining why that step is needed
7-methylguanosine joined to the mRNA via a 5' → 5' triphosphate linkage.
The 5'- cap of eukaryotic mRNAs is a(n): 7-methylcytosine joined to the mRNA via a 2',3'-cyclic linkage. 7-methylguanosine joined to the mRNA via a 5' → 3' diphosphate linkage. 7-methylguanosine joined to the mRNA via a 5' → 5' triphosphate linkage. N6-methyladenosine joined to the mRNA via a 5' → 5' phosphodiester bond. O6-methylguanosine joined to the mRNA via a 5' → 5' triphosphate linkage.
both circular and found in a nucleoid
The bacterial chromosome is usually circular. found in a nucleoid. found in a nucleus. both circular and found in a nucleoid. both circular and found in a nucleus
is the 3´ (third) base
The base in the wobble position of a codon: is the 5´ (first) base. is the 3´ (third) base. is the second base. often contains adenine. contains Inosine.
the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.
The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that: the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose. the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups. ATP contains three high-energy bonds; the nucleoside triphosphates have two. ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells. triphosphate monomers are active in the nucleoside triphosphates, but not in ATP
the cyclic AMP and lactose levels are both high within the cell.
The lactose operon is likely to be transcribed when: there is more glucose in the cell than lactose. the cyclic AMP levels are low. there is glucose but no lactose in the cell. the cyclic AMP and lactose levels are both high within the cell. the cAMP level is high and the lactose level is low
the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction
The leading and the lagging strands differ in that: the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. the leading strand is synthesized at twice the rate of the lagging strand.
combines with the core enzyme to confer specific binding to a promoter
The sigma factor of E. coli RNA polymerase: associates with the promoter before binding to the core enzyme. combines with the core enzyme to confer specific binding to a promoter. is inseparable from the core enzyme. is required for termination of an RNA chain. will catalyze synthesis of RNA from both DNA template strands in the absence of the core enzyme.
transformation
The transfer of DNA fragments from a dead cell to a live, competent recipient cell that results in a changed recipient cell is transduction replication transformation transmission mitosis
Direct selection possible
The use of an antibiotic-resistance gene on a plasmid used in genetic engineering makes Replica plating possible. Direct selection possible. The recombinant cell dangerous. The recombinant cell unable to survive. All of the above.
to attach the DNA fragments to a permanent substrate
To carry out hybridization, why is DNA transferred from a gel to a nitrocellulose paper? to attach the DNA fragments to a permanent substrate to separate the two complementary DNA strands to transfer only the DNA that is of interest to prepare the DNA for digestion with restriction enzymes to separate out the PCRs
promoter
Transcription begins near a site in the DNA called the ________, while the terminator specifies the end of transcription. promoter enhancer response element transcription unit regulatory sequence
Larger quantities are available
What is one of the advantages of producing human growth hormone (HGH) from a cloned gene in a bacterial cell? The product can be administered by infecting a person with the recombinant bacteria. A gene cloned from mice, rather than from humans can be used. The bacterial protein has a different amino acid sequence that is more effective. Larger quantities are available. As the protein is introduced therapeutically, it transfers the HGH gene as well
In the prokaryotic mRNA translation can begin while transcription is still in progress, mRNA does not have introns in the prokaryote. In the eukaryotic mRNA is transcription must be complete before translation can occur and the mRNA must be spliced to remove introns
What are the major differences in the synthesis and structure of prokaryotic and eukaryotic mRNAs
an exact copy of a DNA, cell or organism
What is a clone? any cell that contains recombinant DNA a protein produced by a recombinant bacterium an exact copy of a DNA, cell or organism any animal that contains recombinant DNA any DNA cut with a restriction enzyme
Epitope tagging modifies gene of interest by appending a short DNA sequence to it that encodes a short stretch of amino acids recognized by a known monoclonal antibody. The epitope tagged form of the protein can be detected by immunofluorescence labeling of the cells with the antibody.
What is epitope tagging? What is its application?
The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
What is meant by the description "antiparallel" regarding the strands that make up DNA? The twisting nature of DNA creates nonparallel strands. The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. Base pairings create unequal spacing between the two DNA strands. One strand is positively charged and the other is negatively charged. One strand contains only purines and the other contains only pyrimidines.
A possible reason to allow nonstandard base pairing during protein synthesis could be to let protein synthesis happen at a more efficient rate. The mRNA can be translated to protein with less tRNA. The decrease number of tRNA can let the protein synthesis happen at a faster rate.
What is one possible reason why nonstandard base pairing (wobble) is allowed during protein synthesis?
Sheep will produce recombinant protein that is chemically more similar to humans
What is the advantage of producing human factor IX in sheep rather than in bacteria? Sheep will produce recombinant protein that is chemically more similar to humans. No cloning or recombinant DNA manipulation is required. Sheep organs producing factor IX can be transplanted directly into hemophiliacs. The sheep do not secrete the protein, so not as much is lost. The human gene is not required because the sheep protein is identical to the human.
The poly A tail increases mRNA stability in eukaryotes.
What is the function of the poly A tail? The poly A tail is required for the proper entry of mRNA into the nucleus. The poly A tail serves as a termination sequence for RNA polymerase III. The poly A tail increases mRNA stability in eukaryotes. The poly A tail increases mRNA stability in prokaryotes
Relieving strain in the DNA ahead of the replication fork
What is the function of topoisomerase? Relieving strain in the DNA ahead of the replication fork Elongating new DNA at a replication fork by adding nucleotides to the existing chain Adding methyl groups to bases of DNA Unwinding of the double helix Stabilizing single-stranded DNA at the replication fork
E P A
What is the order of the tRNA binding sites on the 70S ribosome with respect to the 5′->3′ direction of the mRNA? E P A P A E A E P P E A
It joins Okazaki fragments together
What is the role of DNA ligase during DNA replication? It synthesizes RNA nucleotides to make a primer. It catalyzes the lengthening of telomeres. It joins Okazaki fragments together. It unwinds the parental double helix. It stabilizes the unwound parental DNA
The initiation stage and elongation stage of translation require energy
What stages of translation require energy?
4, 5, 1, 2
What was the order of events in producing a cloned animal? 1. Two cells were fused using a small electrical current. 2. An embryo was implanted into a "surrogate mother". 3. All nuclear DNA was removed from a sperm. 4. A cell was taken from an adult sheep. 5. All nuclear DNA was removed from an egg.
Replication forks.
When a DNA molecule is described as replicating bidirectionally, that means that it has two: Chains. Independently replicating segment. Origins. Replication forks. Termination points
inducer
When a/n ________________ binds to the repressor, then the repressor can no longer bind to the operator
male germ cells that give rise to gametes
Where would one expect to find the most telomerase? male germ cells that give rise to gametes skin cells from a 80-year-old individual skin cells from a 15-year-old individual a nerve cell from a 60-year-old individual a nerve cell from a 18-year-old individual
a bacterial plasmid combined with a human gene
Which choice is an example of "recombinant DNA"? DNA that has been amplified by PCR any DNA that has been removed from a cell DNA that has been cut with a restriction enzyme a bacterial plasmid combined with a human gene a human protein produced by a bacterial cell
AUG
Which codon serves as the start codon in mRNA for translation? AGU AUG UGA UGG UAA
removing all the nuclear DNA from a human egg
Which is NOT a part of cloning a human gene into a recombinant plasmid? removing all the nuclear DNA from a human egg combining a plasmid and genomic DNA cut with the same restriction enzyme cutting the plasmid with a restriction enzyme generating a small fragment of human genomic DNA introducing the recombinant plasmid into bacteria by transformation
Only found in DNA, not in RNA
Which is incorrect about purines? Only found in DNA, not in RNA Are nitrogenous bases Always paired with a specific pyrimidine Include adenine and guanine Found within nucleotides
transcription factors
Which protein influences the ability of RNA polymerase to transcribe genes? DNA polymerases DNA helicases transcription factors snRNPs tRNA
2, 1, 4
Which of the following best describes the complete sequence of steps occurring during EVERY cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double-stranded target DNA. 3. Fresh DNA polymerase is added to the reaction mixture. 4. DNA polymerase extends the primers to make a copy of the target DNA. 2, 1, 4 1, 3, 2, 4 3, 4, 1, 2 3, 4, 2 2, 3, 4
The cell is treated with agents that render it permeable to the plasmid
Which of the following is TRUE regarding the step in gene cloning when bacterial cells take up recombinant vector? The process is known as transformation when a viral vector is used. The process is known as transfection when a plasmid vector is used. The cell is treated with agents that render it impermeable to the plasmid. The cell is treated with agents that render it permeable to the plasmid.
cDNA lacks introns and reflects all the genes expressed by a particular tissue or organism.
Which of the following is an advantage of cDNA libraries? cDNA libraries are easy to make. cDNA libraries utilize genomic DNA, which is easy to obtain. cDNA lacks introns and reflects all the genes expressed by a particular tissue or organism. cDNA lacks exons. cDNA libraries are more stable than other DNA libraries
Initiator tRNA in bacteria carries tryptophan
Which of the following is incorrect about transfer RNA? Has a bottom hairpin loop with an anticodon An anticodon is complementary to a codon Contains a binding site for an amino acid The initiator tRNA that binds to the P site has the anticodon UAC Initiator tRNA in bacteria carries tryptophan
Uses electrophoresis to separate the DNA
Which of the following is not true of fluorescent in situ hybridization (FISH)? Applied to intact cells Can detect activity of specific genes Can detect RNA in cells Uses electrophoresis to separate the DNA
the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA
Which of the following is the first event to take place in translation in eukaryotes? elongation of the polypeptide base pairing of activated methionine-tRNA to AUG of the messenger RNA binding of the larger ribosomal subunit to smaller ribosomal subunits covalent bonding between the first two amino acids the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA
guanine-cytosine
Which of the following is the strongest base pair? guanine-cytosine adenine-uracil adenine-thymine guanine-thymine both adenine-uracil and adenine-thymine
C+A=G+T
Which of the following relationships about nucleotide composition in DNA is TRUE? C+G=A+T C+A=G+T C=A G=T C=T
double-stranded DNA, four kinds of dNTPs, primers, origins
Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication? double-stranded DNA, four kinds of dNTPs, primers, origins topoisomerases, telomerases, polymerases G-C rich regions, polymerases, chromosome nicks nucleosome loosening, four dNTPs, four rNTPs ligase, primers, nucleases
Core enzyme selectively binds promoter regions, but cannot initiate synthesis without a sigma factor
Which of the following statements about E. coli RNA polymerase is false? Core enzyme selectively binds promoter regions, but cannot initiate synthesis without a sigma factor. RNA polymerase holoenzyme has several subunits. RNA produced by this enzyme will be completely complementary to the DNA template. The enzyme adds nucleotides to the 3' end of the growing RNA chain. The enzyme cannot synthesize RNA in the absence of DNA
The enzyme will use any tRNA species, but is highly specific for a given amino acid.
Which of the following statements about aminoacyl-tRNA synthetases is false? These enzymes have editing/proofreading capability. The enzymes attaches an amino acid to the 3' end of a tRNA. The enzyme splits ATP to AMP + PPi. The enzyme will use any tRNA species, but is highly specific for a given amino acid. There is a different synthetase for every amino acid
Polyadenylate polymerase
Which of these polymerases does not require a template? RNA pol I RNA pol II Reverse transcriptase Polyadenylate polymerase RNA replicase
The amount of thymine closely approximates that of guanine within a particular organism.
Which of the following statements about the structure or composition of DNA is FALSE? DNA is a double helix. Complementary base-pairing occurs between pyrimidine and purine bases. The amount of thymine closely approximates that of guanine within a particular organism. Each nucleotide within a DNA is separated by about 0.34 nm Adenine pairs with thymine and guanine with cytosine
a deletion of two nucleotides
Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product? a deletion of a codon a deletion of two nucleotides a substitution of the third nucleotide in an ACC codon a substitution of the first nucleotide of a GGG codon an insertion of a codon
Introns would remain in the mature mRNA.
Which of the following would occur if a cell's splicesomes were mutated so they no longer functioned normally? Introns would remain in the mature mRNA. Exons would be missing in the mature mRNA. Transcription would cease. A functional protein would still be produced. RNA processing would remain intact
2, 1, 3, 4, 5
Which sequence of events is most CORRECT for the initiation and elongation steps of translation? (1) initiator tRNA binds start codon on mRNA (2) small ribosomal subunit binds to mRNA (3) large ribosomal subunit binds (4) tRNA entry and peptidyl transfer reaction (5) translocation of ribosome and release of tRNA 1, 2, 3, 4, 5 1, 2, 3, 5, 4 1, 3, 2, 4, 5 2, 3, 1, 5, 4 2, 1, 3, 4, 5
3
Which step was NOT part of producing a cloned animal? 1. Two cells were fused using a small electrical current. 2. An embryo was implanted into a "surrogate mother". 3. All nuclear DNA was removed from a sperm. 4. A cell was taken from an adult sheep. 5. All nuclear DNA was removed from an egg.
The synthesis of the lagging strand of DNA is discontinuous. The DNA strand is anti-parallel. A primer will bind the wound DNA. This will allow the polymerase to synthesize the DNA in the 5' to 3' direction using Okazaki fragments. The RNA primer of the fragments are removed and replaced with DNA chain growth. DNA ligase joins adjacent DNA fragments that replace the Okazaki fragments.
Why is DNA synthesis discontinuous? Why is DNA ligase needed to join fragments of one strand of DNA?
centromeres, telomeres, and an origin of replication
Yeast artificial chromosomes contain which of the following elements? Centromeres only Telomeres only origin of replication only centromeres and telomeres only centromeres, telomeres, and an origin of replication
shuttle
_____________ vectors can replicate both in yeast and E. coli and can be used to construct yeast genomic libraries
hybridaization
_________________________ refers to the association of 2 complementary nucleic acid strands to form double-stranded molecules, which can contain two DNA strands, two RNA strands, or one DNA and one RNA strand