Genetic Exam 3
Deoxyribonucleotides bind together to form polynucleotides. This bond occurs between the phosphate group of one nucleotide and the C- ____' position of a ___________of another nucleotide. The type of bond formed in this interaction is called a ________________bond.
3 sugar phosphodiester
The extraordinary accuracy of the DNA polymerase III enzyme lies in its ability to "proofread" newly synthesized DNA, a function of the enzyme's _______.
3'-to-5' exonuclease activity
If there are five molecules of DNA containing the target region at the beginning of a PCR reaction, how many copies of the target will be present after three rounds of amplification?
40 (The number of target sequences is doubled with each replication cycle.)
What conclusion(s) could Griffith draw from his experiment? Select all that apply.
A transforming factor from a virulent strain of bacteria can make a non-virulent strain virulent.
The enzyme that can replicate DNA is called
DNA polymerase
Avery, Macleod, and McCarty expanded on Griffith's experiment to prove that DNA is the hereditary molecule required for transformation. What treatment of the heat-killed SIII bacteria extract prevented transformation from taking place?
Destroying type SIII DNA with DNase
A tRNA in the P site of the ribosome will enter the ________ site after translocation of the ribosome.
E
What is one difference between DNA replication in bacteria versus eukaryotes?
Eukaryotic chromosomes have many origins of replication, while bacteria have only one origin of replication.
Ribosomal subunits are large complexes composed of numerous polypeptides and at least one rRNA molecule. Which subunits include three rRNA molecules? See Section 9.1 (Page 316) .
Eukaryotic large subunits
Which of the following is characteristic of transcription in eukaryotes but not in prokaryotes?
Exon splicing catalyzed by the spliceosome
DNA helicase inhibitors are well studied as potential drug targets. What would you expect to see if DNA helicase activity is inhibited?
Helicase catalyzes ATP hydrolysis and DNA strands separation, so the helix cannot be unwound and strands will not separate.
________ helps control ribosome formation and binding of the initiator tRNA.
Initiation factor protein
How does the eukaryotic ribosomal small subunit recognize the start codon on the mRNA?
It binds an Met-tRNA to the first AUG codon after the Kozak sequence. Submit
In a single strand of DNA, what fraction of the nucleotides in a molecule are cytosine and thymine (% C and % T added together)?
It depends on the DNA sequence Submit
What is the DNA replication fork?
It is the site where the DNA helix opens to two single DNA strands.
Which of the following best describe(s) the function of the 5' mRNA cap?
It provides a site for ribosome binding in the cytoplasm. To protect the transcript from degradation
What is the purpose of alternative splicing in eukaryotic cells?
Produce multiple polypeptide sequences from a single primary transcript.
What is the type of each eukaryotic protein that primarily transcribes mRNA, tRNA, and rRNA, respectively?
RNA Polymerase II, III, I
Why does rho-dependent transcriptional termination in bacteria require the rho protein?
RNA Polymerase stalls on the termination stem-loop and rho is needed to displace the RNA Polymerase.
What are two distinguishing features of RNA?
RNA has a ribose sugar and uracil nitrogenous base.
Through which process does miRNA regulate protein production?
RNA interference
You want to design a drug that prevents transcription of mRNAs but does not affect transcription of other RNAs. What enzyme would you target?
RNA polymerase II
A plant cell exhibits defects in transcription of transfer RNA genes. The gene encoding of which polymerase is likely to be mutated in this cell?
RNA polymerase III
What must eukaryotes do to initiate transcription of a gene?
Recruit the transcription factors and RNA Polymerase that compose the pre-initiation complex.
Why are telomeres problematic for eukaryotic chromosome replication?
Removal of the lagging strand primer leaves a gap in the one of the strand's DNA sequences. Submit
Which of the following statements about DNA replication in E. coli is true? See Section 7.3 (Page 245) .
Replication proceeds in both directions from a single origin of replication. See Figure 7.10 for more information.
If Single-Stranded Binding protein (SSB) is NOT present during DNA replication, what would you expect to see?
SSB prevents reannealing of the separated strands, so strands would quickly reanneal and DNA replication cannot proceed.
Which units that describe the speed of sedimentation of a substance during centrifugation are ribosomal subunits measured in?
Svedberg units (S)
Prokaryotes have a -10 and -35 consensus sequence in their promoter. What are the three eukaryotic promoter sequences elements (or "boxes")?
TATA CAAT GC- rich
In the Hershey-Chase experiment, bacteriophages were produced in either 32P-containing or 35S-containing medium. Where were these isotopes eventually detected when the radioactively-labeled bacteriophages were introduced to a fresh bacterial culture?
The 32P was associated with the bacterial cells and 35S was associated with the phage particles.
How does the eukaryotic initiation complex locate the correct start codon?
The initiation complex moves the small ribosomal subunit through the 5' UTR, scanning for the start AUG.
Based on Griffith's results, what would you expect if you injected both heat-killed type RII and living type SIII?
The mouse dies.
Which of the following statements about DNA structure is true?
The nucleic acid strands in a DNA molecule are oriented antiparallel to each other, meaning they run in opposite directions.
What is the function of the sigma subunit in bacterial RNA polymerase? See Section 8.2 (Page 280) .
The sigma subunit induces a conformational change in the RNA polymerase core enzyme that switches it to its active form.
The RNA transcribed from a gene will be complementary and antiparallel to which of the following? See Section 8.2 (Page 280) .
The template strand of the DNA
Which of the following statements about the basic structural features of DNA are true?
The twisting of the DNA double helix is attributed to the tight packing of DNA bases and base-stacking. In a DNA macromolecule, the two strands are complementary and antiparallel.
Which of the following lists steps of mRNA production in eukaryotes in the correct order?
Transcription, 5' cap addition, addition of poly-A tail, exon splicing, passage through nuclear membrane
What is the corresponding sequence of bases in the RNA that is produced? Begin with the first base added to the growing RNA strand, and end with the last base added. 3' CCGAGT 5' (coding strand) 5' GGCTCA 3' (template strand)
UGAGCC
What is required for DNA polymerase to initiate DNA strand synthesis?
a short RNA primer synthesized by the enzyme primase
Which enzyme is required to initiate 5' capping of eukaryotic mRNA transcripts by removing the terminal phosphate group?
guanylyl transferase
One type of RNA editing involves inserting uracils into edited mRNA with the assistance of which type of specialized RNA?
guide RNA
What characteristic of the polymerase isolated from Thermus aquaticus makes it unique and highly useful for maintaining the enzyme efficiency during PCR?
heat stability
A portion of an mRNA attached to a ribosome reads: 5' GACCAUUUUUGA 3' If a tRNA with a Phenylalanine amino acid attached is in the P site of the ribosome, an empty tRNA will be present in the E site that delivered which amino acid?
histidine
RNA polymerase is called a ________, meaning it is an intact complex with full enzymatic capacity.
holoenzyme
What types of bonds are formed between complementary DNA bases?
hydrogen bonds
The nitrogenous bases of each nucleotide project __________the double helix. They form complementary base pairs through the formation of ______________bonds with bases on the opposite DNA strand.
into hydrogen
The Shine-Dalgarno sequence in bacteria ________.
is a purine-rich consensus sequence found in the 5' UTR of the mRNA
The new DNA strand that grows continuously in the 5' to 3' direction is called the
leading strand
How might you choose a region of DNA for a PCR primer so as to increase the temperature necessary for primer annealing (to minimize nonspecific PCR products)?
look for higher GC concentrations
Prokaryotes and eukaryotes produce which of the following types of RNA?
mRNA, tRNA, rRNA
What are the regions where DNA-binding proteins can make direct contact with exposed nucleotides?
minor groove major groove
During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a __________
replication fork
A large, complex aggregation of proteins and enzymes that assembles at the replication fork is known as the ________.
replisome
What proteins bind to silencer sequences, forming a protein "bridge" that bends the DNA over the promoter and prevents transcription?
repressor proteins
What are the mechanisms for transcription termination in bacteria?
rho-dependent intrinsic
What is the general name for the components of the spliceosome, which removes introns from mRNAs?
small nuclear ribonucleoproteins
Which type of RNA interacts with nuclear proteins to form a ribonucleoprotein complex responsible for intron removal?
snRNA
Transcription of inverted repeats produces an mRNA with complementary segments. What type of secondary structure do they form through folding?
stem-loop
Polyadenylation begins with the binding of ________ near a six-nucleotide mRNA sequence, AAUAAA, downstream of the stop codon.
the cleavage and polyadenylation specificity factor (CPSF)
Which of the following initially determines which DNA strand is the template strand, and therefore in which direction RNA polymerase II moves along the DNA?
the specific sequence of bases along the DNA strands
Immediately after the primers have annealed to the target sequence, _______.
the temperature is raised so that taq polymerase can extend the primers Submit
Using the prokaryotic DNA sequence above, describe the relationship between the highlighted regions. The -10 and -35 consensus sequences are important because of:
their location relative to one another their nucleotide content their location relative to the start of transcription
The role of the primers in PCR is _______.
to define the target region and provide a 3' end that can be extended by taq polymerase
What proteins aid in the recognition of the promoter sequence and binding of RNA polymerase II in eukaryotes?
transcription factors
The process by which Pneumococcus transfers DNA between living type RII and heat-killed type SIII cells is known as
transformation
Guanine and adenine are purines found in DNA.
true
What is removed from dNTPs to provide the energy required for DNA polymerase to catalyze DNA strand elongation?
two phosphates
What normally binds to an open A site on the ribosome? See Section 9.1 (Page 316) .
A tRNA that carries the next amino acid to be added to the polypeptide chain
What is the cellular location of the stages of translation in bacteria and eukaryotes?
cytosol for bacteria and cytosol, mitochondrion, and plastid for eukaryotes
After replication is complete, the strand of new DNA, called ______________, is complementary to the parental strand.
daughter DNA
Which of the following would you find in a Sanger sequencing reaction but not in a polymerase chain reaction?
ddNTPs
What are the three steps of each PCR cycle?
extension annealing denaturation
Which type of research technique was used to track newly synthesized RNA within a eukaryotic cell?
pulse-chase
Adenine and guanine, which have a nine-member double-ring, are called
purines
Cytosine and thymine, which have a six-member single-ring, are called
pyrimidines
Adenine complementarily binds with thymine and forms (how many?)______(what type?)_______________bonds.
2 hydrogen
If there is 24% guanine in a DNA molecule, then there is ________ cytosine.
24%
How many different RNA polymerases do eukaryotes have?
3
Guanine complementarily binds with cytosine and forms (how many?)_________(what type?)________________bonds.
3 hydrogen
What is the complementary DNA sequence to 5′ ATGCTTGACTG 3′?
5′ CAGTCAAGCAT 3′
Which of the following temperature cycles would you expect to see in a standard polymerase chain reaction (from denaturation to annealing to extension)?
95° → 55° → 72°
In 1928, Frederick Griffith conducted a series of experiments that demonstrated which of the following? See Section 7.1 (Page 237) .
A "transformation factor" could be released from one cell and picked up by another cell, thus changing the genetic identity of the recipient cell.
Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus?
A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA. A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA. Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes.
What is the difference between a nucleotide and a nucleoside?
A nucleoside with a phosphate ester linked to the sugar is a nucleotide.
Where would you expect to find telomerase activity?
At the end of a chromosome in a cancerous eukaryotic body cell.
How may mutations in each region affect gene expression?
Mutation in any consensus sequence is likely to alter how efficiently a protein binds to the promoter.
During translation initiation in bacteria, the amino acid on the initiator tRNA is ________.
N-formylmethionine (fMet)
______________ are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA.
Okazaki fragments
Why do origins of replication in various bacteria have conserved DNA consensus sequences?
Origins need to be recognized by replication initiation proteins to open up their AT-rich regions.
________ must be added to a PCR to direct the polymerase where to begin synthesis.
PCR primers
Which of the following is an example of the phenomenon termed "RNA editing"? See Section 8.4 (Page 295) .
Posttranscriptional insertion of uracil nucleotides facilitated by a guide RNA
What proteins are bound to enhancers, forming a protein "bridge" that bends the DNA over the promoter to initiate transcription?
activator proteins
In intrinsic termination, inverted repeat DNA sequences followed immediately by a string of ________ produce an mRNA stem-loop followed by a string of ________.
adenines uracils
Adenine, guanine, cytosine and thymine are
nitrogenous bases
DNA is comprised of four different types of ______________. Each one is made up of a pentose ___________, a ______________group, and one of four ____________________.
nucleotides sugar phosphate nitrogenous bases
You wish to prevent transcription of all three types of RNA in bacteria. How many different types of RNA polymerase would you need to inhibit?
one
What type of bond is formed between the hydroxyl group of one nucleotide and the phosphate group of an adjacent nucleotide, forming the sugar-phosphate backbone of DNA?
phosphodiester bond
Which of the following is part of a DNA molecule?
promoter
Which region(s) of a gene are NOT found within the mRNA transcript?
promoter and termination regions
You wish to create a mutation that prevents access of RNA polymerase to the gene. Which region of a gene would you mutate?
promoter sequence
