Microbio Exam 2

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1. Which sequence below shows increasing numbers of genes?

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gene, operon, regulon

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2. During DNA replication, each new nucleotide adds on to

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the hydroxyl group on the 3′-C of the sugar.

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3. Chromosome replication differs from the rolling-circle method of plasmid replication in that

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only chromosomal replication produces Okazaki fragments.

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4.Which of the following statements is true?
a)# Eukaryotic genomes are composed mostly of noncoding DNA, whereas prokaryotes have mostly coding DNA.
b) # Eukaryotic genomes are composed mostly of double-stranded DNA, whereas prokaryotes have mostly single-stranded DNA.
c) # Eukaryotic genomes are composed mostly of circular DNA, whereas prokaryotes have mostly linear DNA.
d) # Eukaryotic genomes are composed mostly of positively supercoiled DNA, whereas prokaryotes have mostly negatively supercoiled DNA.

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a) # Eukaryotic genomes are composed mostly of noncoding DNA, whereas prokaryotes have mostly coding DNA.

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5. Bacteria, archaea, and eukaryotes all

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have double-stranded DNA genomes.

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6. Denaturation of DNA refers to

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how the helix separates into single strands.

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7. A shuttle vector is so named because it

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contains a replication origin compatible with E. coli and a second origin that will allow the plasmid to replicate in a eukaryote or archaea.

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8. The polymerase chain reaction (PCR) has many cycles of three temperature steps: 95°C, 55°C, and 72°C. At the 72°C stage,

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a thermostable DNA polymerase synthesizes DNA.

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9. The enzyme DNA primase is

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an RNA polymerase.

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10. Which of the following is an example of a DNA control sequence?

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the promoter region of a gene

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11. Which protein is necessary for replicating the linear ends of eukaryotic chromosomes?

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telomerase

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12. Which statement about DNA versus RNA is true?

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Only RNA contains a hydroxyl group on the 2′-carbon of ribose.

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13. A plasmid singly cut with a restriction enzyme that leaves cohesive ends

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can ligate to any DNA cut with the same restriction enzyme.

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14. Which of the following is an example of vertical transmission?

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cell division

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15. In most bacterial species the DNA is

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negatively supercoiled.

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16. If the deoxyadenosine methylase (Dam) enzyme is inhibited in E. coli, then the next generation time

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will increase due to more persistent SeqA binding.

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17. E. coli DNA polymerase III has which of the following activities?

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3′ to 5′ exonuclease

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18. Which of the following is true of plasmids?
a) They may contain antibiotic resistance genes.
b) They may exist in multiple copies in a single cell.
c) They may be transmitted horizontally from one bacterium to another.
d) all of the above

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-->ALL OF THESE

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19. Restriction enzymes do not cut the bacterial DNA that produced them because

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The DNA is protected by site-specific methylating enzymes.

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20. The polymerase chain reaction has many cycles of three temperature steps: 95°C, 55°C, and 72°C. At the 95°C stage,

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the DNA strands denature.

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21. The semiconservative nature of DNA replication indicates that

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each daughter cell receives one parental strand and one newly synthesized strand.

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22. Bacterial genomes consist of

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the genome structure depends on the species.

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23. Enzymes that regulate DNA supercoiling are called

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topoisomerases.

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24. Often researchers will have bacteria produce a segment of DNA that they are interested in. To obtain the largest amount of the DNA sequence of interest, it is best to put the DNA into

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a high-copy-number plasmid.

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25. A gene is

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a string of nucleotides that can be used as a template to produce a functional RNA.

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26. Initiation of DNA replication in a bacterial species

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is influenced by environmental factors.

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27. Which statement is true?

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Organisms differ in their genome size.

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28. What is present in a
DNA
sequencing reaction but not DNA replication in vivo?

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dideoxynucleotides

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Replication of a bacterial chromosome occurs at the DNA sequence called

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oriC.

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With respect to controlled protein degradation

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proteolysis requires ATP.

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Sigma factors are necessary in which phase of transcription?

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initiation

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RNA polymerase does not have binding sites for

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individual deoxyribonucleotides.

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Which of the following are ribozymes?

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some of the rRNAs in the ribosome

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Which pair of amino acids is not considered similar?

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glutamine and glutamate

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The number of nucleotides in a codon is

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three

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The energy for translation comes from

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GTP hydrolysis.

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Which of the following statements is true?

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DNA is transcribed into mRNA and mRNA is translated into proteins

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Each segment of double-stranded DNA contains how many possible open reading frames?

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six

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What is the correct temporal sequence for factors binding to an mRNA in bacterial translation initiation?

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30S ribosomal subunit, N-formylmethionine-tRNA, 50S subunit

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When a genome is annotated, it means that

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an attempt has been made to locate all the genes in the genome.

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Most tRNAs become charged with

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an amino acid

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Sigma factors are responsible for

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binding of RNA polymerase to consensus sequences on DNA.

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Proteins destined for the bacterial inner membrane

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usually contain long stretches of amino acids with hydrophobic side chains that will span the bilayer.

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Heat shock proteins are which kind of proteins?

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chaperonins

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When a stop codon is in the A site,

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release factors bind to the A site and activate peptidyl transferase.

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Ubiquination of proteins

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is a covalent post-translational modification of proteins.

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The statement “codons are redundant” refers to the fact that

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most amino acids are specified by more than one codon.

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Eukaryotic ORFs are more difficult to identify than prokaryotic ORFs because

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eukaryotic genomes contain introns.

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A bacterial cell that lacked the Rho protein would be

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resistant to several antibiotics

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The acronym ORF stands for

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open reading frame.

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The prokaryotic ribosome consists of

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three RNAs and many proteins.

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The 30S and 50S ribosomal subunits are so designated because

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the numbers indicate their sedimentation rate in a centrifuge.

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In a mutant E. coli strain, a protein that normally resides in the inner membrane is mis-localized in the cytoplasm. All other proteins show normal localization. This strain probably has the following defect:

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The amino terminal signal sequence for this particular protein is missing.

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In contrast to tRNAs and rRNAs, mRNAs

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encode for proteins.

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The final three-dimensional shape of a protein is

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determined by the gene encoding that protein.

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In prokaryotic cells,

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transcription and translation occur in the same compartment at the same time.

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The codons on mRNA bind to the anticodons on tRNAs through

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hydrogen bonds.

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The covalent attachment of a phosphate to a protein is an example of

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post-translational modification.

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Transcription in prokaryotes does not require which of the following factors?

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DNA polymerase

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The SecA dependent secretion pathway delivers proteins to

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the periplasm

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In ABC transporters, the ATP binding cassette faces the

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cytoplasm.

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If a segment of RNA reads 5′ GCCUUAA 3′, then the corresponding DNA template strand reads

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5′ TTAAGGC 3′

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A protein 100 amino acids long would have a mass of approximately

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10,000 Daltons.

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Which of the following enzymes is used in methyl mismatch repair, nucleotide excision repair and base excision repair?

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DNA polymerase I