Biology Chapter 17

Last update by mayurcooled on 04/17/2014
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9) Which of the following provides some evidence that RNA probably evolved before DNA?

A) RNA polymerase uses DNA as a template.

B) RNA polymerase makes a single-stranded molecule.

C) RNA polymerase does not require localized unwinding of the DNA.

D) DNA polymerase uses primer, usually made of RNA.

E) DNA polymerase has proofreading function.

Answer:
D) DNA polymerase uses primer, usually made of RNA.

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    10) Which of the following statements best describes the termination of transcription in prokaryotes?

    A) RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase.

    B) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

    C) RNA polymerase transcribes through an intron, and the snRNPs cause the polymerase to let go of the transcript.

    D) Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome.

    E) RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.

    B) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.
  • lindsaygreenman2008
    Answered in Biology Chapter 17

    11) Which of the following does not occur in prokaryotic eukaryotic gene expression, but does in eukaryotic gene expression?

    A) mRNA, tRNA, and rRNA are transcribed.

    B) RNA polymerase binds to the promoter.

    C) A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.

    D) Transcription can begin as soon as translation has begun even a little.

    E) RNA polymerase requires a primer to elongate the molecule.

    C) A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.
  • lindsaygreenman2008
    Answered in Biology Chapter 17

    12) RNA polymerase in a prokaryote is composed of several subunits. Most of these subunits are the same for the transcription of any gene, but one, known as sigma, varies considerably. Which of the following is the most probable advantage for the organism of such sigma switching?

    A) It might allow the transcription process to vary from one cell to another.

    B) It might allow the polymerase to recognize different promoters under certain environmental conditions.

    C) It could allow the polymerase to react differently to each stop codon.

    D) It could allow ribosomal subunits to assemble at faster rates.

    E) It could alter the rate of translation and of exon splicing.

    B) It might allow the polymerase to recognize different promoters under certain environmental conditions.
  • lindsaygreenman2008
    Answered in Biology Chapter 17

    13) Which of the following is a function of a poly-A signal sequence?

    A) It adds the poly-A tail to the 3' end of the mRNA.

    B) It codes for a sequence in eukaryotic transcripts that signals enzymatic cleavage ~1035 nucleotides away.

    C) It allows the 3' end of the mRNA to attach to the ribosome.

    D) It is a sequence that codes for the hydrolysis of the RNA polymerase.

    E) It adds a 7-methylguanosine cap to the 3' end of the mRNA.

    B) It codes for a sequence in eukaryotic transcripts that signals enzymatic cleavage ~1035 nucleotides away.
  • lindsaygreenman2008
    Answered in Biology Chapter 17

    14) In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?

    A) ligase

    B) RNA polymerase I

    C) RNA polymerase II

    D) RNA polymerase III

    E) primase

    C) RNA polymerase II
  • lindsaygreenman2008
    Answered in Biology Chapter 17

    15) Transcription in eukaryotes requires which of the following in addition to RNA polymerase?

    A) the protein product of the promoter

    B) start and stop codons

    C) ribosomes and tRNA

    D) several transcription factors (TFs)

    E) aminoacyl synthetase

    D) several transcription factors (TFs)
  • lindsaygreenman2008
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    16) A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate?

    A) The sequence evolves very rapidly.

    B) The sequence does not mutate.

    C) Any mutation in the sequence is selected against.

    D) The sequence is found in many but not all promoters.

    E) The sequence is transcribed at the start of every gene.

    C) Any mutation in the sequence is selected against.
  • lindsaygreenman2008
    Answered in Biology Chapter 17

    17) The TATA sequence is found only several nucleotides away from the start site of transcription. This most probably relates to which of the following?

    A) the number of hydrogen bonds between A and T in DNA

    B) the triplet nature of the codon

    C) the ability of this sequence to bind to the start site

    D) the supercoiling of the DNA near the start site

    E) the 3-D shape of a DNA molecule

    A) the number of hydrogen bonds between A and T in DNA
  • lindsaygreenman2008
    Answered in Biology Chapter 17

    18) What is a ribozyme?

    A) an enzyme that uses RNA as a substrate

    B) an RNA with enzymatic activity

    C) an enzyme that catalyzes the association between the large and small ribosomal subunits

    D) an enzyme that synthesizes RNA as part of the transcription process

    E) an enzyme that synthesizes RNA primers during DNA replication

    B) an RNA with enzymatic activity
  • lindsaygreenman2008
    Answered in Biology Chapter 17

    19) A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that

    A) many noncoding stretches of nucleotides are present in mRNA.

    B) there is redundancy and ambiguity in the genetic code.

    C) many nucleotides are needed to code for each amino acid.

    D) nucleotides break off and are lost during the transcription process.

    E) there are termination exons near the beginning of mRNA.

    A) many noncoding stretches of nucleotides are present in mRNA.
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    Answered in Biology Chapter 17

    20) During splicing, which molecular component of the spliceosome catalyzes the excision reaction?

    A) protein

    B) DNA

    C) RNA

    D) lipid

    E) sugar

    C) RNA