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Why are there fewer tRNA anticodons than the 61 needed to match each mRNA codon that codes for an amino acid?


A) There is some flexibility in pairing between the 5' base of the codon and the 3' base of the anticodon.
B) There is some flexibility in pairing between the middle base of the codon and the middle base of the anticodon.
C) There is some flexibility in pairing between the 3' base of the codon and the 5' base of the anticodon.
D) There is some flexibility in pairing between all 3 bases of the codon and all 3 bases of the anticodon.

E) All of the above
F) B) and C)

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Initiation of transcription differs from initiation of DNA replication in several ways.One difference is that initiation of transcription does not require


A) a promoter.
B) enzymes.
C) a primer.
D) a DNA template strand.

E) All of the above
F) A) and D)

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C

A scientist makes three artificial mRNA strands: (x) 5' AAAUUUAAAUUUAAAUUUAAAUUUAAA 3' (y) 5' UUUCCCUUUCCCUUUCCCUUUCCCUUU 3' (z) 5' AUAUAUAUAUAUAUAUAUAUAUAUAU 3' When he analyzes the polypeptides produced, he finds that: X produces a polypeptide that is 50% phenylalanine and 50%lysine.y produces a polypeptide that is 50% phenylalanine and 50% proline.z produces a polypeptide that is 50% isoleucine and 50% tyrosine.Based on these results only, the best conclusion to make is that


A) AUA codes for isoleucine
B) AAA codes for phenylalanine
C) AAA codes for lysine
D) AAA codes for lysine and AUA codes for isoleucine

E) All of the above
F) B) and C)

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What is required for formation of the transcription initiation complex in eukaryotes?


A) binding of a transcription factor to the TATA box, followed by recruitment of additional transcription factors and recruitment of RNA polymerase II
B) binding of a transcription factor to the transcription bubble, followed by recruitment of additional transcription factors and recruitment of RNA polymerase III
C) binding of the sigma subunit to the start site followed by recruitment of RNA polymerase II
D) binding of RNA polymerase II to the TATA box, followed by recruitment of transcription factors

E) All of the above
F) C) and D)

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Codons that serve as "stop" signals for translation are recognized by


A) tRNA.
B) release factors.
C) anticodons.
D) translation terminators.

E) A) and D)
F) A) and C)

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In prokaryotes, the form of RNA polymerase that can accurately initiate synthesis of RNA is called


A) the holoenzyme.
B) the core polymerase.
C) RNA polymerase II.
D) RNA polymerase III.

E) A) and B)
F) A) and C)

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Eukaryotes have ____ type(s) of RNA polymerase.


A) two
B) three
C) four
D) one

E) None of the above
F) B) and D)

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The polypeptide-making organelles, which consist of protein combined with RNA, are called


A) ribosomes.
B) Golgi bodies.
C) lysosomes.
D) centrosomes.

E) B) and D)
F) B) and C)

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The strand of DNA that is not transcribed is called the ______ strand.


A) coding
B) non-coding
C) template
D) complementary

E) B) and D)
F) C) and D)

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Eukaryotic mRNA molecules may contain non-coding sequences that must be removed before translation.These are called


A) anticodons.
B) introns.
C) exons.
D) nucleosomes.

E) C) and D)
F) A) and D)

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To remove noncoding sequences in the pre-mRNA of eukaryotes, multiple snRNPs combine with proteins to form a larger complex called the ___________ .


A) 5' cap
B) introsome
C) ribosome
D) spliceosome

E) A) and B)
F) A) and C)

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D

If the sequence of bases in the template strand of a DNA molecule is 3' ATCGCTCC 5', what is the sequence of bases in the RNA that is transcribed from this molecule?


A) 3' UAGCGAGG 5'
B) 3' TAGCGAGG 5'
C) 5' UAGCGAGG 3'
D) 5' TAGCGAGG 3'

E) A) and C)
F) A) and D)

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Ribosomes are complex aggregates of


A) RNA and DNA.
B) RNA and proteins.
C) RNA and sugars.
D) DNA and proteins.

E) C) and D)
F) All of the above

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Cells conserve energy and resources by making active proteins only when they are needed.If a protein is not needed, which of the following methods of control would be the most energy-efficient?


A) block transcription
B) degrade the mRNA after it is made
C) prevent translation of the mRNA
D) degrade the protein after it is made

E) All of the above
F) A) and D)

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A codon is composed of how many bases?


A) one
B) two
C) three
D) four

E) None of the above
F) All of the above

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A gene that codes for a protein was removed from a eukaryotic cell and inserted into a prokaryotic cell.Although the gene was successfully transcribed and translated, it produced a different protein than it produced in the eukaryotic cell.What is the most likely explanation?


A) There are slight differences in the genetic code for prokaryotes and eukaryotes.
B) Unlike eukaryotes, which have three different RNA polymerases, prokaryotes have a single RNA polymerase.
C) Eukaryotic genes often contain introns while prokaryotic genes do not.
D) Eukaryotic transcripts have a 5' cap while prokaryotic transcripts do not.

E) B) and C)
F) A) and D)

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The template strand of a DNA segment that codes for mRNA has the sequence: ATGCGT.Which tRNA anticodons would pair with the mRNA that is coded for by this sequence?


A) AUG CGU.
B) ATG CGT.
C) UAC GCA.
D) UAG CGU.

E) A) and D)
F) A) and C)

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Two 6-base sequences are present in bacterial promoters: TATAAT (located 10 nt upstream from the start site) and TTGACA (located 35 nt upstream from the start site) .What is the significance of the fact that these two base sequences are different?


A) Binding sites for both the holoenzyme and ATP are provided.
B) Both the location of the start site and the direction of transcription can be established.
C) Binding sites for both the core polymerase and holoenzyme are provided.
D) The transcription bubble can be properly formed.

E) None of the above
F) A) and B)

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You are working to characterize a novel protein in mice.Analysis shows that high levels of the primary transcript that codes for this protein are found in tissue from the brain, muscle, liver, and pancreas.However, an antibody that recognizes the C-terminal portion of the protein indicates that the protein is present in brain, muscle, and liver, but not in the pancreas.What is the most likely explanation for this result?


A) The gene that codes for this protein is not transcribed in the pancreas.
B) The transcript is immediately degraded in the pancreas.
C) The transcript receives a 5' cap in the pancreas.
D) Alternative splicing in the pancreas creates a protein missing the domain that the antibody recognizes.

E) A) and C)
F) A) and B)

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During the splicing reaction, the intron-exon junctions are recognized by


A) snRNPs.
B) miRNAs.
C) SRP RNAs.
D) the lariat.

E) B) and C)
F) None of the above

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A

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