1.Comparing mRNA molecules from human and E. coli cells, which of the following
ID: 96863 • Letter: 1
Question
1.Comparing mRNA molecules from human and E. coli cells, which of the following is not typically true?
A. A human mRNA has a special 5' cap, while bacterial mRNA does not.
A human mRNA has a poly-A tail, while a bacterial mRNA does not.
C. A typical human mRNA encodes one protein, while many bacterial mRNAs encode several different proteins.
D. All of the above are true.
2. Which of the following is FALSE regarding eukaryotic transcription?
a.RNA polymerases (along with its sigma factor) can initiate transcription on its own.
b. RNA polymerase requires the general transcription factors to assemble at the promoter before polymerase can begin transcription.
c. TFIID along with TATA binding protein is required for initiation of transcription.
d. RNA polymerase must be phosphorylated at its C-terminal tail for transcription to proceed.
3. Eukaryotic pre-mRNAs undergo a number of modifications such as capping at the 5' end. A 5' cap _____.
a.Consists of a modified terminal adenine nucleotide.
b. Consists of a string of modified adenines.
c. Consists of a methylguanosine added to the 3' end.
d. Consists of a methylguanosine added to the 5' end.
B.A human mRNA has a poly-A tail, while a bacterial mRNA does not.
C. A typical human mRNA encodes one protein, while many bacterial mRNAs encode several different proteins.
D. All of the above are true.
2. Which of the following is FALSE regarding eukaryotic transcription?
a.RNA polymerases (along with its sigma factor) can initiate transcription on its own.
b. RNA polymerase requires the general transcription factors to assemble at the promoter before polymerase can begin transcription.
c. TFIID along with TATA binding protein is required for initiation of transcription.
d. RNA polymerase must be phosphorylated at its C-terminal tail for transcription to proceed.
3. Eukaryotic pre-mRNAs undergo a number of modifications such as capping at the 5' end. A 5' cap _____.
a.Consists of a modified terminal adenine nucleotide.
b. Consists of a string of modified adenines.
c. Consists of a methylguanosine added to the 3' end.
d. Consists of a methylguanosine added to the 5' end.
Explanation / Answer
Answer:
1. (D) All of the above are true.
Explanation:
The 5' end of eukaryotic mRNA has a cap and the 3' end possess a poly-A tail which are absent in bacterial mRNA. In bacteria, mRNA molecules are polycistronic having transcripts of several genes, while it is monocistronic in eukaryotes (humans).
2. (a) RNA polymerases (along with its sigma factor) can initiate transcription on its own.
Explanation:
Sigma factor is an initiation factor required for specific binding of RNA polymerase to the promoter DNA for initiating transcription (RNA synthesis) in bacteria.
3. (d) Consists of a methylguanosine added to the 5' end.
Explanation:
5' capping of the pre-mRNA involves the addition of 7-methylguanosine (m7G) to the 5' end
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