1. Which subunit of E. coli RNA polymerase is needed for RNA polymerase to ident
ID: 10749 • Letter: 1
Question
1. Which subunit of E. coli RNA polymerase is needed for RNA polymerase to identify
promoter sequences?
A. s (sigma) subunit
B. a (alpha) subunit
C. ß (beta) subunit
D. ß’ (beta’) subunit
E. y (gamma) subunit
2. The main promoter region in both prokaryotes and eukaryotes is usually located
A. on the RNA transcript, signaling termination.
B. on the RNA polymerase molecule.
C. on the DNA in the region 3’ relative to the start of transcription.
D. on the DNA in the region 5’ relative to the start of transcription.
E. none of the above
3. Hairpin secondary structures in prokaryotic mRNA are involved in
A. identification of termination sites for transcription.
B. identification of sites for polyadenylation.
C. recognition of promoter sequences for binding by RNA polymerase.
D. all of the above
E. none of the above
4. One function of the 5’ cap on eukaryotic mRNA is
A. to identify the 5’ terminus of the transcript as a signal for termination.
B. to protect the 5’ end of the transcript from exonuclease degradation.
C. to act as the “initiator” nucleotide at the start of transcription by RNA polymerase.
D. to help initiate the unwinding necessary to form a “transcription bubble”.
E. none of the above.
Explain with answer. Thank you !
Explanation / Answer
1) Ans: A.s(sigma)subunit. In bacteria, transcription begins with the binding of RNA polymerase to the promoter in DNA. RNA polymerase is a core enzyme consisiting of five subunits: 2 subunits, 1 subunit, 1' subunit and 1 subunit. A the start of intiation, the core enzyme is associated with a sigma factor that aids in finding the appropriate -35 and -10 base pairs downstream of promoter sequences. 2)Ans: E. none of these. The main promoter region in both prokaryotes and eukaryotes is usually located on DNA template. The promoter region for prokaryotes is -35 and -10 base pairs downstream. The promoter region for the eukaryotes is a shor DNA sequence known as a TATA box, found 25-30 base pairs upstream. 3) Ans: A. Identification of termination sites for transcription. The hairpin loop occurs when two region of the same strand, usually complementary in nucleotise sequence read in opposite direction, base-pair to form a double helix that ends in an unpaired loop. This is the key building block of many RNA secondary structures. The hairpin loop or stem-loop structures in an mRNA strand during transcription and causes the RNA polymerase to become dissociated from the DNA template strand. This process is known as termination, and the sequence involved are called as terminator sequences. 4)Ans: C. To act as the initiator nucleotide at the start of transcription by RNA polymerase. The 5' cap is a specially altered nucleotise on the 5' end of precursor messenger RNA and some other primary RNA transcripts as found in eukaryotes. Capping ensures the messenger RNA's stability while it undergoes translation in the process of protein synthesis and is a highly regulated process that occurs in the cell nucleus. In bacteria, transcription begins with the binding of RNA polymerase to the promoter in DNA. RNA polymerase is a core enzyme consisiting of five subunits: 2 subunits, 1 subunit, 1' subunit and 1 subunit. A the start of intiation, the core enzyme is associated with a sigma factor that aids in finding the appropriate -35 and -10 base pairs downstream of promoter sequences. 2)Ans: E. none of these. The main promoter region in both prokaryotes and eukaryotes is usually located on DNA template. The promoter region for prokaryotes is -35 and -10 base pairs downstream. The promoter region for the eukaryotes is a shor DNA sequence known as a TATA box, found 25-30 base pairs upstream. 3) Ans: A. Identification of termination sites for transcription. The hairpin loop occurs when two region of the same strand, usually complementary in nucleotise sequence read in opposite direction, base-pair to form a double helix that ends in an unpaired loop. This is the key building block of many RNA secondary structures. The hairpin loop or stem-loop structures in an mRNA strand during transcription and causes the RNA polymerase to become dissociated from the DNA template strand. This process is known as termination, and the sequence involved are called as terminator sequences. 4)Ans: C. To act as the initiator nucleotide at the start of transcription by RNA polymerase. The 5' cap is a specially altered nucleotise on the 5' end of precursor messenger RNA and some other primary RNA transcripts as found in eukaryotes. Capping ensures the messenger RNA's stability while it undergoes translation in the process of protein synthesis and is a highly regulated process that occurs in the cell nucleus.Related Questions
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