Give correct explanation, why RNA polymerase can initiate a new RNA chain on a DNA template without any primer?

A. Because RNA polymerase starts most transcripts with an A, and that ribonucleotide binds the template nucleotide (T) with only two hydrogen bonds.

B. The enzyme has to make specific interactions with one or all of the DNA template strand, the initiating ribonucleotide, and the second ribonucleotide—holding one (or all) rigidly in the correct orientation to allow chemical attack on the incoming NTP.

C. The structure of the open complex shows that the s region 3/4 linker interacts with the template strand, organizing it in the correct conformation and location to allow initiation.

D. Consistent with this, in experiments using an RNA polymerase containing a s70 derivative lacking this part of s, initiation requires much lower than normal concentrations of one or both of the first two ribonucleotides.

#Question id: 4234

#Unit 3. Fundamental Processes

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the __.

#Question id: 4235

#Unit 3. Fundamental Processes

What would be the consequence of a mutation in a bacterial cell that produces a defective aminoacyl-tRNA synthetase that attaches a lysine instead of the normal phenylalanine to tRNAs with the anticodon AAA?

#Question id: 4236

#Unit 3. Fundamental Processes

In bacteria, there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. Which of the following statements explains this fact?

#Question id: 4237

#Unit 3. Fundamental Processes

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5′-CCGACG- 3′ (mRNA). The following charged transfer RNA molecules (with their anticodons shown in the 3′ to 5′ direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form. Which of the following dipeptides will form from this mRNA?

#Question id: 4238

#Unit 3. Fundamental Processes

Use the following information to answer the question. A part of an mRNA molecule with the following sequence is being read by a ribosome: 5′-CCGACG- 3′ (mRNA). The following charged transfer RNA molecules (with their anticodons shown in the 3′ to 5′ direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form.

#Question id: 4239

#Unit 3. Fundamental Processes

Use the figure to answer the question. What type of bonding is responsible for maintaining the shape of the tRNA molecule shown in the figure?