Which molecule serves as the structural component of ribosomes?
Ribosomal RNA (rRNA) combines with proteins to form the structural units of the ribosome (both large and small subunits) and also has catalytic activity.
Question 122 of 668
📘 CLASS XII
In the Lac operon, lactose is hydrolyzed into?
The enzyme beta-galactosidase hydrolyzes the disaccharide lactose into two monosaccharides: glucose and galactose.
Question 123 of 668
📘 CLASS XII
The probe used in DNA fingerprinting is usually?
Probes are single-stranded DNA or RNA molecules tagged with radioactive isotopes that hybridize to complementary sequences (VNTRs) on the membrane.
Question 124 of 668
📘 CLASS XII
Polycistronic mRNA is characteristic of?
Prokaryotic mRNA is often polycistronic, meaning it carries coding information for several proteins (genes) that are translated together (e.g., Lac operon). Eukaryotic mRNA is typically monocistronic.
Question 125 of 668
📘 CLASS XII
The first amino acid added during translation in prokaryotes is?
In prokaryotes, the initiator tRNA carries a modified methionine called N-formylmethionine (fMet). In eukaryotes, it is unmodified methionine.
Question 126 of 668
📘 CLASS XII
Which site of the ribosome holds the tRNA carrying the growing polypeptide chain?
The P (Peptidyl) site holds the tRNA attached to the growing polypeptide chain. The A site holds the incoming amino acid, and the E site is for exit.
Question 127 of 668
📘 CLASS XII
Select the correct complementary base pairing rule.
To maintain a uniform distance between the two strands of the double helix, a large purine (A or G) always pairs with a small pyrimidine (T or C).
Question 128 of 668
📘 CLASS XII
The net electric charge of DNA is?
DNA is negatively charged at physiological pH due to the phosphate groups in the backbone, which release protons.
Question 129 of 668
📘 CLASS XII
Which of the following is required for the initiation of transcription in E. coli?
The Sigma factor is essential for the RNA polymerase holoenzyme to recognize and bind to the promoter region to initiate transcription.
Question 130 of 668
📘 CLASS XII
A terminator sequence is involved in?
The terminator is a DNA sequence that signals the RNA polymerase to stop transcription and release the RNA transcript.
