🧬 Biochemistry Solved MCQs with Answers

Practice 1490 approved 🧬 Biochemistry questions with verified answers from the 🧬 Medical Science subject for Pakistan exams.

1490 solved MCQs

Cyclins are proteins thatAnswer: Regulate passage from one stage of cell division to another Over 50% of common cancers are associated with damage to a protein, p53. This proteinAnswer: Is a tumor supressor Protein folding isAnswer: Mediated by other proteins called chaperones Sickle cell disease is due toAnswer: A mutation in the beta chain of Hb The four subunits of the hemoglobin (Hb) gene represent protein'sAnswer: Quaternary structure On the ribosome, mRNA bindsAnswer: To the small subunit Type I proteins (plasma membrane) have aAnswer: Cleavage N- terminal signal sequence and a hydrophobic stop transfer sequence Which of the following is not a necessary component of translation?Answer: Ligase A polysome could be best described asAnswer: An active site of protein synthesis. Eukaryotic mRNA binding to the ribosomes is facilitated by __________ .Answer: The 7-methyl guanosine cap Amino acids are joined together into a protein chain by which of the following?Answer: Transfer RNA Phosphorus is taken up by the cell during the process ofAnswer: ATP synthesis. Protein synthesis rates in prokaryotes are limited by the rate of mRNA synthesis. If RNA synthesis occurs at the rate of 50 nucleotides/sec, then rate of protein synthesis occurs atAnswer: 17 amino acids/sec The site of protein synthesis isAnswer: Ribosome The structure in a bacterium that indicates an active site for protein synthesis isAnswer: A polysome. The lac operon contains the z, y and a structural genesAnswer: Encoding p-galactosidase, galactose permeases and thio-galactosidase transacetylase respectively Proteins contain __________ different amino acids, whereas DNA and RNA are composed of __________ different nucleotidesAnswer: 20,4 Which of the following is not necessary for protein synthesis to occur, once transcription is completed?Answer: DNA Ribosomes select the correct tRNAsAnswer: Solely on the basis of their anticodons Signal peptide protein removal that is translocated across a membrane is accomplished byAnswer: Signal peptidase The direction of amino acid transfer to the growing polypeptide chain isAnswer: From the P site to the A site on the ribosome The pathway of a tRNA during polypeptide elongation on the ribosome isAnswer: A site → P site → E site Which of the following has unusual bases?Answer: tRNA The site on a bacterial chromosome that marks the termination point for chromosome replication is calledAnswer: Ter Degenerated codon differs mostly inAnswer: Both (b) and (c) Translation in prokaryotes begins by the formation of a 30S initiation complex between theAnswer: 30S ribosomal subunit, mRNA, initiation factors and N-fMet tRNA The anticodon of tRNAAnswer: Binds to an mRNA codon The peptidyl transferase reaction occursAnswer: On the large subunit Processive synthesis is a characteristic feature ofAnswer: DNA Pol III at a replication fork. Which site of the tRNA molecule binds to the mRNA molecule?Answer: Anticodon