🧬 Biochemistry Solved MCQs with Answers

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

1490 solved MCQs

The transcriptional regulatory proteins in eukaryotes which induce transcription usually haveAnswer: At least two distinct domains of protein structure, a DNA binding domain and an activation domain In prokaryotes, transcription isAnswer: Terminated by a protein called rho In eukaryotes, there are three different RNA polymerases. The RNA polymerase responsible for transcription of mRNA isAnswer: RNA polymerase II The nucleons of eukaryotic cell hasAnswer: All of the above Upstream regions which are essential for correct transcription are calledAnswer: Promoters Transcription of each set of rRNA genes by RNA polymerasel producesAnswer: A single 45S rRNA precursor molecule The regions of a gene located at -10 and -35, with respect to the start of transcription, are termedAnswer: Promoters. Which of the following conditions would cause the release of the lac repressor protein from the lac operator site on DNA?Answer: Both (b) and (c) A nicked RNA molecule can be ligated byAnswer: T4 DNA ligase The tertiary structure of yeast tRNAAnswer: All of the above Which of following RNA characteristically contains unusual purines and pyrimidmes?Answer: tRNA The anticodon is a structure onAnswer: tRNA. The genetic material of retroviruses such as HIV isAnswer: RNA Retroviruses replicate via __________ intermediateAnswer: DNA During RNA synthesis, the DNA template sequence 5'Tp Ap Gp Cp 3' Would be transcribed to produce which of the following RNA sequence?Answer: 5'-Gp Cp Up Ap-3' RNA instability in alkaline solutions is due toAnswer: Ribose In RNA, uracil pairs withAnswer: Adenine Two features of the tRNA molecule associated, in converting the triplet codon to an amino acid, areAnswer: In the anticodon loop and the 3' CCA end Which of the following is the smallest of the RNAs?Answer: Transfer RNAs The mRNA from which of the following would contain a poly-A tail?Answer: Human insulin What is the average size (in bp) of a mature t-RNA?Answer: 80 bp What modified base is at the 5' extremity of a capped eukaryotic m-RNA?Answer: 7-methyl-guanosine What is the function of messenger RNA?Answer: It is a direct copy of a gene Which of the following techniques was carried out by Nirenberg and Matthaei in 1961 to determine the first codon?Answer: In vitro synthesis of a polypeptide using UUUUU Bacterial protein called catabolic activator protein (CAP) is an example ofAnswer: Second type of positive control of gene expression How many different codons are possible?Answer: 64 The genetic code isAnswer: Universal except for rare exceptions in mitochondria and some protozoa Which of the following has been used as an evidence that primitive life forms lacked both DNA and enzymes?Answer: RNA can both code genetic information and act as a catalyst Crick demonstrated that the genetic code involved three bases and suggested that the code was degenerated. What experimental technique Crick conducted to suggest genetic code degeneration?Answer: Frameshift mutagenesis Codon that specify the amino acids often differs in theAnswer: Third base