🦠 Microbiology Solved MCQs with Answers

Practice 1927 approved 🦠 Microbiology questions with verified answers from the 🧬 Medical Science subject for Pakistan exams.

1927 solved MCQs

A level of regulation, demonstrated by the termination of transcription if tryptophan is abundant, by the tryptophan operon in E.coli cells is calledAnswer: attenuation An mRNA transcript of a gene containsAnswer: all of these Which of the following proteins first binds to TATA box during transcription?Answer: TF II D The components found in all prokaryotic transcription terminators isAnswer: a hairpin structure A specific __________ factor helps RNA polymerase bind to late promoters and transcribe late genes.Answer: sigma Which binding is inhibited by pactamycin?Answer: Initiator-tRNA to 30S/40S initiation complexes Which of the following act as the blueprint or template for the process of protein synthesis that takes place on ribosomes?Answer: mRNA Negative regulation of protein synthesis is accomplished byAnswer: the binding of a repressor to the DNA Site in the ribosome from which the tRNA donates amino acids to the growing polypeptide chain isAnswer: P site When was the genetic code completed?Answer: 1966 Which stop codon has been found to encode selenocysteine?Answer: UGA Which of the following is a nontranslated sequence located between the transcription and the translation start site?Answer: Leader sequence Which phage always carries a small piece ofE.coli genome?Answer: Mu The final step of gene expression is protein synthesis, which is also known asAnswer: translation What is the maximum number of different amino acids in a polypeptide chain coded by the synthetic polyribonucleotides (UCAG)5?Answer: Three What is the direct cause of cell death by diphtheria toxin?Answer: Inactivation of a translational elongation factor The development of global regulatory systems in prokaryotesAnswer: regulates many genes under varying environmental conditions The interaction between the mRNA and tRNA determined the position of amino acid in a polypeptide sequence. This is called theAnswer: adaptor hypothesis What are the Svedberg values for the subunits of the 70S ribosomes of E. colli?Answer: 50S and 30S Which of the following three codons translate as serine (Ser)?Answer: AGU The role of molecular chaperones is toAnswer: aid a newly synthesized polypeptide in folding to its proper shape What is the action of tetracycline in prokaryotes?Answer: It blocks the binding of amino-acyl tRNA to the A site of ribosomes A quorum sensing systemAnswer: senses a compound produced by the bacterium itself The Shine-Dalgarno sequence isAnswer: a short sequence that acts as a ribosomal binding site Which of the following statement is correct?Answer: Amino acid sequence of a protein can be deduced from corresponding cDNA nucleotide What was the first bacterial genome to be sequenced and made public?Answer: Haemophilus influenzae Which of the following modified amino acid is used at the starting of most prokaryotic proteins?Answer: N-formylmethionine During amino acid activation a(n)Answer: amino acid is bound to tRNA The nonsense codon(s) is/areAnswer: all of these Which of the following defines an open reading frame (ORF)?Answer: A possible gene predicted by DNA sequencing