🧬 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 first step in translation isAnswer: Binding of mRNA to the small ribosomal subunit Which of the following amino acid starts all proteins synthesis?Answer: Methionine The growing polypeptide chain is released from the ribosomes whenAnswer: A chain terminating codon is reached Which of the following RNAs bind to an amino acid?Answer: tRNA How many bases of nucleic acid determine a single amino acid?Answer: Three The ribosomes are composed ofAnswer: both (a) and (b) Which is required for protein synthesis?Answer: All of these The complex of RNA polymerase, DNA template and new RNA transcript is calledAnswer: Transcription bubble RNA polymerase in prokaryotes has a removableAnswer: Sigma subunit Promoters for tRNAs are locatedAnswer: Downstream from the start codon The binding of lac repressor to DNA could be considered to be analogous toAnswer: Competitive inhibition of an enzyme Rho-dependent termination of transcription in E. coliAnswer: Both (a) and (b) Enhancers are regions thatAnswer: Modulate transcription Transcription by E. coli polymerase occurs inAnswer: Three phases known as initiation, elongation and termination Which of the following is necessary for transcription to occur?Answer: Both DNA & RNA polymerase Multiple copies of 5S genes, located at a chromosomal site distinct from the other rRNA genesAnswer: Are transcribed by DNA polymerase I Each tRNA molecule has a cloverleaf secondary structure consisting ofAnswer: three stem loops What is a promoter?Answer: A specific sequence of DNA to which RNA polymerase binds The function of the sigma factor of RNA polymerase is toAnswer: Assure that transcription begins at the proper point In both eukaryotes and prokaryotes, a promoter region that is rich in AT bases is called asAnswer: TATA box The RNA polymerases that transcribe bacterial DNA areAnswer: Multisubunit enzymes Immediately after transcriptionAnswer: A methylated guanine cap is added to the 51 end of the transcript Transcription factors areAnswer: Proteins which bind to DNA and regulate transcription The major function of RNA polymerase's sigma factor isAnswer: Recognition of the transcriptional start sequence Most transcripts of protein coding genes are cleavedAnswer: At the 3' end just after a poly adenylation signal RNA is synthesized on a DNA template in a process called __________ , which utilizes the enzyme __________Answer: transcription, RNA polymerase The closed complex at bacterial promoters isAnswer: In equilibrium with free RNA polymerase and the promoter Transcription beginsAnswer: Upstream from the start codon Transcription results inAnswer: Messenger RNA RNA polymerase holoenzyme initiates transcription which involvesAnswer: Recognition of the -10 sequence and -35 sequence