Free Molecular Biology MCQs with Answers

• A. Deoxy pentose sugar
• B. Adenosine
• C. Phosphoric acid
• D. Purine bases

Explanation: Complete DNA hydrolysis yields deoxyribose, phosphoric acid and nitrogenous bases such as adenine and guanine.

• A. It gets broken down to nucleotides
• B. It becomes single stranded irreversibly
• C. It becomes single stranded reversibly
• D. It becomes double stranded irreversibly

Explanation: Denaturation separates the two complementary DNA strands by disrupting hydrogen bonds, without breaking the covalent backbone.

• A. COmplimentary copy of rRNA
• B. Double stranded complimentary copy of DNA
• C. Complimentary copy of RNA
• D. Single stranded complimentary copy of DNA

Explanation: Transcription uses one DNA strand as a template to produce a single-stranded RNA molecule with complementary base pairing.

• A. Binds the antibiotic Rifampicin
• B. Specifically recognizes the promoter site
• C. Is inhibited by a-amanitin
• D. Is part of the core enzyme

Explanation: The sigma subunit gives bacterial RNA polymerase promoter specificity by recognizing promoter regions such as the -10 and -35 sequences.

• A. Amino acid sequence of ribonuclease
• B. RNA nucleotide sequence
• C. DNA nucleotide sequence
• D. Cell walls

Explanation: A mutation is a permanent change in the nucleotide sequence of genetic material, usually DNA in cellular organisms.

• A. UAG
• B. UAA
• C. UUU
• D. AUG

Explanation: AUG is the usual initiation codon and codes for methionine, establishing the reading frame for translation.

• A. Elongation of polypeptide chain
• B. Pre-translational modification of protein
• C. Initiation of protein synthesis
• D. Termination of protein synthesisOrder DNA Kits

Explanation: Nonsense codons, including UAA, UAG and UGA, do not specify amino acids; they signal release of the completed polypeptide.

• A. Transcription
• B. Transduction
• C. Translocation
• D. Conjugation

Explanation: Transcription is the process of copying genetic information from DNA into RNA, usually by RNA polymerase.

• A. SIngle stranded DNA
• B. Double stranded DNA
• C. SIngle stranded RNA
• D. Polypeptide

Explanation: Restriction endonucleases usually recognize specific sequences in double-stranded DNA and cleave the phosphodiester backbone of both…

• A. Ribonucleic acid
• B. Lipoproteins
• C. Deoxy ribonucleic acid
• D. Chromo proteins

Explanation: A gene is a sequence of genetic information, usually composed of DNA in cellular organisms, that can encode an RNA or a protein.

• A. Covalent bond
• B. Vander wall forces
• C. Disulfide linkage
• D. Hydrogen bond

Explanation: The two DNA strands are held together mainly by hydrogen bonds between complementary bases, with adenine pairing with thymine and guanine…

• A. Adenine
• B. Uracil
• C. Cytosine
• D. Guanine

Explanation: DNA contains adenine, guanine, and cytosine, whereas uracil is the pyrimidine base that replaces thymine in RNA.

• A. Splicing
• B. 5′ capping
• C. Glycosylation
• D. 3′ polyadenylation

Explanation: Splicing, 5′ capping, and 3′ polyadenylation are standard post-transcriptional processing steps for eukaryotic RNA.

• A. Frame shift mutation
• B. Transversion
• C. Silent mutation
• D. Nonsense mutation

Explanation: A nonsense mutation changes a codon specifying an amino acid into a termination codon, causing premature stopping of translation.

• A. Transcription
• B. Transduction
• C. Translation
• D. Translocation

Explanation: Transcription is the RNA polymerase-mediated synthesis of RNA using a complementary DNA strand as the template.

• A. Nucleus
• B. Mitochondria
• C. Lysosomes
• D. Golgi apparatus

Explanation: Mannose-6-phosphate acts as the sorting signal for newly synthesized lysosomal enzymes.

• A. Non Sense mutation of beta chain
• B. Deletion of beta chain
• C. Degradation of beta chain
• D. Missense mutation of beta chain

Explanation: Sickle-cell disease results from replacement of glutamic acid by valine in the β-globin chain, which changes one amino acid and therefore…

• A. Translation
• B. Mutation
• C. Transcription
• D. Conjugation

Explanation: Translation is the stage in which ribosomes read the codons of messenger RNA and assemble the corresponding amino acid sequence into a…