Biology

Molecular Genetics

917 Questions

Molecular genetics explores the mechanisms of genetic information transfer, including DNA replication, transcription, and translation. It is a core component of biology syllabi. These concepts frequently appear in general science sections of major competitive exams.

DNA replicationTranscription processTranslation processRNA typesCentral dogma

Molecular Genetics Questions

Multiple choice

Which of the following is NOT a stop codon?

  1. UAA

  2. UAG

  3. UGA

  4. AUG
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

UAA, UAG, and UGA are the three stop codons in the genetic code. AUG, on the other hand, is the start codon, which signals the beginning of protein synthesis.

Multiple choice

What is the role of release factors in translation?

  1. To bind to the ribosome and release the newly synthesized protein

  2. To proofread the sequence of amino acids in the protein

  3. To recruit tRNA molecules to the ribosome

  4. To terminate transcription of the mRNA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Release factors bind to the ribosome when a stop codon is encountered in the mRNA. This binding causes the ribosome to release the newly synthesized protein and terminate translation.

Multiple choice

Which of the following is NOT a component of the translation initiation complex?

  1. mRNA

  2. tRNA

  3. Ribosome

  4. Initiation factors
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The translation initiation complex consists of mRNA, the ribosome, and initiation factors. tRNA molecules are not involved in the initiation complex, but they are required for the elongation stage of translation.

Multiple choice

What is the role of elongation factors in translation?

  1. To recruit tRNA molecules to the ribosome

  2. To catalyze the formation of peptide bonds between amino acids

  3. To proofread the sequence of amino acids in the protein

  4. To release the newly synthesized protein from the ribosome
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Elongation factors are responsible for recruiting tRNA molecules to the ribosome, based on the sequence of codons in the mRNA. They also help in the movement of the ribosome along the mRNA.

Multiple choice

What is the sequence of events that occurs during the elongation stage of translation?

  1. Binding of tRNA to the ribosome, Peptide bond formation, Translocation

  2. Initiation, Elongation, Termination

  3. Transcription, Translation, Replication

  4. Glycolysis, Krebs Cycle, Electron Transport Chain
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The elongation stage of translation involves the sequential addition of amino acids to the growing polypeptide chain. This process consists of three main steps: binding of tRNA to the ribosome, formation of a peptide bond between the amino acids, and translocation of the ribosome along the mRNA.

Multiple choice

What is the role of GTP in translation?

  1. To provide energy for the movement of the ribosome along the mRNA

  2. To catalyze the formation of peptide bonds between amino acids

  3. To proofread the sequence of amino acids in the protein

  4. To release the newly synthesized protein from the ribosome
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

GTP is a molecule that provides energy for various cellular processes. In translation, GTP is used to power the movement of the ribosome along the mRNA during the elongation stage.

Multiple choice

What is the role of the Shine-Dalgarno sequence in translation?

  1. To recruit the ribosome to the start codon of the mRNA

  2. To proofread the sequence of amino acids in the protein

  3. To release the newly synthesized protein from the ribosome

  4. To terminate transcription of the mRNA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Shine-Dalgarno sequence is a short sequence of nucleotides located upstream of the start codon in prokaryotic mRNAs. It helps in recruiting the ribosome to the start codon and initiating translation.

Multiple choice

Which of the following is NOT a type of RNA molecule involved in translation?

  1. mRNA

  2. tRNA

  3. rRNA

  4. snRNA
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

mRNA, tRNA, and rRNA are the three main types of RNA molecules involved in translation. snRNA is involved in a different cellular process called splicing, which occurs during the processing of pre-mRNA.

Multiple choice

What is the role of the Kozak sequence in translation?

  1. To recruit the ribosome to the start codon of the mRNA

  2. To proofread the sequence of amino acids in the protein

  3. To release the newly synthesized protein from the ribosome

  4. To terminate transcription of the mRNA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Kozak sequence is a short sequence of nucleotides located around the start codon in eukaryotic mRNAs. It helps in recruiting the ribosome to the start codon and initiating translation.

Multiple choice

Which of the following is NOT a modification that can occur to tRNA molecules?

  1. Methylation

  2. Pseudouridylation

  3. Phosphorylation

  4. Deamination
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Methylation, pseudouridylation, and deamination are common modifications that occur to tRNA molecules. Phosphorylation, on the other hand, is not a typical modification for tRNA.

Multiple choice

What is the role of the peptidyl transferase center in translation?

  1. To catalyze the formation of peptide bonds between amino acids

  2. To proofread the sequence of amino acids in the protein

  3. To release the newly synthesized protein from the ribosome

  4. To terminate transcription of the mRNA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The peptidyl transferase center is a component of the ribosome that catalyzes the formation of peptide bonds between amino acids during the elongation stage of translation.

Multiple choice

What is the central dogma of molecular biology?

  1. DNA → RNA → Protein

  2. RNA → DNA → Protein

  3. Protein → DNA → RNA

  4. DNA → Protein → RNA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The central dogma of molecular biology states that the information in DNA is transcribed into RNA, which is then translated into protein.

Multiple choice

Which of the following is essential for the synthesis of DNA and RNA?

  1. Nucleotides

  2. Amino acids

  3. Fatty acids

  4. Glycerol
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nucleotides are the building blocks of DNA and RNA and are essential for their synthesis.

Multiple choice

Which of the following is an example of an epigenetic mechanism?

  1. DNA methylation.

  2. Histone modification.

  3. RNA interference.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA methylation, histone modification, and RNA interference are all examples of epigenetic mechanisms.

Multiple choice

What is the term for the process by which DNA is transcribed into RNA?

  1. Mitosis

  2. Meiosis

  3. Replication

  4. Transcription
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Transcription is the process by which the information in DNA is copied into a complementary RNA molecule.