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 among the following is not a function of nucleolus?

  1. Production of proteins

  2. Control of hereditary information

  3. Storage of RNA

  4. Synthesis of ribosomes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nucleolus is a round-shaped body present inside the nucleus. It helps to produce ribosomes, DNA and RNA. Hereditary characters of a person are controlled by genes.

Multiple choice

Which of these is a minute particle consisting of RNA and associated proteins, found in eager numbers in the cytoplasm of living cells?

  1. RNA

  2. DNA

  3. Ribosome

  4. Cytoplasm acid

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ribosomes are cellular organelles composed of RNA and proteins that synthesize proteins. They exist in large numbers in the cytoplasm. RNA alone is just a nucleic acid, DNA carries genetic information, and cytoplasmic acid is not a standard cellular structure.

Multiple choice

Which of the following statements is true in case of RNA polymerase III enzymes?

  1. They are responsible for synthesis of precursors for large ribosomal RNAs.

  2. They are responsible for the synthesis of precursor mRNA and small nuclear RNAs.

  3. They are responsible for the synthesis of small ribosomal RNAs.

  4. They are responsible for synthesis of tRNA and small ribosomal RNAs.

  5. They are responsible for synthesis of precursor of hetero nuclear RNAs.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

RNA polymerase III participates in the formation of tRNAs and small ribosomal RNAs during transcription from the template DNA.

Multiple choice

Wobble hypothesis was proposed by F.H.C.Crick (1966) from the structure of anticodon loop in tRNA. Which one of the following is established by this hypothesis?

  1. Economy in tRNA molecules

  2. Initiation of peptide chain

  3. Termination of peptide chain

  4. Elongation of peptide chain

  5. Non-ambiguous nature of genetic code
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A single tRNA type is able to recognise two or more codons by their anticodon loops differing only in the third base, which is known as Wobble position. This kind of Wobbling allows economy of the number of tRNA molecules because several codons meant for the same amino acid are recognised by the same tRNA.

Multiple choice

Translation of proteins from mRNA is characterised by formation of specific structures during the process. Which one is correct for polysome formation?

  1. Ribosomes with several subunits bind with Shine Dalgarno sequence.

  2. Several ribosomes are attached to a single mRNA during translation.

  3. Many ribosomes are attached to membrane of rough endoplasmic reticulum.

  4. Several subunits of ribosomes are attached with each other in a linear arrangement.

  5. Several 30S subunits are attached to mRNA.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During translation, several ribosomes are arranged in linear manner over a single mRNA. This is known as polysome. It helps in formation of globuler structure of proteins as many polypeptides are formed together.

Multiple choice

Which of the following is a short lived RNA having molecular weight ranging from 500000 to 1000000?

On the basis of life span, molecular weight, function, etc. RNAs are classified into various types like mRNA, rRNA, tRNA smRNA, scRNA, etc.

  1. rRNA

  2. mRNA

  3. tRNA

  4. smRNA

  5. scRNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is 5% to 10% of total RNA having molecular weight ranging from 500000 to 1000000, which is short lived in nature. It carries genetic information from DNA to protein.

Multiple choice

Viriods have

  1. protein uncoated ssDNA

  2. protein coated dsDNA

  3. protein coated dsRNA

  4. protein uncoated ssRNA
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice

A virion is a

  1. naked and infectious piece of RNA

  2. complete and infectious virus particle

  3. nucleic acid without a capsid

  4. a naked and infectious piece of DNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A virion is the complete, extracellular infectious form of a virus - consisting of nucleic acid (DNA or RNA) enclosed in a protein capsid. Options A and D describe only the nucleic acid component without the capsid, while option C lacks the capsid. Only option B correctly describes the complete virus particle.

Multiple choice

During protein synthesis in eukaryotes, when does the tRNA-met bind to 5’ mRNA?

  1. Before binding of the small ribosomal subunit.

  2. After binding of the small ribosomal subunit.

  3. Before binding of the large ribosomal subunit.

  4. After binding of the large ribosomal subunit.

  5. Before binding of both the ribosomal subunits.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The initiator tRNA (tRNAimet) binds to the 5’ end of mRNA before binding of the small (40S) ribosomal subunit. The large ribosomal subunit in eukaryotes is 60S subunit, which binds to 5’mRNA after initiator tRNA, the 40S subunit and initiation factors bind to mRNA.

Multiple choice

Match the following: Column A Column B A. Cycloheximide 1. Inhibits bacterial protein synthesis by blocking the A-site on the ribosome. B. Puromycin 2. Inhibits bacterial protein synthesis by blocking peptidyl transfer. C. Chloramphenicol 3. Inhibits protein synthesis by resembling an amino acid. D. Tetracyclin 4. Misreads the genetic code and inhibits initiation of protein synthesis.

  1. A - 4, B - 3, C - 2, D - 1

  2. A - 3, B - 4, C - 2, D - 1

  3. A - 1, B - 2, C - 3,D - 4

  4. A - 4, B - 4, C - 1, D - 2

  5. A - 2, B - 3, C - 2, D - 4
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cycloheximide inhibits initiation of protein synthesis, puromycin inhibits protein synthesis by resembling an amino acid attached to terminal adenosine of t-RNA, chloramphenicol is an antibiotic that inhibits bacterial protein synthesis by blocking the translation elongation and tetracyclin is also an antibiotic that inhibits bacterial protein synthesis by blocking the a-site on ribosome.

Multiple choice

What is Readseq?

  1. Tool which helps to read and translate nucleotide sequence

  2. Tool which converts sequence in one format to another

  3. Database which helps to download nucleotide sequence

  4. Tool which reads the nucleotide sequences
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

These are various formats of sequence file. Each tool is designed to accept the input sequence in the specific formats. Readseq tool is used to convert sequence from one format to another.