Biology

Molecular Genetics

851 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

Where does the transcription of rDNA occur?

  1. FC region of nucleolus

  2. FC region or FC-DFC boundary

  3. DFC region

  4. GC-DFC boundary
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is the correct option. Transcription of rDNA takes place either in FC region or at FC-DFC boundary.

Multiple choice

Cajal bodies are associated with

  1. DNA replication

  2. transcription

  3. RNA processing

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

Cajal bodies are involved in a number of roles in RNA processing like snRNA maturation and histone mRNA modification.

Multiple choice

Which of the following statements is not correct?

  1. rRNA is the most abundant type of RNA in a cell.

  2. Anticodon occurs in mRNA.

  3. Okazaki fragments are formed during replication.

  4. Nonsense codons do not code for any amino acid.

  5. DNA replication is semiconservative.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because anticodon is a sequence of three adjacent nucleotides in transfer RNA (tRNA) that binds to a corresponding codon in messenger RNA (mRNA) and designates a specific amino acid during protein synthesis.

Multiple choice

Which of the following statements about transcription is not correct?

  1. Transcription is the first step of gene expression.

  2. Transcription is a process that involves the transcribing of genetic information from DNA to RNA.

  3. The coding region of a gene is bounded near the 5' end by a start codon.

  4. The regulatory sequence before the coding sequence is called the 3'UTR.

  5. DNA is read from 3'UTR → 5'UTR during transcription.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct because the regulatory sequence before the coding sequence is called the five prime untranslated region (5'UTR).

Multiple choice

A nematode Meloidegyne incognitia infects the roots of tobacco plants and causes a great reduction in yield. It can be prevented by RNA interference (RNAi). What does this method involve?

  1. Silencing of a specific DNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA.

  2. Silencing of a specific tRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA.

  3. Silencing of a specific mRNA due to a complementary ssRNA molecule that binds to and prevents translation of the mRNA.

  4. Silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA.

  5. Silencing of a specific rRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

RNA interference (RNAi) involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA.

Multiple choice

Large eukaryotic ribosome’s sub-unit consists of__________.

  1. 23S rRNA + 5S rRNA + 4.5 rRNA + 33 proteins

  2. 23 rRNA + 5.8 S rRNA + 33 proteins

  3. 28S rRNA + 18S rRNA + 41 proteins

  4. 28S rRNA + 5.8S rRNA + 5S rRNA + 49 proteins
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Large eukaryotic ribosome’s sub-unit consists of 28S rRNA + 5.8S rRNA + 5S rRNA + 49 proteins.

Multiple choice

A precise evidence, which states that in particular cases, RNA produces genetic hereditary material comes from the fact that__________.

  1. RNA initially enters genes followed by DNA

  2. when virus particles are extracted individually from infected host, only RNA is present to form infection

  3. RNA is capable of dissociating itself & can enter the genetic materials

  4. RNA codes for DNA, which then produces protein molecules
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A precise evidence, which states that in particular cases, RNA produces genetic hereditary material comes from the fact that RNA codes for DNA, which then produces protein molecules

Multiple choice

RNA directed DNA polymerase is the other name for

  1. RNA polymerase

  2. reverse transcriptase

  3. ribozymes

  4. DNA polymerase

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

Reverse transcriptase, also referred to as RNA-directed DNA polymerase, is an enzyme encoded from the genetic material of retroviruses. It catalyzes the transcription of retrovirus RNA (ribonucleic acid) into DNA (deoxyribonucleic acid). This catalyzed transcription is the reverse process of normal cellular transcription of DNA into RNA, that is why it is called the reverse transcriptase.

Multiple choice

Match the following:

 
RNA polymerase type Responsible for transcription
A. RNA polymerase I 1. hnRNA
B. RNA polymerase II 2. rRNA
C. RNA polymerase III 3. snRNA

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

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

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

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

  5. A - 3, B - 1, C - 2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because all are correctly matched. RNA polymerase I transcribes rRNAs (28S, 18S and 5.8S). RNA polymerase II transcribes precursor of mRNA, the heterogeneous nuclear RNA (hnRNA). RNA polymerase III is responsible for transcription of tRNA, 5srRNA and snRNAs (small nuclear RNAs).

Multiple choice

Assertion: In capping, methyl guanosine triphosphate is added to the 3'-end of hnRNA. Reason: In tailing, adenylate residues are added at 5'-end in a template independent manner.

Directions: In the following question, there are two statements, Assertion (A) and Reason (R). Consider both the statements independently and mark your answer as under:

1. A and R both are correct and R is the correct explanation of A.
2. A and R both are correct and R is not the correct explanation of A.
3. A is correct and R is incorrect.
4. A is incorrect and R is correct.
5. A and R both are incorrect.

  1. (1)

  2. (2)

  3. (3)

  4. (4)

  5. (5)
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This option is correct because in capping, methyl guanosine triphosphate is added to the 5'-end of hnRNA. In tailing, adenylate residues are added at 3'-end in a template independent manner. It is the fully processed hnRNA, now called mRNA, that is transported out of the nucleus for translation.

Multiple choice

r RNA is formed by __________.

  1. DNA

  2. ATP

  3. t RNA

  4. Gene

  5. Nucleolus
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DNA forms all types of RNA including ribosomal RNA{r RNA}, transfer RNA and m RNA , by the process called as transcription.