During DNA replication, the leading strand is synthesized?

[Molecular-Basis-of-Inheritance] [class-xii ]

• Discontinuously
• Continuously
• In fragments
• Randomly
Correct Option: B  [ Continuously ]

Remark: The leading strand is synthesized continuously in the 5-prime to 3-prime direction towards the replication fork.

RNA polymerase III is responsible for transcription of?

[Molecular-Basis-of-Inheritance] [class-xii ]

• rRNA
• mRNA
• tRNA and 5S rRNA
• hnRNA
Correct Option: C  [ tRNA and 5S rRNA ]

Remark: RNA Polymerase III transcribes tRNA, 5S rRNA, and snRNAs.

In the absence of lactose, the repressor binds to which region of the Lac Operon?

[Molecular-Basis-of-Inheritance] [class-xii ]

• Promoter
• Structural gene
• Operator
• Inducer
Correct Option: C  [ Operator ]

Remark: When lactose is absent, the repressor binds to the operator region, blocking RNA polymerase from transcribing the genes.

The coding sequences of eukaryotic genes are called?

[Molecular-Basis-of-Inheritance] [class-xii ]

• Introns
• Exons
• Promoters
• Operators
Correct Option: B  [ Exons ]

Remark: Exons are the coding sequences or expressed sequences that appear in mature/processed RNA.

Which process involves the removal of introns?

[Molecular-Basis-of-Inheritance] [class-xii ]

• Capping
• Tailing
• Splicing
• Termination
Correct Option: C  [ Splicing ]

Remark: Splicing is the process of removing non-coding introns from the primary transcript.

A nucleosome consists of DNA wrapped around a core of how many histone molecules?

[Molecular-Basis-of-Inheritance] [class-xii ]

• 4
• 6
• 8
• 10
Correct Option: C  [ 8 ]

Remark: The nucleosome core is a histone octamer, consisting of 8 histone molecules (two each of H2A, H2B, H3, and H4).

Euchromatin is characterized by being?

[Molecular-Basis-of-Inheritance] [class-xii ]

• Loosely packed and transcriptionally active
• Densely packed and inactive
• Darkly stained
• Absent in nucleus
Correct Option: A  [ Loosely packed and transcriptionally active ]

Remark: Euchromatin is the loosely packed, light-staining form of chromatin that is transcriptionally active.

The DNA dependent DNA polymerase catalyzes polymerization in which direction?

[Molecular-Basis-of-Inheritance] [class-xii ]

• 3-prime to 5-prime
• 5-prime to 3-prime
• Both directions
• Random
Correct Option: B  [ 5-prime to 3-prime ]

Remark: DNA polymerases can only add nucleotides to the 3-prime OH end, so synthesis always proceeds in the 5-prime to 3-prime direction.

Match List-I with List-II regarding the experiments on genetic material.

[Molecular-Basis-of-Inheritance] [class-xii ]

• A-III, B-IV, C-I, D-II
• A-II, B-I, C-IV, D-III
• A-III, B-I, C-IV, D-II
• A-IV, B-III, C-I, D-II
Correct Option: A  [ A-III, B-IV, C-I, D-II ]

Remark: Frederick Griffith (1928) discovered the Transforming Principle using Streptococcus pneumoniae. Avery, MacLeod, and McCarty biochemically characterized this principle as DNA by using enzymes like DNase, RNase, and Protease. Hershey and Chase (1952) provided unequivocal proof that DNA is the genetic material using bacteriophages and radioisotopes. Taylor and colleagues proved semi-conservative replication in eukaryotes (Vicia faba) using radioactive thymidine.

Match List-I with List-II regarding DNA structure dimensions (B-DNA).

[Molecular-Basis-of-Inheritance] [class-xii ]

• A-III, B-I, C-IV, D-II
• A-III, B-IV, C-I, D-II
• A-I, B-III, C-IV, D-II
• A-II, B-I, C-IV, D-III
Correct Option: A  [ A-III, B-I, C-IV, D-II ]

Remark: The pitch of the DNA helix (one complete turn) is 3.4 nm (34 Angstrom). The distance or rise between adjacent base pairs is 0.34 nm. The diameter of the B-DNA helix is constant at 20 Angstroms (2 nm). The total length of DNA in a human diploid cell is calculated as 6.6 x 10^9 bp multiplied by 0.34 nm, resulting in approximately 2.2 meters.