If a double stranded DNA has 100 base pairs, what is its length?

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

• 34 nm
• 340 nm
• 200 nm
• 3.4 nm
Correct Option: A  [ 34 nm ]

Remark: The distance between base pairs is 0.34 nm. If there are 100 base pairs, the length is 100 x 0.34 nm = 34 nm.

Which RNA carries amino acids to the ribosome?

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

• mRNA
• tRNA
• rRNA
• hnRNA
Correct Option: B  [ tRNA ]

Remark: Transfer RNA (tRNA) is responsible for transporting specific amino acids from the cytoplasmic pool to the ribosome during protein synthesis.

The termination of transcription in bacteria involves?

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

• Binding of Sigma factor
• Binding of Rho factor
• Unwinding of DNA
• Removal of Introns
Correct Option: B  [ Binding of Rho factor ]

Remark: In bacteria, transcription termination is facilitated by the Rho factor, which binds to the RNA polymerase and helps release the nascent RNA.

Expressed Sequence Tags (ESTs) are associated with?

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

• Identifying all genes
• Identifying genes expressed as RNA
• Protein sequencing
• DNA fingerprinting
Correct Option: B  [ Identifying genes expressed as RNA ]

Remark: ESTs is a methodology used in the Human Genome Project focused on identifying all the genes that are expressed as RNA (coding sequences).

Which vector can clone the largest DNA fragment?

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

• Plasmid
• Cosmid
• BAC
• YAC
Correct Option: D  [ YAC ]

Remark: Yeast Artificial Chromosomes (YACs) have the highest cloning capacity among common vectors, capable of cloning DNA fragments up to 1000 kb or more, making them useful for genome projects.

The bulk of the human genome consists of?

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

• Repetitive sequences
• Protein coding genes
• Regulatory sequences
• Viral DNA
Correct Option: A  [ Repetitive sequences ]

Remark: A very large portion of the human genome is made up of repetitive sequences (Satellite DNA) which do not code for proteins but have structural and evolutionary roles.

Which enzyme is used to remove phosphate from the 5-prime end of DNA?

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

• Kinase
• Alkaline Phosphatase
• Ligase
• Polymerase
Correct Option: B  [ Alkaline Phosphatase ]

Remark: Alkaline Phosphatase is used to remove phosphate groups from the 5-prime end of DNA molecules, often to prevent self-ligation of vectors.

What is the approximate number of genes in the human genome?

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

• 100,000
• 30,000
• 1,000,000
• 10,000
Correct Option: B  [ 30,000 ]

Remark: The Human Genome Project estimated that there are approximately 30,000 genes in the human genome, much fewer than originally predicted.

Which of the following is true for the structure of B-DNA?

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

• Left-handed helix
• Right-handed helix
• Parallel strands
• Variable diameter
Correct Option: B  [ Right-handed helix ]

Remark: B-DNA, the most common form of DNA in cells, forms a right-handed double helix structure.

The DNA strand that is synthesized away from the replication fork is?

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

• Leading strand
• Lagging strand
• Template strand
• Coding strand
Correct Option: B  [ Lagging strand ]

Remark: The lagging strand is synthesized discontinuously in the direction away from the replication fork, requiring multiple primers and the formation of Okazaki fragments.