The site on the ribosome where the peptide bond is formed is the?

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

• A site
• P site
• E site
• O site
Correct Option: A  [ A site ]

Remark: While the growing peptide chain is held at the P site, the new amino acid enters at the A (Aminoacyl) site. The peptide bond forms between the chain on the P site and the amino acid on the A site, effectively transferring the chain to the A site.

Untranslated regions (UTRs) are found on?

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

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

Remark: UTRs are sequences on messenger RNA (mRNA) located before the start codon (5-prime UTR) and after the stop codon (3-prime UTR). They are not translated into protein but are crucial for efficient translation and stability.

Lactose acts as an inducer in the Lac operon by binding to?

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

• Promoter
• Operator
• Repressor
• Beta-galactosidase
Correct Option: C  [ Repressor ]

Remark: Lactose (specifically allolactose) acts as an inducer by binding to the repressor protein. This binding causes a conformational change in the repressor, preventing it from binding to the operator and allowing transcription to proceed.

Which gene in the Lac operon codes for Permease?

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

• lac Z
• lac Y
• lac A
• lac i
Correct Option: B  [ lac Y ]

Remark: The lacY gene encodes the enzyme Permease. This enzyme acts on the cell membrane to increase its permeability to beta-galactosides (like lactose), allowing entry into the cell.

Regulation of the Lac operon by the repressor is referred to as?

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

• Positive regulation
• Negative regulation
• Feedback inhibition
• Neutral regulation
Correct Option: B  [ Negative regulation ]

Remark: The regulation is called negative because the binding of the regulatory protein (repressor) prevents transcription. Positive regulation also occurs (via CAP-cAMP), but the repressor mechanism specifically is negative control.

A method of sequencing genomes that involves sequencing coding and non-coding regions and then assigning functions is?

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

• Expressed Sequence Tags
• Sequence Annotation
• DNA Fingerprinting
• Polymerase Chain Reaction
Correct Option: B  [ Sequence Annotation ]

Remark: Sequence Annotation involves sequencing the whole genome (both coding and non-coding regions) and then using analytical tools to assign functions to the different regions. ESTs, in contrast, focus only on expressed (coding) genes.

BACs and YACs are used in HGP as?

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

• Enzymes
• Vectors
• Probes
• Primers
Correct Option: B  [ Vectors ]

Remark: BAC (Bacterial Artificial Chromosome) and YAC (Yeast Artificial Chromosome) are cloning vectors used to handle large DNA fragments. They were essential in the Human Genome Project for cloning and amplifying DNA segments for sequencing.

Single Nucleotide Polymorphisms (SNPs) were identified at approximately how many locations in the human genome?

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

• 1.4 million
• 2.4 million
• 14,000
• 1.4 billion
Correct Option: A  [ 1.4 million ]

Remark: The Human Genome Project found that single nucleotide differences (SNPs) occur at about 1.4 million locations in the human genome. These are important for understanding disease susceptibility and evolutionary history.

The blotting technique used in DNA fingerprinting is?

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

• Northern Blotting
• Western Blotting
• Southern Blotting
• Eastern Blotting
Correct Option: C  [ Southern Blotting ]

Remark: DNA fingerprinting uses Southern Blotting. In this technique, DNA fragments separated by electrophoresis are transferred to a membrane (nitrocellulose or nylon) and hybridized with radioactive probes.

Which chromosome has the fewest number of genes?

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

• Chromosome 1
• Chromosome X
• Chromosome Y
• Chromosome 22
Correct Option: C  [ Chromosome Y ]

Remark: Chromosome Y contains the fewest genes (231), while Chromosome 1 contains the most (2968), according to the findings of the Human Genome Project.