Untranslated Regions (UTRs) are present at?

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

• Only 5-prime end
• Only 3-prime end
• Both 5-prime and 3-prime ends
• Within the coding region
Correct Option: C  [ Both 5-prime and 3-prime ends ]

Remark: UTRs are found both before the start codon (5-prime UTR) and after the stop codon (3-prime UTR) and are essential for efficient translation.

In the Lac Operon, the regulator gene (i gene) codes for?

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

• Beta-galactosidase
• Permease
• Repressor protein
• Transacetylase
Correct Option: C  [ Repressor protein ]

Remark: The 'i' gene (inhibitor) codes for the Repressor protein which binds to the operator to block transcription in the absence of an inducer.

Lactose functions as an Inducer by binding to the?

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

• Promoter
• Operator
• Repressor
• RNA Polymerase
Correct Option: C  [ Repressor ]

Remark: Lactose (allolactose) binds to the Repressor protein, causing a conformational change that prevents the repressor from binding to the operator, thus turning the operon on.

The gene 'lac Z' codes for which enzyme?

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

• Beta-galactosidase
• Permease
• Transacetylase
• Repressor
Correct Option: A  [ Beta-galactosidase ]

Remark: The lac Z gene codes for Beta-galactosidase, which hydrolyzes lactose into glucose and galactose.

The gene 'lac Y' codes for which enzyme?

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

• Beta-galactosidase
• Permease
• Transacetylase
• Repressor
Correct Option: B  [ Permease ]

Remark: The lac Y gene codes for Permease, which increases the permeability of the bacterial cell to lactose.

The gene 'lac A' codes for which enzyme?

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

• Beta-galactosidase
• Permease
• Transacetylase
• Repressor
Correct Option: C  [ Transacetylase ]

Remark: The lac A gene codes for Transacetylase.

The Lac Operon is an example of?

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

• Inducible operon
• Repressible operon
• Constitutive operon
• None of these
Correct Option: A  [ Inducible operon ]

Remark: It is an inducible system because it is normally off but can be induced (turned on) by the presence of lactose.

Which molecule serves as the inducer in the Lac Operon?

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

• Glucose
• Galactose
• Lactose
• Fructose
Correct Option: C  [ Lactose ]

Remark: Lactose (or Allolactose) acts as the inducer that inactivates the repressor.

The Human Genome Project (HGP) used two major approaches: ESTs and?

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

• Sequence Annotation
• RNA Interference
• PCR
• Cloning
Correct Option: A  [ Sequence Annotation ]

Remark: The two approaches were Expressed Sequence Tags (identifying expressed genes) and Sequence Annotation (sequencing the whole genome and assigning functions).

Approximately how many genes were estimated to be in the human genome by HGP?

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

• 30,000
• 100,000
• 140,000
• 3 Billion
Correct Option: A  [ 30,000 ]

Remark: The HGP found approximately 30,000 genes, which was much lower than the earlier estimates of 80,000-140,000.