6. Temperature sensitive mutation are importantin molecular biology because it helps in studying functions of
(1) genes for heat stress
(2) genes for cold stress
(3) genes necessary for survival of cell
(4) genes required for development

Introduction

Temperature-sensitive (TS) mutations are invaluable tools in molecular biology that allow scientists to study essential genes—those necessary for cell survival—without causing immediate lethality. By enabling conditional inactivation of gene function at non-permissive temperatures, TS mutations facilitate detailed analysis of gene roles in vital cellular processes. This article explains why TS mutations are particularly important for studying genes necessary for survival of the cell.

What Are Temperature-Sensitive Mutations?

• TS mutations produce proteins that function normally at a permissive (lower) temperature but become nonfunctional or unstable at a restrictive (higher) temperature.

• This temperature-dependent behavior allows researchers to toggle gene function on or off by simply changing the incubation temperature.

• TS mutations often affect protein folding or stability, causing loss of function only under stress conditions (e.g., heat).

Why Are TS Mutations Important for Studying Essential Genes?

1. Avoiding Lethality

• Many essential genes cannot be studied by traditional loss-of-function mutations because their inactivation kills the cell.

• TS mutations circumvent this by allowing normal gene function at permissive temperatures, enabling cell growth and viability.

• Researchers can then shift cells to restrictive temperatures to temporarily inactivate the gene, observing immediate effects on cellular processes.

2. Temporal Control

• TS mutants provide precise temporal control over gene activity.

• This is critical for studying dynamic processes like DNA replication, cell division, and protein synthesis, where timing is crucial.

3. Functional Dissection

• By observing phenotypes at restrictive temperatures, scientists can dissect the specific roles of essential proteins in various pathways.

• TS mutations help differentiate between structural and regulatory functions of proteins.

4. Reversibility

• Shifting back to permissive temperature can restore protein function, allowing reversible studies of gene activity and recovery.

Applications of TS Mutations

• Studying DNA replication machinery components in yeast and bacteria.

• Dissecting cell cycle regulators and checkpoints.

• Investigating protein folding and stability mechanisms.

• Modeling disease-related mutations in essential genes.

Why Other Mutation Types Are Less Suitable

Summary Table

Conclusion

Temperature-sensitive mutations are uniquely suited for studying genes necessary for the survival of the cell because they allow controlled, reversible inactivation of essential gene functions. This conditional approach enables detailed functional analysis without causing immediate lethality, making TS mutations indispensable in molecular biology research.

Answer:
Temperature-sensitive mutations are important because they help in studying (3) genes necessary for survival of cell.