How Smoking Impacts Gene Expression

Subject : Biology

Question:

You read a study that explains that a specific gene in smokers is suppressed while they smoke. However, after they quit smoking, the expression of this gene returns and is no longer suppressed (or is suppressed less). What is this study describing?

A. Optogenetics

B. Gene mutation

C. Natural adaptation

D. Epigenetics

Expert Verified Solution:

The correct answer is D. Epigenetics.

This study describes an epigenetic process, which refers to changes in gene expression that do not involve alterations in the underlying DNA sequence. Epigenetics studies how certain behaviors and environmental factors, such as smoking, can lead to chemical modifications in our genes, influencing how they are expressed. These changes can turn genes “on” or “off,” impacting their activity levels without changing the genetic code itself.

In this case, while smoking, a specific gene in smokers becomes suppressed, meaning its activity is reduced or turned off. Once the individual quits smoking, this suppression can reverse, and the gene’s normal expression can resume. This suppression and reactivation of gene expression are classic examples of epigenetic regulation. For example, smoking can lead to the addition of methyl groups to the DNA, a process called DNA methylation, which silences certain genes. When the person stops smoking, the methylation marks may be removed, allowing the gene to express itself again.

Why Epigenetics?

Epigenetics is a study of how gene expression is regulated by chemical tags that are added to DNA or associated proteins. These tags can be influenced by environmental factors, such as diet, stress, or exposure to chemicals like cigarette smoke. Importantly, these changes do not affect the DNA sequence itself but can have long-lasting effects on how genes are expressed.

Smoking’s epigenetic impact: Smoking is known to induce a wide range of epigenetic changes, particularly through DNA methylation, where methyl groups are added to the DNA, altering the expression of specific genes. Smoking can suppress genes that may be involved in repairing damaged cells or protecting the lungs, contributing to long-term health problems such as cancer and respiratory diseases. However, quitting smoking can lead to the gradual return of normal gene expression, as the body starts to remove these methylation marks.

Why Not Other Options?

Optogenetics (A): This technique involves the use of light to control cells within living tissue, usually neurons. It is not related to gene suppression or the effects of smoking.

Gene mutation (B): A gene mutation is a permanent alteration in the DNA sequence. The study in the question refers to gene suppression, which is reversible, meaning the DNA sequence itself remains unchanged. Thus, this is not a gene mutation but a temporary modification of gene expression.

Natural adaptation (C): Natural adaptation is an evolutionary process that occurs over generations, where organisms adapt to their environment through inherited traits. The study described involves individual changes in gene expression due to smoking, which does not involve long-term evolutionary changes.

The study is explaining an epigenetic phenomenon where smoking temporarily alters gene expression, but this suppression can reverse once the person quits smoking. This field is a key area of research, as it highlights how lifestyle choices and environmental factors can have a significant impact on our genetic health, often in ways that are reversible.