Free Radicals in the Body

12 Questions

What is a free radical?

A molecular species that can contain an unpaired electron in its atomic orbital

What happens to the energy released during the breaking of bonds?

It is used to form molecules of adenosine triphosphate (ATP)

What is the term for oxygen with one unpaired electron?

Superoxide

Why are free radicals highly reactive?

Because they have unpaired electrons

What can free radicals cause?

Chain reactions that ultimately damage cells

What happens when a superoxide molecule reacts with a fatty acid?

The fatty acid loses one of its electrons

What happens to receptor proteins designed to react to insulin levels when they undergo a structural change?

Their function is altered or stopped

What is the result when the amount of free radicals exceeds the body's ability to eliminate or neutralize them?

Oxidative stress

What is a common source of free radicals in the environment?

Excessive sunlight and ozone

What is the result of sustained oxidative damage?

Lipid, protein, RNA, and DNA destruction

What is oxidative stress associated with?

A variety of diseases, including cancer, arthritis, and Alzheimer's disease

What is the current understanding of oxidative stress in the aging process?

Oxidative stress is not the initial trigger for age-related decline, but rather a consequence of metabolic dysfunction

Study Notes

Free Radicals

A free radical is a molecular species with an unpaired electron in its atomic orbital that can exist independently.
Free radicals share common properties due to the unpaired electron.
They are highly reactive, posing a threat to macromolecules such as DNA, RNA, proteins, and fatty acids.

Generation of Free Radicals in the Body

Energy released from breaking bonds is used to form molecules of ATP.
Electrons are extracted from glucose in a stepwise manner and transferred to other molecules.
Occasionally, electrons "escape" and are transferred to an oxygen molecule, forming superoxide.
Superoxide is a molecule with two atoms and one unpaired electron, also known as a reactive oxygen species.

Characteristics of Free Radicals

The unpaired electron in free radicals destabilizes them, making them highly reactive.
Other reactive oxygen species include hydrogen peroxide and the hydroxyl radical.
Free radicals can cause chain reactions that ultimately damage cells.

Effects of Free Radicals

Free radical reactions can continue unchecked unless stopped by a defense mechanism.
Chain reactions can change the permeability and fluidity of cell membranes, decrease protein activity, and alter receptor protein structure.

Sources of Free Radicals in the Environment

The body creates free radicals through normal metabolic processes.
Environmental sources such as excessive sunlight, ozone, smoke, heavy metals, ionizing radiation, asbestos, and other toxic chemicals can increase the amount of free radicals in the body.
These environmental sources can contribute to disease by overwhelming the free radical detoxifying systems and repair processes.

Oxidative Stress

Oxidative stress refers to an imbalance between the amount of free radicals and the capabilities of the detoxifying and repair systems.
Sustained oxidative damage results only under conditions of oxidative stress.
Oxidative stress has been implicated as a contributing factor to various diseases, including cancer, atherosclerosis, arthritis, diabetes, kidney disease, Alzheimer's disease, Parkinson's disease, schizophrenia, bipolar disorder, emphysema, and cataracts.

Aging and Oxidative Stress

Aging is a process that is genetically determined but modulated by environmental factors.
Tissue function declines with age, and oxidative stress is thought to contribute to this decline.
Recent scientific evidence suggests that oxidative stress is not the initial trigger for age-related decline of tissues, but rather a consequence of progressive dysfunction of metabolic processes.