Free Radicals

What are free radicals and why are they reactive?

• Free radicals are reactive species with unpaired electrons that seek to stabilize themselves by reacting with other molecules.

• Free radicals are stable molecules that do not react with others.

• Free radicals are large molecules that cannot interact with other substances.

• Free radicals are always positively charged ions.

Answer explanation

Free radicals are reactive species with unpaired electrons, making them unstable. They seek to stabilize themselves by reacting with other molecules, which is why the correct choice highlights their reactivity.

How do free radicals affect cellular components like proteins and lipids?

• Free radicals enhance protein and lipid function by reducing oxidative stress.

• Free radicals have no effect on cellular components like proteins and lipids.

• Free radicals only affect carbohydrates, leaving proteins and lipids unharmed.

• Free radicals damage proteins and lipids by causing oxidative stress, leading to denaturation and lipid peroxidation.

Answer explanation

Free radicals cause oxidative stress, which damages proteins by denaturation and lipids through lipid peroxidation. This highlights the harmful effects of free radicals on cellular components, making the correct choice clear.

What is the significance of the unpaired electron in free radicals?

• The unpaired electron has no effect on the molecule's behavior.

• Free radicals are always beneficial and promote cellular health.

• The unpaired electron stabilizes the molecule, reducing its reactivity.

• The unpaired electron in free radicals makes them highly reactive, leading to potential cellular damage.

Answer explanation

The unpaired electron in free radicals makes them highly reactive, which can lead to cellular damage. This reactivity is a key characteristic of free radicals, distinguishing them from more stable molecules.

Can you name two examples of reactive oxygen species (ROS)?

• sulfur dioxide and ammonia

• carbon dioxide and methane

• nitric oxide and ozone

• hydrogen peroxide and superoxide anion

Answer explanation

Reactive oxygen species (ROS) include molecules like hydrogen peroxide and superoxide anion, which are known for their role in oxidative stress and cellular signaling. The other options do not qualify as ROS.

What potential damage can free radicals cause to DNA?

• Free radicals have no effect on DNA.

• Free radicals can cause oxidative damage, leading to mutations and structural alterations in DNA.

• Free radicals only affect RNA, not DNA.

• Free radicals enhance DNA repair mechanisms.

Answer explanation

Free radicals can cause oxidative damage to DNA, resulting in mutations and structural changes. This highlights the significant impact they have on genetic material, making the correct choice about their damaging effects.