Final answer:
UVA acts primarily as an oxidizer, leading to indirect DNA damage through free radicals, while UVB stimulates the production of melanin, which acts as a protective pigment against UV radiation. The body tans as a defense mechanism against UVB-induced DNA damage, with melanin helping to absorb and block further UV penetration.
Step-by-step explanation:
When it comes to UV radiation and its interaction with our skin, it's important to understand the different roles played by UVA and UVB rays. UVA radiation is known for causing mostly free radicals, leading to indirect DNA damage. This process is similar to an oxidizer, as UVA can generate oxidative stress in the skin cells. UVB, on the other hand, is directly responsible for stimulating the production of melanin, the pigment that gives our skin its color and helps to protect against DNA damage from sun exposure.
UVB radiation does this by exciting the DNA molecules in our skin, causing distortions in the DNA helix that can lead to mutations and potentially to skin cancer. In response to UVB exposure, the body's defense mechanism is to produce more melanin pigment, which absorbs future UV radiation in inert layers of skin, thereby protecting the living cells beneath. This process results in tanning, which is a visible sign of the skin's response to UVB radiation.
While both UVA and UVB can cause harm to the skin cells and increase the risk of skin cancer, they do so in different ways, and our body's natural production of melanin plays a crucial role in defending against these effects.