UV Light & Protecting Our DNA

Vocabulary practice flashcards covering wave physics, the electromagnetic spectrum, atmospheric ozone layers, ultraviolet (UV) radiation types, DNA damage and repair mechanisms, cancer biology, and sun safety practices.

Wave

A disturbance that carries energy through space, such as sunlight traveling to Earth.

Wavelength

The distance between identical points on adjacent waves, measured from crest-to-crest or trough-to-trough, typically expressed in nanometers ($1\,\text{nm} = 10^{-9}\,\text{m}$).

Energy Rule

The relationship where shorter wavelength corresponds to higher frequency and greater energy, establishing that higher energy light carries a greater potential for biological damage.

Visible Light

The band of electromagnetic radiation with wavelengths between $380\,\text{nm}$ and $750\,\text{nm}$ that can be perceived by the human eye.

Infrared Light

Electromagnetic radiation with wavelengths spanning from $780\,\text{nm}$ to $1\,\text{mm}$ that transmits thermal heat from sources such as the sun, fire, and radiators.

Ultraviolet (UV) Light

High-energy, invisible electromagnetic radiation with wavelengths spanning from $100\,\text{nm}$ to $400\,\text{nm}$ that possesses high potential for biological harm.

Atmosphere

The layer of gases acting as a giant electromagnetic filter that protects life by entirely blocking lethal radiation such as X-rays, gamma rays, and UVC, while permitting infrared and visible light to pass through.

Ozone Layer

A protective concentration of ozone ($\text{O}_3$) located in the stratosphere that absorbs and blocks most, but not all, harmful ultraviolet radiation.

UVA

The longest wavelength ($320\text{--}400\,\text{nm}$) and least energetic form of ultraviolet radiation; it reaches Earth's surface fully, penetrates deep into skin layers, and causes aging and wrinkles.

UVB

Mid-spectrum ultraviolet radiation ($280\text{--}320\,\text{nm}$) partially blocked by the ozone layer that aids in Vitamin D synthesis but induces sunburns, DNA mutations, and skin cancer.

UVC

The shortest wavelength ($100\text{--}280\,\text{nm}$) and most energetic form of ultraviolet radiation, which is $100\%$ blocked by Earth's atmosphere.

Good Ozone

Ozone ($\text{O}_3$) found high in the stratosphere that protects living organisms by absorbing harmful solar ultraviolet radiation like a natural sunscreen.

Bad Ozone

Ground-level tropospheric ozone produced as smog from industrial pollutants such as volatile organic compounds (VOCs) and nitrogen oxides ($\text{NO}_x$), causing toxicity to eyes and respiratory systems.

Ozone Depletion

The breakdown of stratospheric ozone ($\text{O}_3$) driven by synthetic chemicals like chlorofluorocarbons (CFCs), resulting in increased levels of ultraviolet radiation reaching Earth's surface.

Ozone Hole

A severe thinning of stratospheric ozone concentrated over Antarctica, caused by extreme cold and polar winds accelerating CFC degradation reactions.

Pyrimidine Dimer

A molecular lesion formed when UV photons cause adjacent thymine (T) or cytosine (C) bases within a DNA strand to covalently bond together, forming a physical kink.

Nucleotide Excision Repair (NER)

A cellular DNA repair mechanism that identifies and excises structural distortions like pyrimidine dimers; failure to repair these kinks blocks DNA replication, leading to permanent mutations or cell death.

Saccharomyces cerevisiae

A species of yeast utilized in laboratory experiments because its nucleotide excision repair (NER) pathways function similarly to those of human cells.

Cancer

A pathological state defined by uncontrolled cellular growth and division triggered by accumulated DNA mutations.

Proto-oncogenes

Normal genes responsible for promoting cell growth and division that, when mutated, remain permanently active as oncogenes.

Tumor Suppressor Genes

Regulatory genes that inhibit cell division and trigger apoptosis (programmed cell death) in response to DNA damage.

Non-melanoma Skin Cancer

Prevalent forms of skin cancer (including Basal Cell Carcinoma and Squamous Cell Carcinoma) that are typically manageable through localized surgical excision.

Melanoma

A highly lethal and aggressive form of skin cancer capable of metastasizing (spreading) rapidly to other internal organs.

Cataracts

An ocular condition caused by cumulative ultraviolet radiation damage that leads to clouding of the eye's natural lens.

Sun Protection Factor (SPF)

A metric describing how much longer skin protected by sunscreen takes to burn compared to unprotected skin (e.g., SPF $30$ provides protection $30$ times longer).

Broad-Spectrum Sunscreen

A topical sunscreen formulation designed to absorb and protect skin against both UVA and UVB rays.

Melanin

A natural pigment in human skin that provides baseline defense against sun exposure via tanning, though it cannot entirely prevent DNA mutations.