Following a low dose of UV radiation,
DNA replication is inhibited and the cells undergo a transient arrest re-entering the cell cycle by 24 h
. Instead, a high dose of UV damage leads to an initial replicative arrest followed by death of the cells by apoptosis.
How does UV radiation cause mutations?
Ultraviolet (UV) light is a form of radiation that acts as a mutagen, an agent that causes mutations in DNA.
Exposure to ultraviolet light causes chemical changes that alter the shape of your DNA
, and the process that corrects DNA’s shape can also cause changes to the DNA code.
What damage does UV light cause in DNA and how does this lead to mutation?
UV exposure doesn’t always lead directly to mutations in the DNA. In fact,
UV-A radiation commonly causes the creation of a free radical that then interacts with and oxidizes DNA bases
. These oxidized bases don’t pair correctly during replication, causing mutations.
How does UV radiation damage bacterial cells?
Ultraviolet light inactivates microorganisms
by forming pyrimidine dimers in RNA and DNA, which can interfere with transcription and replication
(Goosen and Moolenaar, 2008; Cutler and Zimmerman, 2011).
How does UV radiation weaken the immune system?
UV radiation suppresses the immune system in multiple ways. It
inhibits antigen presentation, stimulates the release of immunosuppressive cytokines and induces the generation of lymphocytes of the regulatory subtype
. The major molecular target for UV-induced immunosuppression is UV-induced DNA damage.
What are some of the biological effects of UVB radiation quizlet?
+Exposures can damage skin first, leading to a perfect path for the more damaging effects of UVB radiation, which can lead to cancer. +Although considered less harmful, is still dangerous. The most dangerous type of UV radiation and is responsible for
sunburn, suntan, skin aging, skin cancer, and eye damage
.
How does UV radiation damage DNA by breaking weak bonds?
Any place along the strand that has two thymine bases in a row is vulnerable to this damage.
The energy of the UVB light alters a chemical bond in the thymine. The altered bond causes the neighboring thymine bases to stick to each other
. This pair of stuck-together thymine molecules is called a dimer.
How does UV radiation damage DNA quizlet?
UV light damages the DNA of exposed cells by
causing bonds to form between adjacent pyrimidine bases, usually thymines, in DNA chains
. The thymine dimers inhibit correct replication of the DNA during reproduction of the cell.
How does UV light and other ionizing radiation damage DNA molecules?
How does UV light and other ionizing radiations damage DNA molecules?
creating thymine dimers between adjacent thymines in the DNA chain
.
What type of damage does UV light cause?
UV rays, either from the sun or from artificial sources like tanning beds, can cause sunburn. Exposure to UV rays can cause
premature aging of the skin and signs of sun damage such as wrinkles, leathery skin, liver spots, actinic keratosis, and solar elastosis. UV rays can also cause eye problems
.
Does UV light destroy DNA?
One way ultraviolet light can harm cells is by directly damaging DNA
. This is something many of us are reminded of every spring and summer – it’s the cause of sunburn! As the name suggests, direct DNA damage occurs when a photon of UV light hits DNA.
How does UV radiation control microbial growth?
In the process of controlling microorganisms,
UV light damages their DNA
, where organisms grow by cell division and genetic information is transmitted from a generation of cells to the next by the splitting of the DNA. The DNA includes two chains of molecules which are very long and twisted together.
How does ultraviolet light destroy bacterial cells quizlet?
UV causes mutation called thymine dimers which put kinks in DNA strands, rendering the molecule useless for transcription
. What damage does UV cause which makes it effective in killing bacteria? bacteria can synthesize their own repair enzymes to fix the damages caused by mutagens like UV light.
How much UV radiation would you need to cause mutagenesis to the bacterial cell?
We will therefore ‘wash’ the bacteria by centrifugation and resuspend them in a UV-transparent medium (phosphate-buffered saline or PBS). Optimal mutagenesis occurs when the level of bacteria that survive exposure to UV is
~1%
. Using your lamp, how long an exposure will you need?
Is UV radiation harmful?
UV exposure increases the risk of potentially blinding eye diseases, if eye protection is not used.
Overexposure to UV radiation can lead to serious health issues, including cancer
. Skin cancer is the most common cancer in the United States.
How much UV light is harmful?
| Skin type Maximum amount of time | I 10 minutes | II 20 minutes | III 30 minutes | IV 50 minutes |
|---|
Which type of UV radiation is most harmful?
Short-wavelength UVC
is the most damaging type of UV radiation. However, it is completely filtered by the atmosphere and does not reach the earth’s surface. Medium-wavelength UVB is very biologically active but cannot penetrate beyond the superficial skin layers.
What are two molecules that UV radiation can damage?
The two main DNA lesions formed by exposure to UVB are
cyclobutane pyrimidine dimers (CPD) and 6-4 pyrimidine pyrimidone photoproducts (6-4PPs)
, and its Dewar isomers.
What are two molecules in the body that UV radiation can damage?
UV radiation causes two classes of DNA lesions:
cyclobutane pyrimidine dimers (CPDs, Figure 1) and 6-4 photoproducts (6-4 PPs, Figure 2)
.
How does melanin protect these molecules from UV damage quizlet?
How does melanin protect these molecules from UV damage?
They form a shield that protects important molecules circulating in blood vessels in the dermis
. What are pyrimidine dimers, what causes them, and why are they dangerous?
How does UV radiation break bonds?
UV radiation has enough energy to break chemical bonds.
Due to their higher energies, UV photons can cause ionization, a process in which electrons break away from atoms
. The resulting vacancy affects the chemical properties of the atoms and causes them to form or break chemical bonds that they otherwise would not.
How does UV light damage RNA?
UV light induces damage to the genomes of bacteria, protozoa, and viruses,
breaking bonds and forming photodimeric lesions
in nucleic acids, DNA, and RNA (1, 2). These lesions prevent both transcription and replication and ultimately lead to inactivation of the microorganisms (3, 4).
How does UV radiation break bonds in DNA?
UV has a lethal effect on most organisms primarily because of
its ability to cause the formation of thymine dimers in DNA
. Thymine dimers are two adjacent thymine bases that are abnormally linked together by covalent bonds. This dimerization inhibits DNA replication, which may lead to death of the organism.
What causes UV radiation is applied to cells it quizlet?
UV radiation is lethal because of its mutagenic properties. When DNA absorbs UV light, it causes the formation of
pyrimidine dimers
which form when a covalent bond forms between two adjacent thymine or cytosine molecules in a strand of DNA.
How does UV light affect microorganisms quizlet?
What does UV light create? Thymine-thymine dimmers which in turn
disrupts DNA replication
. This type of mutation is lethal to bacteria which means UV light can be a very effective way to prevent microbial contamination(unwanted bacterial growth).
What limited protection do cells have against the damaging effects of UV radiation?
What limited protection do cells have against the damaging effects of UV rediation?
SOS system activated by light
. These enzymes repair the pyrimidine dimers. What types of damage to human tissues can result from prolonged exposures to UV radiation?
