Question

There are many environmental factors that may lead to cancer. Keeping that in mind, please answer the following questions. a. Describe two types of environmental factors that are considered carcinogens. Make certain to clearly describe the mechanism of action for their carcinogenic properties. b. Howdoesthebodyrepairtheabovementionedcarcinogens’ damages? Make certain to describe the repair mechanism in detail.

Answer 1

ANSWER=
Environmantal factors that causes cancer as=

1] biological agents- specific viruses or bacteria

2]physical agents - ultraviolet light,X-rays

Uv radiations comes from the sun,sunlamps and tanning beds.

they causes the skin cancer

mechanism of action= in fact most skin cancers are a direct result of exposure to the UV rays in sunlight.Both basal cell & squamous cell cancers tend to be found on sun-exposed parts of the body,& their occurence is typically related to lifetime sunexposure.

the risk of melanoma ,more serious but less common type of skin cancer.also related to sun exposure.

UVA UVB causes cancer

3]Chemicals - many chemicals are direct acting carcinogens.many require metabolic activation in order to exert their carcinogenecity.

some chemicals are direct acting while others are indirect acting

Direct acting carcinogens-

are reactive electrophiles .

they chemically react with nitrogen or oxygen atoms in DNA.it modify certain nucleotides so as to disort the normal pattern of base pairing.

Indirect acting carcinogens=

are unreactive,water insoluble compounds.They can act as a potent cancer inducers only after conversion to ultimate carcinogens by introduction of electrophillic centers.

such a metabolic activation of carcinogens is carried out by enzymes

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b] the body repair the above mentioned carcinogens’ damages as follws:

1]Photoreactivation repair= UV light is a physical agent can cause cancer.VU radiation causes formation of pyrimidine dimers when 2 pyrimidine bases occurs together in single strand of dna.

A repair mechanism photoreactivation can repair this mutation.

when UV radiated population of bacteria is subsequently exposed to visible light of 300-450 nm,the survival rate increases and frequency of mutation decreases.this is due to the activation of photoreactivating enzyme photolyase,which splits thymine dimer.

in the dark the enzyme bind with thymine dimer & in presence of visible light the enzyme split thymine dimer.

2]Inducible repair system- anmal cells also have inducible repair systems,because radiation or carcinogen induced DNA damage must be repair before DNA is replicated ,cells have sensing mechanisms that react to DNA damage & stop dna replication.

these mechanisms involve checkpoint control proteins such as the p53 protein,which acts to stop the cell cycle if DNA is damaged.thus to supress the production of tumors.