APY248 Exam 3 Review

APY248 Exam 3 Review - Genetics and Environmental Hazards...

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Genetics and Environmental Hazards Radiation effects Direct hit on DNA by high radiation = ionized parts not rejoining correctly Can also cause indirect DNA damage Ionizing radiation: all highly penetrating X-rays (mutagenic = mutation causing) Cosmic rays Gamma radiation Sources of ionizing radiation: Radio isotopes (materials that produce radiation) X-rays and gamma rays Atomic bomb Radiation is linear More exposure= more damage Cumulative(increasing) effects Radiologists had more deaths from heart disease than other doctors We need x-rays: a risk benefit UV radiation: not high energy (lower form) Long wave-length Can lead to sunburn Can lead to skin cancer UV does this by upsetting DNA leading to errors in replication Thymine dimer: molecular lesions(damage) formed from thymine bases Thymine dimer = not good!!! Lead to difficulty in DNA replication Bonded together and not available to bond to incoming adenine Incorrect bases: being incorporated into new DNA strand Can be repaired Excision repair : Removes thymine dimer Cutting bond between adjacent thymine’s DNA can repair damage When new DNA is synthesized a proof reading goes on If error is found it, it recognizes the original strand with correct sequence Enzyme excises new strand and additional enzyme to see that correct base is put in DNA damage is normal, but there are systems that repair the damages Xeroderma pigmentosum (XP): autosomal recessive disorder (missing enzymes) Very sensitive to sunlight High chance of acquiring skin cancer Inability to repair thymine dimers that result from UV damage CAUSES ADJACENT THYMINE TO JOIN ONE ANOTHER INSTEAD OF THE CORRECT CORRESPONDING ADENINE ON THE OTHER DNA STRAND THE WRONG BASE BECOMING INCORPORATED = WRONG DNA STRAND
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8/9 missing enzymes Homozygous at any 8 or so autosomal loci (specific position of gene on chromosome) UV protection reduction in ozone layer causes increase exposure to UV Ex: 1930s Dupont Propellant: material that produces pressurized gas; common chemical (gas, jet fuel) or liquids (nitrous oxide, alkane) Dupont discovered alkane propellants in hairspray Can destroy ozone layer New propellants created to protect ozone layer Chemical effects Sodium nitrate Pesticides in food and food additives found to be mutagenic Capable of causing mutations in body (cancer) Exposure in additives in food are less damaging than water-source (water we drink) More damaging chemicals in agricultural runoffs (water leaving areas of agricultural land use) Agricultural runoff greater impact for mutation and cancer Carcinogens: any substance that is an agent directly involved in causing cancer First require activation before becoming mutagenic Liver can activate materials accidentally when metabolizing/detoxifying chemicals Become mutagenic and carcinogenic
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APY248 Exam 3 Review - Genetics and Environmental Hazards...

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