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  • Cystic fibrosis is an inherited disease that is relatively common in the U.S. Cystic fibrosis affects multiple parts of the body including the pancreas, the sweat glands, and the lungs. When someone has cystic fibrosis, they often have lots of lung problems. The cause of their lung problems is directly related to basic problems with diffusion and osmosis in the large airways of the lungs. <br /> People without cystic fibrosis have a small layer of salt water in the large airways of their lungs. This layer of salt water is under the mucus layer which lines the airways. The mucus layer in the airways helps to clear dust and other inhaled particles from the lungs. <br />
  • In people without cystic fibrosis, working cystic fibrosis proteins allow salt (chloride) to enter the air space and water follows by osmosis. The mucus layer is dilute and not very sticky. <br /> In people with cystic fibrosis, non-working cystic fibrosis proteins mean no salt (chloride) enters the air space and water doesn&apos;t either. The mucus layer is concentrated and very sticky. <br /> People with cystic fibrosis have lung problems because: <br /> Proteins for diffusion of salt into the airways don&apos;t work. (less diffusion) <br /> Less salt in the airways means less water in the airways. (less osmosis) <br /> Less water in the airways means mucus layer is very sticky (viscous). <br /> Sticky mucus cannot be easily moved to clear particles from the lungs. <br /> Sticky mucus traps bacteria and causes more lung infections. <br /> Therefore, because of less diffusion of salt and less osmosis of water, people with cystic fibrosis have too much sticky mucus in the airways of their lungs and get lots of lung infections. Thus, they are sick a lot. <br />

62mutations2008 62mutations2008 Presentation Transcript

  • Mutations AP Biology 2007-2008
  • Mutations  Point mutations single base change  base-pair substitution   silent mutation  no amino acid change  redundancy in code  missense  change amino acid  nonsense  change to stop codon AP Biology When do mutations affect the next generation?
  • Point mutation leads to Sickle cell anemia What kind of mutation? AP Biology Missense!
  • Sickle cell anemia  Primarily Africans recessive inheritance pattern  strikes 1 out of 400 African Americans  AP Biology hydrophilic amino acid hydrophobic amino acid
  • Mutations  Frameshift  shift in the reading frame   insertions   changes everything “downstream” adding base(s) deletions  AP Biology losing base(s) Where would this mutation cause the most change: beginning or end of gene?
  • Cystic fibrosis  Primarily whites of European descent  strikes 1 in 2500 births   normal allele codes for a membrane protein that transports Cl- across cell membrane     AP Biology 1 in 25 whites is a carrier (Aa) defective or absent channels limit transport of Cl- (& H2O) across cell membrane thicker & stickier mucus coats around cells mucus build-up in the pancreas, lungs, digestive tract & causes bacterial infections without treatment children die before 5; with treatment can live past their late 20s
  • Chloride channel Effect on Lungs normal lungs airway Cl- transports chloride through protein channel out of cell Osmotic effects: H2O follows ClCl- channel H2O cells lining lungs cystic fibrosis ClH2O bacteria & mucus build up thickened mucus hard to secrete AP Biology mucus secreting glands
  • Deletion leads to Cystic fibrosis delta F508 loss of one amino acid AP Biology
  • What’s the value of mutations? AP Biology 2007-2008
  • What’s the value of mutations? AP Biology 2007-2008