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. 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.
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. In people with cystic fibrosis, non-working cystic fibrosis proteins mean no salt (chloride) enters the air space and water doesn't either. The mucus layer is concentrated and very sticky. People with cystic fibrosis have lung problems because: Proteins for diffusion of salt into the airways don't work. (less diffusion) Less salt in the airways means less water in the airways. (less osmosis) Less water in the airways means mucus layer is very sticky (viscous). Sticky mucus cannot be easily moved to clear particles from the lungs. Sticky mucus traps bacteria and causes more lung infections. 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.
single base change
no amino acid change
redundancy in code
change amino acid
change to stop codon
When do mutations
affect the next
Point mutation leads to Sickle cell anemia
What kind of mutation?
Sickle cell anemia
recessive inheritance pattern
strikes 1 out of 400 African Americans
shift in the reading
Where would this mutation
cause the most change:
beginning or end of gene?
Primarily whites of
strikes 1 in 2500 births
normal allele codes for a membrane protein
that transports Cl- across cell membrane
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
Effect on Lungs
transports chloride through
protein channel out of cell
Osmotic effects: H2O follows ClCl- channel
bacteria & mucus build up
hard to secrete
mucus secreting glands
Deletion leads to Cystic fibrosis
loss of one
What’s the value of
What’s the value of
A particular slide catching your eye?
Clipping is a handy way to collect important slides you want to go back to later.