2.3 Flashcards
What is the effect of CF on the airways?
Thick sticky mucus, which is hard to cough up, gets trapped and builds up, leading to lung infections and slow diffusion = less efficient gas exchange.
What is the effect of CF on the liver?
The bile duct becomes blocked with sticky mucus - and bile emulsifies lipids.
What is the effect of CF on the pancreas?
The tube that connects the pancreas to the small intestine can become blocked with mucus, preventing digestive enzymes produced by the pancreas from reaching the small intestine. This reduces the ability of someone with CF to digest food so fewer nutrients are absorbed.
The mucus can cause cysts to form in pancreas - these inhibit production of enzymes.
What is the effect of CF on the small intestine?
The mucus lining the small intestine is abnormally thick which inhibits the absorption of nutrients.
A low concentration of enzymes within the small intestine reduces rate of digestion. Food is not fully digested so faeces contain undigested food = malabsorption.
What is the effect of CF on the reproductive tract?
In some men with CF, the tubes connecting the testicles to the penis are absent and can become blocked by the thick mucus in others. So any sperm produced can’t reach the penis.
In women, thickened cervical mucus can prevent the sperm from reaching the egg = mucus plug.
What is the effect of CF on the skin?
Sweat glands are exocrine glands that secrete salt and water solution into their lumen. In CF, the CFTR protein doesn’t allow reabsorption of salt from sweat - salty sweat.
What are enzymes?
Globular proteins that act as biological catalysts.
Why are enzymes essential in cells?
Enzyme function is determined by their complex 3D structure. The reaction takes place in a small part of the enzyme called the active site while the rest of the protein acts as scaffolding.
What is activation energy?
The energy needed to break bonds and start a reaction.
How do enzymes lower activation energy?
They provide an alternative pathway for the substrates to react that requires less activation energy.
The specific shape of the enzymes’ active site and substrate is such that electrically charged groups on their surfaces interact. The attraction of oppositely charged groups may distort the shape of the substrate and assist in the breaking of bonds or in the formation of bonds.
What is the lock and key model?
The substrate fits into the enzyme in the same way that a key fits into a lock. But scientists realised this model didn’t give the full story, because the enzyme-substrate complex changes shape slightly to complete the fit, locking the substrate even more tightly to the enzyme.
What is the induced fit model?
Explains why enzymes are so specific and only bond to one particular substrate. The substrate doesn’t only have to be the right shape to fit the active site, it has to make the active site change shape in the right way as well.
Why does increasing the temperature increase the rate of reaction?
Enzymes gain more kinetic energy so they knock into each other harder and more frequently which increases rate.
Why does the rate of reaction decrease above the optimum temperature?
Enzymes become denatured at high temperatures and the shape of their active site changes so the substrate no longer fits, so they stop working and the rate of reaction slows.
How can changing the pH either side of the optimum pH value have an affect on how the enzyme works?
The pH value will mean bonds are influenced by H+ and OH- ions in such a way that their active sites will not fit with their substrates. A change in pH affects side groups and R groups.
