Topic 4 Digestion Flashcards
(26 cards)
Enzymes
Proteins that act as biological catalysts, meaning they speed up reactions without being used up thmselves
Substrate
The molecule the enzyme works on
Products
Molecules formed by the enzyme and substrate reaction
Substrate specific
The enzyme will only work on one type of substrate and only on one at a time. For example, amylase is only complementary to starch, so will only break down starch, not protein or fat
How is an enzyme-substrate complex formed?
When enzymes and substrates collide. It is within this complex that the reaction takes place
What is the lock and key model?
It shows the relationship between an enzyme and substrates. It gives us a visual of the enzyme-substrate complex. The key represents the enzyme , and it unlocks the lock, which represents the substrate. Once the lock is opened and this represents the broken down products of the reaction
What are the enzyme and products of carbohydrate?
Carbohydrase works on carbohydrate to form sugar and glucose
What are the enzyme and products of starch?
Amylase works on starch to form glucose
What are the enzyme and products of protein?
Protease works on protein to form amino acids
What are the enzyme and products of lipids?
Lipase works on lipids to form fatty acids and glycerol
Inhibitors
Molecules which fit loosely or partially into the active site of some enzymes
How do inhibitors affect the rate of reaction?
While they occupy the active site, substrate molecules cannot enter to be broken down, which leads to a reduced rate of reaction
What factors affect enzyme activity?
Temperature, pH and enzyme concentration
What affect does low temperature have on enzyme activity?
Reduced kinetic energy/moving slowly, resulting in few collisions and therefore a low rate of enzyme activity
What affect does high temperature have on enzyme activity?
Increases kinetic energy/moving quickly, resulting in more collisions and a higher rate of enzyme activity
What happens to the enzyme when the temperature/pH deviates too much from the optimum?
Causes the enzyme’s active site to become DENATURED and active site loses its shape, meaning it can’t react with substrate anymore
Optimum
The maximum rate of reaction
What happens to the rate of activity when the temperature/pH fluctuates too much from the optimum?
Causes a decrease in activity due to DENATURATION. The further from the optimum, the lower the enzyme activity
Denaturation
An irreversible change to the shape of the active site
What does a higher concentration of enzymes mean for the rate of activity?
The higher the concentration, the more enzymes can form enzyme-substrate complexes, leading to an increase in enzyme activity. This is only up to a certain point. Enzyme activity then levels out (plateaus) as there aren’t enough substrate molecules to react with the extra enzymes
Why are enzymes needed?
To break down the food we eat so they are small and soluble and can be used by the body when absorbed
Digestion
The breakdown of large, complex, insoluble molecules into small, simple, soluble ones
What is the ileum and what does it do?
The small intestine. Its main function is the absorption of digested food products
How is the ileum adapted for absorption?
LARGE SURFACE AREA - due to being long and folded
THIN - digested food doesnt have to travel far to reach the blood
PERMEABLE - digested food can pass through easily
GOOD BLOOD SUPPLY - to maintain the concentration gradient for diffusion between the ileum and bloodstream
VILLI - fingerlike projections that further increase surface area
