Organisation - enzymes Flashcards
what are enzymes
a protein that increases the rate of reaction / biological catalyst
what is a catalyst
substances that speed up reactions without being changed or used up
what is an active site
The active site of an enzyme binds a specific substrate and breaks it down into its products
for the enzyme to work, what needs to happen
- the substrate needs to fit in the active site, if it doesn’t match the active site, the reaction won’t be catalysed
Describe the lock and key mechanism of enzyme action.
-enzymes have a complementary shape, meaning their active site will only bind to a substrate of a specific shape. Once they have joined together, the chemical reaction will be catalysed
what does denatured mean
stops working and is unable to catalyse a reaction
what factors affect the rate of an enzyme- catalysed reaction
pH, temperature
how does temperature affect the rate of an enzyme catalysed reaction
- increasing temperature increases rate of reaction
- this is because as temperature increases, the active site and substrate move faster, so there are more collisions per second between the substrate and active site
- too hot, bonds holding enzyme will break and this will change the shape of the active site so the substrate won’t fit anymore and be broken down into its products, the enzyme will become denatured
what is an optimum pH or temperature
a pH or temperature that enzymes works best at
how does pH affect the rate of enzyme - catalysed reactions
- enzymes have optimum pH
- too high or too low, changes shape of active site and enzyme becomes denatured
- optimum pH usually pH7
how to calculate rate of reaction
calculated by picking two points on the graph, then dividing the change in the value on the y axis (mass) by the change in the x axis value (time), between those two points.
reaction rate=
change in time
change in mass
what do digestive enzymes do
break down big molecules like starch, proteins and fats into smaller ones like sugars, amino acids, glycerol
what are the main enzymes in digestion
amylase
protease
lipase
what is amylase and what does it do
- amylase is an enzyme and a type of carbohydrase
- it breaks down starch into maltose and other sugars
what does a carbohydrase do
converts carbohydrates into simple sugars
what is protease and what does it do
- protease is an enzyme which converts proteins into amino acids
what is lipase and what does it do
- lipids are enzymes that convert lipids into glycerol and fatty acids
what does bile do
it neutralises the HCl in the stomach and turns it alkaline so that enzymes work, the enzymes in the small intestine work best at alkaline pH
- also emulsifies fats - breaks fat down into tiny droplets, giving fat a much bigger surface area for the lipase to work on, making digestion faster
Why is it necessary to break down large, insoluble food molecules into smaller, soluble molecules
Large, insoluble food molecules can’t be absorbed into the bloodstream, small , soluble molecules can and are used to construct new carbohydrates, proteins and lipids in the body.
Some glucose produced by digestion is used for respiration.
sites of action of amylase
mouth
small intestine
pancreas
Action sites for proteases
small intestine
stomach
where is lipase produced
small intestine
pancreas
When investigating the rate of enzyme activity, what factors need to be kept constant?
pH
temperature
substrate concentration
where is protease made
- stomach ( pepsin)
- pancreas
- small intestine
where is lipase made
- small intestine
-pancreas
where is amylase made
- salivary glands
- pancreas
- small intestine
what do digestive enzymes do
convert food into small soluble molecules that can be
absorbed into the bloodstream - e.g- starch to small sugars
what is the role of bile
- helps speed up the digestion of lipids but is not an enzyme
- converts larger lipid droplets into smaller ones (emulsifies)
- this massively increases the surface area of the lipid droplets
- this increases the rate of lipids broken down by lipase
- also neutralises stomach acid, creating alkaline conditions, in the small intesting, and this also increases rate of lipid breakdown
what is a substrate
the part of the enzyme that attaches to the active site and is broken down and released
whats an example of an enzyme which would probably work best in acidic conditions
a protease enzyme in the stomach
whats an example of an enzyme which would probably work best in alkaline conditions
lipase, released from the pancreas into the small intestine
