Enzymes Flashcards
What are enzymes?
Biological catalysts
What is a catalyst?
A substance that increases the rate of reaction without being changed or used up in the reaction
What are enzymes made from?
Large proteins - formed from amino acids
How are enzymes specific?
Folded into a specific shape - active site is specific - can only catalyse a specific reaction
Describe the induced fit model of enzyme action
When the substrate is close to the active site, the active site changes shape to bind to the substrate
Describe how the rate of enzyme catalysed reactions can be changed
By changing the temperature and pH
As temperature increases there are more frequent collisions as particles have more energy so rate of reaction increases up until a point where the temperature becomes so high the enzyme denatures and rate of reaction decreases as the enzyme can no longer catalsye the reaction.
The pH interferes with the bonds in the protein in the active site changes the shape of the active site and denaturing the enzyme.
At what pH does pepsin work best at?
2
Found in acidic conditions in the stomach
At what pH do most enzymes work best at?
7 - neutral
How can you investigate the effect of pH on enzyme activity?
Practical with amylase catalysing the breakdown of starch to maltose using iodine solution
How is the rate of reaction calculated?
Amount something has changed / time taken
Describe the digestion of starch
Starch is digested into maltose and other sugars e.g dextrins by carbohydrase enzyme amylase
Where is amylase made?
Salivary glands
Pancreas
Small intestine
Describe the digestion of proteins
Proteins are digested by proteases into amino acids
Where are proteases made?
Stomach (pepsin)
Pancreas
Small intestine
Describe the digestion of fats/lipids
Lipids are digested by lipases into fatty acids and glycerol
Where are lipases made?
Pancreas
Small intestine
Where are the products of digestion used?
To make new proteins and carbohydrates
Glucose used in respiration
Why is digestion necessary?
Large molecules like proteins and fats cant diffuse into the blood and can not be absorbed so must be broken down into smaller molecules
Where is bile produced, stored and release?
Produced by liver and stored in the gallbladder before it is released into the small intestine
What is the purpose of bile?
Neutralises the hydrochloric acid from the stomach and provides an optimum pH for enzymes to work in the small intestine
Emulsifies fats- breaks the fats into smaller droplets increasing the surface area for which lipases can work
Describe the function of the salivary glands in digestion
Produce amylase in the saliva
Describe the function of the oesophagus in digestion
Passage of food from mouth to the stomach
Describe the function of the stomach in digestion
Pummels food with its muscular walls
Produces protease enzyme pepsin
Produces hydrochloric acid which kills bacteria and gives the right pH for the protease enzyme to work (pH 2)
Describe the function of the pancreas in digestion
Produces protease, amylase and lipase enzymes
Releases these into the small intestine
