Digestion Flashcards
(31 cards)
What is the active site on an enzyme?
Part of enzyme molecule substrate molecule fits into as complementary shapes.
What is a catalyst?
Something which speeds up rate of reaction but is unchanged by reaction.
What does complementary mean?
Shapes that fit into each other.
E.g. enzyme and its substrate.
What is denaturation?
Irreversible change in shape of enzyme.
It is no longer complementary to substrate and cannot catalyse reaction.
What is digestion?
Enzymes breaking down large, complex, insoluble food molecules into small, simple, soluble ones which can be absorbed across walls of ileum into blood.
What is enzyme specificity?
Ability of enzyme to catalyse only one type of substrate.
What is an inhibitor?
Molecule which fits into active site of enzyme and stops normal substrate entering so reducing reaction rate of enzyme.
What is the ‘Lock and Key Model’?
Model used to explain how enzyme reacts with its substrate.
What is a substrate?
Molecule that is acted upon by enzyme.
What are villi?
Small finger-like projections lining wall of ileum which increases its surface area for absorption by extending into the lumen.
What does optimum mean?
Value of a factor which allows reaction to happen at its fastest rate.
What are thermostable enzymes?
Enzymes are to function over wide range of temperatures without being broken down.
What are enzymes?
Biological catalysts that speed up rate of reactions without being used up themselves. Made up of proteins.
What are the enzyme and products of starch?
Enzyme - amylase
Products - simple sugars, glucose
What are the enzyme and products of Fats (lipid)?
Enzyme - lipase
Products - glycerol, fatty acids
What is the enzyme and product of protein?
Enzyme - protease
Product - amino acids
What are the enzyme and products of carbohydrates?
Enzyme - carbohydrase
Products - simple sugars, glucose
What is the ‘Lock and Key Theory’ of enzyme action?
Enzyme’s active site is exact shape of substrate. Enzyme is lock and substrate is key. Two molecules are complementary, ie. they specifically match.
How do inhibitors affect the rate of enzyme action?
Molecules called inhibitors fit loosely or partially into active site of enzyme.
While they occupy active site, substrate molecules cannot enter and be broken down, leads to reduced rate of reaction.
How does temperature affect enzyme action?
- Increase in temperature causes kinetic energy of enzyme and substrate molecules to increase.
- Leads to increases collisions between enzymes and substrates.
- Leads to more successful collisions.
- Equals faster rate of reaction.
At optimum temp for enzyme (37-40oC), enzyme works best and has 100% activity.
How does denaturation occur?
At high temp molecules have a lot of kinetic energy and vibrate vigorously.
Weakens bonds that hold enzyme in specific shape.
Changes shape of active site and enzyme no longer matches shape of substrate.
Rate of reaction decreases as enzyme can no longer catalyse reaction.
How does pH affect enzyme activity?
Each enzyme has optimum pH.
Either side of pH they work less well because shape of active site changes.
At extremes of pH enzyme denatures and stops working.
What are examples of different enzymes and their pH conditions?
Amylase (mouth) - slightly alkaline
Trypsin (protease, small intestine) - slightly alkaline
Pepsin (protease, stomach) - acidic
How does enzyme concentration affect enzyme activity?
If unlimited supply of substrate, higher enzyme concentration and faster reaction rate.
As enzyme concentration increases more enzyme molecules are in same volume solution and so greater chance of substrate colliding with enzyme active site.
If supply of substrate is limited, rate of reaction levels off as no more substrate molecules to collide with enzyme.
