Enzymes & Digestion Flashcards
Active Site
Region of an enzyme where the substrate attaches.
Amylase
An enzyme that can break down starch into simple sugars.
Complementary
Shapes that fit together like jigsaw pieces.
Concentration Gradient
The difference in concentration between two solutions, between different cells or between cells and a surrounding solution.
Denaturation: Simplified
When an enzyme’s active site loses its shape meaning it can no longer work.
Denaturation: Explained
Active site loses its important shape
= Can no longer form enzyme-substrate complexes
Leading to a decrease in enzyme activity.
Denaturation is a permanent change.
Digestive System
Organ system involved in breaking food down so that it can be absorbed into the bloodstream.
Enzymes
Proteins that act as biological catalysts, meaning they speed up reactions without being used up themselves.
Epithelium
Type of tissue that lines or covers surfaces of an organism.
Made up of epithelial cells.
Inhibitor
Molecules that partially fit into an enzyme’s active site
- but are not broken down.
They inhibit the reaction.
If in the active site - substrate cannot enter to be broken down
- reducing the rate of reaction.
Lacteal
Tube that absorbs the products of Fat digestion
Before returning them to the Blood.
Kinetic Energy
Energy which an object possesses by being in motion.
Optimum
The temperature, pH or enzyme concentration that allows the enzyme to work at its best.
Lipase
Enzyme that breaks down lipids (fats and oils)
pH
Scale of acidity or alkalinity.
pH (power of hydrogen) value below 7 = acidic
pH value above 7 = alkaline.
Protease
Enzyme that breaks down proteins.
Substrate
A substance on which enzymes act.
Thermostable
Work at a wide range of temperatures.
Allows biological washing powder to be used at low temp - saves energy and money.
The Small Intestine (ileum)
Main function:
Absorption of digested food products into the bloodstream,
so they can be transported to the cells of the body.
Villi
Finger like projections that line the small intestine.
Enzyme Action:
’Lock and Key Model’
- Enzyme works on 1 substrate to form products; it is substrate specific
- Active site and substrate are complementary in shape.
- They collide to form enzyme-substrate complexes
- Substrates are broken down (or in some cases built up)
- Products are released
- Enzyme is free to act again/ repeat
Examples of Enzymes
- Amylase
- Carbohydrase
- Lipase
- Protease
Enzyme: Carbohydrase
Substrate: Carbohydrate
Enzyme: Amylase
Substrate: Starch
Enzyme: Lipase
Substrate: Fat(lipid)
Enzyme: Protease
Substrate: Protein
Enzymes required for digestion
Amylase
Lipase
Protease
Enzymes during Digestion
Used break large, complex, insoluble food molecules into small, simple, soluble molecules so they can be absorbed into the bloodstream.
Enzymes and their Substrate
Carbohydrase - Carbohydrate
Amylase - Starch
Protease - Protein
Lipase - Fat (lipid)
Examples of Substrates
- Carbohydrate
- Starch
- Protein
- Fat (lipid)
Carbohydrase + Carbohydrate
Enzyme) (Substrate
= Simple Sugar, Glucose
(Product)
‘Lock and Key Model’
Explains why each enzyme only works on 1 substrate
E.g Active Site of Amylase is only complementary to Starch and will therefore only break down starch - not protein or fat
Amylase + Starch
Enzyme) (Substrate
= Simple Sugar, Glucose
(Product)
Lipase + Fat(lipid)
Enzyme) (Substrate
= Glycerol and 2 Fatty Acids
(Product)
Protease + Protein
Enzyme) (Substrate
= Amino Acid
(Product)
Factors Affecting Enzyme Activity
- Temperature
- pH
- Enzyme Concentration
- Optimum - temp, pH, enzyme concentration
Factors Affecting Enzyme Activity - pH
Deviating from the optimum pH (too high or too low) causes the enzyme’s active site to become denatured.
Active Site loses its important shape.
Can no longer form enzyme-substrate complexes = leading to decrease in enzyme activity.
Factors Affecting Enzyme Activity- Enzyme Concentration
Higher the enzyme concentration = more enzymes there are to form enzyme-substrate complexes
Leading to an increase in enzyme activity.
Happens up to a certain point.
Enzyme activity then levels off (plateaus) as there are not enough substrate molecules to react with the extra enzymes.
Factors Affecting Enzyme Activity - Optimum: temp, pH, enzyme concentration
Optimum value for these factors - value that allows the maximum rate of reaction.
Adaptation of the Ileum for absorption
Large surface area – due to being long and folded.
Thin – digested food doesn’t 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 – finger like projections that further increase surface area.
Adaptation of the Ileum for absorption: Thin
Digested food doesn’t have to travel far to reach the blood.
Adaptation of the Ileum for absorption:
Large Surface Area
Due to being long and folded.
Adaptation of the Ileum for absorption: Permeable
Digested food can pass through easily.
Adaptation of the Ileum for absorption: Good blood supply
To maintain the concentration gradient for diffusion between the ileum and bloodstream.
Adaptation of the Ileum for absorption:
Villi
Finger like projections that further increase surface area.
Features of the Villi that aid absorption: Explained
Good blood supply – villus has a large network of capillaries. Once blood becomes high in digested food products it is transported away and replaced with blood that is low in digested food products - Maintains the concentration gradient necessary for diffusion between the ileum and bloodstream.
Lacteal – tube that absorbs the products of fat digestion before returning them to the blood.
Single layer of surface epithelium cells – reduces the diffusion distance that digested food products have to travel in order to enter the bloodstream.
Permeable – digested food can pass through easily.
Features of the Villi that aid absorption: Simplified
- Good blood supply
- Lacteal
- Single layer of surface epithelium cells
- Permeable
Features of the Villi that aid absorption: Good Blood Supply
Villus has a large network of capillaries. Once blood becomes high in digested food products it is transported away and replaced with blood that is low in digested food products - Maintains the concentration gradient necessary for diffusion between the ileum and bloodstream.
Features of the Villi that aid absorption: Lacteal
Tube that absorbs the products of fat digestion before returning them to the blood.
Features of the villi that aid absorption: Single layer of surface epithelium cells
Reduces the diffusion distance that digested food products have to travel in order to enter the bloodstream.
Features of the Villi that aid absorption: Permeable
Digested food can pass through easily.
Where does the simple food molecule enter the bloodstream?
Ileum wall
Factors Affecting Enzyme Activity - Temperature
Temp increases to optimum = kinetic energy of the enzyme and substrate increases = more collisions between the enzyme & substrate.
Causes the formation of more enzyme-substrate complexes = increase in enzyme activity.
Increase in temp beyond optimum causes
Active Site = become denatured.
Some enzymes are thermostable.
Where is food digested?
Mouth, stomach and finally in the ileum
by amylase, protease and lipase.
