4.1 Enzyme Action Flashcards
(19 cards)
What are enzymes?
Globular proteins that act as biological catalysts
What is the metabolism?
All of the reactions in a cell
What is the metabolism broken down into?
Catabolism and anabolism
What is the catabolism?
The reactions that break down molecules (Large –> small)
What is the anabolism?
The reactions that build up molecules (Small –> large)
What do enzymes do?
They lower the activation energy needed for a reaction to begin
What is an extracellular enzyme?
Enzymes that have their effect outside the cells that produce them (eg amylase)
What is a substrate?
A substance used or acted on by a process or a substance (eg glucose is a substrate)
What is an intercellular enzyme?
Enzymes that have their effect inside the cells that produce them (eg catalase)
What factors have an effect on the rate of a chemical reaction?
pH, temperature and pressure
What has to occur for a reaction to happen?
Molecules need to collide in the right orientation
What is the specificity of an enzyme?
The amount of biological reactions that it will catalyse (typically one)
How do enzymes reduce the activation energy?
Holding the molecules in place, helping them to collide successfully.
What are the names of the two hypotheses which suggest how enzymes work?
Lock and Key theory, and induced fit theory
Explain the Lock and Key Theory.
- Active site of the enzyme has tertiary structure complementary to the shape of the specific substrate molecule
- When the substrate is bound to the enzyme, the ENZYME-SUBSTRATE COMPLEX is formed.
- The substrates then react, and the products are formed in an ENZYME-PRODUCT COMPLEX
- The R-groups within the enzyme also interact with the substrate, forcing the reaction along
- The products are released, leaving the enzyme UNCHANGED, and able to take part in other reactions
Explain the Induced Fit Hypothesis
- Initial interactions between the enzyme and substrate are relatively weak,
- Interactions rapidly induce changes in the enzyme’s tertiary structure that increase binding
- This can weaken particular bonds in the substrate, therefore lowering the activation energy.
What do all reactions happening in cells need to make the products required?
Raw materials
How are raw materials needed in reactions supplied to cells?
-Nutrients present in the diet supply the materials
-Nutrients are often found in the form of polymers, so are broken down by extracellular proteins to enter the cell
Describe the steps involved in the digestion of starch
1- Starch polymers are partially broken down into maltose (catalysed by amylase)
2- Maltose digested into glucose (catalysed by maltase)
3- Glucose is small enough to be absorbed into cells lining the digestive system, before being absorbed into the bloodstream.
