CB1 Enzymes Flashcards
What are enzymes?
Biological catalysts that increase the rate of a chemical reaction without being permanently altered themselves
What is an advantage of enzymes in the body?
They enable cellular reactions to take place at lower temperatures.
What is the active site of an enzyme?
The region of an enzyme to which a substrate molecule binds and the reaction takes place.
Why are enzymes described as having a ‘high specificity’ for their substrate?
Only substrates with a specific, complementary shape can fit into an enzyme’s active site
Describe the ‘lock and key’ model
- Substrate collides with the active site of an enzyme
- Substrate binds, enzyme-substrate complex forms
- Substrate converted to products
- Products released from the active site which is now free to bind with another substrate
What factors affect the rate of an enzyme controlled reaction?
-Temperature
-pH
-Substrate concentration
Explain how increasing temperature initially affects the rate of an enzyme controlled reaction
-As temperature increases molecules have more kinetic energy
-Movement of molecules increases
-Probability of a successful collision increases
-More enzyme-substrate complexes form
-Rate of reaction increases
Explain how increasing temperature above the optimum affects the rate of an enzyme-controlled reaction
-Temperature increases above the optimum
-Increased vibrations break bonds in enzyme’s structure
-Active site changes shape so enzyme will become denatured
-No more enzyme-substrate complexes can form
-Rate of reaction decreases
Explain how pH affects the rate of an enzyme controlled reaction
-Enzyme’s have an optimum pH
-pH shifts from the optimum
-Bonds in the enzyme’s structure are altered
-Active site changes shape, enzyme is denatured
-Rate of reaction decreases
Explain how the substrate concentration affects the rate of an enzyme-controlled reaction
-Substrate concentration increases
-Number of substrate molecules in the same volume increases
-Probability of a successful collision increases
-More enzyme-substrate complexes form
-Rate of reaction increases
-Once all active sites become full, the rate of reaction plateaus
How can the rate of an enzyme-controlled reaction be calculated when given a value for time?
Rate = 1/time
What are the units rate?
S to the -1
Why must large organic molecules be broken down into smaller, simpler molecules in the body?
-Large molecules are too big to be absorbed across the surface of the gut wall
-large molecules are broken down into smaller molecules for absorption into the bloodstream
Give an example of the breakdown of large molecules into smaller molecules in plants
Starch is broken down by enzymes into simpler sugars which are respired to release energy
What type of molecules are proteins and carbohydrates?
Polymers
