3.1.4.2 Proteins - Enzyme Action Flashcards
How did scientists discover the induced fit model of enzyme action?
They noticed that other molecules could bind to enzymes, which then affected the enzyme’s activity. This led to the conclusion that the enzyme shape must be changing.
What is a substrate?
The substance on which an enzyme acts
Why are enzymes essential to organisms?
They allow essential chemical reactions to occur rapidly at low temperatures e.g. 37 °C.
Enzymes that catalyse chemical reactions outside of cells are called…
extracellular enzymes
The functional part of an enzyme is called the…
active site
Describe the lock and key model of enzyme action
- A substrate is specific to an enzyme.
- A substrate binds to the active site of an enzyme.
- This lowers the activation energy.
- Product is released from enzyme.
Which 3 conditions must be satisfied for a chemical reaction to take place?
- The substrates must collide with sufficient energy to alter the arrangement of their atoms
- The energy of the products must be lower than the substrates.
- The activation energy needs must be met.
Which have a higher energy level: substrates or products?
products
The specific 3D shaped active site of an enzyme is determined by..
its sequence of amino acids (primary structure)
Enzymes that catalyse reactions inside of cells are called…
intracellular enzymes
When a substrate binds to the active site we call the resulting structure an…
enzyme-substrate complex
A substrate does not have the same shape as the active site it has a _____________ shape.
complementary
What does the following describe:
- A substrate is specific to an enzyme.
- A substrate binds to the active site of an enzyme.
- This lowers the activation energy.
- Product is released from enzyme.
The lock and key model of enzyme action
Hormones are proteins that have a binding site so that they can switch on or off bodily processes. Are they enzymes?
No - many proteins have binding sites or receptor sites. These are not active sites.
Which type of biological molecule are enzymes?
Proteins
Which structural type of protein are enzymes?
Globular proteins
What do we call the initial energy required for a chemical reaction to take place?
Activation energy
Define an enzyme
Enzymes are biological catalysts that speed up chemical reactions without being used up or changed.
How does a substrate temporarily bind to an enzyme active site?
The substrate temporarily forms bonds with certain amino acids in the active site.
What does the following describe:
- Substrate approaches active site
- Enzyme changes shape and forms functional active site.
- Enzyme moulds to substrate
- Change in shape puts a strain on bonds of substrate, lowering activation energy.
- Product is released from enzyme.
The induced fit model of enzyme action
What is the name of the currently accepted model of enzyme action?
The induced fit model of enzyme action
Describe the lock and key model of enzyme action.
- A substrate is specific to an enzyme.
- A substrate binds to the active site of an enzyme.
- This lowers the activation energy.
- Product is released from enzyme.
Why are enzymes still effective even in small amounts?
Because they are not used up or changed so can be used again and again.
Describe the induced fit model of enzyme action
- Substrate approaches active site
- active site not complementary/will fit substrate
- active site changes shape and forms functional active site - as substrate binds
- Enzyme moulds to substrate
- Change in shape puts a strain on bonds of substrate, lowering activation energy.
Why does formation of enzyme substrate complex increase rate of reaction?
Reduces activation energy
due to the bending/weakening of bonds
