Enzymes Flashcards
What are enzymes?
Biological catalysts that speed up the rate of metabolic reactions
What type of reactions determine structure and function of organisms?
Intracellular and extracellular which determines the structure and function from cellular to whole organism level
What type of polymer are enzymes?
Proteins
Give the structure of an enzyme
Enzymes have a specific 3D tertiary shape and active site
What is the role of the active site?
To bind to complimentary substrate molecules to form enzyme-substrate complexes
Give the three way word that gives at least one mark on enzymes
Enzyme- substrate complexes
Define Activation energy
The amount of energy required to speed up the rate of reaction
How does enzymes relate to activation energy?
Enzymes lower the activation energy of the reaction it catalyses
Why are enzymes highly specific
Because of their tertiary structure
What do enzymes combine to?
Complimentary substrates to form enzyme-substrate complexes
What type of proteins are enzymes
Globular proteins
Describe the ‘lock and key’ model
- The substrate fits into the active site like a key fits into a lock
- Active site is rigid
Describe the ‘induced fit’ model
• The active site is flexible
• When substrate binds to active site, it changes its shape slightly to mound itself around the substrate
What determines the active site shape?
The tertiary structure
Different enzymes have….?
Different tertiary structures
What factor can change the structure of enzyme produced?
Gene/ mutation in the primary structure
What happens if the structure of enzyme is altered in any way?
It changes the shape of the active site and enzyme-substrate complexes can’t be formed
List 3 factors affecting enzyme activity
• High/low Temperature
• pH
• Enzyme/substrate concentration
How does an increase in temperature affect the rate of reaction?
It increases the rate of reaction
How does temperature affect rate of reaction?
It increases the kinetic energy of enzyme and substrate molecules which lead to more collisions between enzyme and substrate molecules
An increase leads to what?
More enzyme-substrate complexes binding
At what temperature do enzymes become denatured
Optimum temperature/40C
What happens if enzymes hit optimum Temperature (5)
• High amount of energy causes bonds to break
• Changes 3D structure
• Changes shape of active site
• Enzymes become denatured
• Enzyme substrate complexes can’t be formed
Draw a graph on Temperature effect on enzyme-controlled reactions
Search if you got the answer right
How does pH affect rate of enzyme activity? (5)
•Above/below pH can break hydrogen and ionic bonds that hold the tertiary structure
• It makes the enzyme change shape
• Active site looses its shape
• Enzyme becomes denatured
•Enzyme-substrate complexes can’t be formed
How does substrate concentration affect rate of reaction?
• Increasing rate of substrate concentration increases rate of reaction
• More enzymes will bind to form enzyme-substrate complexes
• However, beyond a certain point, SATURATION will occur
• This is when there are no more enzyme molecules to catalyze substrate molecules
How does enzyme concentration affect rate of reaction (4)
- Increasing enzyme molecules will increase the rate of reaction
- more substrates will bind to enzyme active site
- More enzyme-substrate complexes will be formed
- However beyond a certain saturation, rate will no longer be increased because all substrate molecules have been binded to enzyme active site
Characteristics and functions of competitive inhibitors (4)
• They have a similar shape to substrate molecules
• They bind to the active site of enzymes to block substrate molecules, however no reaction happens
• They block so substrate molecules can’t fit in
• Increasing the substrate concentration will increase the rate of reaction. Competitive inhibitors can be cancelled by this because substrate molecules will reach the active site quicker
• Prevents complimentary base pairing
Characteristics of Non-competitive inhibitors and functions (4)
• They bind away from the active site
• Causes the shape of the enzyme to change so substrate molecules cannot fit in
• Thus changes the shape of the active site
• Increasing the substrate concentration will not increase the rate of reaction. Enzyme activity will still be inhibited
Describe 1 similarity and 1 difference between lock and key and induced fit model
• Substrate fits/ binds to active site
• Active site changes shape but does not change in lock and key
