Unit Three - Enzymes Flashcards
What is the function of an enzyme? (2)
- Speed up the rate of a chemical reaction
- By lowering the activation energy
Why can enzymes be reused over and over again? (2)
AFTER A CHEMICAL REACTION
- Enzymes are not changed or used up
- Only a small amount is needed to catalyze numerous rxns
Are enzymes organic and why?
Yes, contain C - H bonds
Are enzymes specific? (3)
Yes
1. Each enzyme can only catalyze 1 substance
2. Isomers aren’t interchangeable
3. b/c SHAPE of active site is unique
What do enzymes normally end in?
- ase
What is another word for reactant in enzyme reactions?
Substrate
How can an enzymatic rxn be anabolic? (3)
- Endergonic & Synthesis Rxn
- Substrate is the Raw Material
- Bonds & larger molecules are formed
Ex: Dehydration Synthesis, Photosynthesis
What is the enzymatic reaction called when it is endothermic?
Anabolic
What makes an enzymatic reaction catabolic? (2)
- Exergonic & Breakdown Rxn
- Bonds & large molecules are broken down (into smaller building blocks)
Ex: Cellular Respiration & Hydrolysis
What is the enzymatic reaction called when it is exothermic?
Catabolic
Definition of Optimum Temperature
Temp. at which enzymes function at max. rate
(37°C)
Definition of Active Site (3)
- Site where substrate & enzyme touch
- Activates to create unstable bonds that need to be stabilized
- Enabling the catabolic & anabolic reactions
What are the three factors that determines whether the enzyme and substrate is compatible?
- Opposite Charges
- Shape
- Active Site Configuration
Definition of Induced Fit (2)
- When substrate binds to the activation site
- Enzyme slightly changes shape to fit substrate
(Like a handshake!)
Definition of Competitive Inhibition (4)
How, Competes For, Result
- Substance mimics substrate’s shape
- Competes for binding site
- Blocks substrate from binding to AS
- Decreases enzyme activity & reaction
Definition of Noncompetitive Inhibition (3)
Definition, effect
- Inhibitor binds to allosteric site
- Enzyme’s shape is changed due to induced fit
- Substrate cannot bind w/ altered activation site
Noncompetitive Inhibition Analogy
Read Through
Someone (noncompetitive inhibitor) comes along and bends the keyhole out of shape. A key (substrate) might still fit in, but it can’t turn to unlock the door (catalyze the reaction).
Definition of the ES Complex
Substrate is binded to Enzyme
What is Acidic?
PH Level & Contains
pH Level: 1 - 6.9
Contains more H+
Contains less OH -
What’s Basic?
PH Level & Contains
pH Level: 7.1- 14
Contains less H+
Contains more OH -
What’s Neutral?
PH Level & Contains
pH Level: 7
H+ = OH -
What happens to the enzyme when the temperature increases past optimum temperature and decreases past optimum temperature? (5)
Decrease, Increase, Paragraph
Decreases: Metabolic Reactions Slow Down
Increases: Enzyme Denatures, Ceasing Function
- Changed Shape = Changed Function
- In secondary structure, breaks H - Bonds
- In tertiary structure, breaks H - Bonds, Disulfide Bonds, Ionic Bonds & Hydrophobic Interactions
- In quaternary structure, breaks all bonds as shown above
- Enzyme can’t combine w/ substrate
What happens to the enzyme when the pH level increases past the optimum pH level and decreases past the the optimum pH level?
It denatures, so it will not perform its enzymatic reactions
- Changed Shape = Changed Function
- In secondary structure, breaks H - Bonds
- In tertiary structure, breaks H - Bonds, Disulfide Bonds, Ionic Bonds & Hydrophobic Interactions
- In quaternary structure, breaks all bonds as shown above
- Enzyme can’t combine w/ substrate
Why can’t the enzyme function well when it the pH level and temperature changes?
(HINT: EXPLAIN HOW SHAPE CHANGES AND HOW IT CHANGES THE FUNCTION) (5)
- Changed Shape = Changed Function
- In secondary structure, breaks H - Bonds
- In tertiary structure, breaks H - Bonds, Disulfide Bonds, Ionic Bonds & Hydrophobic Interactions
- In quaternary structure, breaks all bonds as shown above
- Enzyme can’t combine w/ substrate
How do you know where to locate the optimum temperature in a “function” graph and a “substrate concentration” graph?
Function: Peak
SC: Right before the line flattens
Definition of Substrate Concentration (5)
Definition, Result, Explain
- Fixed amount of enzyme but increasing amount of substrate
- Rxn rate increases as SC increases
- Enzyme will be saturated with substrates (more production of products)
- Fully saturated enzymes don’t need more substrates
- Rate will no longer inrease & and level off
Definition of Enzyme Concentration and Explain What Happens (3)
Definition, Result, Explain
- Fixed amount of substrate but increasing amount of enzymes
- Increases rxn rate as EC increase
- If all substrates are already binded to an enzyme, increasing enzyme won’t increase rate
What’s an analogy about why increasing substrate and enzyme concentration will not speed up the reaction if it’s already fully saturated?
Read Through
When you first add more raw goods (substrates), the machines (enzymes) can process them faster and produce more products because there’s more work to be done. However, if you keep adding raw goods but don’t increase the number of machines, the machines will eventually reach their maximum capacity.
At this point, each machine is working as fast as it can, so adding more raw goods doesn’t increase production—there aren’t enough machines to process the extra material. Similarly, if you add more machines (enzymes) but don’t have enough raw goods (substrates), some machines will sit idle, and the reaction won’t speed up.
The production rate levels off when all machines are fully occupied, and no additional raw goods or machines can increase the output without increasing the other.
Definition of Coenzymes (3)
Structure, Function
- Organic molecule attatches to an enzyme
- Required for enzyme function
- Allows Substrate to bind & necessary for rxn to occur
Definition of Cofactors (3)
- Metal Ions attatch to enzyme (non - protein helpers)
- Attach to Enzyme
- Allows Substrate to Bind & Rxn to occur
Ex: Hemoglobin allows oxygen to attach to the blood
Function of Inhibitors
Slow the rate of enzyme catalyzed reactions
Definition of Irreversible Inhibitors (3)
Definition & Result
- Forms a covalent bond at active site
- Permanently blocks the substrate
- ENDS reaction
Definition of Reversible Inhibitor (3)
Definition, Result, How to Overcome
- Forms a temporary bond at active site
- Slows reaction rate
- Effects can be overcome by increasing substrate concentration
Definition of Metabolic Pathways
Read Through
- A series of enzyme-catalyzed reactions in a cell
- Convert substrates to products
Definition of the Allosteric Enzyme (3)
- Enzyme that regulates its own activity
- By the binding of non - competitive inhibitors at the allosteric site
- Changes shape of the enzyme
(effectively allowing the enzyme to “self-regulate” in response to the cellular environment)
Enzymes that have shapes that can be altered by the binding of “signal” molecules to their surfaces
Definition of Feedback Inhibition (4)
Definition, How & Why
- End product of metabolic pathway acts as an inhibitor
- Turns the reaction on/off
- Inhibits enzyme involved in initial stages
- Maintain sbalance by preventing overproduction & waste of resources
Why does enzyme activity increase when pH increases? (4)
Read Through
- PH can change charge of the active site
- b/c AA can lose or gain H+ based on the pH
- When pH is at optimal value
- Active Site will be correctly ionized
Why does enzyme activity increase when temperature increases? (3)
- Increase in molecule speed
- Increase in molecule collisions, overcoming activation energy
- More ES complex will form
Is exergonic or endergonic reaction spontaneous? Why? (2)
- Exergonic
- No need for an input of energy, occurs naturally
Definition of Activator and Inhibitor in terms of an allosterically regulated enzyme
Activator: Turns on the reaction (still binds to the non - active site)
Inhibitor: Turns off the reaction
HOW do coenzymes and cofactors assist enzyme function? (3)
- Stabilizes 3D shape
- Maintains Active Sites
- Assists in the binding of ES
Definition of Hydrolase
Enzyme that splits molecules through usage of water
In data, how do competitive inhibitors affect chemical reactions?
Data shows it reduces the concentration of the enzyme
What’s the lock and key theory for enzymes?
Read Through
Enzyme = Lock: The enzyme has a specific active site (like a lock).
Substrate = Key: The substrate has a shape that fits perfectly into the enzyme’s active site (like a key).
