Module 2.3 Enzymes Flashcards
What is an enzyme
It is a biological catalyst
Where are biological catalyst found
In organism
What are the two types of enzyme actions
They can be
1) Intercellular
2) Extracellular
Name an intracellular enzyme and it’s function
Catalase
What does it do?
- It works inside cells to catalyse the breakdown of hydrogen peroxide.
Why does catalase need to breakdown hydrogen peroxide
They need to do it because it is toxic.
If not removed can kill cells
Give an example of an extra cellular enzyme
Amylase: secreted by salivary glands. Catalyses thé hydrolysis of starch into maltose
Trypsin- produced by pancreatic cells and secreted into small intestine catalyses the hydrolysis of peptide bonds. So turns polypeptides into smaller ones
What is the structure of enzymes
They are globular protein (water soluble)
The active site is determined by the enzymes tertiary structure
How do enzymes speed up reactions?
They lower the activation energy.
What is a catabolic enzyme
Dirty mistresses club
An enzyme is catalysing a breakdown of reaction
It can put a strain on the substrates bond
Which will break it up easier
What is an anabolic enzyme
The marriage councillor
It will reduce any repulsion between molecules by holding the substrates together so they can bond easier
Describe the lock and key model
The enzyme is complimentary to the substrate
This means the enzyme is specific
The substrate will bind to the active site
An enzyme substrate complex forms
Then an enzyme product complex forms
Describe the induced fit model
The enzyme is complimentary to the substrate
This means the enzyme is specific
The enzymes active site changes shape to accommodate the substrate
This forms an enzyme substrate complex
A reaction happens to from an enzyme product complex
Why is amylase described as being extra cellular
It works outside a cell
Suggest why the lock-and-key and induced-fit explanations are termed models
Because it a representation of how it works
Helps us visual the process
Suggest why most scientists now accept the induced-fit model rather than the lock-and-key model.
There is more evidence/ new research
Explain the term biological catalyst
1) enzymes are used in metabolism
2) lowers the activation energy
Describe how an enzyme, such as pepsin, breaks down a substrate.
- The substrate is complimentary to the shape of Pepsin
- So pepsin is specific
- Then the substrate binds to the active site of the enzyme
- This forms an enzyme substrate complex
- A reaction happens which puts strain on the bonds (forms a enzyme product complex)
- The products leave the active site
Name the covalent bond between two adjacent amino acids in a chain of amino acids.
Peptide bonds
What factors affect enzyme activity
Temperature
ph
Substrate concentration
Enzyme concentration
Describe and explain what happens to enzyme activity when temperature increases
1 Kinetic energy increases
- More vibrations happen
- Enzymes more likely to have frequent successful collisions with substrates
- More enzyme substrate complex’s can form
- After optimum ph the enzyme will denature
Why?
The increase in temperature will change the proteins tertiary structure, making the enzyme unable to work properly
How does ph affect enzyme activity
If the ph is too acidic then it can break the hydrogen and ionic bonds in the enzymes tertiary structure
Making the enzyme denature
What is Q10
how rate increases with 10 degrees
What is a competitive inhibitor
- has a similar shape to the substrate
- competes with the substrate
- if successful will block the active site
- but this depends on how much substrate there is, as if the substrate is > then it can outcompete inhibitor
Give an example of a competitive inhibitor
Antiviral or biotic drugs
penicillin catalyses the
the cell wall of bacteria
What is a non-competitive inhibitor
- binds to the allosteric site
- changes shape of active site
- substrate can no longer bind to enzyme
Give examples of non-competitive inhibitors
- Cyanide prevents respiration
- aresnick, malonate
Give examples of non-competitive inhibitors
- Cynadie prevents respiration
- aresneic, malonate
Give examples of non-competitive inhibitors
- Cynadie prevents respiration
- aresneic, malonate
What is a reversible inhibitor
they bind to the active site for a short period and then leave.
when inhibitor is removed it leaves the enzyme unaffected
What is an irreversible inhibitor
bind permanently to the enzyme molecule. Any enzyme molecules denatured if bound to
How does the mechanism of end product inhibition work
- process slowed down when substrate made binds onto alternative site of enzyme
- can reattach when product is needed
- regulates the amount of substrate
What is an apo-enzyme
inactive enzyme
What is a holo enzyme
an activated enzyme
How do we activate the apoenzyme
- through another enzyme
- through conditions like pH, temp
- through co factors
What is a cofactor
- inorganic (na+, cl-)
- temporary bound to enzyme
eg chloride ions in amaylse
What is a cofactor
- inorganic (na+, cl-)
- temporary bound to enzyme
eg chloride ions in amaylse
What is coenzyme
- temporarily bound
- organic cofactors made from vitamins
- constantly recycled
- act as carriers
examples Nad required for alcohol dehydrogenase
What is a prothetic group
- Permenantly bound to enzyme
- Example is Fe2+ , zinc ions in carbonic anhydrase
