Enzymes Flashcards
What do enzymes do?
They are biological catalysts that reduce the activation energy needed to start a reaction
Stages of reactions using enzymes
Substrate fits into a specific enzyme’s active site forming an enzyme-substrate complex.
They have complementary shapes.
Once reaction is complete there is a enzyme-product complex
The products are released
Enzyme is unchanged
What is the lock and key hypothesis?
Substrate fits into the enzyme. It is precisely the correct shape to fit into the active site
What is the induced fit hypothesis?
As the substrate binds to the active site, the active site changes shape slightly to fit the substrate more closely.
What are the 2 categories of enzyme?
Intracellular
Extracellular
Describe intracellular enzymes
Work inside the cell
For example, the enzymes in lysosomes
Describe extracellular enzymes
Work outside the cell
For example, in digestion the enzymes in the stomach (doesn’t happen in the cells)
And
fungal hyphae (fruit becoming furry)
How enzymes break things up
Strain the bonds between them
How enzymes help join things together
Hold reactants together in correct orientation to help make the bonds.
What are inhibitors?
Substances that affect enzymes.
Slow down the rate of enzyme-controlled reactions.
What are competitive inhibitors?
They are complementary to the enzymes active site.
Competitive because both the CI and the substrate can fit into the active site (they have SIMILAR shapes)
How do competitive inhibitors work?
CI blocks active site so enzyme-substrate complex can’t be formed, reducing the rate of reaction
Can you overcome competitive inhibitors?
Yes, by increasing substrate concentration.
Increases the chance of the substrate binding with the active site before the CI.
It is REVERSIBLE
How do non competitive inhibitors work?
Bind to Allosteric site, this changed the shape of the enzymes active site so an enzyme substrate complex can’t be formed, reducing the rate of reaction.
Substrate and NCI have different shapes.
Is it possible to overcome non competitive inhibitors?
No, enzyme is permanently changed so substrates, no matter how many there are, can bind to the active site.
It is IRREVERSIBLE.
What is the equation for the temperature coefficient?
Rate of reaction at T+10 degrees celsius
Rate of reaction at T degrees celsius`
What is the normal temperature coefficient for enzyme reactions?
2
`What are cofactors?
An inorganic ion that increases the activity of an enzyme
What is a coenzyme?
Organic molecule required for enzyme function
What is a prosthetic group?
Permanently bound to the enzyme, required for enzyme function.
What is product inhibition?
When the product made from an enzyme controlled reaction acts as an inhibitor
Can be good - stop too much being made - waste
What is the product, substrate and cofactor of amylase?
Glucose/maltose
Starch
Calcium ions
When enzymes build larger molecules from smaller ones what is it called?
An anabolic enzymatic reaction
How effective is the Software that predicts the 3D shape of a protein based on it’s amino acid sequence is at discovering the function of the enzyme
Tertiary structure determines shape of active site which relates to the function.
Protein folding is highly complex and there can be multiple solutions.
Therefore, function can be narrowed down but not fully predicted.
What is a common source of coenzymes for humans?
Vitamins
Similarity between cofactors and prosthetic groups?
Both bind to an enzyme to make formation of the enzyme substrate complex easier
Difference between cofactor and prosthetic groups?
Prosthetic groups are permanently attached to the enzyme while cofactors can move or attach to the substrate
