Enzymes Flashcards
What is a chemical reaction?
Converting substrate into product
by breaking old bonds
forming new ones
What is activation energy?
Energy required to be put into the substrate in order to start it off
What is the transition state?
Point of maximum energy
have intermediate between substrate and product
How can the rate of a reaction be increased?
Increase temperature
Increase concentration
How does increasing temperature increase rate of reaction?
Molecules have more energy
more molecules with activation energy
How does increasing concentration increase rate of reaction?
More collisions between molecules
What are enzymes?
Biological catalysts
What do catalysts do?
Increase the rate of reaction
How do enzymes increase the rate of reaction?
Lower activation energy
Facilitate formation of transition state
How do enzymes lower the activation energy of chemical reactions?
Bring substrate molecules closer to each other
more likely to collide
Weaken the bonds in substrates
so less energy is required to break them
What is the active site of an enzyme?
Point where substrate binds
where the chemical reaction occurs
How much space of the enzyme does the active site take up?
Small amount
What is the function of the rest of the enzyme, other than the active site?
Act as a scaffold to form the active site
How are the amino acids that form the active site related to each other?
Active site is formed by amino acids at different points in the primary sequence
they come together by folding of the protein
What structure do most active sites form? Why?
Form clefts or crevices
to exclude water
How does the active site relate to the subtrate?
Active site has complementary shape to substrate
What is the lock and key hypothesis?
Substrate has completely complementary shape to active site
substrate fits into active site perfectly
What is the induced fit hypothesis?
Substrate has somewhat complementary shape to active site
binding of substrate to active site induces conformational change in active site
so that they fit together properly
How do substrates bind to active sites of enzymes? Why?
By multiple non-covalent bonds
binding must be weak
What are some examples of bonds that form between the substrate and active site?
Hydrogen bonds
Van der waals
Hydrophobic interactions
What shape would a graph of y axis-product against x axis-time look like? Describe the shape
Rectangular hyperbola
- steep
- flatter
- completely flat
What does the gradient of a graph of y axis-product against x axis-time measure?
Measures the rate of reaction
Why does a graph of y axis-product against x axis-time take a hyperbolic shape?
Initially, lots of substrate molecules so have high rate of reaction
Then fewer substrate molecules, reduced rate of reaction
Then no substrate molecules, reaction stops
Why does more substrate molecules means an increased rate of reaction?
More likely to collide with each other
form more product
