1.4 Enzymes Flashcards
(25 cards)
What does the term metabolism refer to?
To all reactions of the body.
What does anabolic mean?
Building up molecules.
What does catabolic mean?
Breaking molecules down.
Metabolic pathways are controlled by what?
Enzymes.
Enzymes are what proteins that have a what structure?
Enzymes are globular proteins that have a tertiary structure.
What is an enzyme that can act inside the cell?
Intracellular enzymes.
What is an enzyme that can act outside the cell?
Extracellular enzymes.
The 3D shape of an enzyme creates what?
An active site.
What is an active site?
A 3D space in the molecule into which specific substrate molecule(s) can fit and bind.
The specific shape of the active shape is determined by what?
The sequence of amino acids in the polypeptide.
If the sequence of amino acids changes, what happens to the active site?
The active site will change shape and the substrate will not bind to the active site because they are no longer complementary.
What are the functions of enzymes?
- Speed up reactions
- They are not used up
- They are not changed.
- They have a high turn over number
What is formed when an enzyme and a substrate collide successfully?
An enzyme-substrate complex.
The ability of the R groups and the substrate to form bonds is affected by?
Temperature and pH.
Why do temperature and pH affect ability of the R groups and the substrate to form bonds
Bonds in the substrate are distorted, which puts strain on the bonds that are going to be broken and increase the chance that they will break.
What is the energy needed for the reaction to take place called?
Activation energy.
What happens to activation energy when an enzyme-substrate reaction forms?
It is reduced (the reaction takes place faster).
Each enzyme is specific to a particular what?
Substrate. This means that even if substrates undergo the same reaction, different enzymes are needed to carry out the same function.
What are the two enzyme theories?
Lock and key hypothesis and Induced fit hypothesis
What is the lock and key hypothesis?
The active site in the enzyme is like a lock into which only one substrate molecule can fit like a key.
What does the lock and key hypothesis think of the active site?
It is a fixed shape so a substrate has to collide in the correct orientation with the active site in order that bonds can form and produce an enzyme-substrate complex.
What is the induced fit hypothesis?
That the active site changes shape based off of the forces of attraction between the substrate and the R groups/polar atoms of the amino acids.
What does the inducted fit hypothesis think of the active site?
The shape of the active site to changes and stronger bonds are then
formed with the substrate. This weakens/strains the bonds in the substrate, which lowers the activation energy of the reaction. When the products are released from the substrate, the active site returns to its original shape.
Where has the induced fit been shown to occur?
In the enzyme lysozyme.
