Topic 2: Enzyme theory Flashcards
Enzymes speed up _________ __________.
Without enzymes the reactions in the body (or other organisms) would take place too slowly at _____ __________ to keep us alive.
chemical reactions
body temperature
Key Summary: List the 5 properties of an enzyme
- A GLOBULAR PROTEIN, so has tertiary structure
- A BIOLOGICAL CATALYST – {speeds up the rate of a chemical reaction/reduces activation energy/not used up in the reaction/made by cells}
- Show SPECIFICITY for a particular substrate due to the SPECIFIC SHAPE OF THEIR ACTIVE SITE WHICH FITS THE COMPLEMENTARY SHAPE OF THE SUBSTRATE
- Works at a SPECIFIC TEMPERATURE AND pH level
- SOLUBLE IN WATER - due to hydrophilic amino acid R groups on the outside
Key Summary: Define Biological catalyst
4 points
- Molecule produced by {organisms/cells}
- that speeds up the rate of reactions
- by reducing the activation energy.
- It is not used up or destroyed in the reaction.
Key Summary:
Define Activation energy (1 point)
Activation energy is reduced by ________
by… (1 point)
- Energy needed for a reaction to occur
enzymes
- By causing bonds to BREAK, WEAKEN, or FORM.
Enzymes ______ the ACTIVATION energy for a reaction, allowing the reaction to take place.
reduce
How does an enzyme lower the activation energy in a JOINING reaction?
(2 points)
- the active site will hold the substrate molecules together overcoming any repulsion or allowing specific electrically charged groups in the substrates to interact
- so bonds can form more easily
How does an enzyme lower the activation energy in a BREAKING reaction?
(2 points)
- the way the substrate fits into the active site may put strain on some bonds
- so substrate distorted and bonds can be broken more easily
______ _____ can have acidic amino acids which provide an ________ environment or basic amino acids which form an ________ environment – each of these may be favourable for a specific _______.
Active sites
acidic
alkaline
reaction
Key Summary: Describe the 3D structure of an enzyme
4 points
- It is a GLOBULAR PROTEIN (in a question, can then describe the molecular structure of a globular protein)
- Bonds eg. ionic, disulphide, hydrogen, between R groups
- Hydrophobic and hydrophilic interactions – hydrophilic amino acids on the outside, hydrophobic inside
- Has an ACTIVE SITE with a SPECIFIC SHAPE to fit the substrate
Enzymes are large molecules made up of hundreds of ______ ______.
Most of the _______ ______ maintain the ______ structure of the enzyme (bonds form between _ groups). The specific 3D shape allows the enzyme to work, as it makes sure the active site is the right shape – _____________ to the shape of the substrate.
amino acids
amino acids
tertiary
R
complementary
Define active site
2 points
- the region where the SUBSTRATE BINDS which has a COMPLEMENTARY SHAPE to the substrate,
- and where the reaction takes place
Usually less than __ amino acids form the active site.
10
Enzymes are involved in ________ _______ which change one substance into another.
chemical reactions
Name the 2 theories of how the enzyme and substrate bind
- The lock and key theory
2. The induced fit theory
Explain the lock and key theory
3 points
- the substrate fits into the active site of the enzyme,
- they bind together and form the enzyme substrate complex.
- The shape of the enzyme fits the shape of the substrate EXACTLY (like a lock and key)
