TOPIC 1: INTRODUCTION Flashcards
All organisms, whether single cells or multicellular need to:
o Obtain energy
o Make proteins
o Regulate the exchange of materials
o Duplicate their hereditary material and reproduce
Catabolic pathway
where complex molecules are broken down into simple molecules
Anabolic pathway
where simple molecules are used to build larger more complex molecules
Activation energy
is the amount of energy required to bring all of the molecules in 1 mole of substrate to the transition state
To increase rate of reaction, we either need to:
- Add more energy to the system
- Decrease AG‡
We use a catalyst to do what
Decrease AG‡
Enzymes enhance the reaction rate by
lowering the activation energy - very efficient catalysts
Prior to the reaction occuring what is formed?
an enzyme-substrate complex
substrate binds to a specific region of the enzyme called the
active site
enzyme binding to active site is described as_______ as therefore occurs by relatively _______ chemical bonding such as:
transient
weak
Van der Waal’s forces
Hydrogen bonds
Electrostatic bonds
For many enzymes rate of reaction (u) varies with
substrate concentration ([S])
The Michaelis-Menten model was first derived in
1913
Michaelis-Menten model requires the existence of an _____ as an intermediate
ES complex
What is Km value
o Km is the substrate concentration at which the reaction rate is half maximum (Vmax)
The smaller the Km, the greater or lesser the affinity the enzyme has for its substrate
greater
Enzyme activity is regulated in many ways:
- Enzyme production
- Compartmentalization
- Post-translational modification
- Environment
- Activation and inhibition
Most enzymes follow what kind of curve
hyperbolic
Enzymes can be regulated by
substrate molecules and non-substrate (allosteric) molecules
substrate molecules are associated with
homotropic interaction
homotropic interaction
- At low [S], when one substrate molecule binds to the enzyme, it makes it easier for the next to bind
allosteric enzymes are
oligomeric
non-substrate (allosteric) molecules are associated with
heterotropic interaction
heterotropic interaction
- Regulation of an enzyme by the binding of an effector molecule at the protein’s allosteric site
Positive allosteric effectors (activators)
enhance enzyme activity
Negative allosteric effectors (inhibitors)
decrease enzyme activity
allosteric regulation is very important in
feedback systems
Major parts of the enzyme curve: transition site
