Lecture 4 Energy and Enzymes Flashcards
What do aspartic and glutamic acid contain on their side chains?
Carboxylic acids (ionised at pH 7) Has a negative charge
What do lysine and arginine have in common?
Fully protonated at pH 7, therefore positively charged
Where is energy stored?
In chemical bonds
Why can’t cells deprive benefits from heat energy?
Because it is not directly linked to processes that maintain order in the cell
Second law of thermodynamics
The universal tendency for things to become disordered. Energy is required to maintain ‘order’ or to reverse the shift towards greater entropy
Describe Gibbs Free Energy
A chemical reaction can only proceed if it results in a net overall increase in the disorder of the universe.
Disorder increases when useful energy that could be harnessed to do work is dissipated as heat
What does an energetically favourable reaction have?
A negative delta G
What does delta mean?
Delta means ‘change in’
Why do we need to reach activation energy?
The reaction can only occur when activation energy is reached.
The rate of the reaction is also increased. Heat can be supplied to increase the number of molecules that reach the activation energy
Why does the chemical reaction go one way but not the other?
Chemical reactions proceed in the direction that causes loss of free energy. Most of the chemical energy stored in bonds is lost as heat which released G
What is the role of an enzyme?
Reduces the required activation energy for a chemical reaction thereby accelerating the rate of the reaction.
Cannot alter the direction or the equilibrium of a reaction
How does concentration of molecules impact the rate of reaction?
Y -> X
As the concentration of X increases the concentration of Y decreases therefore the rate of reaction is slower.
Unless more Y is added then the reaction will eventually slow and stop
What do energetically unfavourable reactions have?
A positive delta G, because it creates order. Occurs as a second reaction with a negative delta G.
Where do substrates bind on an enzyme?
The active site
What does the enzyme react on during the reaction?
The substrates
