Chapter10 Flashcards
(31 cards)
What is a chemical reaction?
A process that either forms or breaks chemical bonds that hold atoms together
What do all chemical reactions need/do?
They either require an input of energy or release energy
What is an exergonic reaction
A reaction that releases energy , reactants contain more energy than the products
What is a endergonic reaction?
A reaction that requires an input of energy , meaning the products contain more energy than the reactants
What do all chemical reactions need?
An initial investment of energy
What is activation energy ?
The amount of initial energy that is required in order for the reactant molecules to contort so bonds can break
Where does Ea from come from?
-often supplied in the form of heat that reactants absorb from the envirnoment
-heat causes the reactants to move more quickly so they collide more
-collisions also make the bonds more ready to break
-once enough energy is absorbed so that bonds can break EA has been met
What happens when Ea is low
Can proceed at room temp in a short time
What happens when the EA is very high
At very high levels of EA and at room temp the reaction may proceed at a unnoticeable rate
What would happen if tractions were to proceed at reasonable rates?
One reaction would have to increase the proportion of molecules that have enough energy to
How can reactions increase the proportion of molecules that have enough energy
1)heating
The problem with heating
I) in living systems ,heat can kill cells
ii)would not be specific >all chemical reactions would speed up
2) decreasing the EA
By doing so one will ensure that a greater proportion of molecules will collide in order for the reaction to occur
iii) the EA can be decreased by the use of a catalyst
What is a catalyst in a biological system?
An enzyme which is a protein
Do enzymes change the reaction in any way?
Enzymes do not change the reaction they just speed up the reaction , they enable the reactant molecules to absorbs enough energy to reach the transition state even at mod temps
What is the effect of enzymes on rate of reaction?
They lower the EA , less collisions need to occur for transition state to reach
What is a substrate ?
The reactant an enzyme acts on
How are enzymes and substrates related?
Enzymes bonds to the substrate forming an enzyme substrate complex
What is the active site?
The region on the enzyme where the substrate binds
What is an induced fit?
The shape of the enzyme changes slightly when the substrate enters and this is due to the interactions that happen between the chemical groups of the substrate and amino acids that make up the active site
How does an enzyme lower the EA ?
-The active site can lower the barrier by orienting the substrates correctly to help the reaction occur
-straining substrate bonds
-Providing the micro environment that is favourable for reactions to occur
May participate directly in the chemical rxn
How can an enzymes activity be affected ?
By the general environmental factors
What do each enzymes need in order to function?
They have an optimal temperature where it functions
Has an optimal pH which it can function in
What happens if an enzymes environment changes
The protein becomes denatured, biologically inactive
What do many enzymes require ?
They require cofactors which are non protein chemical compounds that are required for an enzymes to act as a catalyst
What are examples of inorganic cofactors
Metal atoms such as zinc, copper and iron , these bind allosterically to enzymes and changes the structure and chemical potential of active site
