Chapter 6 Flashcards
What is an enzyme? What do they do and how do they work?
A biomolecule, most are proteins, although evidence indicates some enzymes are actually RNA molecules.
Enzymes lower activation energy of reactions.
3-D shape of enzymes allow them to stabilize a temporary association between substrates.
If you place table sugar (sucrose) into water, what happens? if you then add sucrose to the sugar water, how will this change the reaction?
The water and sucrose will not break into glucose and fructose because it does not have enough activation energy.
Adding sucrose will speed up the break down of carbs/starches (sugar) from polymers into monomers.
What is meant by activation energy (Ea) What do enzymes do to the Ea of a reaction?
Extra energy needed to de-stabilize existing chemical bonds to lower activation energy needed to initiate reactions.
Enzymes lower the activation energy of the reaction.
What is meant by the Delta-G of a reaction? Imagine the Delta-G of a chemical reaction is -40kcal/mol. if you add the appropriate enzyme to the chemical reaction, what will happen to the Delta-G (increase, decrease, or no change)?
The difference between the energy available to do work at the beginning and the end of a reaction.
Reactants have more energy than the products when delta-G is positive. Energy is released, you do not need to add an enzyme the reaction will proceed on its own.
Adding enzyme would speed up the reverse reaction where Delta-G is negative, but have no effect when Delta-G is positive.
Describe the factors that can alter enzyme activity
Temperature Hyrophobic/Hydrophillic environments Cofactors (elements like zinc, magnesium, organic molecules) pH Salt
What is the difference between competitive inhibition and noncompetitive inhibition?
Competitive - binds at active site, competing with substrate for the same active site, occupying active site prevents the substrate from binding
Noncompetitive- binds away from the active site, makes active site less effective; changes the shape of the active site, making it unable to bind to the substrate - most bind to an allosteric site.
Statins are a type of drug. You might know someone who takes a type of statin for the treatment of cardiovascular disease. Look up information on statins and describe their mechanism of action (hint: what enzyme do they target and why?)
Statins - medicine used to lower blood cholesterol levels
Drugs are able to block the action of a chemical in the liver that is necessary for making cholesterol
-inhibit an enzyme (HMG-CoA reductase) which controls cholesterol production in the liver, decreases cholesterol production and body responds by increasing production of LDL receptors.
What is an activated Carrier?
A molecule that can store energy for easy release (cofactor)
Non-protein chemical compound that is bound to a protein and is required for the proteins biological activity
“helper molecules” that assist in biochemical transformations
How does the structure of ATP allow it to store energy?
Electron configuration - 3 phosphate groups have a total of 4 negative charges in a small area that repel each other making potential energy of the molecule very high.
ATP undergoes hydrolysis - ADP + P are stabilized because electrons are distributed between them.
The H+ from H2O surrounds the phosphate to reduce the charge. ATP Hydrolysis is exergonic and can do work on its surroundings. Uses free energy to phosphorylate (add phosphates to) molecules.
Look up 5 examples of how ATP is used in a cell.
Transport work - moving substances across cell membranes
Mechanical work - supplying the energy needed for muscle movements
Chemical work - supplying the needed energy to synthesize the multi-thousands of types of macromolecules that the cell needs to exsist
On/Off switch to control chemical reactions and send messages
Bond to one part of a protein molecule
Supplies energy to the heart muscle
