6.4: Enzymes speed up metabolic reactions by lowering energy barriers

Question 1

Why may a spontaneous reaction never happen?

Answer 1

A spontaneous reaction may never happen because of how slow the process will be, this is why an enzyme is needed

Question 2

enzyme

Answer 2

a macromolecule that acts as a catalyst(mainly proteins here)

Question 3

catalyst

Answer 3

a chemical agent that speeds up a reaction without being consumed by the reaction

Question 4

What must a reactant molecule do in order to make new bonds

Answer 4

in order for a reactant molecule to make new bonds, it must first contort to a highly unstable state which is obtained through the reactant molecule absorbing energy from their surroundings

Question 5

How does a molecule go back to its new stable state?

Answer 5

the molecule goes back to its original form by releasing its energy through heat

Question 6

activation energy(EA)

Answer 6

the energy required to contort the reactant molecules so the bonds can break/change , the energy needed to push the reactant uphill(top of energy barrier) so that the downhill part can happen

Question 7

transition state

Answer 7

the unstable state of a reactant after it had absorbed the surrounding thermal energy to get past the uphill and be able to break bonds

Question 8

How does heat impact Enzymes reaction speed ?

Answer 8

heat can speed up reactions but it can also denature proteins and kill cells

Question 9

catalysis

Answer 9

is used instead of heat, a catalyst/enzyme selectively(due to shape) speeding up a reaction, Enzymes Only changes the rate by lowering the activation energy needed(the barrier) so the reaction can happen better

Question 10

substrate

Answer 10

the reactant and enzyme acts on

Question 11

enzyme-substrate complex

Answer 11

when an enzyme binds to a substrate, soon forms a product(s)

Question 12

active site

Answer 12

where only a certain area of the enzyme actually binds to the substrate

Question 13

How often does the substrate attach to the enzyme

Answer 13

the enzyme is constantly changing shapes and only attaches to the substrate when the shape is right

Question 14

induced fit

Answer 14

when the enzyme tightens around the bonded molecule

Question 15

What holds the substrate to the active site ?

Answer 15

The substrate is held by the active site through weak interactions like hydrogen bonds and ionic bonds

Question 16

enzyme mechanism

Answer 16

1. enzyme changes to fit the reactant when they first attach

2. then the enzyme dissociates from reactants and restores shape

Question 17

mechanisms for lowering FA

Answer 17

• enzymes template a way to react between 2 or more reactants
• distorting the substrate’s bonds makes EA need lower since the bonds are now easier to break
• the active site makes a sub environment for a certain reaction that is more conducive for that reaction, low pH for H+ transfer.
• amino acids in the activity site can covalently bond to the substrate and the side chain of an amino acid of the enzyme

Question 18

How is efficiency of an enzyme impacted?

Answer 18

the efficiency of an enzyme is affected by environmental factors, such as temperature and pH, also affected by chemicals that influence enzymes which can also be used to our advantage(inhibitors)

Question 19

optimal conditions(enzymes)

Answer 19

the right conditions for a certain enzyme

Question 20

How does heat impact the efficiency of an enzyme ?

Answer 20

heat can increase the rate of collisions of substrates since molecules speed up, thermal energy can however agitate hydrogen bonds and ionic bonds that stabilize the shape of the enzyme

Question 21

optimal temp for humans

Answer 21

35-40C(each enzyme has an optimal pH as well)

Question 22

cofactors

Answer 22

personal nonprotein helpers for enzymes are inorganic(metals)

Question 23

coenzyme

Answer 23

organic cofactor, vitamins, reaction will not happen without this if the enzyme requires coenzyme

Question 24

competitive inhibitors

Answer 24

these inhibitors take the active site of the enzyme before the substrate, reversible and bond or not permanent

Question 25

noncompetitive inhibitors

Answer 25

binds to a nonactive site region of the enzyme and changes the shape of the protein, nonreversible