T12-WHAT IS THE CURRENCY OF ENERGY/ATP

Question 1

ATP

Answer 1

adenosine triphosphate
- adenine - nucleotide
- ribose sugar
- adenine and ribose = adenosine
- 3 phosphate groups

Question 2

phosphate high energy bonds

Answer 2

the bonds between the phosphate groups have very high energy as the electrons are at a high energy state
- when broken, the electrons will return to a lower energy state to become more stable (exergonic) and this will release lots of energy

Question 3

ATP hydroylsis

Answer 3

ATP + H2O –> ADP + PI + ENERGY
it is an exergonic reaction so happens spontaneously however, has a high activation energy which requires ATPase
- energy is required for water to nucleophilicly attack the phosphate group due to electron repulsion

Question 4

activation energy in ATP hydroylsis

Answer 4

this prevents the spontaneous high energetically favoured breakdown of atp to occur all the time
- allowing for energy to be stored and controlled release

Question 5

ATPASE

Answer 5

an enzyme that surrounds that ATP with positive magnesium ions to lower the electron repulsion so that water can attack, therefore, lowering the activation energy

Question 6

reaction coupling

Answer 6

exergonic and endergonic reactions become coupled so that the exergonic can drive the endergonic
- phosprhylating compounds is one way

Question 7

phosphorylating glucose compounds

Answer 7

glucose + po42- –> glucose -6-phosphate
makes it harder for glucose to leave cell due to the neg charger

however, this is an endergonic reaction, so need ATP hydroylsis to allow this reaction to occur

ATP + H2O –> ADP + PO42-

coupling together =
ATP + Glucose –> Glucose -6-phosphate + ADP using the enzyme hexokinase

Question 8

enzymes

Answer 8

act as a biological catalyst to lower activation energy which increases rate of reaction
- have a specific 3ry structure complementary to a specific substrate- binding to the active site via induced fit

Question 9

enzyme inhibitors

Answer 9

competitive inhibitors
- they have a similar shape to substrate and bind to the active site to block and prevent enzyme sub-complex forming, decreasing the rate of reaction
- however, increasing the sub conc increases the rate of reaction

non-competitive
- binds to the allosteric site of enzymes
- this changes the active site permanently so it no longer comp to the sub, no e/s complex forms,
- increase sub conc does nothing

Question 10

michaelis - menten constant KM

Answer 10

for enzymes, 2 constants characterize the dynamics
- the substrate conc at which the rate of production is half of max (km)

maximum rate of production formation (Vm)