Lecture 2

Question 1

Increasing work

Answer 1

By exercising. The [ADP] increases as we use ATP immediately which increases [ADP substrate] available for ATP synthase to generate more ATP. ATP synthase rotates, allowing more H+ to enter the mitochondrial matrix. At the proton pumps, the conc. gradient of H+ intercellarly decreases so, more H+/e- can flow down the ETC quickly and easily. NADH and FADH2 can remove their H+ more easily and frequently. They can go back and carry more electrons quickly and easily.

Question 2

Coupling

Answer 2

Link between the quantities. As ATP stores are very low, it must be generates as it’s being used. The rate of ATP synthesis exactly matched to rate of ATP use.

Question 3

Gentle exercise

Answer 3

Need to elevate rate of ATP generation. More ADP available. Everything speeds up. We use glucose as fuel.

Question 4

Fuel switch

Answer 4

Once BGL lower, hormonal response shifts from glycolysis to B oxidation.

Question 5

Excessive ac-CoA

Answer 5

If there’s sufficient FA, there’ll be excessive ac-CoA for Kreb’s. [ac-CoA]. increases enough to inhibit PDH from converting pyruvate to ac-CoA

Question 6

Gentle exercise steps

Answer 6

1. Glucose is used
2. After several mins, fatty acids take over (released from white adipose tissue)
3. Glucose still gets into muscle as lactate
4. Gluconeogenesis

Question 7

Moderate exercise

Answer 7

Rate of fatty acid utilisation increases but, the enzymes that catalyse fatty acid oxidation. Soon reach their capacity so, fatty acid oxidation alone cannot maintain ATP production and the inhibition on glucose oxidation is removed. Glucose oxidation occurs and liver glycogen stores deplete. Excess ac-CoA used too.

Question 8

strenuous exercise

Answer 8

Now limits on speed of oxidation of blood glucose. Rate of supply and transport from blood can’t keep up. Fatty acid is still going as fast as they can. So, muscle glycogen now broken down. Endogenously stored

Question 9

Very-strenuous exercise

Answer 9

Now, rate of ATP production can’t be met up by oxidative phosphorylation alone. Mitochondrial process too slow. Need to top up with extra boost from glycolysis which is fast but inefficient. Blood lactose rises and an extra 2 ATP molecules used.

Question 10

Importance of glycogen

Answer 10

When glycogen runs out, metabolism slows to what B-O2 can supply what the mitochondria can process.

Question 11

Sprinting

Answer 11

Muscle fibres T2 use ATP quickly. Creatine phosphate then anaerobic glycolysis. Lots of lactate produced and poor blood supply to take it away.

Question 12

Buying time

Answer 12

Takes several seconds to get glycogenolysis going. Creatine phosphate is instant store of ATP. Only have 5 seconds worth of energy.

Creatine phosphate + ADP -> ATP + creatine