BLOCK 1 lecture 1

ATP and energy balance

Most of your energy output is unrelated to the amount of exercise you are doing

major metabolic pathways and hormones

overview of glycolysis

 

Glucose-6-phospate is widely considered to be the start of glycolysis because glucose is usually phosphorylated when it enters the cell

• Helps compartmentalise the glucose so it cant move into and out of cells

Glycolysis = transformation to pyruvate

Anaerobic - does not require oxygen

Produces some ATP, some NADH and consumes some ATP

Consume 2 ATP and produce 4 so net production of 2 ATP

But also produce 2 NADH at the same time

overview of the CAC

This is also a non-aerobic process as it does not directly require oxygen itself

Pyruvate (cytosol) to acetyl coA (mitochondria)

Produces more NADH and CO2

Acetyl CoA can also come from lots of other sources

Can be used to make fatty acids or ketone bodies or can be oxidised

It is a process of oxidation (CAC) although does not involve oxygen itself:

Acetyl CoA is fused with oxyloacetate to make citrate which then goes through a number of changes

• Rearrangements

• Addition of water across double bonds

• Produces CO2

• Production of reducing equivalents

• FADH

• More substrate level phosphorylation (GDP->GTP in humans)

And end up with the same thing that we started with - oxyloacetate

Circular nature is important because you cannot have a branchign system in which the intermediates are also used for other purposes as you see in linear pathways - reducing intermediates reduces efficacy

proton pumping in the ETC

Proton gradients are fundamental to the way the mitochondria works and therefore are fundamental to the aerobic metabolism

Note that glycolysis and CAC don’t use oxygen itself but produce reducing equivalents

• Limited supply

• Most goes into proton pumping in the electron transport chain

CO2 from CAC and pyruvate dehydrogenase

Water is made in this procress

Electron flow through complexes is associated with the flow of protons from the matrix into the membrane space - ATP produced through ATP synthase when this happens

coupling of ATP synthesis and oxygen consumption

ADP has to be bound for this enzyme to work

Alows formation of ATP

Protons flow through the rotor

Process is linked back to ADP

Decrease in proton motor force stimulates ETC to transport more protons because the ETC is sensitive to proton motor force

It can also slow down when there is a large gradient/force

Converting more NADH to NAD also stimulates the CAC

mitochondrial uncouplers

Most of our energy is used to maintain our body temperature

Uses uncoupling

Women making explosives would get hyperthermia because of the uncouplers in these

beta-oxidation

semi-cyclic pathway

Removing 2 carbons at a time from a fatty acyl coA molecule

Each time the cycle goes rounf is produces an acetyl Coa and shorten the fatty acid

Also involves NADH

Final step get to a 4 carbon fatty acid and generate 2 acetyl coA

16 carbon molecule requires 7 turns of this pathway (because last step produces 2)

beta-oxidation overall reactions

amino acids as fuels

 

Amino acids are eventually broken down and will be converted into either acetyl coA or pyruvate

Each group of amino acids has its own degradation pathway

And some can make multiple - go through multiple steps and pathways

what can be done with pyruvate

Can use the pentose phosphate pathways which is similar to glyolysis but do it in places like red blood cells which don’t have any mitochondria

Also when exercise means needs are too high for aerobic metabolism

Prodiuces lactate

Anaerobic organisms also use this 

Also used in yeast to make ethanol and carbon dioxide (anaerobically)

• Alcohol and bread