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What is the overall yield from Glycolysis?

2 x Pyruvate

2 x ATP

2 x NADH


Explain the basic process of glycolysis

Glucose is activated so that it can be metabolised

- This requires 2xATP and the enzyme PFK-1


Fructose-1,6-biphosphate is split into two 3C molecules, of which Triose Phosphate Isomerase converts one to the other


Glyceraldehyde-3-phosphate is then converted to pyruvate

- This occurs twice, due to 2xglyceraldehyde-3-phosphate being formed from each glucose molecule


What is the purpose of anaerobic respiration?

Pyruvate --> R-Lactate


This oxidises NADH --> NAD+, which can then be used in glycolysis


What is the process used to convert pyruvate to glucose


And what is the enzyme used to reverse anaerobic respiration?



Lactate dehydrogenase converts D-Lactate to pyruvate


What is needed to form Oxaloacetate in gluconeogenesis? And where does this occur in the cell?


And how many ATP/NADH is needed in this whole process?

Pyruvate - ATP - CO2      --> In the mitochondria


2 x ATP and 1 x NADH


Explain how glucagon can determine whether glycolysis or gluconeogenesis occurs more frequantly?

Glucagon is secreted when blood glucose is low

This inhibits the production of fructose-2,6-biphosphate


This promotes gluconeogensis to occur more frequently


Where in the mitochrondria are the enzymes needed for the TCA cycle kept?

The matrix


What are the products of the TCA cycle?

2 x CO2

3 x NADH and H+

1 x FADH2

1 x GTP


Citrate is formed from the combination of the end products (oxaloacetate and Acetyl-CoA)


What happens when there is a depletion in oxaloacetate (due to biological reactions occuring) and an accumulation of Acetyl-CoA?

The build up of Acetyl-CoA casues a decrease in pyruvate dehydrogeanse (which is used to create Acetyl-CoA)


It also causes an increased activity in Pyruvate Carboxylase (which is used to form Oxaloacetate)


So the levels of each are balanced out --> which is important for Citrate production


Explain how Oxidative Phosphorylation / Chemi-osmosis works?


Also what is the yield of ATP from this process?

Takes place in the inner mitochondrial membrane


Protons are taken up by proteins in the membrane (via NADH and FADH2), and then pumped into the intermembrane space, creating a proton gradient

The energy for this process is formed by the movement of electrons through the proteins


Protons then move down their concentration gradient to create a conformational change in ATP-synthase --> causing it to release a molecule of ATP


This allows a new ADP + Pi to bind to the enzyme --> creating more ATP


26-30 ATP is created in this process


What is the precursor molecule for glycogen?



Explain what occurs in 1,4 glycosydic bond formation and degradation



UDP leaves, forming a oxycation which can then bind with another molecule of glycogen (via its anomeric carbon)




This is done by the enzyme Glycogen Phosphorylase (which is increased by the prescence of glycogen)


How are the 1-6 glycosydic bonds degraded?

Glycerol Transferase moves 3,  1,4 bond residues


How is glycogen metabolism regulated?

Glucagon binds to its receptors --> increasing cAMP/PKA


This inhibits glycogen synthase --> allowing more glucose to be formed


Insulin does the opposite


How are fats stored and broken down?

Stored - In adopise tissue as triglycerides


Lipases are activated by glucagon and adrenaline (via PKA)


Where are fatty acids degraded?

Mitochrondria (cytosol) - Degrades straight chain fatty acids --> Acetyl CoA (forming ATP)


Perioxisomes - Unusual fatty acids are removed


How many ATP is formed during one cycle of Beta-Oxidation?



Explain the process of Fatty Acid Biosynthesis

Carboxybiotin and Acetyl-CoA --> Malonyl CoA (using Acetyl-CoA Carboxylase)


Acetyl CoA and Malonyl CoA are then transfered to an Acyl Carrier Protein (ACP)


Each cycle adds a saturated C2 unit


What is the importance of Malonyl-CoA?

High levels = Fatty acid biosynthesis

It also inhibits the transport of fatty acids into the mitochondria for degradation


What is ketogenesis?

When very low levels of glucose are present...


Fatty acids --> Acetyl CoA --> Ketone Bodies (Acetoacetate/3-hydroxybutyrate)


Ketone bodies are water soluble and can be transported around the body --> They can also be converted to propanone (acetone)


What is the equation for calculating the number of ATP produced from beta oxidation?

(Number of carbons/2) -1 = X


((X x 4) + (Number of carbons/2 x 10) -2) = ATP produced