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?
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