Lloyds Respiration

Question 1

What is the overall yield from Glycolysis?

Answer 1

2 x Pyruvate

2 x ATP

2 x NADH

Question 2

Explain the basic process of glycolysis

Answer 2

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

Question 3

What is the purpose of anaerobic respiration?

Answer 3

Pyruvate –> R-Lactate

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

Question 4

What is the process used to convert pyruvate to glucose

And what is the enzyme used to reverse anaerobic respiration?

Answer 4

Gluconeogenesis

Lactate dehydrogenase converts D-Lactate to pyruvate

Question 5

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?

Answer 5

Pyruvate - ATP - CO2 –> In the mitochondria

2 x ATP and 1 x NADH

Question 6

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

Answer 6

Glucagon is secreted when blood glucose is low

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

This promotes gluconeogensis to occur more frequently

Question 7

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

Answer 7

The matrix

Question 8

What are the products of the TCA cycle?

Answer 8

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)

Question 9

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

Answer 9

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

Question 10

Explain how Oxidative Phosphorylation / Chemi-osmosis works?

Also what is the yield of ATP from this process?

Answer 10

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

Question 11

What is the precursor molecule for glycogen?

Answer 11

UDP-Glucose

Question 12

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

Answer 12

Formation

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

Degradation

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

Question 13

How are the 1-6 glycosydic bonds degraded?

Answer 13

Glycerol Transferase moves 3, 1,4 bond residues

Question 14

How is glycogen metabolism regulated?

Answer 14

Glucagon binds to its receptors –> increasing cAMP/PKA

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

Insulin does the opposite

Question 15

How are fats stored and broken down?

Answer 15

Stored - In adopise tissue as triglycerides

Lipases are activated by glucagon and adrenaline (via PKA)

Question 16

Where are fatty acids degraded?

Answer 16

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

Perioxisomes - Unusual fatty acids are removed

Question 17

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

Answer 17

14

Question 18

Explain the process of Fatty Acid Biosynthesis

Answer 18

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

Question 19

What is the importance of Malonyl-CoA?

Answer 19

High levels = Fatty acid biosynthesis

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

Question 20

What is ketogenesis?

Answer 20

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)

Question 21

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

Answer 21

(Number of carbons/2) -1 = X

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