Glycolysis And Gluconeogenius Summary Important *

Front 1

Is it Anaerobic?

Back 1

Is anaerobic up to a point

Front 2

where does it occur?

Back 2

cytoplasm

Front 3

How many mols of glucose per mol of pyruvate?

Back 3

Takes 1 molecule of glucose to 2 molecules of pyruvate

Front 4

Yield?

Back 4

2 NADH + 4 ATP, but 2 ATP used at beginning of pathway

Front 5

Pyruvate to acetyl coa
Occurs?

Back 5

Occurs in mitochondria with an enzyme complex that utilises thiamin as a coenzyme

Front 6

which step requires oygen?

Back 6

2 molecules pyruvate from 1 molecule glucose yields 2 NADH and 2 acetyl co A molecules this step requires oxygen

Front 7

If Oxygen is not available? What happens to Pyruvate and when?

Back 7

Pyruvate is converted to lactate
Can be converted back to pyruvate when at rest, or can be converted to glucose in liver (gluconeogenesis)
This can occur in muscle during strenuous exercise

Front 8

What about the NADH from Glycolysis?

Back 8

Yield either 1.5 or 2.5 molecules ATP (glycerol phosphate and malate aspartate)
Electrons have to be shuttled into the mitochondrion
So we can only give an approximate range of ATP yield

Front 9

Functions of glycolysis

Back 9

Energy liberation and conservation – through the oxidation of glucose and the formation of ATP and NADH
2. Provides precursors for biosynthesis – glucose 6-phosphate and pyruvate
3. Permits metabolism of other nutrients – galactose and fructose can also enter pathway

Front 10

In the absence of oxygen is glucose the major source of ATP?

Back 10

In the absence of oxygen glucose is the major source of ATP but in the presence of oxygen the TCA cycle fulfils this role; more ATP is produced as a result of the TCA cycle operating than during glycolysis. ATP production is not the sole function of glycolysis; it also serves to provide precursors for synthesis of a variety of metabolites

Front 11

Gluconeogenesis is defined as?

Back 11

The production of glucose from non carbohydrate sources such as glycerol, from
triglyceride sources, lactate from anaerobic glycolysis in RBCs and muscle amino acids from muscle protein breakdown.

Front 12

Is gluconeogenesis a complete reversal of glycolysis?

Back 12

During glycolysis in muscle glucose is converted to lactate, and when the tissue is allowed to relax lactate is converted back into glucose. A large number of stages in glycolysis are freely reversible, ie there is only a small free energy change and during gluconeogenesis these reactions are reversed. However three stages of glycolysis involve large changes in free energy and these are bypassed by different enzymes (the glycolytic enzymes involved are hexokinase, phosphofructokinase and pyruvate kinase).
Gluconeogenesis is therefore not a complete reversal of glycolysis, nor is it a distinct pathway..

Front 13

Do glycolysis and gluconeogenesis take place in all tissues in the human body?

Back 13

Glycolysis takes place in all tissues in the human body, but gluconeogenesis is restricted in its distribution and occurs predominantly in the liver. In keeping with this, phosphatase occurs in the liver but not in muscle.

Front 14

Does gluconeogenesis produce ATP?

Back 14

Gluconeogenesis requires an input of energy. The bypassing of pyruvate kinase involves two enzyme reactions, each of which effectively uses a molecule of ATP, so that gluconeogenesis uses more ATP than is produced during glycolysis. One of these enzymes uses GTP and not ATP, GTP is energetically equivalent to ATP.

Front 15

What is the function of gluconeogenesis?

Back 15

Gluconeogenesis is very important in maintaining the blood glucose concentration and in supplying glucose to tissues (especially the brain) when carbohydrate in the diet is low. It also conserves materials. If lactate was excreted more carbon substrates would have to be consumed. By converting lactate back into glucose the carbon is reutilised and therefore conserved. It is clearly advantageous since it requires an input of energy.