Catabolism Of Glucose- Glycolysis

Question 1

What is anabolism and catabolism

Answer 1

Anabolism - assimilation of molecules and complex structures form the building blocks of life
Requires energy

Catabolism - breakdown of molecules to obtain the anabolic “buildings blocks” of life and substrates for energy
Break down molecules for energy

Question 2

Where does our energy come from?

Answer 2

Ultimately all comes form the sun
Plants synthesise macromolecules using sunlight energy
Catabolic pathways oxidise macromolecules create ATP
ATP can be used to drive biosynthetic reactions

Question 3

What is important about glucose

Answer 3

Most important carbohydrate - starch, cellulose and glycogen
Primary energy source oxidised to CO2 and water
Some cellse need glucose as an energy source (rbc’s, renal medulla, cancer cells)

Question 4

What are the structure of glucose

Answer 4

Linear glucose (D or L) 
Ring structures (alpha or beta)

Question 5

What is glucose used for

Answer 5

Storage ( glycogen, starch, sucrose, conv to lipids)
Oxidation to pyruvate though anaerobic oxidation
Fermented to lactate by anaerobic glycolysis
Oxidised to ribose-5-Phosphate through pentose phosphate pathway

Question 6

How is glucose transported in cells

Answer 6

Via Na/glucose symporters - needs indirect energy from atpase mechanism

Via passive facilitated diffusion glucose symporters - GLUT 1 (brain)

Question 7

What is GLUT 1

Answer 7

Bindinf of glucose to the outside triggers s conformational change
Binding site faces inwards
Glucose can be released inside
Conformational change regenerates the binding site on the outside
Glucose and sodium released and the charge imbalance goes back to normal

Question 8

What is glycolysis

Answer 8

Initial pathway of conversion of glucose to pyruvate
Glucose + 2ADP + 2Pi + 2NAD+
–> 2 pyruvate + 4ATP + 2water + 2NADH + 2H+

Question 9

What is the reducing agent in glycolysis

Answer 9

nADH

Question 10

What are the steps of glycolysis

Answer 10

1- glucose trapped and destabilised
2 - two interconvertible 3C molecules a reformed
3 - generation of ATP happens twice per mol of glucose

Question 11

What are the 3 control point of glycolysis

Answer 11

1 - hexokinase - substrate energy
2- phosphofructokinase - rate of flow
3 - pyruvate Kinase - product exit

Question 12

What is phosphofructokinase

Answer 12

Key enzyme in controlling rate of substrate movement along glycolytic pathway

Question 13

What are the activators and inhibitors of phosphofructokinase

Answer 13

Activators
* AMP and fructose-2,6-bi phosphate which will increase glycolysis if energy is needed

Inhibitors

• ATP - will slow glycolysis if energy abundant
• citrate - tca cycle intermediate slows pyruvate into TCA
• hydorgen ion- slows glycolysis if too much lactic acid is produced

Question 14

What is the energy change

Answer 14

The ATP:AMP ratio
Is cell full of ATP = charged (ATP is rapidly used up )
If cell full of AMP + Pi = discharged

Question 15

What transports electrons

Answer 15

NAD

Question 16

What happens if mitochondrial metabolism is inhibited by lack of oxygen

Answer 16

NADH used to ferment pyruvate to lactic acid
NADH is regenerated at beginning of stage 3
If lactate accumulates in tissues = poisonous

Question 17

What is the Warburg effect

Answer 17

Up reg of anaerobic glycolysis in cancer cells

Cancer cells = produce energy by high rate of glucose metabolism to lactate - anaerobic glycolysis

Question 18

What are the advantages and disadvantages of the Warburg effect

Answer 18

Ads–> rapid energy prod

  - -> support other pathways for nucleotide synthesis 
  - -> supports rapid cell growth -prolif

Disads –> produces (H+) snd lactate as end products

        - -> very inefficient ATP synthesis 
        - -> high glucose consumption demand 
        - -> cancer patients lose weight

Question 19

What are some ways of treating cancer by targeting glycolysis

Answer 19

2-Deoxy-glucose –> comp inhib blocks G6P
3-Bromopyruvate –> comp inhib block prod of 1,3-biphosphoglycerate
Dichloroacetate –> lactic acid to pyruvate slows glycolytic rate and can’t let cells grow

Question 20

What is the metabolism

Answer 20

All chemical reactions that maintain the living state of cells and organisms