Glycolysis

?
  • Created by: JS007
  • Created on: 27-05-18 13:49

Step 1

  • Glucose --> glucose-6-phosphate (G6P)
  • Enzyme = hexokinase
  • Requires ATP & Mg2+

-Traps glucose inside the cell

-Maintains glucose concentration gradient so more can be taken into the cell

Hexokinase is inhibited by G6P, this prevents an unnecessary drop in blood glucose levels. Liver cells instead use the glucokinase enzyme which is not affected by G6P, allowing liver cells to take up lots of glucose to store it as glycogen

1 of 8

Step 2

  • Glucose 6-phosphate --> fructose-6-phosphate
  • Enzyme = phosphohexose isomerase
  • Requires Mg2+

-Makes the molecule more symmetrical in preparation for splitting

-Fructose is easier to phosphorylate

Conversion to fructose-6-phosphate also decreases the concentration of G6P and therefore inhibition of hexokinase is limited, allowing more glucose to enter glycolysis 

2 of 8

Step 3

  • Fructose-6-phosphate --> fructose-1,6- bisphosphate
  • Enzyme = phosphofructokinase (PFK)
  • Requires ATP and Mg2+

-The molecule is further activated ready for splitting

PFK is stimulated by adrenaline and fructose-1,6-bisphosphate stimulates the pyruvate kinase enzyme, so when adrenaline is released (e.g. during exercise), more fructose- 1,6- bisphosphate is produced, leading to more production of pyruvate by stimulating pyruvate kinase 

3 of 8

Step 4

Fructose-1,6-bisphosphate is split into:

  • dihydroxyacetone phosphate
  • glyceraldehyde-3-phosphate (GAP)
  • Enzyme = aldolase

-Only GAP is able to progress further in glycolysis

4 of 8

Step 5

  • Dihydroxyacetone phosphate --> glyceraldehyde-3-phosphate
  • Enzyme = triose phosphate isomerase 

-Allows glycolysis to progress down a single pathway 

5 of 8

Step 6

  • Glyceraldehyde-3-phosphate --> 1,3-bisphosphoglycerate
  • Enzyme = glyceraldehyde-3-phosphate dehydrogenase
  • Requires NAD+, which is converted to NADH

-This stage allows for net generation of ATP in glycolysis

6 of 8

Steps 7,8 & 9

  • 1,3- bisphosphoglycerate --> phosphoenolpyruvate

-A series of (relatively unimportant) reactions allow this stage

7 of 8

Step 10

  • phosphoenolpyruvate --> pyruvate
  • Enzyme = pyruvate kinase
  • Requires ADP, Mg2+, K+

-Pyruvate kinase can be stimulted by fructose-1,6-bisphosphate

A net yield of 2 moles of ATP is produced

8 of 8

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all glycolysis resources »