Glycolysis Flashcards
What is glycolysis
-oxidizing of glucose molecules into pyruvate
How is glucose transported into cell and why
- through glut proteins
- water soluble
List types of glut proteins and where found
Glut 1 - fetus , blood brain barrier , blood ( RBC )
Glut 2 - kidney , liver , pancreas
Glut 3 - placenta , kidney , neuron
Glut 4 - muscle , fat ( adipose )
Diff between glut 1-3 and 4
-glut 4 is insulin dependent and and efficiency proportional to insulin conc
Why is glucose anchored with molecule when in cell and what’s the molecule
What enzyme mediates the process
Which c atom is the molecule added to / Now name of glucose
- to prevent it from moving out of cell through bi-directional glut protein
- phosphate
- hexokinase or gkucokinase
- carbon 6 / glucose-6-phosphate
Location of hexokinase and glucokinase
Where does the phosphate come from
- mainly in muscle but also in a lot of tissue
- only liver has glucokinase
- ATP is hydrolyzed into ADP
What is the next step after glucose phosphorylation, what mediates and is the reacting reversible
- glucose-6-phosphate is isomerized into fructose 6 phosphate ( ketone ) by phosphahextose isomerase
- irreversible
What happens to fructose-6-phosphate and what mediates
- converted into fructose 1-6 bisphophatase ( bis due to carbon spaces in between the phosphates )
- phosphafructokinase 1 ( PFK 1 )
- ATP hydrolyzed into ADP
What happens to fructose 1,6 BP and what is the enzyme involved
Products formed and differentiate them
- cleaved into 2 three carbon fragments by Aldose
- dihydroxyacetonephosphatase ( DHAP ) has ketone in middle and not used so converted into GA3P
- glyceraldehyde 3 phosphate ( GA3P ) has aldehyde and end and used in further reactions
What converts DHAP into GA3P
-triose phosphate isomerase
What happens to GA3P ( it’s next 2 steps )
/phosphorylation at carbon 1 by glycealdehyde-3-phosphate dehydrogenase into 1,3 bisphosphate
-NAD+ reacted with 1,3 BP by GA3P DHand is now NADH ( took hydrides ) and GA3P phosphorylated
Why are 2 mols of GA3P present
-cause DHAP is convert into GA3P by triose-phosphate-isomerase and there will be 2 mols of GA3P
Next step after 1,3 BP formed
-phosphate removed from carbon 1 and now we form 3 phosphoglycerate and enzyme is called phosphoglycerate kinase ( phosphorylation of ADP into ATP )
What happens to 3 phosphoglycerate and mediators and product formed
-mutated and phosphate shifter to carbon 2 by phosphoglycerate mutase into 2-phosphoglycerate
What occurs to 2-Phosphoglycerate and mediators and product formed
- converted into Enol but with phosphate at alcohol of carbon 2
- now called phosphoenol pyruvate ( has c double bond at carbon 2-3 )
-mediated by enolase
Fate of phosphoenol pyruvate and mediators and products formed
- phosphate is removed by pyruvate kinase which phosphorylates ADP
- pyruvate formed
2 fates of pyruvate depending on O2 conc
1 anaerobic - hydrides unloaded on pyruvate forming lactic acid
2 aerobic - converted into 2 carbon molecule ( taken to specific molecules for electron transport chain to form ATP )
How is lactic acid formed
Effects and fate of glucose
-pyruvate plus NADH into NAD+ and lactic acid by lactate dehydrogenase
- liver covnverted into glucose
- decrease pH ( acidosis , chromatin clumping )
Meaning of high LDH levels
Causes
- lot of pyruvate being converted into lactic acid
/myocardial infarction
/necrotic bowel
Where does glycolysis occur
-cytoplasm
