lecture 3 - carbohydrate metabolism Flashcards
what is glycolysis?
breakdown of glucose to produce energy
what is the end product of the breakdown?
pyruvate - starts with one molecule and end up with 2 molecules with 3 diff elements (carbon atoms)
when is glycolysis especially important?
high intensity exercise
what is insulin?
an activator
what is glucagon?
an inhibitor
is glycolysis aerobic or anaerobic?
both
aerobic yields more ATP and therefore more energy
how many reactions does glycolysis have?
10
what are reactions 1-5 called?
the investment phase - where we use up energy and ATP
what are reactions 6-10 called?
the paying off phase - where ATP is generated
where does anaerobic glycolysis take place?
cytosol - fluid inside the cell
what are glucose transporters called?
GLUT1-GLUT5
what happens in the first 3 reactions?
Glucose enters the cytosol of the cell via a number of different GLUT transporters on the CM.
In the cytosol, G is phosphorylated to G-6P
via the enzyme hexokinase – this reactions requires ATP; hence, investment
G-6-P is converted to F-6-P via PI enzyme – note this reaction is irreversible
F-6-P is converted to F,1,6, bis via the enzyme PFK
what happens in phases 4-5?
One molecule splits int 2 molecules
Everything that we generate we have to multiply by 2
what happens in reactions 4-6?
We form an NADH molecule – from a NAD+ molecule to a NADH molecule
If dehydrogenase in name of a reaction – goes with NAD+ and NADH
what happens in reactions 7-10?
Can now generate ATP from ADP
Kinase – removes a phosphate group and adds it onto something else
4 ATP molecules are generated
Pyruvate molecule can have 2 fates – 1 is that it can convert into lactate – causes the burning sensation that eventually stops us exercising – not wither or – some will shift to lactate even in resting conditions
what is glycogenesis?
formation of new glycogen
- activated after a meal
what is glycogenolysis?
breakdown of glycogen
- free up available glucose molecules for energy production
- activated when fasting/high intensity exercise
where is glycogen stored?
muscles or liver
what does muscle glycogen mean?
likes to be kept for itself, all glycogen stored in the muscle will only be used by the muscle for glycolysis
what does liver glycogen mean?
doesn’t keep all for itself – liver glycogen is where the glucose is not exclusively used in the liver but given to other organs for energy production
when is glycogenesis most likely to occur?
After eating a meal – insulin is released and activates the pathways
what is elongation?
extends the existing strand of glucose molecules within glycogen
what is the layout of glycogen?
Not just one very long string – at diff points branches out into diff strings
what is phosphorolysis?
breaking up of glycogen molecule by adding a phosphoryl group
what is the point of glycogenolysis
to convert the branched glycogen molecule into a straight one
