BIOC192 Lecture 28 - Glycolysis Flashcards
what pathway is glucose oxidised in?
glycolysis
what organisms perform glycolysis?
all organisms
- animals
- plants
- fungi
- bacteria
what are the 2 pathways that glycolysis can undergo?
1) cytoplasmic pathway (usually the pathway used)
2) mitochondrial pathway
what is glucose essential for as fuel?
- essential as fuel for red blood cells
- essential as fuel for the brain
- favoured fuel for the eye
- white muscle cells favour glucose over fats
do RBC’s have mitochondria?
no they do not have mitochondria therefore they lack the other pathways
can glucose cross the blood/brain barrier?
glucose can readily cross the blood/brain barrier
can fats cross the blood/brain barrier?
fats cannot cross the blood/brain barrier
how much glucose does the human brain require per day?
around 120g of glucose per day
why can the eye only perform glycolysis in the cytoplasm?
because here is a low number of mitochondria
what are the 3 characteristics of white muscle?
- sprinting
- fast twitch
- glucose as fuel
what is glycolysis?
the splitting of glucose
what is the start product and end product of glycolysis?
6 carbon glucose is split into 2 pyruvate with 3 carbons each
what 2 molecules is energy conserved into?
1) ATP
2) NADH
can pyruvate be further metabolised?
yes pyruvate may be further metabolised
what are the 2 ways pyruvate can be further metabolised?
1) aerobically
2) anaerobically
what are the 2 phases of glycolysis?
1) energy investment phase
2) energy payoff phase
what is the first phase of glycolysis?
the energy investment phase
what is the second phase of glycolysis?
the energy payoff phase
what occurs during the first phase of glycolysis?
-the energy investment phase
the activation of glucose is caused by getting the molecule into a form so that energy can be captured
2ATP –> 2ADP
what occurs during the second phase of glycolysis?
-the energy payoff phase return on the investment of energy by making a profit of ATP from 2ATP to 4ATP 4ADP --> 4ATP 2NAD+ --> 2NADH -end product is 2 pyruvate
what occurs in the energy investment phase in terms of carbon?
splitting of 6 carbons to 3 carbons (2x) of the molecule occurs at the end of the energy investment phase
what occurs in the energy payoff phase in terms of carbon?
after a conversion both of 3 carbon molecules are processed the same way
what are the 4 reactions for the activation of glucose?
glucose –> glucose-6-phosphate (G-6-P) –> fructose-6-phosphate (F-6-P) –> fructose- 1,6-biphosphate (FBP)
what is the impact of the reaction of glucose-6-phosphate having a positive delta G of +1.6kJ/mol?
because this reaction is in the middle of the reactions for the activation of glucose it does not effect the overall delta G which is negative
what is the reaction of the phosphorylation of ADP to ATP?
ADP + Pi –> ATP
where does energy come from in a substrate level phosphorylation?
energy comes from the substrate
what is one way to release energy to a substrate level phosphorylation?
the cleavage of a high-energy phosphate bond on the substrate
-however the next step is critical because we still need a net gain of ATP in glycolysis
what is the 1st substrate-level phosphorylation for making an ATP profit?
- the number 1 carbon phosphate of 1,3-BPG is very reactive
- removal of this P releases energy (delta G = -49.3 kJ/mol) that is used for substrate-level phosphorylation. (ADP + Pi –> ATP deltaG = +30 KJ/mol)
- P is also transferred to ADP to make ATP
why does arsenic poison glycolysis?
arsenate substitutes fro phosphate and the resulting compound is unstable and senate is hydrolysed
-ATP is not synthesised
what is the 2nd substrate-level phosphorylation for making an ATP profit?
- removal of P from phosphoenolpyruvate (PEP) releases energy (deltaG = -61.9 kJ/mol) that is used for substrate-level phosphorylation (ADP + Pi –> ATP deltaG = +30 kJ/mol)
- P is also transferred to ADP to make ATP
what is pyruvate converted to under aerobic conditions?
under aerobic conditions pyruvate is converted into acetyl-CoA
where does the conversion of pyruvate occur?
occurs in the mitochondrial matrix
what is the net reaction of pyruvate conversion under acidic conditions?
oxidate decarboxylation
