BIOC192 Lecture 28 - Glycolysis

Question 1

what pathway is glucose oxidised in?

Answer 1

glycolysis

Question 2

what organisms perform glycolysis?

Answer 2

all organisms

• animals
• plants
• fungi
• bacteria

Question 3

what are the 2 pathways that glycolysis can undergo?

Answer 3

1) cytoplasmic pathway (usually the pathway used)

2) mitochondrial pathway

Question 4

what is glucose essential for as fuel?

Answer 4

• 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

Question 5

do RBC’s have mitochondria?

Answer 5

no they do not have mitochondria therefore they lack the other pathways

Question 6

can glucose cross the blood/brain barrier?

Answer 6

glucose can readily cross the blood/brain barrier

Question 7

can fats cross the blood/brain barrier?

Answer 7

fats cannot cross the blood/brain barrier

Question 8

how much glucose does the human brain require per day?

Answer 8

around 120g of glucose per day

Question 9

why can the eye only perform glycolysis in the cytoplasm?

Answer 9

because here is a low number of mitochondria

Question 10

what are the 3 characteristics of white muscle?

Answer 10

• sprinting
• fast twitch
• glucose as fuel

Question 11

what is glycolysis?

Answer 11

the splitting of glucose

Question 12

what is the start product and end product of glycolysis?

Answer 12

6 carbon glucose is split into 2 pyruvate with 3 carbons each

Question 13

what 2 molecules is energy conserved into?

Answer 13

1) ATP

2) NADH

Question 14

can pyruvate be further metabolised?

Answer 14

yes pyruvate may be further metabolised

Question 15

what are the 2 ways pyruvate can be further metabolised?

Answer 15

1) aerobically

2) anaerobically

Question 16

what are the 2 phases of glycolysis?

Answer 16

1) energy investment phase

2) energy payoff phase

Question 17

what is the first phase of glycolysis?

Answer 17

the energy investment phase

Question 18

what is the second phase of glycolysis?

Answer 18

the energy payoff phase

Question 19

what occurs during the first phase of glycolysis?

Answer 19

-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

Question 20

what occurs during the second phase of glycolysis?

Answer 20

-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

Question 21

what occurs in the energy investment phase in terms of carbon?

Answer 21

splitting of 6 carbons to 3 carbons (2x) of the molecule occurs at the end of the energy investment phase

Question 22

what occurs in the energy payoff phase in terms of carbon?

Answer 22

after a conversion both of 3 carbon molecules are processed the same way

Question 23

what are the 4 reactions for the activation of glucose?

Answer 23

glucose –> glucose-6-phosphate (G-6-P) –> fructose-6-phosphate (F-6-P) –> fructose- 1,6-biphosphate (FBP)

Question 24

what is the impact of the reaction of glucose-6-phosphate having a positive delta G of +1.6kJ/mol?

Answer 24

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

Question 25

what is the reaction of the phosphorylation of ADP to ATP?

Answer 25

ADP + Pi --> ATP

Question 26

where does energy come from in a substrate level phosphorylation?

Answer 26

energy comes from the substrate

Question 27

what is one way to release energy to a substrate level phosphorylation?

Answer 27

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

Question 28

what is the 1st substrate-level phosphorylation for making an ATP profit?

Answer 28

- 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

Question 29

why does arsenic poison glycolysis?

Answer 29

arsenate substitutes fro phosphate and the resulting compound is unstable and senate is hydrolysed -ATP is not synthesised

Question 30

what is the 2nd substrate-level phosphorylation for making an ATP profit?

Answer 30

- 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

Question 31

what is pyruvate converted to under aerobic conditions?

Answer 31

under aerobic conditions pyruvate is converted into acetyl-CoA

Question 32

where does the conversion of pyruvate occur?

Answer 32

occurs in the mitochondrial matrix

Question 33

what is the net reaction of pyruvate conversion under acidic conditions?

Answer 33

oxidate decarboxylation