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Question 1

What is glucose used as?

Answer 1

A fuel in all organisms (animals, fungi, plants, bacteria)

Question 2

What is glucose oxidised in?

Answer 2

Glycolysis

Question 3

Where does glycolysis happen

Answer 3

usually cytoplasmic in eukaryotes (other pathways mitochondrial)

Question 4

Some cells in animals rlly on/ preferentially use…

Answer 4

Glucose

Question 5

Glucose is essential as fuel for______ why?

Answer 5

red blood cells
Red blood cells do not have mitochondria, so do not have the other pathways

Question 6

What is the preferred fuel in the brain but expand on ‘preferred’

Answer 6

• High energy requirement: human brain requires around 120 g of glucose per day
• Brain cells have mitochondria - can do other pathways

Question 7

Why is glucose a preferred molecule?

Answer 7

ORIGNALLY: - Glucose easily crosses the blood-brain barrier, but fats do not (fats being the alternative source)

NOW: - A high level of fatty acid metabolism is dangerous - Relying on mitochondrial reactions and higher levels of oxygen risks anoxia (low oxygen) and higher production of damaging reactive oxygen species

Question 8

Glucose is the favoured molecule in the _ _ _ WHY?

Answer 8

Eye
- blood vessels (bringing oxygen) and mitochodria would refract light in the optical path (lens, cornea) to retina

Question 9

White muscles tend to use ______ red muscles tend to use_____

Answer 9

Question 10

What is glycolysis

Answer 10

Splitting of glucose

• Conversion of one molecule of glucose (6 carbon) to two molecules of pyruvate (3 carbon)
• Pyruvate may be further metabolized aerobically or anaerobically

Question 11

Where is energy conserved in glycolysis

Answer 11

Energy conserved in ATP and NADH

Question 12

Two phases of glycolysis and the net

Answer 12

• Activation of glucose Getting the molecule into a form so energy can be captured Requires an energy input
• Return on the investment Making an ATP profit

(After glycolysis there is still carbon in pyruvate that can be extracted for energy)

Question 13

What does the ‘energy investment’ phase entail? What does the ‘energy payoff’ phase entail?

Answer 13

• Splitting (6C to 3C) the
  molecule occurs at the end of the investment phase
• After a conversion, both 3C molecules are processed the same way

(On both sides ADP is getting phosphorlyated to ATP - both sides) - so for each split glucose these reactions are happening twice

Question 14

The two molecules that split then what happens?

Answer 14

G3P continues on in glycolysis
DHAP cant go directly through and must be converted to G3P first

Question 15

Key reactions for the activation of glucose

Answer 15

Question 16

The splitting or aldolase reaction - what drives to relation of DHAP to G-3-P?

Answer 16

G-3-P is used in the energy payoff phase
- keeps concentration low
- drives reaction from DHAP to G-3-P

Question 17

In terms of carbons and number of molecules and numbers of phosphates

Answer 17

Question 18

The splitting or aldolase reaction

Answer 18

Question 19

What enzyme allows the change from DHAP to G-3-P?

Answer 19

Triose phosphate isomerase (rearrangement)

Question 20

How come DHAP and G-3-P aren’t actually at travelling in equal directions (equilibrium)

Answer 20

There isn’t 1 mol of each, G-3-P is used in the reaction pathway and therefore the reaction favours making more G-3-P from DHAP

(Always making both and only removing G-3-P)

Question 21

Pathways for processing food molecules for ATP synthesis - Two key types of reactions:

Answer 21

1. Those involving ADP and ATP ATP synthesis: ADP + Pi —> ATP
   a. substrate-level phosphorylation
   
   • direct (A + ADP —> B + ATP) - energy comes from
     substrate
     b. oxidative phosphorylation - Indirect (reduced co-enzymes)
2. Redox reactions Fuel molecules get oxidized

Question 22

What is Substrate level phosphorylation (SLP)

Answer 22

The DIRECT use of energy from a substrate molecule to drive the synthesis of ATP (or equivalent)

Question 23

How do you release the energy to drive a substrate-level phosphorylation what’s the problem with that?

Answer 23

One way to release the energy to drive a substrate-level phosphorylation is the cleavage of a high-energy phosphate ester bond on a substrate

But
But 1 ATP has been spent to add each phosphate on G-3-P….
….and we need a net gain of ATP in glycolysis

Question 24

A key reaction for making an ATP profit: Oxidation of glyceraldehyde-3-phosphate - how does this work?

Answer 24

• NAD+ is reduced (provides oxidising power)
• phosphate from solution added to substrate

The addition of phosphate is powered by oxidation of G-3-P
The addition of phosphate does not require ATP

• glyceraldehyde-3-phosphate dehydrogenase uses the energy from the exisiting reaction to add the phosphate

(THIS IS HAPPENING TWICE FOR EACH GLUCOSE MOLECULE)

Question 25

A key reaction for making an ATP profit: the 1 st substrate-level phosphorylation (SLP)

Answer 25

The #1 carbon phosphate of 1.3-BPG is very reactive - phosphate is cleaved (phosphoglycerate kinase) releases energy (ΔG0´= -49.3 kJ/mol) - energy used for substrate level phosphorylation ADP + Pi —->ATP (ΔG0´= +30 kJ/mol) Overall ΔG0´= -19.3 kJ/mol (coupled reaction) P is also transferred to ADP to make ATP (not what makes it an SLP - its the energy that makes it a SLP)

Question 26

How does arsenic poison glycolysis ?

Answer 26

- Arsenate (AsO4 -3) substitutes for phosphate (PO4-3) - Unstable, arsenate hydrolyzed but energy not captured (as the enzyme is not used) - ATP not synthesized by phosphoglycerate kinase No net gain of ATP in glycolysis

Question 27

How do we get form 3PG to PEP (what happens after first SLP)

Answer 27

Rearrangement: Getting the molecule into a form that enables the following reactions

Question 28

A key reaction for making an ATP profit: the 2 nd substrate-level phosphorylation (SLP)

Answer 28

Phosphate cleaved: releases energy ΔG0´= - 61.9 kJ/mol Energy used for substrate- level phosphorylation ADP + Pi —-> ATP ΔG0´= +30 kJ/mol Overall ΔG0´= -31.9 kJ/mol (coupled reaction) P is also transferred to ADP to make ATP (not what makes it an SLP)

Question 29

Overall reaction for glycolysis

Answer 29

Glucose + 2NAD + + 2ADP + 2Pi —-> 2 pyruvate + 2 NADH + 2ATP + 2H+ Glycolysis overall: ΔG0 ´= -73.3 kJ/mol Pathway is energetically favourable

Question 30

What happens to private under aerobic oxidation (O2 available)

Answer 30

Pyruvate is converted to acetyl-CoA to be further metabolized In the citric acid cycle

Question 31

aerobic oxidation - standard thing that will happen -

Answer 31

Occurs in the mitochondrial matrix Pyruvate dehydrogenase (enzyme)reaction - Multienzyme complex with lots of cofactors/ coenzymes Net reaction is an oxidative decarboxylation - CO2 released (decarboxylation; 3C to 2C) - pyruvate is oxidized, energy captured in NADH and used to add Coenzyme A (CoA) to two-carbon chain

Question 32

What does it mean Anaerobic glycolysis

Answer 32

Low oxygen - red blood cells, muscles in anaerobic conditions

Question 33

Anaerobic glycolysis of Pyruvate

Answer 33

When NADH is oxidised, the energy captured in the coenzyme NADH is lose Lactate causes muscle fatigue

Question 34

Why is pyruvate transformed into lactate in Anaerobic glycolysis

Answer 34

- low concentration of coenzymes in cells - during aerobic oxidation coenzymes are oxidized (regenerated) in oxidative phosphorylation - lactate dehydrogenase reaction oxidizes NAD - allows for sufficient NAD+ for the glyceraldehyde-3- phosphate dehydrogenase reaction - glycolysis can continue to generate ATP