1. RESPIRATION

3. GLYCOLYSIS (an ancient metabolic pathway)
State that Glycolysis occurs in the cytoplasm of cells.
Outline the process of glycolysis
State that in Aerobic respiration, pyruvate is actively transported into Mitochondria

4. Glucose

5. Starter How many carbons in a Hexose sugar?
Define a hydrolysis reaction.

6. Glycolysis is a metabolic pathway where each molecule of glucose is broken down into two molecules of pyruvate. It occurs in the cytoplasm of all living cells and is common to anaerobic and aerobic respiration.
What do we mean by anaerobic and aerobic respiration?

7. Glycolysis converts Glucose to a molecule of Pyruvate and in so doing releases energy from the glucose molecule. This energy is packaged as Adenosine Triphosphate (ATP), which can be used to power many cellular processess when needed.
ADP + Pi
Aerobic respiration
Lactate or Ethanol fermentation

9. Pyruvate
In Aerobic respiration (eukaryotes) Glycolysis plays an important role because the pyruvate it produces enters into subsequent metabolic pathways which are found in the MITOCHONDRIA which are able to produce more ATP molecules.
In Anaerobic respiration (prokaryotes and also oxygen starved tissue such as overworked muscles) Glycolysis is the only way of releasing energy in the form of ATP from Glucose. The pyruvate is then removed by fermentation reactions.

10. GLYCOLYSIS involves 10 separate reactions before Glucose can be converted to Pyruvate, each step is catalysed by a different enzyme. Co-enzyme NAD is also required.
You will need to know :
A simplifed three stage version of this pathway.
How many ATP molecules consumed and at which point.
Where ATP molecules are formed and how many.
Where NAD is reduced and how many.
The net gain of ATP molecules.
The fate of Pyruvate.

12. P STAGE 1 Phosphorylation. glucose Glucose 6-phosphate hexokinase -1
ATP COUNTER= -1
STAGE 1 Phosphorylation.
Glycolysis begins the breakdown of glucose
ATP
ADP P
glucose
Glucose 6-phosphate
hexokinase

13. P STAGE 1 Phosphorylation. Glucose 6-phosphate Fructose 6-phosphate
ATP COUNTER= -1
STAGE 1 Phosphorylation. P
Glucose 6-phosphate
Fructose 6-phosphate
Phosphoglucoisomerase

14. P P STAGE 1 Phosphorylation. Fructose 6-phosphate
ATP COUNTER= -2 -1
STAGE 1 Phosphorylation.
Fructose 1,6 bisphosphatehas been activated to Hexose 1,6 bisphosphate by the energy from two hydrolysed ATP molecules. It can now not escape the cytoplasm.
ATP
ADP P P
Fructose 6-phosphate
Fructose 1,6-bisphosphate
Phosphofructokinase

15. P P STAGE 2 Splitting of hexose 1,6 bisphosphate
ATP COUNTER= -2 -1
STAGE 2 Splitting of hexose 1,6 bisphosphate P P
Hexose 1,6-bisphosphate
2x Triose phosphate (3C)

16. Extension

17. Dehydrogenase enzymes
ATP COUNTER= -2
STAGE 3: Oxidation of Triose Phosphate
2 x Intermediate Compound (3C) P P
Dehydrogenase enzymes H
NAD NADH H
NAD NADH
ATP
ATP
Substrate level phosphorylation

19. P P P P PYRUVATE STAGE 4: Conversion of Triose Phosphate to pyruvate
ATP COUNTER= +2
STAGE 4: Conversion of Triose Phosphate to pyruvate
2 x Intermediate Compound (3C) P P
4 enzyme catalysed reactions required to convert triose phosphate to pyruvate
PYRUVATE P P
ATP
ATP
ADP
ADP

20. Summary

21. Products of Glycolysis
Net gain of 2- molecules of ATP per glucose molecule.
4 were actually made bit two were required to phosphorylate glucose to hexose 1,6-bisphosphate.
Two molecules of reduced NAD, these will carry hydrogen atoms, indirectly via a shunt mechanism, to the inner mitochindrial memebranes and be used to generate more ATP during oxidative phosphorylation
Two moelcules of Pyruvate. Actively transported into the mitochondrial matrix for the next stage of aerobic respiration. In absence of oxygen it is fermented to ethanol and lactate.

22. Glucose (6C)
ATP
Glucose-6-phosphate
Fructose-6-phosphate
2 ATP
Hexose-1-6-phosphate
2x Triose Phosphate (3C)
2 reduced NAD
2x Intemediate compound (3C)
ATP hydrolysis
2x Pyruvate (3C)
Substrate level phosphorylation
Dehydrogenases remove hydrogen atoms from triose phosphate

24. R2: The link Reaction and Krebs Cycle

25. The Link reaction
Pyruvate produced during Glycolysis is transported across the outer and inner membrane of the mitochondria into the matrix.
The link reaction prepares pyruvate for the next series of reactions in the KREBS cycle
Pyruvate is changed into a 2 carbon compound of acetate, which is oxideised in Krebs.

26. Link Reaction Summary:
Pyruvate Dehydrogenase removes Hydrogen atoms from Pyruvate
Pyruvate Decarboxylase removes a carboxyl group which eventually becomes CO2
The coenzyme NAD accepts hydrogen atoms and becomes reduced NAD
Coenzyme A (CoA) accepts acetate to become Acetyl CoA.
CoAs role is to deliver Acetate to Krebs Cycle.
2pyruvate + 2NAD+ + 2CoA CO2 +2 reduced NAD + 2 acetylCoA

31. The Krebs Cycle
1) What reactions occur in
2) Total up the products of the Cycle
3) Is there any substrate level Phosphorylation occuring? explain your answer
4) What are the similarities and differences with the Calvin Cycle?
5) Summarise in a black box diagram.

32. R3: The Electron Transport Chain

37. Terminal electron acceptor is Oxygen
4H+ + 2e- + O H2O

39. Evaluating the evidence of Chemiosmosis
HSW.

40. R4
Starter-
Mini-whiteboards 5C 4C 4C

41. Anaerobic Respiration in mammals and yeast
Explain why anaerobic respiration should produces a much lower yield of ATP than aerobic respiration.
Compare and contrast anaerobic respiration in mammals and in yeast.

42. Anaerobic Respiration
Glycolysis
LINK REACTION
KREBS CYCLE
ELECTRON TRANSPORT
These can take part only in the presence of Oxygen as it is the final electron receptor.

43. Respiration Without Oxygen
Without oxygen the electron carriers can not give up their electrons.
Resulting in NADH dehydrogenase not oxidise reduced NAD as it can not accept its electrons.
If reduced NAD is not recycled then there is no NAD available to accept electrons in KREBS and the Link reactions, these grind to a halt.

44. Glycolysis is all that is left for ATP production, as this does not require oxygen.
Glycolysis still needs the reducing power of the NAD coenzyme so it must recycle the reduced NAD.
Glycolysis also produces Pyruvate which is not used up if there is no LINK or KREBS, this has to be removed.
NAD
Eukaryotic cells have evolved two biochemical pathways to deal with this problem and reoxidise NAD

45. Process 1: Lactate Fermentation
Glycolysis
Pyruvate + Reduced NAD NAD + Lactate
Pyruvate accepts Hydrogen atoms from reduced NAD which is reoxidised.
Pyruvate is reduced to lactate, catalysed by Lactate dehydrogenase
NAD can now accept hydrogen atoms in Glycolysis to enable the production of some ATP

46. Anaerobic Respiration
Anaerobic respiration includes the oxidation of Glucose via Glycolysis and the subsequent oxidation of reduced NAD by lactate fermentation. Releasing a net gain of 2 ATP
2 ATP
4 ATP

47. Lactate Fermentation cont.
Lactate fermentation is most likely to occur in skeletal muscle cells, when exercising vigorously.
They top up their ATP production with Lactate fermentation, as there s not enough Oxygen.
Lactate builds up in the muscle cells, (it can stop the muscles contracting )and diffuses into the blood plasma
High levels of lactate make people feel nauseous and disorientated.
Liver Hepatocytes absorb lactate and convert it back to pyruvate, or can convert it to glucose or glycogen.
Oxygen debt is when you need to breathe heavily supplying hepatocytes with oxygen to metabolise the lactate.

48. Pyruvate decarboxylase
Process 2: Alcoholic Fermentation
Fungi and plants (water logged plant roots) recycle their reduced NAD with an alternative pathway, using different enzymes which result in different end products.
Pyruvate decarboxylase
Each pyruvate is decarboxylated (loses a CO2 molecule) and becomes Ethanal.
Catalysed by Pyruvate decarboxylase (an enzyme not present in animals)
Ethanal is used to oxidise reduced NAD and accepts hydrogen atoms (Ethanal dehydrogenase)

49. Use the information above to calculate
STARTER
Element
Molecular weight
Carbon 12
Oxygen 16
Hydrogen 1
It takes 30.6 kJ to produce 1 mol of ATP
The theoretical energy yield for glucose is 2870 kJmol-1
Use the information above to calculate
How many mols of ATP are produced per mol of glucose?
How many mols of ATP would you produce from a Lucozade drink containing 30 g of glucose.
Actual yield of ATP from 1 mol of glucose is 30ATP, what is the efficiency of ATP yield from glucose? Why?

50. R5
Why is a diet high in Fat also high in energy content?

51. Respiratory Substrates
Define term respiratory substrate
Explain the difference in relative energy values of carbohydrate, lipid and protein respiratory substrates

52. Unless you are the brain and blood cells
Its not just Glucose which can be respired!
Unless you are the brain and blood cells

53. Each substrate is capable of yielding different energy levels,
ENERGY VALUES.
carbohydrate, lipid and protein can all be metabolised to yield energy in the form of ATP by aerobic respiration.
Each substrate is capable of yielding different energy levels,
What is the SCIENCE behind this?
Molecular formula C11H22O2
Molecular Formula C11H12N2O2
Molecular formula
C12H22O11
What are these three respiratory substrates?
Which would yield the most energy and why?

54. CLUE
The majority of ATP produced in Aerobic respiration is produced by oxidative phosphorylation, when hydrogen ions flow through ion channels associated with ATP synthase enzymes.
The rule:
The more hydrogen atoms there are in a respiratory substrate (proportionally compared to oxygen and carbon) then the more ATP can be generated

55. Respiratory substrate Mean energy value/kJg-1
Carbohydrate
15.8
Protein
17.0
Lipid
39.4
Carbohydrates
Glucose is the main respiratory substrate, plants and animals store glucose as glycogen and glucose respectively both are hydrolysed to glucose for respiration.
Other monosaccharides such as FRUCTOSE and GALACTOSE are changed to glucose for respiration

56. 1) Label the LINK reaction. 2) Label the KREBS CYCLE.
Amino Acids enter Krebs Cycle
1) Label the LINK reaction.
2) Label the KREBS CYCLE.
3) Fill in the 5 open boxes (include C Num)
4) (YOU NOW MAY NEED TXT BK) In the box below name and draw the process which allows amino acids to be respired.
5) Indicate where different amino acids join onto Krebs.
6) Explain why
Different amino acids have different ATP yields?
Proteins have higher ATP yields than Carbohydrate. 5C 4C

57. Why is a diet high in Fat also high in energy content?

58. Important respiratory substrates for many tissues, espescially muscles
LIPIDS
Important respiratory substrates for many tissues, espescially muscles
Fatty Acids are long-chain hydrocarbons with a carboxylic acid group. In each molecule there are many hydrogens , which are a source for many protons for oxidative phosphorylation and the production of many ATPs
LIPASE
TRIGLYCERIDE
FATTY ACIDS +
GLYCEROL
Converted to Glucose in Liver and used for respiration

59. Fatty Acid metabolism
Fatty acids activated by addition of CoA which require an ATP which is hydrolysed to AMP.
This Fatty acid (an acyl-CoA) is transported into the mitochondrial matrix.
Here B-oxidation breaks the Acyl-CoA complexes into two carbon-acetyl groups attached to CoA.
B-oxidation reduces NAD and FAD (more for ox phos)
The For each acetate 3 NAD and 1 FAD are reduced and one molecule of ATP by substrate level phosphorylation.

60. NAD Reduced NAD NAD Reduced NAD Acetyl CoA Ethanol Ethanal
Ethanoic Acid
NAD
Reduced NAD
NAD
Reduced NAD
Acetyl CoA

61. NAD Reduced NAD LIPASE TRIGLYCERIDE FATTY ACIDS + GLYCEROL Acetyl Coa
Ethanol
Ethanal
Ethanoic Acid
NAD
Reduced NAD
LIPASE
TRIGLYCERIDE
FATTY ACIDS +
GLYCEROL
Acetyl Coa
β-oxidation
NAD
Reduced NAD
NAD
Reduced NAD
Acetyl CoA

62. Stretch and Challenge
Palmitic acid produces eight 2 –carbon fragments. This requires seven turns of β-oxidation cycle.
For each turn of the β-oxidation cycle one reduced NAD and one reduced FAD are produced. The seven FAD and seven NAD are reoxidised via oxidative phosphorylation. Hydrogen atoms from reduced NAD are involved in chemiosmosis and synthesis of 2.6 ATPs.
Each acetyl group enters the Krebs Cycle and produces one reduced FAD and three reduced NAD as well as one ATP, by substrate level Phosphorylation. Eight turns of the Krebs cycle are needed to deal with the eight fragments produced during β-oxidation .
The energy equivalent to the hydrolysis of two ATP molecules is used to combine the fatty acid with acetyl CoA
Q: Calculate the net gain of ATP for one molecule of palmitic acid β-oxidation and Krebs cycle.

63. STRETCH and CHALLENGE
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