Biochemistry of respiration

1
Biochemistry of respiration
2
Raw materials

• Any organic molecule
• Carbohydrate
• Lipid
• Protein

3
They contain

• too much chemical energy

4
So, respiration involves

• breaking down large complex organic molecules
  to produce a molecule that contains a small
  amount of energy

5
ATP

• ATP is an immediate source of energy because-
• Only one step is necessary to release the energy
• The amount of energy released is small enough to
  be useful.

6
Aim of respiration

• Synthesis of ATP

7
Carbohydrate is the major substrate for
respiration

• Soluble carbohydrates exist so they can easily
  be transported
• Insoluble carbohydrates exist so they can be
  easily stored

8
Overview

• Four stages-
• 1. Glycolysis
• 2. Link reaction
• 3. Krebs cycle
• 4. Hydrogen / electron
• carrier system

9
GLYCOLYSIS

• Occurs in cytoplasm
• Starts with Glucose
• 6 carbon compound

10
GLYCOLYSIS

• Ends with Pyruvate
• 3 carbon compound

11
Glucose to TP

• 2 molecules of ATP are invested

12
(No Transcript)
13
TP to Pyruvate

• Triose phosphate is converted to pyruvate
• (there are a number of intermediate stages)

14
(No Transcript)
15
Energy is recovered

• ATP is made
• Hydrogen is released and NAD is reduced

16
(No Transcript)
17
Over all

• Net production of 2 ATP molecules from each
  molecule of glucose
• and
• 2 reduced NAD molecules

18
Pyruvate moves into the mitochondria
19
Precisely

• Into the matrix

20
LINK REACTION

• Pyruvate is converted into
• acetyl coenzyme A

21

• Pyruvate
• 3 carbon compound
• Acetyl coenzyme A
• 2 carbon compound

22
Oxidative but no oxygen is involved

• Hydrogen is removed
• Combines with NAD
• Producing reduced NAD

23
KREBS CYCLE

• Acetyl Co A (2 carbon compound)
• Combines with a 4 carbon compound
• Producing a 6 carbon compound

24
In a number of steps

• 6 carbon compound breaks down to form the same 4
  carbon compound that combined with acetyl co A
• Hence the Krebs CYCLE

25
What is released?

• Carbon in the form of carbon dioxide
• Hydrogen combining with NAD and another
  coenzyme, FAD to form
• reduced NAD and reduced FAD

26
Anything else?

• There is enough energy released in one of the
  steps to join ADP and Phosphate to make ATP

27
ELECTRON / HYDROGEN CARRIER SYSTEM

• Carriers are in the inner membrane
• Cristae

28
Hydrogen atoms

• From hydrogen carriers
• reduced NAD and reduced FAD
• Accepted by the carriers in the membrane

29

• Hydrogen atoms break down to electrons and
  hydrogen ions (protons)
• Protons build up between the two membranes of the
  mitochondria

30

• Protons move back into the matrix
• Through an enzyme ATP synthetase
• ADP and phosphate join forming ATP

31

• The protons rejoin with electrons and oxygen to
  form water

32
Oxidative phosphorylation

• Phosphate is added to ADP
• phosphorylation
• The energy for the process is the result of the
  removal of hydrogen oxidation

33
Role of oxygen

• Oxygen is the terminal electron acceptor in the
  electron carrier system

34
Oxidation

• Oxidation occurs more than once in respiration
• BUT
• In glycolysis
• the link reaction
• Krebs cycle
• It is the removal of hydrogen

35
Oxidation

• Only in the electron carrier system is oxygen
  needed

36
Aerobic and anaerobic respiration
37
(No Transcript)
38
Fermentation

• Anaerobic respiration
• Occurs when oxygen is limited

39
NAD is oxidised

• Hydrogen combines with pyruvate
• Forming -
• lactate in animals
• ethanol in plants / fungi

40
Glycolysis can continue

• Producing some ATP
• Forming 2 ATP per glucose molecule
• Compared with 38 ATP per glucose molecule with
  aerobic respiration