1. Chapter 8 Topic 8: Cell Respiration and Photosynthesis
Mrs. Ragsdale
Biology SL/HL
Chapter 8 Topic 8: Cell Respiration and Photosynthesis

2. 8.1 Cell Respiration

3. Lil bit of chemistry review
Oxidation and Reduction reactions
Oxidation – loss of an electron
Reduction – gain of an electron
Typically involve trading H⁺ ions

4. Oxidation vs Reduction
Oxidation reactions
Reduction reactions
Loss of electrons
Gaining oxygen
Loss of hydrogen
Gain of electrons
Losing oxygen
Gain of hydrogen

5. Major Lingo Used: Phosphorylation: addition of phosphate groups
Makes reactions that occur in a chain or pathway easier by adding energy
Dephosphorylation: removal of phosphate
Oxidation: loss of hydrogen
Reduction: gain of hydrogen
If compound A is oxidized, then compound B is reduced

6. Cell Respiration: 3 Step Process
Glycolysis – Sugar is converted into pyruvate
Can be aerobic (with oxygen) or anaerobic (without oxygen)
Krebs Cycle – pyruvate is used to charge electron carriers
Link Reaction (happens before Kreb’s Cycle)
Electron Transport Chain – electrons create a hydrogen proton gradient that fuels ATP pumps

7. Cellular Respiration Overview

8. Cytoplasm
Glycolysis – Breakdown of glucose into pyruvate

9. Glycolysis – Converting glucose into pyruvate
4 Step Process:
Two phosphate groups added to one molecule of glucose
Phosphorylation – adding a phosphate group
This raises the energy level and powers the rest of the reaction
Hexose biphosphate is split to form two molecules of triose phosphate.

10. Glycolysis continued
Two atoms of hydrogen are removed from each triose phosphate molecule (oxidation).
When hydrogen bonds break, a large amount of energy is released carrying into the next step.
NAD⁺ is converted into NADH
Extra phosphates that were added are then removed  Pyruvate
End result: 2pyruvate + 2NADH + 2H⁺

11. Breakdown of Steps Add 2 Phosphate to glucose (phosphorylation)
Split this in half and make triose phosphate
Remove 2 hydrogen (oxidation) and make glycerate 3-phosphate
Remove extra phosphates
Net: 2 ATP and 2 NADH + 2H⁺

13. Glycolysis Summary One glucose molecule (C₆H₁₂O₆)
Breaks down into two pyruvate molecules
Two ATP molecules are used per glucose but 4 are produced => net yield of 2 ATP
Two NAD⁺ molecules converted into NADH + H⁺

14. Aerobic vs Anaerobic Respiration
At the end of glycosis a choice must be made!
Oxygen present = pyruvate proceeds to the mitochondria
Oxygen absent = pyruvate is turned into some form of waste
2 ATP is all the energy created

15. Pyruvate’s Fate WITHOUT Oxygen
Anaerobic respiration – when no oxygen is present.
Occurs In the cytoplasm
After glycolysis, pyruvate is converted to a waste product
NO ENERGY IS OBTAINED OR USED
Waste in humans is Lactate (Lactic Acid)
Waste in Yeast is Ethanol and Carbon dioxide

16. Pyruvate’s Fate WITH Oxygen
Aerobic Respiration- when oxygen is present
Occurs in mitochondria
After glycolysis, pyruvate is broken down in the mitochondria
LARGE yield of energy (34 ATP)
Waste products are CO2 and H2O

17. The Mitochondria
Link Reaction, Kreb’s Cycle and Electron Transport Chain

18. Draw and Label: Electron micrograph of Mitochnodria
Outer mitochondrial membrane
Inner mitochondrial membrane
Space between inner and outer membrane
Matrix
70s ribosomes
Cristae

19. Link Reaction: Beginning of the Kreb’s Cycle
Pyruvate is decarboxylated once (CO2 is removed) and oxidized once (H⁺ is removed)
Forms an acetyl group

20. Kreb’s Cycle
Involves 2 additional decarboxylations and four more oxidations
Product gained: high energy electron carrier = NADH and FADH₂

21. Types of Reactions in Kreb’s Cycle
Decarboxylation – carbon dioxide is removed
Remember, CO₂ is a waste product!
Oxidation – hydrogen removed
NAD⁺ becomes NADH
FAD⁺ becomes FADH₂
Both of these reactions release/store energy
Substrate-level phosphorylation
Requires the addition of ATP

22. Kreb’s Cycle

23. Electron Transport Chain
A series of electron carriers located in the inner membrane of the mitochondrion
Oxidative Phosphorylation – the energy released by oxidation turning causing ADP to be phosphorylated into ATP
Chemiosmosis – the coupling of ATP synthesis to electron transport via a concentration gradient of protons

24. Electron Transport Chain – in a nutshell
NADH and FADH₂ donate H⁺ protons along the inner membrane wall creating a high concentration gradient of protons within that small space
An ATP synthase pump works to phosphorylate the ADP into ATP using the H⁺ ions to fuel the pump

27. Oxygen’s Big Star Role
So what happens to the extra H⁺ ions and why is it so important that oxygen be there?
After the ATP synthase “pump” is turned and ATP is created, the H⁺ protons must bond with something
Only if Oxygen is present and available to bind with H⁺ creating H₂O can the additional 30 ATP be made. If no oxygen is present, the extra H⁺ build up will trigger pyruvate to be converted into waste products (lactic acid in humans)

28. Functions of Mitochondrial Structure
Outer mitochondrial membrane – separates the contents of the rest of the cell creating a compartment with ideal conditions for aerobic respiration
Inner mitochondrial membrane – contains electron transport chains and ATP synthase which carry out oxidative phosphorylation
Matrix – fluid inside the mitochondrion containing enzymes for the Kreb’s cycle and the link reaction
70s ribosomes
Loop of DNA

29. Functions of Mitochondrial Structure
Cristae – Tubular shelf-like projections that increase the surface area of the inner membrane making more space for oxidative phosphorylation
Space between inner and outer membrane – Protons are pumped into this space by the electron transport chain
Small space allows for a high proton gradient for chemiosmosis

30. Oxidative Phosphorylation
ADP is phosphorylated into ATP using energy released by the oxidation of NADH into NAD⁺
Phosphorylation – a fancy pants science word for adding a phosphate to ADP
Oxidative – basically oxidation (removing Hydrogen) powers something

31. Chemiosmosis Occurs in the inner mitochondrial membrane
H⁺ protons form a gradient in the intermembrane space of the mitochondria
Protons escape back to the matrix via the ATP pump