1. Energy for life’s activities
Cellular Respiration
Energy for life’s activities

2. Overview of Cellular Respiration
The life processes of all organisms require energy.
The potential energy held in the bonds of food molecules CANNOT be used directly by the cell.
Energy from food must be converted to the ONLY energy source that cells can use ATP!

3. Cellular Respiration
Respiration is the process by which the energy in the bonds of nutrients are used to synthesize ATP.
Respiration occurs continuously in all cells of all organisms.

4. Anaerobic Respiration
Also called fermentation
No oxygen is present
1 Glucose only partially broken down to form waste products and 2 ATP

5. Anaerobic Pathways Glucose  2 lactic acid + 2 ATP
Happens in muscle cells when they run out of oxygen
Happens in bacteria that make yogurt, cheese, dill pickles
Glucose  2 ethanol + 2 CO2 + 2 ATP
Happens in some bacteria
Happens in YEAST

6. Aerobic Respiration Has to have oxygen VERY EFFICIENT
Most organisms on earth are aerobic
1 glucose completely broken down to carbon dioxide and water.
C6H12O6 + 6 O2  6 CO2 + 6 H2O + E

7. Aerobic Pathway Takes place mostly in mitochondria 3 primary steps:
Glycolysis in cytoplasm: produces pyruvate and 2 net ATP (anaerobic)
Kreb’s cycle in matrix of mitochondria: converts pyruvate to Acetyl-CoA (aerobic, makes carbon dioxide)
Electron transport chain on membrane of mitochondria: moves electrons to produce 34 ATP (aerobic, makes water)

8. Comparing Aerobic & Anaerobic Cellular Respiration Pathways
Aerobic (needs oxygen)
Anaerobic
(no oxygen)
Occurs in:
Most organisms
Mostly yeast and bacteria
1 glucose makes:
6 CO2 + 6 H2O
Ethanol + CO2 or lactic acid
Net ATP production: 36 2

9. Adaptations for Respiration
Bacteria, protists & fungi
Respiratory gases are exchanged by diffusion
Plants
Respiratory gases are exchanged through leaves, stems, and roots
Moves in and out of cells by diffusion but leaves and stems also have openings to the environment (stomata and lenticels)

10. Adaptations for Respiration in Animals
Techniques vary:
Simple diffusion across cell membranes
Diffusion across moist skin into a circulatory system
Openings to the environment that can be flapped open and closed with a circulatory system to transport gases
Specialized respiratory structures (e.g. lungs) to speed exchange of respiratory gases