1. Photosynthesis and Cellular Respiration

2. Photosynthesis
Method of converting sun energy into chemical energy usable by cells
Only PLANTS engage in photosynthesis
Photosynthesis takes place in specialized structures inside plant cells called chloroplasts
Light absorbing pigment molecules e.g. chlorophyll

3. Photosynthesis
Plants capture energy by absorbing light and using it to form strong (covalent) chemical bonds between the atoms of carbon-containing (organic) molecules.
These molecules can be used to assemble larger molecules.

4. Photosynthesis Formula:
REACTANTS PRODUCTS
6CO2 + 6 H2O +Sun light energy C6H12O6 + 6O2+ 6H2O
Reactants= Carbon Dioxide and Water
Products= Glucose and Oxygen gas.

5. Photosynthesis
Plants and animals will use the “glucose” produced during photosynthesis for cellular respiration.
Photosynthesis is broken down into two independent reactions:
Light Reactions
Calvin Cycle

6. The ‘dark’ reactions of photosynthesis are the Calvin Cycle

7. Calvin Cycle Overview
The Calvin cycle is part of photosynthesis, which occurs in two stages.
In the first stage, chemical reactions use energy from light to produce ATP and NADPH. (Light Reactions)
In the second stage (Calvin cycle or dark reactions), carbon dioxide and water are converted into organic molecules, such as glucose.
Although the Calvin cycle may be called the "dark reactions," these reactions don't actually occur in the dark or during nighttime. The reactions require reduced NADP, which comes from a light-dependent reaction.

8. Cellular Respiration
Cellular respiration is a fundamental process in every organism, in which cells break down organic compounds to produce energy.
Transformation of chemical energy in food into chemical energy that cells can use, in the form of ATP.

9. Cellular Respiration REACTANTS PRODUCTS
C6H12O6 + 6O Enzymes CO2 + 6H2O + ATP
Reactants = glucose (carbohydrate) and oxygen
Products = carbon dioxide, water, and energy
BOTH plants and animals engage in cellular respiration.

10. Cellular Respiration Process
Begins with Glycolysis:
Glycolyis takes place in the cytocol of cells.
One glucose molecule is oxidized to form two pyruvic acid molecules.
This results with a net production of 2 ATP molecules and 2 NADH molecules.
If oxygen is NOT present….
Glycolysis will lead to
ANAEROBIC RESPIRATION
If oxygen IS present….
Glycolysis will lead to
AEROBIC RESPIRATION

12. Anaerobic Cellular Respiration
Some organisms thrive in environments with little or no oxygen
Marshes, bogs, gut of animals, sewage treatment ponds
No oxygen used= ‘an’aerobic
Also called Fermentation
Results in no more ATP, final steps in these pathways serve ONLY to regenerate NAD+ so it can return to pick up more electrons and hydrogens in glycolysis.

13. Examples of Anaerobic Respiration
Lactic acid fermentation in muscle cells:
An enzyme converts pyruvic acid into lactic acid
Alcoholic fermentation in yeast (beer/bread):
Other enzymes convert pyruvic acid into ethyl alcohol and carbon dioxide.

15. Aerobic Cellular Respiration
Oxygen required=aerobic
Occurs inside the Mitochondria of the cell.
2 more sets of reactions occur within the mitochondria:
2. Kreb’s Cycle
3. Electron Transport Chain

16. Kreb’s Cycle (Citric Acid Cycle)
The pyruvic acid produced during glycolysis is converted to acetyl CoA. The acetyl CoA enters the Kreb Cycle…
Kreb Cycle:
Converts Pyruvate into Carbon Dioxide
Takes the pyruvate (3-carbons) and breaks it down, the carbon and oxygen atoms end up in CO2 and H2O
Hydrogens and electrons are stripped and loaded onto NAD+ and FAD to produce NADH and FADH2
NADH and FADH2 donate their electrons to the electron transport chain in the inner mitochondrial matrix.
Each turn of Krebs cycle generates 3 NADH, 1 FADH2, 1 ATP, and 2 CO2

18. Electron Transport Chain
Electron carriers loaded with electrons and protons from the Kreb’s cycle move to this chain-like a series of steps (staircase).
As electrons drop down stairs, energy released to form a total of 32 ATP
During aerobic respiration, oxygen accepts both protons and electrons from the electron transport chain.
Oxygen waits at bottom of staircase, picks up electrons and protons and in doing so becomes water.

20. Energy Tally
Cellular respiration can produce up to 38 ATP from one single molecule of glucose:
36 ATP for aerobic vs. 2 ATP for anaerobic
Glycolysis ATP
Kreb’s ATP
Electron Transport 32 ATP
36 ATP
Anaerobic organisms can’t be too energetic but are important for global recycling of carbon