1. Photosynthesis and Cellular Respiration
CELL ENERGETICS
Photosynthesis and Cellular Respiration

2. Photosynthesis All energy for Earth is from the sun.
Photoautotrophs- organisms that convert light energy to chemical energy.
This process is called photosynthesis and is summarized in the equation:
light energy
6H2O + 6CO2 6O2+ C6H12O6

3. Photosynthesis Occurs in chloroplasts of plant cells
2 sets of reactions
Light dependent reactions
occur in thylakoid- flattened membrane sac
use water and light energy
Produce Oxygen
Light independent reactions
occur in stroma
use carbon dioxide
produce Carbohydrates.

4. Light Dependent Reactions
Sunlight strikes chlorophyll molecules activating them
Photolysis- occurs when the energy of sunlight splits water molecules
Oxygen atoms are released as O2
Hydrogen atoms are stripped of their electrons
The electrons pass to the electron carrier NADP+ forming NADPH and H+.
H+ forms a concentration gradient
The concentration gradient drives ATP Synthase to make ATP

5. Light Independent Reactions

6. Light Independent Reactions
CO2, ATP, and electrons carried by NADP+ are used to build sugar.
The molecule RuBP rearranges CO2 making the molecule PGA .
PGA is converted to PGAL, using ATP and the NADP+.
Some PGAL is made into glucose; some regenerates RuBP to continue the process.

7. Light Dependent Reactions
Photosynthesis
Water O2
CO2
Carbohydrates
Light Dependent Reactions
ATP + NADPH + H+
ADP + Pi + NADP+
RuBP PGAL
Light Independent
Reactions

8. Cellular Respiration
Both autotrophs and heterotrophs must convert glucose to ATP (the energy currency of the cell) first, then use it to drive any metabolic activity.
This process is cellular respiration and is summarized in the equation:
C6H12O6 + 6O2 6H2O + 6CO2 + ATP
Aerobic organisms use cellular respiration
Aerobic = oxygen using

9. Cellular Respiration
Occurs in cytoplasm & mitochondria of eukaryote cells
3 sets of reactions
Glycolysis occurs in cytoplasm
breaks down glucose to pyruvate
produces 2 molecules of ATP.
Kreb’s Cycle occurs in matrix of mitochondria
breaks down pyruvate
produces CO2 and 2 molecules of ATP.
Oxidative phosphorylation occurs in mitochondrial matrix
uses oxygen
produces 32 molecules of ATP.

10. Glycolysis
Glycolysis breaks down glucose (6-carbon sugar) into 2 molecules of pyruvate (3-carbon intermediate)
some hydrogen atoms are stripped of electrons,
electrons are passed to the carrier NAD+, forming NADH and H+
Glycolysis uses 2 ATP to rearrange glucose
produces 4 ATP
net total of 2 ATP are made by glycolysis

11. Kreb’s Cycle Pyruvate changes into Acetyl-Coenzyme A in the cytoplasm
Acetyl-CoA moves to the mitochondrial matrix,
In a series of reactions
carbon and oxygen molecules are pulled off to release CO2
electrons are passed to NAD+ and FAD
forms NADH and FADH2 and many H+ ions.
produces 2 molecules of ATP each time the cycle runs

13. Oxidative Phosphorylation
Only NADH and FADH2 and H+ move into the mitochondrial membrane
Electrons from hydrogen pass through a series of enzymes and finally to oxygen (the electron acceptor) making O2
As in light dependent reactions, H+ protons develop a steep concentration gradient, driving ATP synthase to produce ATP
32 molecules of ATP are produced.

14. Cellular Respiration Electrons carried via NADH
GLYCOLYSIS
Glucose  Pyruvate
KREB’S CYCLE
OXIDATIVE PHOSPHORYLATION
ATP ATP, CO ATP, H2O
Electrons carried via NADH
Electrons carried via NADH and FADH2 O2

15. Fermentation
Aerobic cellular respiration occurs only when Oxygen is present.
Without oxygen, anaerobic respiration takes place.
Glycolysis occurs.
Fermentation- After glycolysis, pyruvate is converted to lactic acid or ethanol
Fermentation involves very few chemical reactions,
but only makes 2 molecules of ATP.