1. Cell Energy: Photosynthesis & Respiration

2. Today’s Learning Goals
In plants, chlorophyll (found in chloroplasts) captures energy from the sun in order to make food during photosynthesis
Cells release energy from food through either cellular respiration or fermentation
Why it matters: Understanding how plants & animals get energy to grow & develop is an important part of biology.

3. How Does a Plant Make It’s Own Food?
Plants use carbon dioxide (CO2), water (H2O), and sun’s energy to make food.
This is called “photosynthesis”
The food gives plants energy
Animals get the energy stored in plants when they eat them.

4. How Do Plants Get Energy From Sun?
Plants have pigments that absorb energy from light
Chlorophyll (found in chloroplasts) is the pigment used in photosynthesis

5. What “Food” do Plants Make?
The “food” plants make is a sugar called glucose (C6H12O6).
Glucose and oxygen (O2) are made during photosynthesis.

6. Inside a Chloroplast where Photosynthesis Occurs
Stroma-space between grana
Granum-stacks of thylakoids
Thylakoids-structures that contain chlorophyll

7. Light Reactions and the Calvin Cycle
Green-Light Rxns
Blue-Calvin Cycle (Light Independent Rxns)
GlucoseC6H12O6
Chloroplast

8. How Do Organisms Get Energy From Food?
Animals cannot make their own food like plants can.
But, BOTH plants and animals must break down (digest) food in order to get energy from it (so they can live, grow, & develop)
Cells do this 2 ways: cellular respiration and fermentation

9. Cellular Respiration & Fermentation
Cellular Respiration uses oxygen (O2) to break down food
Fermentation does not use oxygen
Cellular respiration releases more energy from food than fermentation (38 ATP
per molecule glucose
vs. 2 ATP)
So most eukaryotes (plants, fungi,
protists & animals) get their energy through cell respiration

10. Where Cellular Respiration Occurs
Cellular Respiration is a chemical process that happens in cells
In prokaryotes, it happens in the cell membranes
In eukaryotes, it happens mostly in the mitochondria

11. Process of Cellular Respiration
Food (glucose) is broken down into CO2 and H2O and energy is released
C6H12O6 + 6 O2  6 CO2 + 6 H2O + energy (ATP)
This energy can be used for:
Keeping a constant body
temperature
Storage (ATP) - to be used
later for metabolic processes
(growth, development,
reproduction, etc…)

12. Cell Respiration Occurs in the Mitochondria

13. The Three Stages of Cell Respiration
Glycolysis-”sugar spliting”, glucose is broken down into two pyruvate (pyruvic acid) molecules in the cytoplasm. Two ATP molecules are formed.

14. When Oxygen is Present (aerobic)
2. Kreb’s Cycle, or the Citric Acid Cycle-pyruvate enters the mitochondron. Through a series of reactions, the carbon atoms in pyruvate are rearranged to form more ATP and NADH, and FADH2 (energy) molecules. Carbon dioxide is released.

15. Finally…the third stage
3. The Electron Transport Chain-electrons, e-, and hydrogen ions, H+, produced in the Kreb’s Cycle, move through the inner mitochondrial membranes. This movement allows enzymes to make ATP.

16. What Do You Notice?

17. Check It Out!
Did you notice that cellular respiration is just the opposite of photosynthesis?

18. When Oxygen Is Not Present (anaerobic) Fermentation
Happens when cells cannot get the oxygen they need for cellular respiration, or in anaerobic conditions
Fermentation is a way to get energy when oxygen isn’t available
Two Types: Alcoholic Fermentation & Lactic Acid Fermentation
1. Alcoholic Fermentation in yeast
+ 2ATP
2. Lactic Acid Fermentation in muscle cells

19. Pop Quiz
1) Plants use carbon dioxide (____), water (____), and the sun’s energy to make food.
CO2 and H2O
2) What type of cell has chloroplasts?
PLANT CELL
3) BOTH plants and animals must break down food in order to get ________from it.
ENERGY
4) How are respiration and photosynthesis related?
THEY ARE THE REVERSE (OPPOSITE) OF EACH OTHER.
5) Fermentation is a way to get energy when ______ isn’t available.
OXYGEN

20. Today’s Learning Goals
In plants, chloroplasts capture energy from the sun in order to make food during photosynthesis
Cells release energy from food through either cellular respiration of fermentation
Why it matters: Understanding how plants & animals get energy to grow & develop is an important part of biology.