1. Photosynthesis & Cellular respiration

2. Remember…Characteristics of Living Things
made up of units called cells
reproduce
based on a universal genetic code (DNA)
grow and develop
obtain and use materials and energy (metabolism)
respond to their environment (adapt)
maintain a stable internal environment (homeostasis)
taken as a group, organisms evolve

3. Energy and Life

4. Energy Energy: the ability to do work
Living things must be able to obtain and use energy in order to exist.
ATP (adenosine triphosphate) – chemical compound that living things use to store energy

5. ATP is made of adenine, ribose (sugar), and 3 phosphate groups.
Energy is stored in bonds between the phosphate groups.
When a cell needs energy, one of the phosphates is removed (leaving ADP or adenosine di-phosphate).
Energy that had been stored in the bond can now be used by the cell.
Chemical Energy & ATP

6. ATP can be compared to a rechargeable battery.
Charged battery
ADP
Partially charged battery (needs charging)

7. ATP and Glucose (C6H12O6) Most cells have only a small amount of ATP
Lasts for a few seconds of activity
Efficient at transferring energy but not for storing energy over a long term
A single sugar molecule stores more than 90 times the energy of 1 molecule of ATP!
Cells can regenerate ATP from ADP as needed by using the energy in carbohydrates like glucose

8. So…where do living things get energy?
To live, all organisms need food and must release energy from that food.
FOOD

9. So…how do living things get food?
Autotrophs
Organisms that make their own food through photosynthesis (AKA: producer)
Examples: plants, some protists, certain bacteria
Chemosynthesis: process by which ATP is synthesized by chemicals as an energy source instead of light
Heterotrophs
Organisms that consume or eat food (AKA: consumer)
Examples: animals, fungi, some bacteria, some protists

10. Photosynthesis: An Overview

11. Photosynthesis… Plants, algae, and some bacteria
Reactants
Products
Sunlight
H20 (water)
CO2 (carbon dioxide)
C6H12O6 (glucose)
O2 (oxygen)
Light energy is converted into chemical energy!

12. Photosynthesis Equation
Photosynthesis: a process that uses the energy of sunlight to convert water and carbon dioxide into glucose and oxygen
  6CO H2O sunlight C6H12O O2
(carbon dioxide) (water) (glucose) (oxygen)

13. The Reactions of Photosynthesis

14. Inside a Chloroplast Photosynthesis takes place within chloroplasts.
Thylakoid membranes (labeled B) – saclike membranes in the chloroplasts that contain chlorophyll to capture energy from the sun
Light dependant reactions take place within the thylakoids.
Stroma (labeled A) – fluid outside the thylakoid membranes
Light independent reactions (Calvin Cycle) takes place within the stroma.

15. Reactions of Photosynthesis: Light Dependent reactions
Requires water and light which is captured by the chlorophyll
Converts ADP and NADP+ into ATP and NADPH which are energy carriers needed to provide energy for the Calvin Cycle
Releases oxygen as waste
Reactions of Photosynthesis: Light Dependent reactions

16. light
6CO2 + 6H2O  C6H12O6 + 6O2
carbon dioxide water carbon sugar: glucose oxygen gas

17. The second stage of photosynthesis uses energy from the first stage to make sugars

18. Converts carbon dioxide into glucose
Reactions of Photosynthesis: Calvin cycle or light-independent reactions
Requires energy from ATP and NADPH produced during the light dependent reaction
Converts carbon dioxide into glucose
Regenerates ADP and NADP+ which go back to the light-dependent reactions for re-charging

19. Overview of the light-independent reactions
6CO2 + 6H2O  C6H12O6 + 6O2
carbon dioxide water glucose oxygen gas

20. Factors Affecting Photosynthesis
photosynthesis occurs best between 0C and 35C; above or below this temp the enzymes that control photosynthesis are affected so photosynthesis slows down
Temperature
photosynthesis requires water so low water availability would slow down the rate of photosynthesis
Water
more light would speed up the rate of photosynthesis; eventually the rate reaches a maximum rate that it cannot exceed
Light

21. Functions of photosynthesis
Does more than make sugars!
Provides materials for plant growth and development
Removes CO2 from the atmosphere

22. How We Came to Understand Photosynthesis

23. The Question: How does a tree increase its mass. From the soil
The Question: How does a tree increase its mass? From the soil? From the water? From the air?

24. Van Helmont’s Experiment (1643)
Concluded that it was water!!

25. Priestley’s Experiment (1771)
Candle burned in the presence of oxygen
A candle could be relit near a plant and it would burn longer because the plant released oxygen

26. Ingenhousz’s Experiment (1779)
Showed Priestley’s experiment only worked when the plant was exposed to light
Light is necessary for plants to produce oxygen

27. Photosynthesis completed!

28. But wait… How do leaves change color?

29. Absorption of Light Energy
Light energy is a form of radiation
Energy in the form of waves that travel through space
Different types of radiation (i.e. light, heat) have different wavelengths

30. Pigment Chlorophyll Carotenoid
A light-absorbing substance that gives another substance or mixture its color
Absorbs certain wavelengths and reflect others
Chlorophyll
Green Pigment
Absorbs violets, blues and reds and reflects greens and yellows
Therefore plants exhibit green and yellow colors
Carotenoid
A pigment that absorbs mostly blue and green light
Therefore it produces yellow and orange fall leaf colors
Color of many fruits, vegetables and flowers

31. Leaf Color Comes From Pigments
Chlorophyll (green)
Carotenoid (yellow, orange, and brown)
Anthocyanins (red)
Chlorophyll covers the carotenoid -- that's why summer leaves are green, not yellow or orange
Trees respond to the decreasing amount of sunlight in the fall by producing less and less chlorophyll

32. Leaf Color Comes From Pigments
Eventually, a tree stops producing chlorophyll
When that happens, the carotenoid already in the leaves can finally show through
The leaves become a bright rainbow of glowing yellows, sparkling oranges and warm browns

33. PART II

34. Is like a mirror of photosynthesis
Cellular respiration
Is like a mirror of photosynthesis

35. Cellular respiration makes atp by breaking down sugars
Reactants
Products
H20 (water)
CO2 (carbon dioxide)
Energy (ATP)
C6H12O6 (glucose)
O2 (oxygen)

36. Chemical Energy and Food
Food provides cells with energy and serves as raw materials for building new molecules.
How do organisms get the energy from their food?
Cells release energy from glucose and other food compounds by the processes of cellular respiration, fermentation, or both.

37. Cellular Respiration C6H12O6 + 6O2  6CO2 + 6H2O + energy enzymes
Glucose oxygen gas carbon dioxide water ATP

38. Overview of Energy Releasing Processes
Cellular Respiration
a process that produces energy (ATP) by breaking down food molecules in the presence of oxygen
Fermentation
a process that produces energy (ATP) by breaking down food molecules in the absence of oxygen

39. The first process cells use to break down food and release energy.
Occurs in the cytoplasm and breaks glucose in half into 2 pyruvic acid molecules creating 2 ATPs.
Glycolysis

40. Cellular Respiration
When oxygen is present, products of glycolysis enter Krebs Cycle and electron transport chain (in mitochondria).
36 ATPs produced during cellular respiration.
Carbon dioxide and water are waste.

41. Fermentation
When oxygen is NOT present, products of glycolysis go through fermentation instead.
Fermentation regenerates starting materials of glycolysis so glycolysis can continue making ATP (only 2 ATPs).
Alcoholic fermentation
Lactic acid fermentation

42. Alcoholic vs. Lactic Acid Fermentation
Alcoholic Fermentation
performed by yeast and other microorganisms
used in bread and alcohol industries because alcohol and carbon dioxide are waste products
Lactic Acid Fermentation
occurs in muscle cells during strenuous exercise when cells aren’t getting enough oxygen
lactic acid produced as a waste product causes muscles to burn during a strenuous workout

43. Comparing Photosynthesis & Cellular Respiration
Function
to store energy by making food
to release energy by breaking down food
Location
Chloroplasts
Mitochondria
Reactants
Carbon Dioxide + Water + Sunlight
Glucose + Oxygen
Products
Carbon Dioxide + Water + Energy
Equation
6H2O + 6CO2 C6H12O6 + 6O2
C6H12O6 + 6O2
6H2O + 6CO2
Organisms
autotrophs
autotrophs and heterotrophs

44. The Cycle of Matter and Energy
sunlight
Photosynthesis and Cellular Respiration work together to cycle matter and energy
CO2 + H2O
O2 + C6H12O6
ATP

45. Remember…Characteristics of Living Things
made up of units called cells
reproduce
based on a universal genetic code (DNA)
grow and develop
obtain and use materials and energy (metabolism)
respond to their environment (adapt)
maintain a stable internal environment (homeostasis)
taken as a group, organisms evolve