1. Photosynthesis and Cellular Respiration

3. Photosynthesis Needed in order for life to survive on Earth
Photosynthesising organisms contain chloroplasts that trap the Sun’s energy
converted into chemical energy and stored as sugars and carbohydrates
Other products produced by the Sun’s energy are oxygen, ATP and heat

4. Cellular Respiration
Used by plants, animals and other multicellular organisms
The break down of energy-rich compounds to release stored energy
broken down inside the mitochondria
This makes ATP

6. ATP Supplies the energy for cellular activities
Used rapidly so cells must be constantly creating it
Used for: active transport, movement of chromosomes, movement of muscles, cilia or flagella, etc.

7. ATP produces energy by breaking a bond to a phosphate group
this produces ADP (adenosine diphosphate) and a free phosphate group
ATP → ADP + P
This process works in reverse to create more ATP

9. Oxidation and Reduction
When atom or molecule loses an electron, it is said to be oxidized
When an atom or molecule gains an electron, it is said to be reduced
Electrons lost by one atom or molecule are gained by another
Atoms or molecules in their reduced form have more energy

11. Chloroplasts leaves are the primary photosynthetic organs of plants
contain chlorophyll inside chloroplasts

12. have two membranes: outer membrane and an inner membrane
the membranes enclose an interior space filled with a protein-rich semi liquid material known as stroma
thylakoids: membrane-bound sacs found within the stroma
these thylakoids stack on top of one another to form columns called grana

13. most chloroplasts have about 60 grana which each have about thylakoids (each chloroplast has thylakoids)
grana are connected by unstacked thylakoids called lamellae
photosynthesis occurs partly within the stroma and partly in the thylakoid membrane
thylakoid membranes enclose a space called the thylakoid lumen

15. Chlorophyll All photosynthetic organism contain chlorophyll
the two main types of chlorophyll: chlorophyll a (blue-green) and chlorophyll b (yellow-green)
they absorb photons with energies in the blue-violet and red regions and reflect everything else

17. Chlorophyll a and b
chlorophyll a is the only pigment that can transfer the energy from sunlight to photosynthesis
chlorophyll b acts as an accessory pigment (“helper”) to catch the photons a misses and transfer the energy absorbed to a
there are other compound, carotenoids, are also “helper” pigments

18. Why do leaves change color?
in winter there is not enough light or water for photosynthesis to occur
plants begin to break down the chlorophyll they have and stop making more
the green color disappears and other colors start to appear (yellow, orange, red)
these colors were always there they were just covered up by the green chlorophyll

19. Mitochondria
Mitochondria enable cells to extract energy from food (where cellular respiration occurs)
Are bound by two membranes
The fluid filled space of the inner membrane is the matrix
The inner membrane has many folds known as cristae to increase the surface area

21. The Process of Photosynthesis
Section 5.2

22. Plants

23. Various energy containing molecules are formed during photosynthesis:
1) Glucose
- energy storage in most cells
2) ATP (adenosine triphosphate)
- used by all living cells for immediate energy

24. 3) NADPH
- starts as NADP+ (nicotinamide dinucleotide phosphate)

25. Light-dependent reactions Light-independent reactions
Throughout the process of photosynthesis there are two different types of reactions that occur:
Light-dependent reactions
Makes ATP and NADPH
Light-independent reactions
Uses the ATP and NADPH to make glucose

26. Light-Dependent Reactions
Requires sunlight in order to work
require chlorophyll; occur in the thylakoid
involves photosystems
photosystems I and II
responsible for capturing light energy

28. solar energy is captured when an electron in a chlorophyll molecule absorbs a photon (photosystem II)
electrons go from low energy to high energy
the “excited” electron is removed from photosystem II and passed through an electron transport chain

29. Once the excited electron has left photosystem II there are four steps that occur
The electron that left photosystem II needs to be replaced before more light can be absorbed
This is done through photolysis (ie. splitting of H2O)

30. Step 2:
The electron in the electron-transport chain is passed from molecule to molecule
As it is passed along it releases energy
This energy pull hydrogen ions from the stroma into the thylakoid lumen

31. Step 3:
Light hits photosystem I
An electron in this photosystem is ‘excited’ and passed onto the smaller electron transport chain

32. Step 4:
The electron that went from photosystem I to the next electron transport chain is used to reduce NADP+ to make NADPH

33. Chemiosmosis
The H+ ions in the thylakoid lumen are unable to escape except through special proteins called ATP synthase complexes
As the H+ ions move through this complex they release energy
The complex uses some of this energy to combine ADP with Pi making ATP
This ATP then moves onto the light- independent reaction to make glucose

36. Light-Independent Reactions

37. Light-Independent Reactions
pHrs
does not require light
Also known as the Calvin-Benson cycle
Will occur when enough NADPH and ATP have been produced
Figure 5.14, page 177

38. Occurs in three stages:
Step 1: Fixing Carbon Dioxide
6 Carbon dioxide molecules bond to 6 five- carbon compounds known as RuBP (ribulose bisphosphate)
This makes 6 six carbon compounds that are unstable
Breaks into 12 three-carbon compounds

39. Step 2: Reduction
The 3-carbon compounds are activated by ATP (given energy) and then reduced by NADPH (given more energy)
The 12 molecules are now known as G3P
2 G3P molecules move on to make glucose, 10 go to Step 3

40. Step 3: Replacing RuBP
Remaining G3P will be used to make more RuBP
ATP will help break and reform the chemical bonds to make the 5-carbon RuBP