1. PHOTOSYNTHESIS Chapter 6

2. The main form of energy from the sun is in the form of electromagnetic radiation
Visible radiation (white light) used for photosynthesis
Remember :
ROY G. BIV?
Living things require energy to stay alive.
The main energy input is fr/ sun.
Wavelength - (crest to crest)
The sun produces many wavelengths but only visible radiation is used for photosynthesis.

3. Why are plants green? pigment a compound that absorbs light
different pigments absorb different wavelengths of white light.
chlorophyll is a pigment that absorbs red & blue light so green is reflected or transmitted.
Chlorophyll is located in the thylakoid membranes
So, Plants are green because the green wavelength is reflected, not absorbed.
Photosynthesis cannot occur w/out chlorophyll.

4. 2 types of chlorophyll Chlorophyll a – involved in light reactions
Chlorophyll b – assists in capturing light energy – accessory pigment
Carotenoids – accessory pigments – captures more light energy
Red, orange & yellow

5. The electromagnetic wavelengths and the wavelengths that are absorbed by the chlorophyll

6. Photosynthesis is -
conversion of light energy into chemical energy that is stored in organic compounds (carbohydrates > glucose)
Used by autotrophs such as:
Plants
Algae
Some bacteria (prokaryotes)
Remember…
Autotrophs (producers) – produce energy fr sunlight
Heterotrophs (consumers) – get energy fr eating autotrophs or heterotrophs-
Bacteria example - cyanobacteria

7. glucose - energy-rich chemical produced through photosynthesis
C6H12O6
Biochemical pathway – series of reactions where the product of one reaction is consumed in the next
E.g. photosynthesis product is glucose which is used in cellular respiration to make ATP
(carbohydrate)
glucose (sugar is carbohydrate).

9. Photosynthesis equation
Light energy
6CO2 + 6H2O C6H12O6 + 6O2
Chlorophyll
Reactants: Carbon dioxide and water
Products: glucose and oxygen which is a byproduct
In words…
6 carbon dioxide molecules plus 6 water molecules with sunlight in the presence of chlorophyll will yield glucose and oxygen

10. Where does photosynthesis take place?
Mainly occurs in the leaves:
a. stoma - pores
b. mesophyll cells
Mesophyll
Cell
Chloroplast
Stoma

11. Stomata (stoma)
Pores in a plant’s cuticle through which water vapor and gases (CO2 & O2) are exchanged between the plant and the atmosphere.
Guard Cell
Oxygen
(O2)
Stoma
Carbon Dioxide
(CO2)
Found on the underside of leaves

12. Chloroplast Organelle where photosynthesis takes place.
Stroma
Outer Membrane
Thylakoid
Granum
Inner Membrane
Thylakoid stacks are connected together

13. Parts chloroplasts – membrane organelle that absorbs light energy
Thylakoids – flattened sacs contain pigment - chlorophyll
Grana (pl: granum) – layered thylakoids (like pancakes)
Stroma – solution around thylakoids
Stomata – pore on underside of leaf where O2 is released and CO2 enters

14. Energy for Life on Earth
Sunlight is the ULTIMATE energy for all life on Earth
Plants store energy in the chemical bonds of sugars
Chemical energy is released as ATP during cellular respiration

15. Structure of ATP ATP stands for adenosine triphosphate
It is composed of the nitrogen base ADENINE, the pentose (5C) sugar RIBOSE, and three PHOSPHATE groups
The LAST phosphate group is bonded with a HIGH ENERGY chemical bond
This bond can be BROKEN to release ENERGY for CELLS to use

16. Photosynthesis SUN Photosynthesis can be divided into two stages:
1. Light Reaction -
Produces energy from solar power (photons) in the form of ATP and NADPH.
2. Calvin Cycle
Also called Carbon Fixation,Uses Co2 & energy (ATP and NADPH) from light reaction to make sugar (glucose).

17. 2 stages of photosynthesis-
The Process of Photosynthesis does NOT Happen all at Once; it occurs in  THREE STAGES:
NADP+ is organic compound that accepts electrons (Nicotinamide adenine dinucleotide phosphate)

18. STAGE 1: Light Reaction (Electron Flow)
Occurs in the Thylakoid membranes

19. Photosystem I and II Step 1 – light excites e- in photosystem II
Step 2 – e- move to primary e- acceptor Step 3 – e- move along electron transport chain (etc)
Step 4 – light excites e- in photosystem I
Step 5 – e- move along 2nd (etc)
End – NADP+ combine H+ to make NADPH
Step 1 – light excites e- in chlorophyll a of photosystem II
Step 2 – e- move to a primary e- acceptor (redox occurs)
Step 3 – e- transferred along electron transport chain
Step 4 – light excites e- in chlorophyll a of photosystem I
Step 5 – e- from photosystem I are transferred along a 2nd electron transport chain
End – combine with NADP+ and H+ to make NADPH

20. Chemiosmosis – synthesis of ATP
Powers ATP synthesis
Takes place across the thylakoid membrane
Uses ETC and ATP synthase
H+ move down their concentration gradient forming ATP from ADP
Concentration of protons is greater in thylakoid than stroma
Concentration gradient is potential energy (remember: concentrations move fr high to low)
ATP Synthase converts potential energy of/ protons concentrated gradient into chem energy of ATP across thylakoid membrane
ATP synthase – multifunctional protein - carrier protein that harnesses energy in thylakoid membrane AND enzyme b/c it catalyzes ATP
How? Makes ATP by adding phosphate group to ADP (adenosine diphosphate)

21. ELECTRON TRANSPORT CHAIN ANIMATION

22. STAGE 2: CALVIN CYCLE
Biochemical pathway in photosynthesis that produces organic compounds (Glucose) using ATP & NADPH from the light reactions of photosynthesis
Carbon fixation – carbon atoms from CO2 are bonded or ‘fixed’ into carbohydrates
occurs in stroma
The Calvin cycle – part of photosynthesis that fix carbon from atmospheric CO2 into organic compounds – carbohydrates - sugar.
Remember – sugar is C6H12O6
The Calvin cycle reactions do not require light directly, but reduction of CO2 to sugar requires the products of the light reactions