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1. Photosynthesis
2. 8-1 Energy & Life Energy is ability to do work
All living things need energy
Without energy, life would cease to exist
Energy can be light, heat, electricity, & stored in chemicals
3. Chemical Energy Living things must release ATP from compounds
Adenosine triphosphate (ATP)
4. The Generation of ATP ATP is generated by the phosphorylation of ADP (adding a PO4)
5. Storing Energy In the form of ADP (adenosine diphosphate)
Only has 2 phosphate groups
When your cells need energy, they add a phosphate group to ADP & a little energy to make more ATP molecules
Use glucose to store long term energy
6. Releasing Energy ATP molecules have bonds between the phosphate groups
ATP is the basic energy source for cells
Your cell breaks the bond to release energy
One breaking bond is enough energy to power active transport, protein synthesis, & cytoskeleton movement in a cell
7. Biochemical Energy Na-K pump in the membrane pumps Na ions out & K ions in
ATP provides the energy to do this
ATP even provides the energy for fireflies to light up!
Glucose is the primary source for ATP
8. Autotrophs Organisms that make their own food.
Example: plants, cyanobacteria, blue-green bacteria, algae make chemical energy from sunlight
9. Heterotrophs Organisms must consume food (plants or animals) to obtain energy
Example: animals, fungi, bacteria
11. 8-2 Overview of Photosynthesis Process of converting water & carbon dioxide into high-energy carbohydrates (sugars & starches)
12. How plants grow--Van Helmonts experiment Mass of dry soil & a seedling
Watered plant for 5 years
Seedling grew to 75 kg mass
Mass of soil was almost unchanged
He concluded most of the mass had come from the water
Actually, the seedling received carbon dioxide from the air to make sugars to grow
13. Joseph Priestly Glass jar over a candle & saw flame go out
He reasoned there was something in the air that the flame needed
He took a sprig of mint leaf & put it in the jar, after a few days he put the candle in & the flame stayed lit for a while
He believed that the plant had made something (oxygen) that the flame needed
14. Jan Ingenhousz Showed that the plant could only keep the flame lit if the plant was exposed to sunlight
Proved sunlight was necessary for the plant to make oxygen
*These experiments proved that plants, in the presence of sunlight will transform carbon dioxide & water into carbohydrates & oxygen
15. Equation 6 CO2 + 6 H 2 O C6 H12 O6 + 6O2
16. Light & Pigments In addition to water & carbon dioxide, photosynthesis requires light & chlorophyll, a molecule in chloroplasts
Sunlight is actually a mixture of different wavelengths
Plants gather the suns energy with light absorbing molecules called pigments
17. Photosynthesis Movie
18. Chlorophyll 2 types of chlorophyll absorbs different light wavelengths
19. Green leaves Green light is reflected by leaves, so thats why they look green
Plants also contain red & orange pigments such as carotene (in carrots) that absorb other light wavelengths
When chlorophyll absorbs light, much of this energy is transferred to the electrons & raises the energy
20. Pigments When carotene and chlorophyll occur in the same leaf, together they remove red and violet light from sunlight that falls on the leaf.
21. Why do leaves change colors in the Fall?
22. Take place inside the chloroplasts
Thylakoids are saclike membranes arranged in stacks called grana
Proteins in thylakoid organize chlorophyll & other pigments into clusters known as photosystems
Photosystems collect light
The Stroma is the fluid
portion outside the thylakoids
Photosynthesis
23. Light movie
24. 8.3 Process of Photosynthesis Light-dependent: take place in the thylakoid
Light-independent (the Calvin cycle): take place in the Stroma, which is outside of the thylakoid membranes
25. Electron Carriers Sunlight excites electrons in chlorophyll
Electron Transport: electron carriers transport the electrons to other molecules
NADP+ (nicotinamide adenine dinucleotide phosphate) can hold 2 high-energy electrons along with a H+ ion
This forms NADPH (energy in chemical form)
26. Light-dependent Reactions Require light to take place
Produce Oxygen gas , ATP, & NADPH
Step 1. Photosystem II absorbs light
Enzymes on the thylakoid break up water molecules into 2 e - s, 2 H+s, and 1 O2
The plant uses the e-s & releases O2 into the atmosphere
27. Step 2. Electron Transport Chain
High-energy e-s move from photosystem II to photosystem I through the electron transport chain
H+s are transported from stroma into inner thylakoid space
28. Step 3. Photosystem I pigments use light energy to reenergize the e-s
NADP+ transports the e-s & H+s to make NADPH
29. Step 4: H+s pumped across membrane
Inside becomes positively charged
This provides energy to make ATP
30. Step 5: ATP synthase allows H+s to pass through membrane
ATP synthase is a protein that rotates like a turbine
As it rotates, ADP is bond to a PO4 to make ATP
31. Overall Light dependent Water, ADP, & NADP+ are used to produce Oxygen, 2 ATPs, & NADPH
This gives energy to make sugars in a later process
32. Light Dependent Needs light energy with chlorophyll to make the products ATP, NADPH, & oxygen in Thylakoid
33. Light Dependent Movie
34. Calvin Cycle Light-independent phase
Uses ATP & NADPH from the light- dependent reactions to produce high-energy sugars
Named after Melvin Calvin who received the Noble prize for his work
35. Calvin Cycle Steps 3 CO2 molecules join to a 3 carbon molecule
ATP & NADPH join the 3 carbon molecules to form the G3P molecules
The cycle must repeat 6 times to form 1 glucose molecule
The G3P molecules are joined to form glucose in the cytoplasm
36. Calvin Cycle Summary Major molecules coming In & Out
6 Turns of the cycle produces 1 glucose molecule
37. Calvin Cycle Light Independent stage in Stroma
Uses ATP & NADPH that was produced in light dependent stage plus the CO2 to make the products high-energy sugars
It take 6 cycles to convert 6 Carbon dioxides into 1 6-carbon sugar
Glucose stores >90 times the energy stored by ATP
38. Calvin Cycle Movie
39. Photosynthesis Summary Definition of Photosynthesis:
40. Factors Affecting Photosynthesis Water -- shortage slows it down
Temperature-- best 0-35C, temps above or below, slows it down
Light Intensity will increase the rate until the limit is reached (for that particular plant), then it plateaus
41. Animated photosynthesis
42. Extreme Conditions Tropics & Desert:
extreme heat plants close the openings in their leaves to keep from drying out
This also reduces the absorption of CO2
Some plants have adapted to these bright & hot conditions
43. Special Plants C4 plants specialized chemical pathway to capture more CO2 (requires more ATP) EX: corn, sugar cane, & sorghum
CAM plants Crassulacean Acid Metabolism allows air in only at night that combines to CO2 to form acids to trap the CO2 in their leaves
Carbohydrates are then formed during the day
The leaves are sealed with a waxy coating to prevent water loss during the day
44. Putting it all together Animation
45. Review The light dependent reactions occur in the
Thylakoid membrane
The Reactants of the light-dependent reactions are
6 H2O, sunlight, chlorophyll
The products of the light-dependent reactions in photosynthesis are
6 O2, ATP, & NADPH
46. Review The Calvin Cycle occurs in the
Stroma
The Reactants in the Calvin Cycle are
9 ATP, 6 NADPH, 6 CO2
The Products in the Calvin Cycle are
9 ADP, 6 NADP+, G3P
2 G3Ps are joined in a glucose molecule in the cytoplasm
47. Standardized Prep pg 219 The principal pigment in plants is
2. Which of the following is NOT produced in the light-dependent reactions of photosynthesis?
48. Standardized Prep pg 219 3. Which equation best summarizes the process of photosynthesis?
4. The color of light that is LEAST useful to a plant during photosynthesis is
49. Standardized Prep pg 219 5. The first step in photosynthesis is the
6. In a typical plant, all of the following factors are necessary for photosynthesis EXCEPT
50. Standardized Prep pg 219 7. Which pigment traveled the shortest distance?
8. A valid conclusion that can be drawn from this information is that spinach leaves
51. Standardized Prep pg 219 9. In which organelles would most of these pigments be found?