|
1
|
|
|
2
|
- Exam 1 Is THIS MONDAY During Lecture!
- Bring pencil(s)
- Eraser
- Student ID
- No cell phone, head phones, Ipods, hats allowed
- You Will Have the Full Two Hours To Take The Exam!
|
|
3
|
- Bring Questions To Review Session:
|
|
4
|
- Plants produce carbohydrates
- by converting light energy
- into chemical energy
- Photosynthesis
- Process by which this takes place
|
|
5
|
|
|
6
|
|
|
7
|
- Leaves:
- Major organs of photosynthesis
- Mesophyll:
- Tissue in interior of leaves
|
|
8
|
|
|
9
|
- Stomata:
- Tiny pores that allow gas exchange
|
|
10
|
|
|
11
|
|
|
12
|
- Chloroplasts:
- Organelles in plant cells
- Site of photosynthesis
|
|
13
|
|
|
14
|
|
|
15
|
- Chloroplasts:
- Light energy is captured & converted in chloroplasts
- Energy is passed through ETC,
- which converts it into
usable
- chemical energy
|
|
16
|
- Light:
- Form of energy called EM radiation
- Travels in waves
- Behaves like matter
|
|
17
|
- Photons:
- Units of energy
- Have fixed quantity of energy
- Energy is inversely related to wavelength
- Shorter wavelength = greater
photon energy
|
|
18
|
|
|
19
|
- Different types of light have characteristic wavelengths associated with
them
- Wavelength(l):
- Distance between two sequential
peaks
- Measured in nanometers (nm) =
10 –9 meters
|
|
20
|
- Electromagnetic (EM) Spectrum:
- Entire range of
- EM radiation
- Visible Light Spectrum:
- Light detectable to the human eye
- 380-750 nm
- Light that drives photosynthesis
|
|
21
|
|
|
22
|
- As Light Meets Matter It May Be:
- Reflected
- Transmitted
- Absorbed
|
|
23
|
- Wavelength & Color:
- We perceive waves of visible light as different colors
- The color we see corresponds to the wavelength that’s
transmitted/reflected
|
|
24
|
- Absorption:
- When matter absorbs l of light, you don’t see that color!
- Absorption is crucial!
- Chloroplasts only harvest
energy if light is absorbed
|
|
25
|
- Pigment:
- Substance that absorbs visible light
- Different pigments absorb light of different l
|
|
26
|
- Chlorophylls:
- Transmit mainly green light
- Chlorophyll a
- Chlorophyll b
- Cartenoids:
- Transmit mainly orange and yellow
|
|
27
|
|
|
28
|
|
|
29
|
|
|
30
|
- Every pigment
- has a characteristic
- Absorption Spectrum
|
|
31
|
- Transformation of solar à chemical energy occurs through 2 metabolic
pathways:
- Light Reactions:
- Convert solar into cellular energy
- Calvin Cycle:
|
|
32
|
- Light Rxns:
- Occur in thylakoid
- Use light to make chem. energy in form of ATP & NADPH
- Produce oxygen as by product
|
|
33
|
- Photosystems:
- Cluster of molecules spanning thylakoid membrane:
- Small organic molecules
- Proteins
- Pigments
|
|
34
|
- More Specifically, Photosystems Consists of:
- Antenna Complex:
- Cluster of pigment molecules
- Reaction Center:
- Single chlorophyll a where light rxns begin
|
|
35
|
- Photosystem Antenna
- Complex:
- When photon strikes a pigment, energy is passed b/w molecules until
reaching the rxn center
|
|
36
|
- Photosystem Reaction Center:
- Where Light Reactions Begin
- Electrons of Rxn center chlorophyll (a) become excited
- e-s captured by acceptor molecule
- Do not return to ground state
|
|
37
|
|
|
38
|
- Photoexcitation:
- Ground State:
- Energy level of non-excited electron (e-)
- Excited State
- Energy level of “stimulated” electron
- Ex: When a pigment absorbs
photons, e-s can be
boosted
- to higher energy
level
|
|
39
|
|
|
40
|
- Transformation of solar à chemical energy occurs through 2 metabolic
pathways:
- Light Reactions:
- Convert light into energy in form of ATP & NADPH
- Calvin Cycle:
- Reduce CO2 to CH2O (sugar)
|
|
41
|
|
|
42
|
- Two Photosystems Cooperate in Light Rxns:
- Photosystem I
- Rxn center
- chlorophyll
- called P 700
- Photosystem II
- Rxn center
- chlorophyll
- is called P 680
|
|
43
|
- Photosystem II :
- Absorbs energy from antennae complex
- Rxn center gives up e-
- Photolysis is triggered:
|
|
44
|
- Photosystem II:
- Excited e- from P680 is accepted by EA1
- e- is passed down ETC1 via proteins embedded in thylakoid
membrane
|
|
45
|
- Chemiosmosis:
- As e-s move down ETC:
- H+ shunted across membrane and released in thylakoid interior
- H+ then allowed to diffuse down gradient through ATPase
|
|
46
|
|
|
47
|
- Photosystem I:
- Electron from (P700) are also excited by light
- Excited e- from P 700 accepted by EA2
- e- from ETC1 fills vacancy in P 700
|
|
48
|
- Photosystem I:
- Electrons are passed from EA2 down ETC2
- Terminal step is catalyzed rxn:
|
|
49
|
|
|
50
|
- Chemiosmosis
- Generates ATP:
- Movement of e- down ETC1 powers pumping of H+
- Diffusion of H+ back
into stroma produces ATP
- H+ diffuses through ATP synthase
|
|
51
|
- Formation of NADPH:
- NADP+ is final e- acceptor
- Accepts 2e-s from ETC 2
- Combines with 1H + à NADPH
- NADPH carries e- into Calvin Cycle, where it reduces organic compounds
|
|
52
|
- The Calvin Cycle:
- Occurs in stroma
- Produces sugar from CO2
- Energy requiring process
- Energy provided by ATP & NADPH from light rxns
|
|
53
|
- Three Phases:
- Carbon Fixation:
- Enzyme catalyzed rxn
- C from CO2 attached to a (5C) organic molecule
- Reduction:
- New molecule accepts e- and H+ from NADPH
- Regeneration:
- Starting material (5 C) recreated to keep cycle going
|
|
54
|
|
|
55
|
- ATP Drives Reactions:
- Breakdown of ATP coupled to non spontaneous rxns
- NADPH Reduces:
- Donation of e- reduces organic compound
|
|
56
|
- ATP & NADPH from light rxns released into stroma
- 18 ATP & 12 NADPH used to phosphorlyate & reduce organic
compounds (respectively)
- ADP, Pi and NADP+ return to site of light rxns
- For every six turns of Calvin Cycle:
- 1 phosphorylated glucose
molecule produced
- Used to form sucrose, starch and cellulose
|
|
57
|
- Light Reactions Produce:
- Oxygen à
released to atmosphere
- Necessary for aerobic respiration
- ATP
- NADPH
- Light Independent Reactions Produce:
- Sugars à
converted to sucrose, cellulose, starch
- Necessary for growth, reproduction
- Water
- NADP+
- ADP + Pi
|
Notes
