Bellringer Without fail, I forget to water my plants. My houses
temperature (electric heat = dry) is kept at 72 o F. Explain, using
your botannical vocabulary, why my house plants shriveled up and
died over the winter.
Slide 4
Set up lab, lecture, finish lab Todays goal: Define pigment.
Explain why plants are green. Give examples of the accessory
pigments and explain their role in photosynthesis.
Slide 5
All you ever wanted to know about photosynthesis Part One
Slide 6
Photosynthesis is the process by which autotrophic organisms
use light energy to make sugar and oxygen gas from carbon dioxide
and water AN OVERVIEW OF PHOTOSYNTHESIS Carbon dioxide
WaterGlucoseOxygen gas PHOTOSYNTHESIS
Slide 7
Energy can be transformed from one form to another FREE ENERGY
(available for work) vs. HEAT (not available for work)
Slide 8
THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH
Slide 9
Almost all plants are photosynthetic autotrophs, as are some
bacteria and protists Autotrophs generate their own organic matter
through photosynthesis Sunlight energy is transformed to energy
stored in the form of chemical bonds (a) Mosses, ferns, and
flowering plants (b) Kelp (c) Euglena (d) Cyanobacteria THE BASICS
OF PHOTOSYNTHESIS
Slide 10
Ingredients and Components 6 CO 2 + 6 H 2 O + light energy C 6
H 12 O 6 + 6 O 2
Slide 11
Food Chain
Slide 12
THE FOOD WEB
Slide 13
WHY ARE PLANTS GREEN? It's not that easy bein' green Having to
spend each day the color of the leaves When I think it could be
nicer being red or yellow or gold Or something much more colorful
like that Kermit the Frog
Slide 14
Electromagnetic Spectrum and Visible Light Gamma rays X-raysUV
Infrared & Microwaves Radio waves Visible light Wavelength
(nm)
Slide 15
Sunlight Form of energy (photons) Measured in wavelengths Sun
radiates full spectrum, atmosphere screens out most, allows
primarily only visible light through (380-750 nm) Amount of energy
is inversely related to the wavelength of light
Slide 16
Different wavelengths of visible light are seen by the human
eye as different colors. Gamma rays X-raysUVInfrared Micro- waves
Radio waves Visible light Wavelength (nm)
Slide 17
Pigment Substances that absorb visible light Different pigments
absorb light of different wavelengths Color we see is the color
most reflected or transmitted by the pigment
Slide 18
Sunlight minus absorbed wavelengths or colors equals the
apparent color of an object. The feathers of male cardinals are
loaded with carotenoid pigments. These pigments absorb some
wavelengths of light and reflect others. Reflected light
Slide 19
Why are plants green? Reflected light Transmitted light
Slide 20
Chlorophyll a Chl a has a methyl group Chl b has a carbonyl
group Porphyrin ring delocalized e - Phytol tail
Slide 21
Spectrophotometer
Slide 22
WHY ARE PLANTS GREEN?
Slide 23
Predict: action spectrum Measure photosynthetic output against
the various wavelengths of light
Slide 24
Action spectrum
Slide 25
So chlorophyll isnt the whole story here
Slide 26
The Pigments Chlorophyll a: blue-green; only pigment that can
participate directly in photosynthesis Accessory (antennae)
pigments - absorb light and transfer it to chlorophyll a:
Chlorophyll b: yellow-green Carotenoids: various shades of yellow
and orange Xanthophylls: purples Anthocyanin: yellow
Slide 27
Fall colors
Slide 28
So what? Demonstration!
Slide 29
Electron Excitation
Slide 30
Slide 31
Excited state ee Heat Light Photon Light (fluorescence)
Chlorophyll molecule Ground state 2 (a) Absorption of a photon (b)
fluorescence of isolated chlorophyll in solution Excitation of
chlorophyll in a chloroplast ee
Slide 32
Okaystill, so what?
Slide 33
Primary electron acceptor Electron transport chain Electron
transport Photons PHOTOSYSTEM I PHOTOSYSTEM II Energy for synthesis
of by chemiosmosis Noncyclic Photophosphorylation Photosystem II
regains electrons by splitting water, leaving O 2 gas as a
by-product
Slide 34
Parts of the chloroplast Thylakoids: flattened sac, pigments of
photosynthesis located in their membranes Grana: stacks of
thylakoids (literally, stacks of coins) Stroma: interior
portion
Slide 35
The location and structure of chloroplasts LEAF CROSS SECTION
MESOPHYLL CELL LEAF Chloroplast Mesophyll CHLOROPLAST Intermembrane
space Outer membrane Inner membrane Thylakoid compartment Thylakoid
Stroma Granum StromaGrana
Slide 36
Go home and read. Pp. 119-132 Make sure to keep the structure
of the chloroplast forefront as you read.
Slide 37
ALL YOU WANTED TO KNOW ABOUT PHOTOSYNTHESIS Day two
Slide 38
The Calvin cycle makes sugar from carbon dioxide ATP generated
by the light reactions provides the energy for sugar synthesis The
NADPH produced by the light reactions provides the electrons for
the reduction of carbon dioxide to glucose Light Chloroplast Light
reactions Calvin cycle NADP ADP + P The light reactions convert
solar energy to chemical energy Produce ATP & NADPH AN OVERVIEW
OF PHOTOSYNTHESIS
Slide 39
Review of photosynthesis The reactants: CO 2 and H 2 O Driving
the reaction: sunlight Products: Glucose and O 2 Sunlight captured
by pigments (chlorophylls and others) Pigments located in the
chloroplasts
Slide 40
Chloroplasts absorb light energy and convert it to chemical
energy Light Reflected light Absorbed light Transmitted light
Chloroplast
Slide 41
What is a pigment? Substance that absorbs visible light
Different pigments absorb light of different wavelengths Arranged
into clusters called photosystems (more on that later!)
Slide 42
Chloroplasts: Sites of Photosynthesis Photosynthesis Occurs in
chloroplasts, organelles in certain plants All green plant parts
have chloroplasts and carry out photosynthesis The leaves have the
most chloroplasts The green color comes from chlorophyll in the
chloroplasts The pigments absorb light energy
Slide 43
Photosystems In the membrane of the thylakoid Contains several
hundred molecules of chlorophyll a and b along with accessory
pigments Named by the wavelength of light they absorb (P680 and
P700)
Slide 44
Why have photosystems? To harvest light over a larger surface
area and larger portion of the spectrum than any single pigment
could harvest.
Slide 45
Primary electron acceptor Photon Reaction center PHOTOSYSTEM
Pigment molecules of antenna Molecular Game of Hot Potato
Slide 46
Photon Water-splitting photosystem NADPH-producing photosystem
ATP mill Two types of photosystems cooperate in the light
reactions
Slide 47
Primary electron acceptor Electron transport chain Electron
transport Photons PHOTOSYSTEM I PHOTOSYSTEM II Energy for synthesis
of by chemiosmosis Noncyclic Photophosphorylation Photosystem II
regains electrons by splitting water, leaving O 2 gas as a
by-product
Slide 48
The O 2 liberated by photosynthesis is made from the oxygen in
water (H + and e - ) Plants produce O 2 gas by splitting H 2 O
Slide 49
2 H + 1 / 2 Water-splitting photosystem Reaction- center
chlorophyll Light Primary electron acceptor Energy to make Electron
transport chain Primary electron acceptor Primary electron acceptor
NADPH-producing photosystem Light NADP 1 2 3 How the Light
Reactions Generate ATP and NADPH
Slide 50
Two connected photosystems collect photons of light and
transfer the energy to chlorophyll electrons The excited electrons
are passed from the primary electron acceptor to electron transport
chains Their energy ends up in ATP and NADPH In the light
reactions, electron transport chains generate ATP, NADPH, & O
2
Slide 51
The electron transport chains are arranged with the
photosystems in the thylakoid membranes and pump H + through that
membrane The flow of H + back through the membrane is harnessed by
ATP synthase to make ATP In the stroma, the H + ions combine with
NADP + to form NADPH Chemiosmosis powers ATP synthesis in the light
reactions
Slide 52
The production of ATP by chemiosmosis in photosynthesis
Thylakoid compartment (high H + ) Thylakoid membrane Stroma (low H
+ ) Light Antenna molecules Light ELECTRON TRANSPORT CHAIN
PHOTOSYSTEM IIPHOTOSYSTEM IATP SYNTHASE
Slide 53
Cyclic Pathway
Slide 54
A Photosynthesis Road Map Chloroplast Light Stack of thylakoids
ADP + P NADP Stroma Light reactions Calvin cycle Sugar used for
Cellular respiration Cellulose Starch Other organic compounds
Slide 55
Join me, on the dark side of photosynthesis
https://www.youtube.com/watch?v=k-t2TeapTH8
ATP is a limiting factor: more is used by calvin cycle Need a
way to fill deficit
Slide 60
Cyclic Photophosphorylation Process for ATP generation
associated with some Photosynthetic Bacteria Reaction Center =>
700 nm
Slide 61
Review: Photosynthesis uses light energy to make food molecules
Light Chloroplast Photosystem II Electron transport chains
Photosystem I CALVIN CYCLE Stroma Electrons LIGHT REACTIONSCALVIN
CYCLE Cellular respiration Cellulose Starch Other organic compounds
A summary of the chemical processes of photosynthesis
Slide 62
It's not that easy bein' green but it is essential for life on
earth!
