photosynthesis watch?v=tshmwiz9fnw
TRANSCRIPT
PHOTOSYNTHESIS
http://www.youtube.com/watch?v=tSHmwIZ9FNw
Objectives Explain plant physiology concepts and
energy conversion in plants. a) Explain the basic process of photosynthesis
and its importance to life on Earth. b) Explain requirements necessary for
photosynthesis to occur, and identify the products and byproducts of photosynthesis.
c)Explain cellular respiration and its importance to plant life.
d)Explain factors that affect cellular respiration, and identify the products and byproducts of cellular respiration.
• 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, andflowering plants
(b) Kelp
(c) Euglena (d) Cyanobacteria
THE BASICS OF PHOTOSYNTHESIS
Light Energy Harvested by Plants & Other Photosynthetic Autotrophs
6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2
WHYWHY ARE ARE PLA PLANTS NTS GREGREEN?EN?
Plant Cells have Green Chloroplasts
The thylakoid membrane of the chloroplast is impregnated with photosynthetic pigments (i.e., chlorophylls, carotenoids).
Chloroplasts absorb light energy and convert it to chemical energy
LightReflected
light
Absorbedlight
Transmittedlight
Chloroplast
THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED
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
Carbondioxide
Water Glucose Oxygengas
PHOTOSYNTHESIS
• 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
LightChloroplast
Lightreactions
Calvincycle
NADP
ADP+ P
The light reactions convert solar energy to chemical energy Produce ATP & NADPH
AN OVERVIEW OF PHOTOSYNTHESIS
Steps of Photosynthesis Light hits reaction centers of chlorophyll, found
in chloroplasts
• Chlorophyll vibrates and causes water to break apart.
• Oxygen is released into air• Hydrogen remains in chloroplast
attached to NADPH• “THE LIGHT REACTION”
Steps of Photosynthesis The DARK Reactions= Calvin Cycle
• CO2 from atmosphere is joined to H from water molecules (NADPH) to form glucose
• Glucose can be converted into other molecules with yummy flavors!
Photosynthesis occurs in chloroplasts
In most plants, photosynthesis occurs primarily in the leaves, in the chloroplasts
A chloroplast contains: stroma, a fluid grana, stacks of thylakoids
The thylakoids contain chlorophyll Chlorophyll is the green pigment that captures light for
photosynthesis
The location and structure of chloroplasts
LEAF CROSS SECTION MESOPHYLL CELL
LEAF
Chloroplast
Mesophyll
CHLOROPLAST Intermembrane space
Outermembrane
Innermembrane
ThylakoidcompartmentThylakoidStroma
Granum
StromaGrana
Chloroplast Pigments Chloroplasts contain several pigments
– Chlorophyll a – Chlorophyll b – Carotenoids– Xanthophyll
Figure 7.7
Chlorophyll a & b•Chl a has a methyl group •Chl b has a carbonyl group
Porphyrin ring delocalized e-
Phytol tail
Different pigments absorb light differently
Cyclic Photophosphorylation
Process for ATP generation associated with some Photosynthetic Bacteria
Ph
oto
n
Ph
oto
n
Water-splittingphotosystem
NADPH-producingphotosystem
ATPmill
Two types of photosystems cooperate in the light reactions
Primaryelectron acceptor
Primaryelectron acceptor
Electron transport chain
Electron transport
Photons
PHOTOSYSTEM I
PHOTOSYSTEM II
Energy forsynthesis of
by chemiosmosis
Noncyclic Photophosphorylation
Photosystem II regains electrons by splitting water, leaving O2 gas as a by-product
Plants produce OPlants produce O22 gas by splitting H gas by splitting H22OO
The O2 liberated by photosynthesis is made from the oxygen in water (H+ and e-)
In the light reactions, electron transport In the light reactions, electron transport chains generate ATP, NADPH, & Ochains generate ATP, NADPH, & O22
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
Chemiosmosis powers ATP synthesis in the light reactions
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
2 H + 1/2
Water-splittingphotosystem
Reaction-center
chlorophyll
Light
Primaryelectronacceptor
Energyto make
Electron transport chain
Primaryelectronacceptor
Primaryelectronacceptor
NADPH-producingphotosystem
Light
NADP
1
23
How the Light Reactions Generate ATP and NADPH
Video to help http://www.youtube.com/watch?
v=hj_WKgnL6MI
Summary—Light Dependent Reactions
a. Overall inputlight energy, H2O.
b. Overall output ATP, NADPH, O2.
Animation is of the Calvin Cycle Note what happens to the carbon dioxide and what the end product is.
Second animation of the Calvin Cycle is very clear and even does the molecular bookkeeping for you.
Light Independent Reactions aka Calvin Cycle
Carbon from CO2 is converted to glucose
(ATP and NADPH drive the reduction
of CO2 to C6H12O6.)
Light Independent Reactions aka Calvin CycleCO2 is added to the 5-C sugar RuBP by the
enzyme rubisco.This unstable 6-C compound splits to two
molecules of PGA or 3-phosphoglyceric acid.
PGA is converted to Glyceraldehyde 3-phosphate (G3P), two of which bond to form glucose.
G3P is the 3-C sugar formed by three turns of the cycle.
Video to help http://www.youtube.com/watch?
v=o1I33Dgcc_M
Summary—Light Independent Reactions a. Overall input CO2, ATP, NADPH.
b. Overall output glucose.
Why high heat? When it is hot, plants close their stomata to
conserve water They continue to do photosynthesis use up
CO2 and produce O2 creates high O2 concentrations inside the plant photorespiration occurs
Review: Photosynthesis uses light energy to make food molecules
A summary of the chemical processes of photosynthesis
Light
Chloroplast
Photosystem IIElectron transport
chains Photosystem I
CALVIN CYCLE Stroma
Electrons
LIGHT REACTIONS CALVIN CYCLE
Cellular respiration
Cellulose
Starch
Other organic compounds