Photosynthesis: Life from Light and Air Energy needs of life All life needs a constant input of...
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Transcript of Photosynthesis: Life from Light and Air Energy needs of life All life needs a constant input of...
Energy needs of life All life needs a constant input of energy
Animals = Heterotrophs get their energy from “eating others”
eat food = other organisms = organic molecules
make energy through respiration Plants = Autotrophs
get their energy from “self”get their energy from sunlightbuild organic molecules (food) from CO2
make energy through photosynthesis
Photosynthesis
This is the equation you are used to seeing, but this is not the whole story…
+ water + energy glucose + oxygencarbondioxide
6CO2 6H2O C6H12O6 6O2light
energy+ ++
What is the main chemical fuel that most living organisms use to store energy?
ATP – adenosine triphosphate
What does an ATP molecule
consist of?Adenine, ribose, and three phosphate groups
What do the lines between the parts of the molecule represent?
Chemical bonds
ATP
WHAT IS THE ROLE OF ATP IN CELLULAR ACTIVITIES?
The characteristics of ATP make it an exceptionally useful molecule that is used by all types of cells as their basic energy source
Even though ATP is very efficient at transferring energy, it is not very good for storing energy over the long term.
Living organisms store large amounts of energy in the form of glucose (90 times more energy than ATP)
Cells can break apart glucose and make ATP molecules very easily to release the energy slowly
How do plants live? Photosynthesis
Energy building reactions collect sun energy make ATP
Sugar building reactions use ATP for energy use CO2 as carbon for new sugars
build sugars glucose, cellulose, starch
build all other organic molecules proteins, lipids, carbohydrates, DNA
store energy for future use starch in seeds & roots
Photosynthesis Actually 2 separate reactions
Energy building use sunlight make energy (ATP)
Sugar building use ATP use CO2
make sugars (C6H12O6)
Energybuilding reactions
Sugarbuilding reactions
sun
ATPADP
CO2sugar
CO2
Chloroplasts
Chloroplasts
LeafLeaf
Chloroplast
absorbsunlight & CO2
makeenergy & sugar
Chloroplastscontain
Chlorophyll
Energy Building Reactions
O2
H2O
Energy BuildingReactions
sunlight
ATP
H2O ATP O2light
energy ++
makes ATP energy releases oxygen
as a waste product
Sugar Building Reactions
sugarsC6H12O6
CO2
SugarBuilding
Reactions
ATP
CO2 C6H12O6 ADPATP ++
ADP
builds sugars uses ATP cycles ADP
back to make more ATP
Putting it all together
sugarsC6H12O6
CO2
ATP
ADP
H2O
O2
sunlight
CO2 H2O C6H12O6 O2light
energy + ++
SugarBuilding
Reactions
Energy Building
Reactions
Plants make both: ATP sugars
WHAT IS THE ROLE OF CHLOROPHYLL IN PHOTOSYNTHESIS?
In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule in chloroplasts
Sunlight, which your eyes perceive as “white” light, is actually a mixture of different wavelengths of light of various colors
Any compound that absorbs light also absorbs energy from that light. When chlorophyll absorbs light, much of the energy is transferred directly to electrons in the chlorophyll molecule, raising the energy levels of these electrons. These high-energy electrons make photosynthesis work
HOW WELL WOULD A PLANT GROW UNDER PURE
YELLOW LIGHT?The plant would not grow well because neither chlorophyll a
nor b absorbs much light in the yellow region of visible light
8-3 THE REACTIONS OF PHOTOSYNTHESIS
Take a look at the picture of a chloroplast on page 208
Photosynthesis is broken down into two reactions light-dependent reactions- occur in
thylakoid membrane light-independent reactions (Calvin
Cycle) – occur in the stroma
WHAT HAPPENS IN THE LIGHT-DEPENDENT REACTIONS?
The light-dependent reactions produce oxygen gas and convert ADP and NADH+ into the energy carriers ATP and NADPH
NADP+ - a carrier molecule that can accept a pair of high-energy electrons and transfer them along with most of their energy to another molecule; NADP+ converts to NADPH when it accepts electrons
WHAT IS THE CALVIN CYCLE?
The Calvin Cycle uses ATP and NADPH from the light-dependent reactions to produce high-energy sugars
Bring In CO2
H2O light
Let Out O2
Move Around sugars
So what does a plant need?
6CO2 6H2O C6H12O6 6O2light
energy + ++
roots
shoot
leaves
Leaf Structure
H2O CO2
CO2
O2 H2O
phloem (sugar)xylem (water)
stomate guardcell
palisadeslayer
spongylayer
cuticleepidermis
gases in & out water out
transpiration O2
Phloem: food-conducting cells
carry sugars around the plant wherever they are needed new leavesfruitseeds
Putting it all together Making a living…
sunlight leaves = solar collectors photosynthesis
gases: CO2 in & O2 out stomates = gases in & out
H2O roots take in water from soil pulled up by leaf evaporation
nutrients roots take in from soil
How are they connected?
glucose + oxygen carbon + water + energydioxide
C6H12O6 6O2 6CO2 6H2O ATP+ + +
Respiration
+ water + energy glucose + oxygencarbondioxide
6CO2 6H2O C6H12O6 6O2light
energy + ++
Photosynthesis
H2O
Energy cycle
Photosynthesis
Cellular Respiration
sun
The Great Circleof Life!
Where’s Mufasa?
glucose O2CO2
plants
animals, plants
ATP
The poetic perspective All of the solid material of every plant
was built out of thin air All of the solid material of every animal
was built from plant material
Then all the cats, dogs, mice, people & elephants…
are really strands of air woven together by sunlight!
sunair