Objective• We will learn that all living things get their energy
from the sun. We will learn the steps of photosynthesis by what reactants are used and which products are made.
PhotosynthesisCh. 8
Welcome to Unit 3
Living things need energy• Autotrophs: _______ and some prokaryotes are
able to use the energy from the _______ to produce food.
• Heterotrophs: __________, some prokaryotes, and most multicellular organisms _________ use the sun’s energy directly, therefore they need to consume ___________ as a food source.
ATP- Adenosine Tri-Phosphate• ATP is the ___________ molecule which plants and
animals use for _________.• 3 Phosphates can be ___________ for energy.• ADP (adenosine di-phosphate) has with only ___
phosphates.
ATP and ADP are like battery strengthOnly 2 phosphate groups vs. all 3 means ______ power.
When does a cell need to use energy?• Active Transport: _____ cross cell membrane thru
protein pump.• Sodium-Potassium ______ (3 Na+ out & 2 K+ in)
• Synthesis of Nucleic Acids: DNA & RNA• Movement:
• ATP needed for cell movement and __________.• ATP is actually only good for ________ term use, its
poor at long-term storage of _______ amounts of energy. • Glucose is much better at long-term storage of _________.• Glucose stores ______ more energy than ATP.
• Cells keep a ______ supply of ATP; they ________ more from ADP when needed, by ___________________carbs like glucose.
Scientists who discovered Photosynthesis• Van Helmont (1643): Discovered
that most of the ______ of a plant comes from ______. He weighed the plant and the soil.
• Joseph Priestley (1771): Discovered a mint plant __________ a substance that kept a candle burning. Plants __________ oxygen.
• Jan Ingenhousz (1779): Discovered that plants _______ produce oxygen in the presence of _________.
• Melvin Calvin (1948): Determined the _________ of the Calvin Cycle.
Photosynthesis• Photosynthesis: is the process of _________ light
energy into biochemical _________.
Where does photosynthesis occur? • Chloroplast: Organelle in plant cells only.• Chlorophyll: _________ that absorbs light. Appears
_______ because it absorbs blue and red light. • Chlorophyll is just one pigment in plants, there are others
colors:• Anthocyanin makes plants _____.• Carotenoids make plants look _________ or orange
• As ___________ breaks down in the fall, we see these colors. Light
Reflected Light
Absorbed Light
Transmitted Light
Reactants & Products• Reactants: CO2 + H2O (______________+ _________)
• Along with light energy (for __________)• Products: C6H12O6 + O2 (__________ + ___________)• Remember, CHO always make carbohydrates in
_:_:_ ratio
Photosynthesis = 2 Reactions• Both occurs in the _________. • Light Reactions: (Light ___________) AKA-
Photophosphorylation• Takes place in two _______________.
• Dark Reactions: (Light ______________) AKA- Calvin Cycle• Dark means __________ light needed, doesn’t necessarily
happen only at night
Light Dependent • AKA- _________________________
• Photo= light, phospho= phosperous to make molecules, lation= process
• Uses ________and _______ to make the energy storing molecules NADPH and ATP (which will be used in the dark reaction) and releases _________ as waste.
• Takes place in the ____________ membrane (stacks).
Light Independent• AKA- ________________• Uses ___________ of light reaction (NADPH and ATP)
to ________ CO2 into C6H12O6 = _________ (sugar)• Takes place in the _________ (spaces)
Converting energy from electrons• The __________ point for photosynthesis• Take the energy from an ________ election (photon
of light) and use it to ________ H2O to make NADPH.
• Occurs by __________ the election from one thylakoid to another.• Stacks of thylakoids = ____________• Chlorophyll pigments are found inside the thylakoid
membranes (green)
Light Dependent Cycle• Photosystem II: Light is ____________ by
chlorophyll, the energy from the light photons are ____________ to electrons, which then perform __________ to break water into ions (H+ and oxygen).
• Photosystem I: Electrons and H+ are _____________ by NADP+ to make NADPH.
• Hydrogen Ion Movement: The inside of the thylakoid ___________ fills up with H+ ions, the makes the inside slightly _________, and the outside of the membrane slightly negative.
• Electron Transport Chain: Electrons from photosystem II move to photosystem I, using their ________ to transport H+ from the stroma space to _________ the thylakoid membrane.
ATP Formation• The _______ phase of light reactions• ATP Synthase: a specialized ________ channel in
the thylakoid membrane, located at the end of the ETC. • Converts ADP to ATP as H+ ions _______ through to the
outside of the membrane. ATP synthase turns/spins like a _________ as ions pass through.
• Chemiosmosis: occurs as H+ ions move across a ___________ to make ATP.
Calvin Cycle (light independent)• Uses ATP and NADPH made from
photophosphorylation to _______ high-energy storage __________ (sugar- glucose).
• Makes NADP+ and ADP (molecules ________ for light reactions).
Calvin Cycle Details• 6 molecules of CO2 enter the cycle from the
___________ (air).• They combine with 6 molecules containing 5 carbons
each, this reactions forms 12 molecules with 3 carbons each.
• ATP and NADPH are used to _________ the 3-carbon molecules into higher-_______ forms.
• 2 of the 3-carbon molecules are used to make 6-carbon sugars such as _________.
• 10 of the 3-carbon molecules remaining are ___________ into 5-carbon molecules, which will be used at the _________ again.
• The Calvin Cycle uses 6 molecules of CO2 to make just __ molecule of 6-carbon glucose at the ____.
Reaction Formulas• Light Dependent Reactions in the _________
• NADP + H excited e- = NADPH• ADP + P ATP Synthase = ATP
• Light Independent Reaction in the _______• ATP + ______ + CO2 = C6H12O6
• Oxidation-Reduction Reactions always take place _______• Oxidation: lose e- and H+, gain O2, _________
energy.• Reduction: lose O2, ______ e- and H+, take in
energy.
Photosynthesis Formula
•6CO2 + 6H2O = C6H12O6 + 6O2
• Reactants: __ carbon dioxides + __ waters
• Products: __ glucose + __ oxygens
Factors that affect photosynthesis• These can either slow down or speed up the
process:• Light Intensity
• More = _______ photosynthesis• Carbon Dioxide amount
• More = ______ photosynthesis• Temperature
• Too high or too low = _______ photosynthesis • High Heat: plants close their ______ (pores in leaves) to conserve
_______. • Different plants have an ideal temperature range.• Trees that lose their leaves in the fall do _____
photosynthesize in the winter.• Type of plant:
• C4 plants perform photosynthesis in different ________ of their leaves
• CAM plants (_________) perform photosynthesis at _______
Plants produce oxygen• Most life on earth depends on ________ to live.• We breathe oxygen every day! • When plants split water during _____________, their
leaves __________ usable O2 in the air/water.
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