photosynthesis honors master
TRANSCRIPT
photosynthesis
Essential Questions• What if the sun quit shining?• Is the process of photosynthesis
dependent on light?• What is photosynthesis?• What organisms undergo photosynthesis?• How do plants make food?• What adaptations does a leaf have to
undergo photosynthesis?• What are the raw materials needed for
photosynthesis?
Essential Questions• What are the inputs and outputs of
photosynthesis.• How do the light dependent reactions
occur?• How do the light independent
reactions occur?• What is the Calvin Cycle?• What factors affect photosynthesis?• Why is photosynthesis important to
the environment?
Important Vocabulary• chlorophyll• Accessory pigment• Stomata • Guard cell• Spongy layer• Palisade layer• Epidermis• CHLOROPLAST
– GRANUM– THYLAKOID– STROMA
• NADP & NADPH
• Photosystem II and I• ATP synthase• Carbon Fixation• Rubp• Rubisco• G3P
• ATP & ADP
The Photosynthesis Song!
Photosynthesis
The Nature of Light
•Visible light is the component of the Electromagnetic spectrum of energy that a plant uses for photosynthesis.
•Photon – particle of light!
What Colors do we see?
• Why do leaves of plants look green?– Leaf pigments….like chlorophyll.
• Pigments can absorb, reflect, or transmit the light energy.
• An object that absorbs all colors is BLACK.
• An object appears that color when it reflects that color----- GREEN PLANTS!
Photosynthetic pigments
Found in the Chloroplast.• Chlorophyll a – absorbs less blue and more
red light. It is directly involved in photosynthesis.
• Chlorophyll b – absorbs more blue and less red light. It is an accessory pigment – assists chlorophyll a.
Other accessory pigments:• Carotenoids – absorb blue light. Reflect
yellow, red, orange light.
What does the graph below represent?
LEAF Structure
Leaves and Photosynthesis
Adaptations for Nutrition – The Leaf• Cuticle – waxy
outermost layer• Epidermis – 1
cell thick. Allows light to penetrate.
• Stomate – on lower epidermis. Gas exchange. Water transpiration.
• Guard Cell – regulates opening of stomate.
Mesophyll – contains vascular bundle AND…
+ Palisade layer – site of photosynthesis.
+ Spongy layer – irregular cells, large air spaces…for diffusion of gases.
Chloroplasts
THE CHLOROPLAST
Chloroplast• Thylakoid –
– photosynthetic membranes. – Arranged in stacks called GRANA. – Contain chlorophyll: photosystems– Light DEPENDENT reactions occur
• Stroma – – Outside the thylakoid– Light INDEPENDENT reactions occur.
Photosynthesis – an overview(the absolute minimum you must know!!!
• 6CO2 + 6H2O light C6H12O6 + 6O2
• Light energy needed - Capture LIGHT - PHOTO• ATP used and generated• NADP+ :the electron carrier, that combines with 2
electrons and one hydrogen ion. • NADP+ becomes reduced into NADPH, when it
receives the electrons.• Glucose (SYNTHESIS) and oxygen are made.
NADP : nicotinamide adenine dinucleotide phosphate
Photosynthesis – an overview
TheLight
Reactions
Light Reactions
Organization of a Thylakoid
Light Reaction(overview)
Produce OXYGEN gas and convert ADP and NADP+ into energy carriers ATP and NADPH.
PHOTOSYSTEM II (PII)• Chlorophyll pigments (purple circles) in thylakoid membrane absorb
light energy. – The energy is absorbed by electrons…passed to ETC.
PHOTOLYSIS• During this process, H2O is broken down, and O2 is released. • Electrons from hydrogen replace electrons in chlorophyll.• H+ begin to create a positive gradient in the THYLAKOID.
• Electrons lose energy as they pass down the ETC.• Energy lost “pumps” more H+ into the Thylakoid thru
membrane by active transport.
PHOTOSYSTEM I• Light energy re-energizes electrons• Electrons combine with NADP and H+ to form NADPH – an
electron carrier• NADPH moves into the stroma for Light Independent Rxns.
Production of ATP
• The concentration of H+ ions inside the thylakoid membrane becomes much higher than the concentration outside.
• H+ ions rush out through membrane protein called ATP synthase.
• The ATP synthase spins like a turbine and the energy is used to bind ADP and P together to form ATP.
Summary of the Light Reactions
• Input:• Light• Water• ADP• NADP+
Output:
• 18 ATP
• 12 NADPH
• Oxygen
What do you need for more light reactions to occur?
Summary of the Light Reactions
• Input:• Light• Water• ADP• NADP+
Output:
• 18 ATP
• 12 NADPH
• Oxygen
ADP, and NADP+
Summary of the Light Reactions
• Input:• Light• Water• ADP• NADP+
Output:
• 18 ATP
• 12 NADPH
• Oxygen
What is the waste product of photosynthesis?
Summary of the Light Reactions
• Input:• Light• Water• ADP• NADP+
Output:
• 18 ATP
• 12 NADPH
• Oxygen
Oxygen
Light Independent Reactions
Light Independent Reactions (overview)
aka – Carbon Fixation, Calvin Cycle, Dark Rxns.
• Uses CO2 to form a 2- 3 carbon molecules
• Needs ATP• Needs NADPH – is oxidized• Carbon Molecule reduced• Leaves 6 – 5 carbon molecules
Light Independent Reactions
Light Independent reactions
Carbon Fixation•6CO2 enter the cycle and
bonds with 6 – 5 carbon molecules (Rubp)– Catalyzed by enzyme Rubisco.
•These molecules split into 12 – 3 carbon molecules.
Light Independent reactions
Reduction:
• Each 3 carbon molecule is REDUCED by 12 NADPH (oxidized).
• 12 ATP IS NEEDED!• Result: G3P the 3 – carbon molecule
that will become glucose. – 2 – G3P exit the Calvin Cycle to become
Glucose
Light Independent reactions
Regeneration:
• 10 – G3P molecules are rearranged into
5 – 6 carbon molecules (Rubp)• 6 ATP needed
Calvin Cycle Reactions
Fate of G3P
Calvin Cycle Reactions
• Importance of the Calvin Cycle– G3P (glyceraldehyde-3-phosphate) can be
converted to many other molecules• The G3P can form:
– Fatty acids and glycerol to make plant oil– Glucose phosphate (simple sugar)– Fructose (which with glucose = sucrose)– Starch and cellulose– Amino acids
Fate of G3P
Photosynthesis and Respiration Compared
How the Rate of Photosynthesis can be
affected.
Rate of Photosynthesis• What is a rate?
• It is the activity per unit time.• What factors can affect the
photosynthetic rate?• Light intensity• Temperature• Oxygen• Carbon Dioxide Concentration
• Sometimes these factors are called LIMITING FACTORS.
The Effect of Light Intensity on Photosynthetic Rate
The Effect of Temperature on Photosynthetic Rate
The Effect of Light Intensity and Temperature on Photosynthetic Rate
Which is the limiting factor here; light intensity or temp.?
Carbon Dioxide Concentration
Oxygen Concentration
What would a graph for increasing levels of CO2 look like?