Photosynthesis honors master

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?



Output:

• 18 ATP

• 12 NADPH

• Oxygen

ADP, and NADP+



Output:

• 18 ATP

• 12 NADPH

• Oxygen

What is the waste product of photosynthesis?



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.


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


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?

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Photosynthesis honors master