The Working Cell: Energy from Sunlight Chapter 8 Notes.

The Working Cell:Energy from Sunlight

Chapter 8 Notes

Ch. 8 The Working Cell: Energy from Light

8.1 Photosynthesis uses light energy to make food.

8.2 The light reactions convert light energy to chemical energy.

8.3 The Calvin cycle makes sugarfrom carbon dioxide.

8.4 Photosynthesis has a global impact.

8.1 Photosynthesis uses light energy to make food.

Objectives

Describe the structure of a chloroplast.

Identify the overall reactants and products of photosynthesis.

Key Terms

Chloroplast

Chlorophyll

Stroma

Thylakoid

Light reactions

Calvin cycle

8.1 Photosynthesis uses light energy to make food.

Photosynthesis is the process by which plants & other producers convert energy of sunlight to energy stored in organic molecules.

Chloroplast – organelle where photosynthesis takes place

Chlorophyll – chemical that gives a green color to chloroplasts.

8.1 Photosynthesis uses light energy to make food.

Chloroplasts structure is key to its function

Has an inner & outer membrane

Inner membrane encloses a thick fluid called the stroma

Suspended in the stroma are thylakoids – disk-shaped sacs

8.1 Photosynthesis uses light energy to make food.

Cellular respiration – fall of electrons form glucose to oxygen gives off energy, which is then used to make ATP.

Photosynthesis is the opposite – electrons from water are boosted uphill by the energy from sunlight.

8.1 Photosynthesis uses light energy to make food.

Excited electrons along with carbon dioxide & water are used by chloroplasts to produce glucose & oxygen.

8.1 Photosynthesis uses light energy to make food.

Photosynthesis occurs in 2 main stages.

Light reactions – convert sunlight to chemical energy

Stored in NADPH & ATP

Calvin cycle – makes sugar from carbon dioxide and H+ ions from the splitting of water.

8.1 Photosynthesis uses light energy to make food.

8.1 Concept check (QUIZ)

Draw & label a simple diagram of a chloroplast that includes the following structures: outer & inner membranes, stroma, thylakoids.

What are the reactants of photosynthesis, what are the products?

Name the 2 main stages of photosynthesis. How are they related?

8.2 The light reactions convert light energy to chemical energy

Objectives

Explain how light interacts with pigments.

Describe how photosystems help harvest light energy.

Identify the chemical products of the light reactions.

Key Terms

Wavelength

Electromagnetic spectrum

Pigment

Paper chromatography

photosystem

8.2 The light reactions convert light energy to chemical energy

Light energy is a form of electromagnetic energyTravels in waves (similar to ocean

waves)

Measured by wavelength – distance between 2 adjacent waves.

8.2 The light reactions convert light energy to chemical energy

Different forms of electromagnetic energy have characteristic wavelengths

Electromagnetic spectrum – the range of types of electromagnetic energy

8.2 The light reactions convert light energy to chemical energy

Pigments – chemical compounds that give a substance its color.Cause different wavelengths to be…

AbsorbedTransmittedReflected

8.2 The light reactions convert light energy to chemical energy

Paper chromatography – lab technique used to observe different pigments in substances.

8.2 The light reactions convert light energy to chemical energy

Harvesting light energy

Photosystems – clusters of pigment molecules

Chlorophyll a

Chlorophyll b

Carotenoids

8.2 The light reactions convert light energy to chemical energy

Harvesting light energy1)Pigments absorb light energy2)transfer energy to electrons3)transfer energy to electronacceptor.4)converts to ATP or NADPH.

8.2 The light reactions convert light energy to chemical energy

Chemical products of the light reactions

Oxygen, released as a waste product of the 1st photosystem.

ATP – produced by the release of energy by the electron transport chain between photosystems.

NADPH – produced by the second photosystem

8.2 The light reactions convert light energy to chemical energy

8.2 Concept check

Explain why a leaf appears green.

Describe what happens when a molecule of chlorophyll a absorbs light.

Besides oxygen, what 2 molecules are produced by the light reactions?

Where in the chloroplast do the light reactions take place?

8.3 The Calvin cycle makes sugar from carbon dioxide

Objectives

Explain how the Calvin cycle makes sugar.

Summarize the overall process of photosynthesis.

The Calvin cycleCalled a cycle because the starting

material RuBP is regenerated each time the process occursRuBP is a 5 carbon sugar

8.3 The Calvin cycle makes sugar from carbon dioxide

Into the Calvin cycleCarbon dioxideATPNADPH

8.3 The Calvin cycle makes sugar from carbon dioxide

From air

From light reactions

Outputs of Calvin cycleG3P (an energy rich sugar)

–Not yet glucose

–Used by plant to make glucoseADP + PNADP+

8.3 The Calvin cycle makes sugar from carbon dioxide

Summary of photosynthesisLight reactions

Convert light energy to chemical energy

Occurs in thylakoidsUses water (reactant) & releases

oxygen (product)

8.3 The Calvin cycle makes sugar from carbon dioxide

Calvin cycleOccurs in stromaUses ATP & NADPHConverts carbon dioxide (reactant)

to sugar (product)

8.3 The Calvin cycle makes sugar from carbon dioxide

8.3 Concept check

What are the inputs & outputs of the Calvin cycle?

Which stage of photosynthesis uses each reactant from the overall photosynthesis equation? Which stage generates each product from the overall photosynthesis equation?

Why is the Calvin cycle called a cycle?

What molecule is the direct product of photosynthesis? How is that molecule then used by the plant cell?

8.3 Concept check

8.4 Photosynthesis has a global impact. Objectives

Describe the path of carbon in the carbon cycle.

Explain how photosynthesis is related to climate.

Key TermsCarbon cycleGreenhouse effect

8.4 Photosynthesis has a global impact.

Processes that occur on a global scale depend on chloroplasts & mitochondrionCarbon cycle – process by which

carbon moves from inorganic to organic & back to inorganic.

8.4 Photosynthesis has a global impact.

Path of carbon in the carbon cycle

1) Producers convert inorganic carbon to organic carbon through photosynthesis.

2) Consumers eat the producers, may be eaten by other consumers.

3) Cellular respiration by both producers & consumers eventually carbon dioxide to the atmosphere

8.4 Photosynthesis has a global impact.

Plants & other photosynthetic organisms make about 160 billion metric tons of organic material.80 trillion copies of book25 stacks reaching to the sun.

8.4 Photosynthesis has a global impact.

Carbon dioxide in the atmosphere traps in heat – greenhouse effect

Keeps world climate warm enough for living things.Average 10°C warmer than it would

be.Amount of carbon dioxide in

atmosphere is rising.

8.4 Photosynthesis has a global impact.

Photosynthesis

Stages of Photosynthesis

Electromagnetic spectrum

Pigments & Color

Harvesting Light Energy

Chemical products of light reactions

Calvin cycle

Photosynthesis

Greenhouse effect

Light Waves