Photosynthesis

Chemosynthesis uses energy released from chemical reactions to produce food for organisms.

Organisms that carry out

chemosynthesis are microbes (bacteria) that live far from the Sun, such as deep on the ocean floor.

What is the ultimate source of all energy

SUN

Photosynthesis!!!! Which organisms carry out

photosynthesis?

Autotrophs such as plants, some protists and some bacteria

Which organelle does plants use to perform photosynthesis?

Chloroplasts

Where do we find chloroplasts?

Chloroplast containing chlorophyll

Chloroplasts are found in cells of leaves.

Stoma (Stomata) - small pores on the underside of leaves where gas exchange occurs

Chloroplast structureDisks that contain contain the pigmentChlorophyll are called Thylakoids.

A stack of thylakoids is a GRANUM

The liquid portion of a chloroplast is the STROMA

GRANUM

OVERVIEW OF PHOTOSYNTHESIS

PLANTS TAKE INCO2 AND H2O

PLANTS MAKE GLUCOSE AND OXYGEN

SUNLIGHT PROVIDES THE ENERGY

FOR PHOTOSYNTHESIS

Chlorophyll

Photosynthesis What is photosynthesis? Photosynthesis is the process

by which:

water

carbon dioxide

oxygen

glucose

TAKE IN AND USING MAKE

PLANTS(producers)

light

chlorophyll

Photosynthesis 2 steps:

Light Dependent reactions Light Independent reactions (aka

Calvin cycle)

Light Dependent Reaction

Light Independent Reaction

Photosynthesis Light Dependent reaction:

Occurs in the granaMust have light

light

Light Reaction Light Independent Reaction

LIGHT REACTION Light Independent Reaction

thylakoid(chlorophyll)

Step 1: Light Dependent Reactions

H2O O2

O2

O2

O2

O2

H H

How doesthe O2 leavethe leaf?

ENERGY

light energy reacts with the chlorophyll

water is split by the light energy

H is kept for the light independent reaction

O2 is released

O

H2

What happens to the H+?

NADP+ picks up the H+ ions (becoming NADPH) and moves them to the stroma for the light independent reaction (Calvin cycle).

NADPH is a high energy electron carrying molecule.

Light Dependent Reactions:

Also uses light energy to make…

ATP

Light Dependent

Occurs in the thylakoid (grana) Water is absorbed through

roots. Sunlight enters the chloroplast,

causing H2O molecules to split. O2 leaves as a waste product

through the stomata.

NADP+ picks up the H+ ions (becoming NADPH) and moves them to the stroma for the light dependent reaction (Calvin cycle)

ATP( ENERGY) helps to fuel the light independent reaction, or the Calvin Cycle.

Photosynthesis Light Independent reactions (aka

Calvin cycle):Occurs in the stroma

Occurs in the light and dark

Light Reaction Light Independent Reaction

Light Reaction LIGHT INDEPENDENT REACTION

stroma(liquid)

Step 2: Light Independent Reactions

AKA: CALVIN CYCLE

CO2

CO2

CO2

CO2

HC6H12O6

How does CO2

enter the plant?

H from the water split in the light reaction is present

CO2 enters the chloroplastthe reactants H and CO2 combine

HH + CO2

glucose is the product

Other carbohydrates besides glucose may be made in photosynthesis

Light Independent Overview

Carbon dioxide from the atmosphere enters the stoma

H+ breaks off from NADPH NADP+ returns to the Light

Dependent Reaction

Carbon dioxide becomes “fixed” with the H+ producing the glucose molecule C6H12O6.

ATP helps to fuel the light independent reaction. ATP becomes ADP and returns to the light dependent reaction.

Photosynthesis Review Light reactions: H2O split into H2 + O

Light independent reactions: H + CO2 = C6H12O6

H2O Light Reaction Light Independent Reaction

CO 2

C6H12O6

O 2

chlorophyll

Photosynthesis Formula How would this be written as a

chemical equation? What goes in? (the reactants) What comes out? (the products)

H2OLight Dependent Reaction

Light Independent Reaction

CO 2

C6H12O6

O 2

chlorophyll

H2O CO2 C6H12O6 O2

Photosynthesis Formula What’s wrong with this equation? The number of atoms is not equal on

both sides of the equation.

Balance the equation so that the number of atoms of each element is equal on both sides.

H2O CO2 C6H12O6 O2

one carbon atom reactant

6 carbon atoms product

6 6 6(1)

Now balance it as if TWO glucose molecules were being produced.

Photosynthesis Review What goes in? (the reactants) What comes out? (the products)

H2O Light Reaction Dark Reaction

CO 2

C6H12O6

O 2

chlorophyll

6CO2 + 6H2O 6O2 + C6H12O6

light

chlorophyll