Chapter 8 Photosynthesis

8.1 Energy and Life

10/27/2005

What is Energy?

Ability to do work

Autotrophs vs. Heterotrophs

Makes their own food

Use the energy of the sun

Ex. Plants

Obtains energy from the foods they consume

ATPAdenosine TriPhosphateMade up of:

Adenine5 Carbon sugar (ribose)Three phosphate groups

KEY TO STORE & RELEASE ENERGY

Storing Energy

ADP (Adenosine DiPhosphate)Similar to ATP2 phosphate groupsKey to the way in which living

things store energyAdd on available energy with a

phosphate to ADP to create ATPAnalogy --> Battery

Releasing Energy

How is the energy stored in ATP released?Breaking the chemical bond

between the second and third phosphate group

Basic energy source of all cells

What is energy used for?

Carry out active transport

protein synthesis

Responses to chemical signals

ATP can only pack small

amounts of energy

P P

Adenine

Ribose

Phosphate

ADP

P P

Adenine

Ribose

Phosphate

ATP

P

8.2 Photosynthesis: An Overview

Photosynthesis

key cellular process identified with energy production

Who goes through photosynthesis?PLANTS

Key PlayersvanHelmont

Most of the gain in mass comes from water

Priestley plant releases oxygen

IngenhouszPlant releases oxygen only

with the presence of light

Photosynthesis Equation

6CO2 6H2O+Carbon dioxide Water

REACTANTS

LIGHT

Photosynthesis Equation

C6H12O6 6O2+Sugar Oxygen

PRODUCTS

LIGHT

Photosynthesis Equation

6CO2 6H2O+ C6H12O6 6O2+LIGHT

DESCRIBE WHAT IS HAPPENING IN THE REACTION.

In photosynthesis, plants use the energy of sunlight to change water and carbon dioxide into high-energy sugars and oxygen.

Lights and Pigments

Plants needLight

Form of energyPigment

light absorbing moleculeChlorophyl

Principal pigment in plants

8.3 The Reactions of Photosynthesis

Chloroplast

where photosynthesis takes place

thylakoid membranes = saclike photosynthetic materials found in chloroplast

Chloroplast Granum = stack of thylakoid

photosystems = organization of chlorophyll and other pigments light collecting units of the chloroplast

Photosystems

2 part processLight dependent

In the thylakoid membranesLight independent (Calvin cycle)

In the stromaRegion outside the

thylakoid membranes

Electron Carriers

Sunlight excites electrons in chlorophyll

electrons gain tons of energy

high energy electrons need special carriers from chlorophyll to other molecules

Electron Transport Chain

carrier molecule = compound that can accept a PAIR of high-energy electrons and transfer them to along with MOST of their energy

NADP+One of the carrier moleculesNicotinamide adenine dinucleotide

phosphateAccepts and holds 2 high-energy

electrons along with H+ (hydrogen ions)

This creates NADPHNADP+ + H+ --> NADPH = converts

energy sunglight into chemical form

NADPH

carries high-energy electrons produced by light absorption in chlorophyll to chemical reactions

used for synthesis of molecules

NADP+

2 high energy e-

H+

NADPH

8.3B

11 / 13 / 06

Light Dependent Reactions

requires lights

uses energy from light to produce ATP and NADPH

Light Dependent Reactions

Products OXYGEN GAS (02)

2 energy carriers ADP -- > ATP NADP+ --> NADPH

Light Dependent Reaction

o Light breaks up H2O to

have electrons, H+, and O

o O2 is released into the air

o H+ released into thylakoid membrane

1. Photosystem II

Light Dependent Reaction

e- absorb light

Creates high-energy electrons

2e- passed through e- transport chain

1. Photosystem II

Light Dependent Reaction

2 high energy electrons provide Energy to move H+ from stroma INTO thylakoid membrane

2. Electron Transport Chain

Light Dependent Reaction

o Light re-energizes electrons

o NADP+ picks up high energy electrons and H+

o H+ + NADP+ --> NADPH (electron carriers)

3. Photosystem I

Light Dependent Reaction

o More H+ are pumped across the membrane

o Inside = positive ionso Outside = more negativeo Importance = provides

energy to make ATP

4. Hydrogen Ion Movement

Light Dependent Reaction

a)ATP Synthase = protein on cell membrane• Allows H+ to pass

through membrane

b)ATP Synthase binds ADP + P+, creating ATP

5. ATP Formation

Light Dependent Reactions

Products OXYGEN GAS (02)

2 energy carriers ADP -- > ATP NADP+ --> NADPH

8.3 C

11 / 14 / 06

Quickwrite

1. What

Calvin Cycle

uses ATP and NADPH from Light Dependent Reaction

Product - High energy Carbohydrates (sugar, starch)

Calvin Cycle

1. 6 CO2 enter the cycle from

atmosphere

2. Combine with six 5-Carbon Molecules

3. Result = twelve 3-Carbon Molecules

A. CO2 Enters the Cycle

Calvin Cycle

1. ATP and electrons from NADPH used

2. 12 3-carbon molecules converted to higher energy forms

B. Energy Input

Calvin Cycle

1. Two 3-Carbon molecules are removed• produce sugars, lipids,

amino acids, and other compounds for metabolism

C. 6-Carbon Sugar Produced

Calvin Cycle

1. ATP is used

2. Ten 3-Carbon molecules convert back to six 5-Carbon molecules

3. 5-Carbon molecules combine with 6 CO2 molecules to begin the next cycle

D. 5-Carbon Molecules Regenerated

Calvin Cycle

It takes 6CO2 to produce a

SINGLE 6-Carbon sugar molecule

Removes CO2 from air

Sugar needed for growth and development

Create a Flow Chart

6 ____ go into cycle

Combines with six ________ molecules

Results = _____________ molecules

ATP and Electrons used from NADPH

____________ molecules converted into higher

energy forms

Two __________ Molecules removed

Produces ________________________________________________

_______

______ 3-Carbon molecules converted back to 6

__________ molecule

Cycle repeats!

Factors Affecting Photosynthesis

shortage of water = slow or stop photosynthesis

temperature = damage or slow down how enzymes work

Factors Affecting Photosynthesis

intensity of light = more light, increase photosynthesisUntil maximum levels are hit