4.2 Overview of Photosynthesis

4.2 Overview of Photosynthesis

KEY CONCEPT

The overall process of photosynthesis produces sugars that store chemical energy.

Radiant Energy  Chemical Energy

4.2 Overview of Photosynthesis

A. Organisms are classified according to how they obtain energy.

1. Autotroph/Producers

1) Producers make their own source of chemical energy.

2) Plants use photosynthesis and are producers.

3) Photosynthesis captures energy from sunlight to make sugars.

NOTE: Some organisms live in places that never get sunlight.

4.2 Overview of Photosynthesis

2. Heterotrophs/Consumers

1). Energy is obtained from food instead of sunlight or

inorganic substances.

4.2 Overview of Photosynthesis

Autotroph or Heterotroph

Are You Ready For The Challenge?

4.2 Overview of Photosynthesis

EVERGREEN

TREES

4.2 Overview of Photosynthesis

PENGUINS

4.2 Overview of Photosynthesis

EARTH

WORMS

4.2 Overview of Photosynthesis

JELLYFISH

4.2 Overview of Photosynthesis

VENUS FLY

TRAPS

4.2 Overview of Photosynthesis

PALM TREE

4.2 Overview of Photosynthesis

SEAL

4.2 Overview of Photosynthesis

Picture Plant

Carnivorous Plant

4.2 Overview of Photosynthesis

MONKEYS

4.2 Overview of Photosynthesis

GIRAFFES

4.2 Overview of Photosynthesis

Venus Fly Trap

4.2 Overview of Photosynthesis

B. Metabolism

1. The sum of all of the chemical reactions in a cell.

2. Two Types:

1) Anabolic: Simpler substances are combined to form more complex molecules

a. Requires energy from catabolic pathways.

b. Energy is in the form of ATP.

2) Catabolic: The break down of more complex organic molecules into simpler substances

a. Releases energy used to drive chemical reactions

4.2 Overview of Photosynthesis

Anabolic or Catabolic

ABCD + H

O  A + B + C + D

4.2 Overview of Photosynthesis

Autotroph or Heterotroph

4.2 Overview of Photosynthesis

Anabolic or Catabolic

A + B + C + D  ABCD + H

O

4.2 Overview of Photosynthesis

Anabolic or Catabolic

Digestion of food.

4.2 Overview of Photosynthesis

Autotroph or Heterotroph

4.2 Overview of Photosynthesis

Anabolic or Catabolic

Making a protein by combining amino acids.

4.2 Overview of Photosynthesis

C. Photosynthesis

6CO ₂ + 6H ₂ O  C ₆ H ₁₂ O ₆ + 6O ₂

In photosynthesis, is the formation of glucose

demonstrating a(n) anabolic or a catabolic

chemical reaction?

4.2 Overview of Photosynthesis

Purpose for Photosynthesis

Transforms light energy into

chemical energy (in the form of organic compounds) through a series of reactions.

Radiant Energy Chemical Energy

4.2 Overview of Photosynthesis

Requirements Needed for Photosynthesis

1) Sunlight (ROY G BIV)

Sunlight (photons): electromagnetic

energy from the sun

4.2 Overview of Photosynthesis

Requirements Continued

2) Pigments (absorb or reflect sunlight)

a. Chlorophyll is the major pigment used in photosynthesis.

(1) Chlorophyll is a molecule that absorbs light energy.

(2) Two types of Chlorophyll

Chlorophyll a (main pigment)

Chlorophyll b (accessory pigment)

(2) In plants, chlorophyll is found in organelles called chloroplasts.

What do accessory pigments do?

They capture the radiant energy that chlorophyll a can not capture

4.2 Overview of Photosynthesis

Requirements Needed for Photosynthesis

3.

Energy-Storing Compounds a. NADP  NADPH

b. ATP 4. Water

5. Carbon dioxide

6. Plants/Autotroph

4.2 Overview of Photosynthesis

C. Photosynthesis

3. Location for Photosynthesis 1) Chloroplast of Plants

a. Grana (thylakoids)

(1) Look like stacks of pennies

b. Stroma

(1) Liquid outside grana (2) Similar to cytoplasm

chloroplast

stroma grana (thylakoids)

4.2 Overview of Photosynthesis

Quick review

1. What is the energy transformation in photosynthesis:

?  ?

2. Carbon dioxide + water  glucose + oxygen

* What process is this chemical reaction demonstrating?

* What is missing from the equation?

3.

4.2 Overview of Photosynthesis

Quick review

1. (anabolic or catabolic) photosynthesis 2. What parts are located in the chloroplast?

liquid (cytoplasm)  stacks 

pieces of the stacks 

3. Where exactly is chlorophyll located? What is its role?

4. Name the 2 energy-storing compounds used in photosynthesis.

5. Why would a plant’s roots lack chloroplast?

* what is the role/job of chloroplast?

* why would the root lack this?

4.2 Overview of Photosynthesis

C. Photosynthesis

4. Two Phases of Photosynthesis

1) The Light Reactions (Light Dependent Reactions)

2) The Calvin Cycle (Light Independent Reactions)

4.2 Overview of Photosynthesis

D. The Light Reactions/Light Dependent Reactions capture energy from sunlight

1. Purpose:

1) Use the energy from the sunlight in order to make the energy-storing compounds.

2. Location:

1) Thylakoids -Grana

chloroplast

stroma grana (thylakoids)

4.2 Overview of Photosynthesis

D. Light Reactions 3. Overall Steps

1) Sunlight is captured by chlorophyll a located in the thylakoids..

2) The energy from sunlight is captured by chlorophyll a and is transferred along the thylakoid membrane.

3) The energy carried along the thylakoid membrane is transferred to the energy-storing molecules of NADP and ATP.

4) Water molecules are broken down.

5) Oxygen from the water molecule is released to the air.

H

O  H

+ O

4.2 Overview of Photosynthesis

Light Reactions Quick Review

1. Sunlight is captured by chlorophyll a

2. This radiant energy moves along the thylakoid membrane and ultimately makes ATP and NADP (NADPH). Energy Storing Compounds 3. Water is broken

Hydrogen is captured by NADP and makes NADPH

Oxygen leaves to the atmosphere as a byproduct

4.2 Overview of Photosynthesis

E. The Calvin Cycle (light-independent reactions) 1. Purpose

1) Make Sugar (C

H

0

)

4.2 Overview of Photosynthesis

E. Calvin Cycle

2. Location

1) Takes place in the stroma

3. When does it occur?

1) Immediately after the Light

reactions.

4.2 Overview of Photosynthesis

E. Calvin Cycle Overall Steps

1) CO

is used to build larger molecules (carbohydrates, lipids and amino acids).

Step 1: Carbon Fixation

1) CO2 joins with a 5-carbon compound called RuBP, making a 6-Carbon compound.

(inorganic Carbon Dioxide is “Fixed” and

turned into an organic compound)

4.2 Overview of Photosynthesis

E. Calvin Cycle Steps Continued

Step 2: The 6-C compound breaks apart into two 3-Carbon compounds (this is called PGA)

Step 3: PGA is converted into PGAL (with the help of ATP and NADPH)

Step 4: PGAL can be used to make: glucose, RuBP,

amino acids and other organic compounds.

4.2 Overview of Photosynthesis

E. Quick Review of the Calvin Cycle CO2 + RuBP  6-Carbon Compound

6-C compound breaks into two 3-C compounds (PGA)

PGA  PGAL

PGAL  glucose (amino acids, RuBP and other

organic compounds)

4.2 Overview of Photosynthesis

• Let’s Review:

6CO

+ 6H

O  C

H

O

+ 6O

H

O was used to form the product of …..

CO

was used to form the product of……

C₆H₁₂O₆ granum (stack of thylakoids)

thylakoid

1 six-carbon sugar 6H₂O

6CO₂

6O₂ chloroplast

1

2

4 3

energy

stroma (fluid outside the thylakoids)

4.2 Overview of Photosynthesis

F. Factors That Affect The Rate of Photosynthesis Temperature

a. As temperature increases, the rate increases to a maximum and then will decrease with a further rise in temperature?

b. Why? Enzymes that catalyze the reaction become ineffective at a certain temperature. Also, the

stomata will close which will limit the amount of

carbon dioxide that will enter the cell.

4.2 Overview of Photosynthesis

F. Factors That Affect The Rate of Photosynthesis Light Intensity

a. Rate increase as light intensity increases.

b. At some point, all available electrons are excited and the maximum rate of photosynthesis will be reached.

The rate will then remain steady regardless of the

amount of light.

4.2 Overview of Photosynthesis

F. Factors That Affect The Rate of Photosynthesis Carbon dioxide levels

a. Same as light levels.

4.2 Overview of Photosynthesis

G. Alternative Pathways to Photosynthesis

1. The C

Pathway

a. Plants that evolved in climates that have hot days and cooler nights will carry out this pathway. (corn, sugar cane, crabgrass)

b. Stomata is partially closed during the hottest part of the day (water conservation)

c. Contain an enzyme that will allow for carbon dioxide fixation even when carbon dioxide levels are low.

The compounds will be sent to another cell will the

Calvin cycle can resume

4.2 Overview of Photosynthesis

G. Alternatives Pathways to Photosynthesis 2. The CAM pathway

a. Plants that have evolved in hot, dry climates.

(cactus, pineapples)

b. Open stomata at night and carbon dioxide fixation

takes place at night and the Calvin cycle will pick up

in the morning. This minimizes water loss.