Comparing Photosynthesis and Cellular Respiration

-Biochemical Pathways for Energy

Section 8-3

Where does the energy needed to make ATP come from?

1.To make ATP, cells must constantly break down glucose. (Glucose = 650 kilocalories).

2.The highly-energized bonds in glucose must be handed over to ATP because ATP holds a much smaller, more manageable amount of energy for the cell to use.

3.This process of making ATP from glucose is called cellular respiration.

Remember that our cells must have ATP to run cellular chemical reactions.

Where does the Glucose come from?

The highly-energized bonds in glucose are formed in a process called photosynthesis, which stores solar energy from the sun in those chemical bonds.

Comparing Cellular Respiration and Photosynthesis

In photosynthesis, energy is stored in the bonds of glucose (C6H12O6).

In cellular respiration, energy is released from glucose and stored in ATP molecules for the cell to use.

Photosynthesis and cellular respiration are life’s most important processes.

Reason: energy!

Molecule Key

CO2 Carbon Dioxide

O2 Oxygen

H2O Water

C6H12O6 Glucose

ATP/ADP Energy carrier

Energy released for Cellular

Reactions**Some lost as heat

C6H12O6 and 6O26CO2 and 6H2O

Photosynthesis

36 ATP Breaks bonds in C6H12O6 to

transfer and store

chemical energy in ATP

36 ADP& 36 P

Cellular Respiration

SolarEnergy

Reactants

ProductsReactants

ProductsTransforms solar energy into chemical energy by creating energy-storing bonds found in

C6H12O6

1.Solar energy is constantly required for this energy cycle to continue supporting life.

2.Carbon, oxygen, and hydrogen atoms are recycled in the environment in order to transfer chemical bond energy.

Notes over Comparison Diagram

Go to Section:

Photosynthesis

Photosynthesis and cellular respiration form a cycle-the products of one are used as the reactants for the other.

Cellular Respiration

Happens

In the

Chloroplast!

Happens

In the

Mitochondria!

Chlorophyll

Go to Section:

Photosynthesis Equation

Photosynthesis produces glucose and oxygen, which are used as reactants in cellular respiration.

Reactants

6 CO2 + 6 H2O — C6H12O6 + 6 O2

Light Energy

Products

Chloroplast

Cellular Respiration produces carbon dioxide and water, which are used as reactants in photosynthesis. (the process of obtaining energy)

Cellular Respiration Equation

C6H12O6 + 6 O2— 6 CO2 + 6 H2O + 36 ATP

Reactants Products

Enzymes

Mitochondria

A Closer Look at Photosynthesis

Photosythesis from leaf into grana

animation

Photosynthesis Overview Animation

Photosynthesis Animations

tutorials

Why study photosynthesis

Photosynthesis is the process producers use to transform solar energy into chemical energy (stored in food)

(used or stored)

1.Light -- Light is a form of energy.

2.Chloroplasts – are green organelles in plants where photosynthesis occurs.

3.Pigments—colored molecules that help absorb light.

4.Chlorophyll -- green pigment found in chloroplasts that absorbs light energy.

5.Water – source of hydrogen atoms to make glucose.

6.Carbon Dioxide – source of carbon atoms to make glucose

Requirements for Photosynthesis

OH H

C

O O

Absorption of Light byChlorophyll a and Chlorophyll b

V B G Y O R

Chlorophyll b

Chlorophyll a

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Chlorophyll Light Absorption

1. Chlorophyll BEST absorbs energy of red & blue light

2. Plants appear green because they REFLECT green light

• Plants grown in green light don’t grow very well. Why?

Plants don’t absorb the energy in green light!

1. In each of the above beakers there is a submerged water plant under a funnel. As the light enters the cells of these plants photosynthesis occurs producing oxygen bubbles that can be seen coming out of the top of the funnel.

• Which beaker will produce the most oxygen bubbles?

• Which beaker will product the least oxygen bubbles?

Light Intensity and Photosynthesis

13

As the intensity of light increases the rate of photosynthesis also increases.

How does Light Intensity effect the rate of photosynthesis?

1. Plants obtain energy DIRECTLY from suna.Plants will breakdown

glucose for energy using cellular respiration

b.Plants store extra glucose as starch to use later

c. Plants use glucose to make cellulose for cell walls

Go to Section:

Benefits of Photosynthesis

2. Animals obtain energy INDIRECTLY from sun

a.Animals can feed on plant’s stored glucose

b.Animals get O2 from plants

Go to Section:

Benefits of Photosynthesis

Comparison Chart

Photosynthesis Cellular Respiration

Location Chloroplast Mitochondria

Purpose Store solar energy into food

Release energy in food to make ATP

Reactants 6H2O & 6CO2 C6H12O6 & 6O2

Reactants Water, carbon dioxide, & light energy

Glucose (chemical energy) & oxygen

Products C6H12O6 & 6O2 6H2O & 6CO2

Products Glucose & oxygen Water, carbon dioxide, & 36 ATP (energy)

What about the animal cells?

Mitochondria – power plant of the cell

Glucose from food sources

Oxygen in fuel molecules (food) burned ATP synthesized CO2 out