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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
Go to Section:
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