Download 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 + H2O  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 + H2O
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
SUNLIGHT
6CO2 + 6H2O

C6H12O6
+
6O2
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
Energy-Storing Compounds
a. NADP  NADPH
b. ATP
4. Water
5. Carbon dioxide
6. Plants/Autotroph
3.
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
grana (thylakoids)
chloroplast
stroma
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
grana (thylakoids)
stroma
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.
H2O  H+ + O2 (released to the air)
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 (C6H1206)
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) CO2 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:
6CO2 + 6H2O  C6H12O6 + 6O2
H2O was used to form the product of …..
CO2 was used to form the product of……
granum (stack of thylakoids)
1
chloroplast
6H2O
thylakoid
6CO2
3
6O2
2
energy
stroma (fluid outside the thylakoids)
1 six-carbon sugar
4
C6H12O6
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 C4 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.