Photosynthesis in Overview
• Process by which plants and other autotrophs
store the energy of sunlight into sugars.
• Requires sunlight, water, and carbon dioxide.
• Overall balanced equation:
Sunlight + 6 CO2 + 6 H20  C6H12O6 + 6 O2
Reactants
Products
• Occurs in the leaves of plants in organelles called
chloroplasts.
• Plants are photoautotrophs
Leaf Structure
• Most photosynthesis occurs in the palisade mesophyll layer.
• Gas exchange of CO2 and O2 occurs at openings called stomata
surrounded by guard cells on the lower leaf surface.
Palisade
Spongy
Chloroplast Structure
• 2 membranes make
up a chloroplast
• Thickened regions
called thylakoids. A
stack of thylakoids is
called a granum.
(Plural – grana)
• Stroma is a liquid
surrounding the
thylakoids.
Why do most plants look green?
Pigment- light gathering molecule used to attract sunlight
What factors effect photosynthesis
rates?
Water Availability- too much or too little
Temperature- too hot or too cool
Light Intensity- not enough or too much
Photosynthesis: The Chemical Process
• Occurs in two main phases.
– Light reactions (Light Dependent) (photo part)
– Dark reactions (aka – the Calvin Cycle) (Light
Independent) (synthesis part)
• Light reactions are the “photo” part of
photosynthesis. Light is absorbed by pigments.
Light Reactions
• Light-dependent reactions occur on the
thylakoid membranes.
– Light and water are required for this process.
– Energy storage molecules are formed. (ATP
and NADPH)
– Oxygen gas is made as a waste product.
Dark Reactions (Calvin Cycle)
• Dark reactions (light-independent) occur in the stroma.
– Carbon dioxide is “fixed” into the sugar glucose
(C6H12O6).
– ATP and NADPH (energy) molecules created during
the light reactions power the production of this
glucose (C6H12O6) production.
– Glucose (C6H12O6) is high energy food for the plant
– Process does not require light, but can occur during
daylight hours
C6H12O6
Making Connections
•
•
•
•
•
What is not a requirement of Photosynthesis?
A Light
B Pigment
C Oxygen
D CO2
Making Connections
• Where would you more than likely find most
of the chloroplasts in a leaf? Top/bottom
Explain?
• If a plant isn’t green does it have Chlorophyll?
Classwork
• Questions 1-5 on pg. 207
• Questions 1-5 on pg. 214
Feel the Burn
• Do you like to run, bike, or swim?
• These all are good ways to exercise. When you
exercise, your body uses oxygen to get energy
from glucose, a six-carbon sugar.
1. How does your body feel at the start of exercise, such as a long, slow
run? How do you feel 1 minute into the run; 10 minutes into the run?
2. What do you think is happening in your cells to cause the changes
in how you feel?
3. Think about running as fast as you can for 100 meters. Could you
keep up this pace for a much longer distance?
All Cells Need Energy
• Cells need energy to do a variety of
work:
–Making new molecules.
–Building membranes and
organelles.
–Moving molecules in and out of the
cell.
–Movement.
Where Does A Cell Get Energy?
• Food is broken down to a form the cell
can use.
• Extra energy is stored in an ATP
molecule, a nucleotide.
What Is ATP?
• ATP – adenosine triphosphate is a
molecule made up of an adenine, ribose,
and 3 phosphate groups.
Adenine
Ribose
How Does ATP Work?
• Energy is stored in the bond
between the second and third
phosphate group.
•Adenine
When the bond is broken, energy
is released and ADP is formed.
Ribose
Cellular Respiration Video:
http://viewpure.com/Gh2P5CmCC0M
Mitochondrion
Electrons carried in NADH
Electrons
carried in NADH
and FADH2
Pyruvic acid
Glucose
Glycolysis
Krebs
Cycle
Electron
Transport Chain
Mitochondrion
Cytoplasm
2
2
32
Cellular Respiration Formula
Cellular Respiration Formula
6O2 + C6H12O6 -> ATP + 6H2O + 6CO2
How is this different from photosynthesis?
Sunlight + 6CO2 + 6H2O -> C6H12O6 + 6O2
They are opposite reactions, mutualistic
Glycolysis
Glucose
2 Pyruvic acid
To the electron
transport chain
Glycolysis
Glucose
2 Pyruvic acid
To the electron
transport chain
Glycolysis
Glucose
2 Pyruvic acid
To the electron
transport chain
Glycolysis Animation
The Krebs Cycle
Citric Acid
Production
Mitochondrion
The Krebs Cycle
Citric Acid
Production
Mitochondrion
Krebs Cycle Animation
Electron Transport Chain
Animation
Electron Transport
Hydrogen Ion Movement
Channel
Mitochondrion
mbrane
ATP synthase
Inner
Membrane
Matrix
ATP Production
Cellular Respiration
Flowchart
Cellular Respiration
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
2
Krebs
Cycle
2
Electron
Transport
Chain
32
38% Efficient, 62% Lost as Heat
Carbon
Dioxide
(CO2)
+
Water
(H2O)
Chemical Pathways
Aerobic Pathway
(34)
(2)
Glucose
Glycolysis
Anaerobic Pathway
Krebs
cycle
Fermentation
(without oxygen)
Electron
transport
Alcohol or
lactic acid
• WHAT IF THERE ISN’T ANY OXYGEN?
• CELLUAR RESPIRATION: Anaerobic (fermentation)
• *yeast cells = alcohol production
• *muscle cells = lactic acid production
Lactic Acid Fermentation
Glucose
Pyruvic acid
Lactic acid
Lactic Acid Fermentation
Usually enough ATP for about 90 secs
Glucose
Pyruvic acid
Lactic acid
Lactic Acid Fermentation
Glucose
Pyruvic acid
Lactic acid
Pros and Cons of Lactic Acid Fermentation
• Pros – your muscle will keep working even
without sufficient oxygen
LIVER
• Cons – you feel it, lactic acid causes sore muscles
and cramping
• Your body will get rid of lactic acid – it diffuses
into blood and goes to liver where it is converted
back to pyruvic acid – ready to enter the Krebs
cycle
Making Connections
• A healthy liver has a multitude of functions
based on the previous slide it would seem
logical that one of those would be?
• A making immediate energy
• B detoxification
Which runner uses which process?
100 meter dash
3200 meter run
• Alcoholic Fermentation
• -occurs in yeast during anaerobic conditions
• Pyruvic Acid + NADH > Alcohol + CO +
NAD+
2
You’re a Runner!
• Your running the 800 meter race in a track meet.
What process will you use to accomplish the task
• A Calvin Cycle
• B Glycolysis
• C Krebs cycle
• D Light Reaction
• E Electron Transport Chain
• F Lactic Acid Fermentation
• G Alcoholic Fermentation
Making Connections
• Name the process that does not release
energy
• A Glycolysis
• B photosynthesis
• C cellular respiration
Making Connections
•
•
•
•
•
Why is it necessary that we breath oxygen?
A to live (the typical sophomore answer)
B to accept H+, and electrons to make water
C to run the Krebs cycle
D to break down pyruvic acid