Download ATP - Wando High School

Photosynthesis and Cellular
Respiration
Trapping the Sun’s Energy
• The process by which plants capture
energy from the sun to build
carbohydrates is called photosynthesis.
– Solar energy converts water and carbon
dioxide into chemical energy stored in
simple sugars.
Trapping the Sun’s Energy
• The simple sugar that photosynthesis
produces is glucose which the plant uses
to store energy.
• The equation that represents
photosynthesis is:
6CO2 + 6H2O  C6H12O6 + 6O2
Solar
energy
Phases of Photosynthesis
• Photosynthesis requires energy from the sun,
but the sun is not available 24 hours a day.
• Photosynthesis must occur in TWO phases
– Light-dependent Reactions (light reactions)
• Convert light energy into chemical energy
(ATP and NADPH)
Phases of Photosynthesis
– Light-independent Reactions (dark
reactions)
• Uses the ATP and NADPH from the
light-dependent reactions to build
glucose
6CO2 + 6H2O  C6H12O6 + 6O2
Solar
energy
The Role of Chloroplasts and Pigments
• Photosynthesis takes place
in the chloroplasts
• Light-dependent reactions
take place in the
membranes of the
thylakoid disks
• Light-independent
reactions take place in the
stroma
The Role of Chloroplasts and Pigments
• The thylakoid membranes contain the
pigments that can absorb certain
wavelengths of sunlight.
• The most common pigment in the
chloroplasts is chlorophyll.
The Role of Chloroplasts and Pigments
• Chlorophyll a and b absorb most
wavelengths of light except for green.
Green is reflected making the plants
appear green.
• In the fall, plants reabsorb chlorophyll
leaving other pigments that reflect other
wavelengths of light – making the leaves
appear red, yellow, or orange.
Light-dependent Reactions
• Sunlight strikes the chlorophyll molecules in the
thylakoid membrane.
• Light energy is transferred to electrons
• The electrons become highly energized and are passed
down an Electron Transport Chain
Light-dependent Reactions
• The electrons become highly energized and are passed
down an Electron Transport Chain
Light-dependent Reactions
• The Electron Transport Chain is a series of
proteins in the thylakoid membrane
• As the electrons are transferred from one
protein to another, some energy is released
which…
Light-dependent Reactions
– helps join ADP and Phosphate to form ATP
– Pump hydrogen ions into the center of the
thylakoid disk to join H+ and NADP+
forming NADPH
– ATP and NADPH will be used during the
light-independent reactions
Light-dependent Reactions
• The electrons excited by the light energy
that passed down the electron transport
chain and left with NADPH need to be
replaced so the reaction can happen again.
Photolysis 
Light-dependent Reactions
• To replace those electrons, a water molecule is
split (photolysis), sending electrons back to the
chlorophyll and releasing Oxygen released to
atmosphere and Hydrogen ions which remain
in the thylakoid – this supplies the oxygen that
we breathe.
Photolysis 
Photosynthesis Step 1: Light Reaction – occurs in the thylakoids inside the chloroplast
eChlorophyll in
the thylakoids
e- - h
e
1d
Water
1a. Light energy
is absorbed by
the chlorophyll
e-+
Electron
transport
chain
O2 + H+
1b. Electrons
raised to
higher energy
level in the
chlorophyll
atoms
ATP
NADP
+H=
NADP
H
1c. Electrons move down
the electron transport
chain (series of proteins
that pass the electrons
along). ADP uses energy
from electrons to make
ATP..
1d. Photolysis: Water is
broken down into oxygen
(given off by plant),
electrons (replace lost
electrons in chlorophyll),
and H+ that join with
NADP to form NADPH.
These electrons return to
chlorophyll so the light
reaction can happen again.
Light-independent Reactions
• The second phase of photosynthesis does
not require light and is called the Calvin
Cycle.
• The Calvin Cycle occurs in the stroma of
the chloroplast.
Light-independent Reactions
• The Calvin Cycle uses the ATP and
NADPH that was built during the lightdependent reactions
Photosynthesis Step 2: Dark Reaction (Calvin Cycle) – Occurs in the STROMA
ATP
Electrons and ATP from
light reaction get
dumped into the Calvin
Cycle to run it.
ATP becomes ADP
NADPH
Carbon
dioxide
from the air
Calvin Cycle
NADPH becomes
NADP
Energy from ATP and
Hydrogen from
NADPH combine to
form glucose.
Calvin Cycle: Series of
steps that build up
compounds using carbon
dioxide from the air.
1 glucose
Photosynthesis Equation
Light Energy
6CO2 + 6H2O
Carbon Dioxide
from the air –
Used in the
Calvin Cycle
during the Dark
Reactions
chlorophyll
C6H12O6 + 6O2
Glucose Made in
the Calvin Cycle
during the Dark
Reactions
Water Split during
Photolysis in the
Light Reactions
Oxygen Released
during Photolysis
in the Light
Reactions
Plants can use this glucose molecule for energy during Cellular Respiration. Plants can
also convert this glucose molecule into other organic compounds such as proteins and
fats/lipids or other carbohydrates like starch and cellulose
What goes in and out
3 Factors that Affect Photosynthesis
• Carbon Dioxide (CO2)
– Without CO2, the plant would not have one of the
raw materials needed in the photosynthesis equation
– CO2 is used in the first step of the Calvin Cycle
• Temperature
– The temperature must be in the appropriate range
for the plant in order for photosynthesis to properly
occur
3 Factors that Affect Photosynthesis
• Intensity of Light
– If the intensity of light is lower, the available energy
for photosynthesis is lower.
• In a greenhouse, if the light source is further
away, intensity is lower and less photosynthesis
can occur
• If light is not available at all, the light-dependent
reactions cannot occur (nor can they provide the
materials used in the light-independent reactions)
Electron
transport
chain
eChlorophyll in
the thylakoids
e-
1d
Water
+ O2 + H+
e-
NADP + H
= NADPH
ATP
ATP
ATP becomes ADP
Carbon
dioxide
from the air
NADPH
Calvin Cycle
glucose
NADPH becomes
NADP
Cellular Respiration
• Cellular Respiration: Process by which
mitochondria break down food molecules to
produce ATP in plants and animals
Nutrients + oxygen  water + ATP + CO2
• Changes the chemical energy in glucose into
the chemical energy in ATP
Cellular Respiration
• There are three stages of Cellular Respiration
– Glycolysis
• Anaerobic – does not require oxygen
– Citric Acid Cycle
• Aerobic – does require oxygen
– Electron Transport Chain
• Aerobic – does require oxygen
Glycolysis
• Glycolysis: Breaks down glucose into two
molecules of pyruvic acid
• This reaction uses enzymes and takes
place in the cytoplasm of the cell
ATP
ATP
ATP
Enzymes + 2 ATP
Glucose
Pyruvate
Pyruvate
ATP
Glucose breaks down into 2 pyruvate and 4 ATPs (Net gain of 2 ATP)
Glycolysis
• Produces
– 2 pyruvic acid molecules (used in the next
step of Cellular Respiration)
– 2 ATP molecules (energy the cell can use)
ATP
ATP
ATP
Enzymes + 2 ATP
Glucose
Pyruvate
Pyruvate
ATP
Glucose breaks down into 2 pyruvate and 4 ATPs (Net gain of 2 ATP)
Into the Mitochondria…
• Before the next step of Cellular Respiration
can occur, the pyruvic acid molecules must
go into the mitochondria.
• The two aerobic reactions are the Citric
Acid Cycle (or Krebs Cycle) and the
electron transport chain.
Pyruvic acid  CO2 + water + ATP
THE KREB’S CYCLE
ATP
Citric Acid Cycle
(Kreb Cycle)
Pyruvate
Pyruvate
e
e- e
- NADH
+
FADH
CO2
Electron Transport Chain
• Electron Transport Chain uses the electron carriers
(NADH and FADH2) to pass electrons down the
protein chain and slowly release energy that is used to
form ATP and water molecules
Electron Transport
Cellular Respiration
2 ATP
Glucose
Pyruvic
Acid
NADH
and FADH
Oxygen
Glycolysis
Citric Acid Cycle
Pyruvic
Acid
CO2
NADH
and FADH
Water
Electron Transport Chain
ATPs
ATPs
Cellular Respiration Equation
C6H12O6 + 6O2
Glucose made in
photosynthesis
by plants or
consumed by
animals
Used in
Glycolysis
Oxygen from the
atmosphere
Used in Electron
Transport Chain
6CO2 + 6H2O + energy
Carbon
Dioxide –
waste
product of
the Citric
Acid Cycle
Water –
released
from
Electron
Transport
Chain
ATP released from
Glycolysis, Citric
Acid Cycle, and
Electron Transport
Chain
Between 34-36 ATP can be made with this process.
This ATP can be used by the cells for cellular metabolism.
Fermentation
• When oxygen is not available anaerobic
respiration, fermentation, can follow glycolysis
in order to continue to produce energy.
• This is not as efficient as aerobic respiration and
produces far fewer ATPs
Fermentation
• Two types of fermentation:
– Lactic acid Fermentation
– Alcoholic Fermentation
Lactic acid Fermentation
• Lactic acid fermentation occurs in muscle cells
during strenuous exercise when a lot of energy
is required and oxygen is scarce (oxygen debt).
Glucose  pyruvic acid  lactic acid + ATP
Lactic acid Fermentation
• The lactic acid is transferred from the muscle
cells to the liver where it will be converted
back into pyruvic acid
• The build up of lactic acid in the
muscles is what causes them to
be fatigued and sore.
Alcoholic Fermentation
• Yeast and some bacteria cells are capable of
alcoholic fermentation during which glucose is
broken down to release CO2 and ethyl alcohol
Glucose  pyruvic acid  alcohol + CO2 + ATP
Alcoholic Fermentation
• The bubbles formed by the CO2 make
bread rise
• The alcohol released
turns grape juice into wine
Photosynthesis vs. Cellular Respiration
Photosynthesis
Stores Energy as glucose
Cellular Respiration


Releases Energy in glucose
Occurs in Living Cells
Uses an Electron Transport
Chain
Occurs in Plant Cells






Occurs in Animal Cells
Releases Oxygen


Releases Carbon Dioxide
Creates Energy

Neither!