Unit 5:
Photosynthesis & Cellular
Respiration
-What cycle is this?
-Name abiotic and
biotic components.
-What is an
ecosystem?
Photosynthesis and Cellular Respiration
• Carbon
travels in and out of plants and animals in
different ways.
• Plants
convert CO2 into glucose (sugar) via
photosynthesis.
• Plants
and animals convert glucose into CO2 via
cellular respiration.
Key Terms
• Biogeochemical
Cycles- The movement of abiotic factors
between the living and nonliving components within
ecosystems; also known as nutrient cycles
• Biotic
Factor- Any living component of an ecosystem
 ex) fish, trees, bacteria, birds, humans, potatoes
• Abiotic
Factor- Any nonliving component of an ecosystem
 ex) Rocks, dirt, water, coal
Key Terms, cont’d
•
Ecosystem- A system composed of organisms and nonliving
components of an environment
 In other words, an ecosystem is the interaction between biotic and abiotic
factors.
•
Carbon Cycle- The movement of carbon through the ecosystem,
from the air into producers and back into consumers.
•
Producer- An organism that uses a primary energy source to
conduct photosynthesis or chemosynthesis.
 A producer is an organism that "produces" its own energy to use in cellular
respiration.
Carbon Cycle
1. Carbon will enter a plant,
algae, or cyanobacteria
through photosynthesis.
 If it doesn't enter one of these,
the Carbon molecule will
typically stay in the
atmosphere.
Carbon Cycle
2. The Carbon molecule can end up
traveling in one of four potential
ways from the plant.
 a. It can end up stored in the plant as
sugar.
 b. That sugar (with the carbon in it)
could then be used in the plant as
energy, and released back into the
atmosphere as CO2.
 c. The plant could die, and the
carbon will end up in the soil or
water as the plant decomposes.
 d. The plant could be eaten, and end
up in a consumer.
Carbon Cycle
3. If the carbon molecule ends up
in a consumer, the Carbon molecule
could end up in one of 3 potential
areas.
 a. It could end up in another
consumer (because the animal was
eaten).
 b. It could be used as energy and end
up in the atmosphere via respiration.
 c. It could end up in the ground if the
consumer dies.
Light & Energy
• Energy
• Light
moves in wavelengths.
is a form of energy.
Light & Energy
• The
energy of light:
 Light is a wave, and travels the same
way other electromagnetic waves
travel.
 This is the same way radio stations,
phone signals, and Wi-Fi travel
through the air.
 Chlorophyll reacts to two different
wavelengths of light:
 Purple & Blue: 400-500 nm (nanometers)
 Red: 650 – 700 nm
`
Light & Energy
• Photon-
a particle of light
• When
photons hit other molecules, one of three
things can happen:
 1. The photon is reflected off the molecule, and the
energy stays with the photon
 2. The molecule will absorb the energy, and the energy
can be lost as heat (this is why you become warm when you
stand in the sun).
 3. The energy is absorbed by the electrons of the molecule
and causes the molecule to interact with other
surrounding molecules.
Light & Energy
• Sometimes
the energy is unable to be transferred,
causing the photon to be reflected back.
• This
reflected light is what gives everything its
color. Whatever is not absorbed is the color seen.
• This
means that plants absorb all light except for
green light.
• Reminder:
All molecules/atoms have electrons, and
those electrons interact with other molecules!
Energy Molecules
• Adenosine
Triphosphate (ATP)-A molecule that provides
energy for cellular reactions and processes
• The
energy is stored between the bonds of the phosphate
molecules, when they break, energy is released!
• Adenosine
Diphosphate (ADP)- A molecule that has
provided energy for cellular reactions, can bind to a
phosphate group again to store more energy.
Energy Molecules
• NADP+-An
energy storage molecule found in
plant cells, it can bind to a proton (H+) to
store energy
• NADPH-
An energy storage molecule found in
plant cells, already storing energy through
the bond between NADP+ and H+.
Energy Molecules
• NAD+-
An energy storage molecule found in
all cells, it can bind to a proton (H+) to store
energy
• NADH-
An energy storage molecule found in
all cells, storing energy in the bond between
NAD+ and H+
Energy Molecules
• FAD-
An energy storage molecule found in
eukaryotic cells, it can bind to protons (H+)
to store energy
• FADH2-
An energy storage molecule found in
eukaryotic cells, storing energy in the bonds
between FAD and (H+)
Photosynthesis
• Plants
convert CO2 and light energy into glucose.
• There
are two parts to photosynthesis:
 Light Dependent
 Light Independent
• Light
Dependent reactions convert light into ATP &
NADPH.
• Light
Independent reactions convert ATP & NADPH into
Glucose.
Photosynthesis
• The
overall formula for photosynthesis:
6CO2 + 6H2O + light
C6H12O6 + 6O2
• Photosynthesis:
a process in which solar radiation is
chemically captured by chlorophyll molecules and
through a set of controlled chemical reactions resulting
in the potential chemical energy in the bonds of
carbohydrate molecules
 Photosynthesis is the use of the sun’s energy to synthesize
sugars.
Photosynthesis
• Photosynthesis
takes place in the
chloroplast of a plant cell
• Grana:
stacked columns of thylakoids
• Thylakoid
membrane: A membrane-bound
compartment inside the chloroplast, it is
the site of all light-dependent reactions
• Chlorophyll:
Found within the thylakoid,
it collects the light energy and has the
green pigment of the plant
Light Dependent Reactions
(Light Reactions)
• The
1.
conversion of light into ATP & NADPH.
Photosystem II - Light is turned into an ATP
molecule
a. A photon strikes a pigment molecule (chlorophyll)
in the thylakoid membrane
b. An electron, provided from a water molecule, is
given this energy, or causes the electron to become
excited
 i. The water molecule splits into oxygen and hydrogen.
Light Dependent Reactions
(Light Reactions)
 c. The electron travels through the thylakoid
membrane to a transmembrane protein.
 d. The transmembrane protein uses the energy from
the electron to pump a proton (H+) into the
thylakoid via active transport.
 e. H+ exits through a different transmembrane
protein (called ATP synthase), down its
concentration gradient, and gives off energy, which
allows ADP to bind to a phosphate to make ATP.
Light Dependent Reactions
(Light Reactions)
2. Photosystem I- Light is turned into a NADPH
molecule
 a. A 2nd photon strikes a different pigment molecule
 b. The same electron from Photosystem II becomes excited
again
 c. The same electron, binds NADP+ & H+ into NADPH
 In order to get extra ATP, sometimes the electron from here is sent back
into photosystem II (step d), to make extra ATP. This can cycle as many
times as necessary!
Light Dependent Reactions
INPUTS
1. Light
2. Water
OUTPUTS
1. ATP
2. NADPH
3. Oxygen
Light Independent Reaction
(Calvin Cycle or Dark Reaction)
• The
conversion of ATP & NADPH into
Glucose.
• In
order for this to occur once, the light
dependent reactions must occur 6 times.
Formula for Light-Independent Reaction:
3 CO2 + 9 ATP + 6 NADPH + water
C 3H7O6P + 8 phosphate + 9 ADP + 6NADP+
Light Independent Reaction
(Calvin Cycle or Dark Reaction)
• 1.
3 CO2 molecules each bind to a
5 carbon sugar (RuBP) via
Rubisco (an enzyme) to create six
3-carbon sugars.
• 2.
Energy from 6 ATP molecules
are added to the six 3-carbon
sugars.
• 3.
Energy from 6 NADPH
molecules are added to the six 3carbon sugars.
Light Independent Reaction
(Calvin Cycle or Dark Reaction)
•
4. One of the six 3 carbon sugars
leaves the cycle.
 This 3 carbon sugar will bind with a
second 3 carbon sugar from a
previous Calvin cycle reaction to
create glucose.
•
5. The remaining five 3 carbon
sugar molecules are then combined
by 3 ATP molecules to recreate
RuBP to start the cycle all over again.
 The Calvin Cycle must run twice
to create glucose.
Light Independent Reactions
INPUTS
1. ATP
2. NADPH
3. CO2
OUTPUTS
1. 3 Carbon Sugar
Has to go twice to
make Glucose
(C6H12O6)
Cellular Respiration
• Plants
and animals convert glucose and
oxygen into CO2 & ATP.
• Bacteria
convert Glucose into CO2 & ATP
without oxygen.
Cellular Respiration
• The
second part of the Carbon cycle
occurs around and within the
mitochondria.
• This
is the opposite chemical reaction of
photosynthesis.
C6H12O6 + 6 O2
• This
6 CO2 + 6 H2O + 36 ATP
energy can be lost as heat or turned into ATP.
Cellular Respiration
•
Just like photosynthesis, cellular respiration can be broken into a
series of steps.
•
Aerobic Respiration- The use of Oxygen to break down sugars
into CO2 and energy
 Aerobic Respiration occurs in eukaryotic cells and requires a
mitochondrion.
•
Anaerobic Respiration- The breakdown of sugars into CO2 and
energy without the aid of oxygen
 Anaerobic respiration occurs in both prokaryotic and eukaryotic cells.
 Anaerobic Respiration is also called Fermentation.
 Anaerobic respiration provides substantially less energy than Aerobic
Respiration.
Glycolysis
1.
Glycolysis creates a small amount of ATP, NADH
and rearranges glucose into two smaller sugars.
 a. 2 ATP are used to bind their phosphate groups to a
glucose molecule
 b. The sugar molecule splits into two 3-carbon sugars
(the phosphates are still attached)
 c. The 3-carbon sugar molecules rearrange and release
their phosphate groups, created 2 NADH and 4 ATP
(giving a net of 2 ATP).
 The molecule generated by this is last reaction is called pyruvate
Glycolysis
2. Glycolysis occurs in all cells (prokaryotes
and eukaryotes), which means it must occur
outside the mitochondria.
3. Glycolysis does not require oxygen to occur.
4. Glycolysis cannot keep a eukaryotic cell
alive by itself.
Glycolysis Summary
INPUTS
1. 2 ATP
2. Glucose
OUTPUTS
1. Two 3 Carbon
Sugars
(Pyruvate)
2. 2 NADH
3. 4 ATP
*So why does Glycolysis only net 2 ATP if 4 ATP are produced?
Fermentation
•
When oxygen isn’t available, eukaryotic cells will use
lactic acid fermentation.
•
Instead of stopping at pyruvate, pyruvate is turned into
lactate.
•
When this happens, our NADH turn back into NAD+.
•
This allows a new glucose molecule to generate ATP.
•
Prokaryotic cells usually use fermentation.
Lactic Acid Fermentation Summary
INPUTS
1. Pyruvate
2. NADH
OUTPUTS
1. Lactate
2. CO2
3. NAD+
Alcoholic Fermentation Summary
INPUTS
1. Pyruvate
2. NADH
OUTPUTS
1. Ethanol
2. CO2
3. NAD+
Oxidation of Pyruvate
• The
3-carbon sugar (pyruvate) from
glycolysis is then modified to create AcetylCoA, giving off NADH and CO2.
• This
occurs twice for each glucose
molecule (once for each pyruvate molecule).
Oxidation of Pyruvate Summary
INPUTS
1. Pyruvate
2. NADH
OUTPUTS
1. Acetyl CoA
2. CO2
3. 1 NADH
*This process runs twice, once for each Pyruvate
molecule.
Krebs Cycle
(Citric Acid Cycle)
• Occurs
in the mitochondria:
1. A two Carbon fragment from Acetyl-CoA binds to a 4carbon molecule.
2. A Carbon breaks off and creates NADH. This carbon
turns into CO2.
3. A 2nd Carbon breaks off and creates NADH. This
carbon turns into CO2.
4. The 4-Carbon molecule rearranges itself, creating
ATP in the process.
Krebs Cycle
(Citric Acid Cycle)
5. The 4-Carbon molecule rearranges itself again, creating
FADH2 (another energy molecule).
6. The 4-Carbon molecule rearranges itself a third time into
the 4-carbon molecule from step 1, creating NADH.
7. This runs twice for each glucose molecule (one for each
Acetyl-CoA).
•
So far, our glucose molecule has created 4 ATP, 10 NADH,
and 2 FADH2.
Krebs Cycle Summary
INPUTS
1. Acetyl CoA
OUTPUTS
1.
2.
3.
4.
3 NADH
1 ATP
1 FADH2
2 CO2
*This process runs twice, once for each Acetyl CoA
molecule.
Electron Transport Chain
• The
mitochondria is the site of the electron
transport chain.
• All
NADH travels to here regardless of where it
was created.
 The NADH from glycolysis requires energy to get
here though, at the cost of 1 ATP each.
Electron Transport Chain
• NADH
gives its energy to an electron, creating
NAD+ and H+.
• This
electron travels through 3 transmembrane
proteins, pumping an H+ out of the mitochondrial
matrix.
 FADH2 enters later in the chain, and the electron only travels
through 2 transmembrane proteins, pumping an H+ out of the
mitochondrial matrix.
Electron Transport Chain
• These
protons enter the mitochondrial matrix through
ATP synthase, creating ATP.
 Each NADH molecule creates 3 ATP.
 Each FADH2 molecule creates 2 ATP.
• These
protons bind to Oxygen, creating water.
 This keeps the concentration gradient of protons low inside the
mitochondrial matrix.
 Without oxygen, the gradient reaches equilibrium, and the electron transport
chain stops working.
Electron Transport Chain Summary
INPUTS
1. 10 NADH
2. 2 FADH2
OUTPUTS
1. 36 ATP
2. H2O