Game
Unit 8 Cellular Energetics
Photosynthesis
I. Autotrophs – Organisms that can “produce” their own food. (“Auto” means “self”; “trophe”
means “feeding”)
II. Heterotrophs – Organisms that “consume” other organisms (living or dead). (“Hetero” means
“other”)
III. Chlorophyll – A light-absorbing pigment found in chloroplasts of plants, algae, and blue-green
bacteria.
A. B.
Found mainly in the mesophyll layer of ground tissue in plant leaves. (“meso” refers to
“middle”)
“phyll” means “pigment”; “”chloro” means “green” (They reflect green light.)
IV. Chloroplast structure (“plast” means “container”) (These are organelles in Eukaryotes.)
A. Thylakoid – Little green discs that contain the pigment chlorophyll found inside the
chloroplast.
1. Site of the light reaction of photosynthesis. (The thylakoid membrane contains
the photosystems.)
a) Primary purpose is to make ATP and NADPH. (Both are Energy
molecules.)
b) Grana – a stack of thylakoids.
B. Stroma – The watery space surrounding the thylakoids. (It holds the water needed for
photosynthesis.)
1. Site of the light – independent reaction (Dark or Calvin Cycle) of photosynthesis.
Primary purpose is to use ATP and NADPH to make sugars using CO2.
a) V. Photosynthesis Chemical Reaction
A. B. Starts by taking sunlight energy and converting it into chemical energy (ATP & NADPH).
Then takes the chemical E (ATP and NADPH) and uses that chemical energy to power the
production of sugar (Sugars are chemical E storage molecules.)
C. 6 CO2 +6 H2O --> (in the presence of sunlight) C6H12O6 + 6O2 + Heat (Key Number is 6 in
balancing.)
D. E. Sugar is stored chemical energy for cellular respiration.
H20 splits by the process of photolysis (splitting of H2O with light) creating the O2 that
we breathe; CO2 does not create atmospheric O2 here.
F. Two processes involved in the conversion of sunlight energy to sugar
1. Light reaction (light dependent) – It changes sunlight into ATP and NADPH.
(Usable chemical energy.)
VI. G. H. 2. Calvin cycle (A.K.A. light independent reaction) – Makes sugar using CO2, ATP ,
and NADPH
a) Melvin Calvin discovered the working process.
NADP+ is converted to NADPH by picking up 2 negative electrons (The first cancels the
charge; the second makes the NADP molecule negative which allows for H+ to attach and
thus create NADPH.)
ADP is phosphorylated (Add a phosphate) by ATP synthase using the free E’s of electron
transport chain on the thylakoid membrane.
Sunlight (It is high quality E. Remember, High quality means it can perform work.)
A. Sunlight travels in waves with different wavelengths. (The Electromagnetic spectrum
shows all the Wavelengths/colors found in sunlight.)
1. Red Light– Has the longest wavelength. (It also has the least E of “white light”
.)
2. Blue Light- Has the shortest wavelength. (It has the most E of “white light”
.)
3. Spectrophotometer – This measures light wavelengths not absorbed by a
specimen.
B. Visible “white” light – ROY G. BIV (red, orange, yellow, green, blue, indigo, violet) are the
colors within.
C. Light travels in units of Energy called Photons
D. Absorption vs. Reflection
1. Absorbed –These colors are usable light E.
a) Plants use Reds and Blues; but not green.
b) Chlorophyll A – Main pigment found in all plants and algae. (It
has a structure that looks like a Mg spider in a carbon ring web.)
c) Chlorophyll B – Helps Chlorophyll A receive sunlight E. (B funnels
E to A.)
d) Carotenoids – These are accessory pigments that help
Chlorophyll A. (They funnel E to A too but reflect red, orange, or
yellow pigments.)
e) Photosystem – Group of light absorbing pigments in thylakoid
membrane. (Chlorophyll A would be in the reaction
center.)(“system” means “group of”).
(1) Photosystem I (P700) – Responsible for ATP and NADPH
production.
(2) Photosystem II (P680) – Responsible for ATP production
only.
2. Reflection – These colors are not usable. (They provide the color of an
object in your vision.)
a) This is why plants appear green to you. Green light is reflected
back toward your eyes
VII. Light Reaction of Photosynthesis
A. This process is used for converting sunlight into usable chemical Energy molecules.
(These molecules are: ATP and NADPH)
B. These two parts are occurring, in the presence of sunlight, at the same time on the
Thylakoid membranes.
C. There are thousands of these Photosystems (I and II) on each Thylakoid membrane.
D. Steps in the process
1. Step 1: Sunlight hits, and splits, the water in the stroma. It also hits the
photosystems I (P700) and II (P680).
2. Step 2: 2 Excited electrons travel down the electron transport chains. They came
from the Mg in the Chlorophyll A molecule. (The 2 excited electrons were able to
leave the Mg because the sunlight heated them up and made them move much
faster. Fast enough to escape the pull from the nucleus’ positive protons) As the
excited electrons go down the electron transport chain, their excited kinetic E
(also called Free E) is being used to power the proteins called Proton pumps.
(Remember, a proton is a Hydrogen ion and is shown as H+) As the electrons
go down their chain, their excited kinetic E decreases.
a) P680’s 2 excited electrons
(1) Free E of the electrons is used to actively transport protons (H+)
into the confined thylakoid space. (As the [H+] goes up inside
the space. The [H+] goes down in the stroma. So a concentration
gradient is created. This is a source of potential E now.) (It would
be like blowing air into a balloon. The pressure builds as more
air is blown in. This is also an example of potential E.)
(2) P700’s 2 excited electron
(a) Combine with NADP+, to make it negative so that
NADPH can be generated.)(This is the ending point for
non-cyclic electron flow.) OR
(b) Cyclic electron flow – P700 loses 2 excited
electrons to the electron transport chain, but
they return to P700. (Remember this makes
extra ATP .)
3. Step 3: The trapped H+, inside the Thylakoid, are released through the ATP
Synthase Complex. This is the group of enzymes in the Thylakoid membrane that
helps make ATP . Just look at its name. (This release of kinetic H+ powers the
phosphorylation of ADP ATP .) (This would be like the air coming out of the
blown up balloon and turning a pinwheel.)
a) This Kinetic movement of H+ produces a large amount of ATP
b) This is an example of Energy Coupling (Two processes working together
to make ATP . The first process was Active transport to pump the H+ into
the Thylakoid to make the concentration gradient. The second process
VIII. 4. is a type of diffusion. The H+ going from high [ ] to low [ ]. The kinetic
movement of the H+ fuels the production of ATP .) This is Chemiosmosis
Step 4: ATP and NADPH will be used to power carbon fixation of CO2 into sugar
in the Calvin Cycle.
Calvin Cycle (A.K.A. light independent reaction)
A. B. This part uses the ATP and NADPH of light reactions to make sugar using CO2.
There are 4 steps to making a single sugar molecule:
1. Step 1: 3 CO2 molecules will be used, in the chloroplasts stroma, by the enzyme
Rubisco to convert RuBPs into G3P molecules. (Remember, these were the 2
halves of a sugar molecule that were seen in Glycolysis.) The energy to power
the conversion comes from ATP and NADPH.
2. 3. Step 2: 1 G3P will be removed to put toward making sugar.
Step 3: The remaining G3P will be reconverted back into RuBP using the extra
ATP from the light reaction.
4. Step 4: Repeat steps 1 - 3 to make the second half of the sugar molecule.
C. These sugars will be needed to feed the whole plant or algae. The sugars will be
consumed in the process of cellular respiration or stored to be used later or passed to
consumers in a food chain.
Unit 8 Cellular Energetics
Cellular Respiration
I. Cellular Respiration
A. This is the process of releasing energy contained in organic molecules (mainly Glucose)
to do work. (This is an example of catabolism.)
1. The process is for making ATP using oxygen, if available
2. The process releases heat (Remember, heat is Low Quality E) and free electrons
B. C. With O2 present in the cell – Cellular Respiration can occur in the mitochondria.
Without O2 present in the cell – Fermentation occurs in the cytoplasm of the cell.
D. 6H20 + C6H12O6 6CO2 + 6O2 + Free E +Heat E
1. The Free E is used to make ATP from ADP by phosphorylation
II. Cellular Respiration is a Three Step Process:
A. Step 1: Glycolysis (This is the breaking of Glucose into 2 molecules of G3P .)
1. All organisms can do this process as it occurs in the cytoplasm of a cell.
2. There will be an additional pyruvate conversation before the Krebs Cycle begins.
B. Step 2: Kreb’s Cycle (This is all about making Electron Carriers in the continued
breakdown.)
C. Step 3: e- Transport Chain (This is where the Free E of the electrons is used to help make
ATP.)
D. The whole process yields a maximum of 38 ATP/ 95% of time only 36 produced though
III. The Process of Glycolysis
A. In this process, Glucose (C6 H12 O6 ) will be broken apart into 2 molecules of G3P . Each
molecule of G3P will then be converted to a molecule of Pyruvate. At the end of the
process, the cell will have 2 molecules of Pyruvate that can be put into the
Mitochondria, if oxygen is present and it is a Eukaryotic Cell.
B. There are two parts to Glycolysis:
1. E Investment Phase
a) Glucose is broken into 2 molecules of G3P
b) To break it in half requires 2 ATP be used. (One phosphate is put on each
side of the Glucose molecule. This makes it unstable and Glucose breaks
in half to make 2 G3P molecules.)
2. E Payoff Phase
a) The 2 molecules of G3P will then be converted to 2 molecules of
Pyruvate
b) This phase will yield 4 ATP + 2 NADH total. (2 ATP and 1 NADH per
molecule.) The cell pays back the two it used for the first part. This
leaves the cell with a payoff of two ATP . (What we refer to as Net
Gain.)
C. D. Remember, this process occurs with or without O2 present in the cell.
All organisms do it as it occurs in the cytoplasm of a cell. Even cells that do not carry on
with anaerobic respiration, use glycolysis as part of fermentation to produce small
amounts of ATP for survival
IV. If Oxygen is present within the Eukaryotic cell (“Aerobic” means “With Oxygen”), the Eukaryotic
cell can perform the other two parts of Cellular Respiration – Krebs Cycle and Electron Transport
Chain
A. In order to enter the inner Mitochondrial space, where the Krebs Cycle occurs,
Pyruvate must be converted to Acetyl Coenzyme A. This is referred to as the Pyruvate
Conversion. It occurs in the space between the outer membrane and the inner
membrane of the Mitochondria.
1. The final product is Acetyl Coenzyme A. (Each molecule is now located in the
inner mitochondrial space.)
B. Kreb’s Cycle (This occurs in the mitochondrial matrix where there is room to work.)
Remember, the main purpose of the Krebs Cycle is to make Electron Carriers by taking
the Hydrogens and attaching them to the Electron carriers. Remember, each
Hydrogen has one electron with it. See how many it makes per Acetyl Coenzyme put
into the cycle.
1. EACH Acetyl Coenzyme A that goes through the cycle will produce
a) 3 NADH, 1 FADH2, 1ATP , and CO2
b) Each Electron carrier can carry 2 electrons to the Electron Transport
Chain
(1) (2) (3) The first negative electron cancels the positive charge on either
NAD+ or FADH+.
The second negative charge makes the FADH or NAD negative.
So a positive H+ will be able to attach to a negative FADH or
NAD.
C. Electron Transport Chain
1. This occurs on the cristae membrane.
a) This membrane is folded (the folds increase surface area =more ATP can
be produced as there is room for more Electron Transport Chains.)
2. The Electron Transport Chain is always in a membrane.
a) For Bacteria- It is the plasma membrane.
b) For Eukaryotes – It is the Mitochondrial inner membrane
3. The whole process is a controlled release of E.
a) Electrons move 2 at a time down the chain toward Oxygen. (Make H2O
at the end.)
b) Energy (electrons) from NADH and FADH2 is used to produce ATP.
c) Free Energy, from the electrons, fuels the active transport of H+ into the
inner mitochondrial space.
(1) H+ (ions/protons) are pumped into the space between the
membranes using the Free E released from electrons as they go
down the chain
(2) The concentration of H+ builds inside the space (like blowing up
a balloon) to create a concentration gradient. High [] in between
and low [ ] in the center.
(3) The H+ are released using ATP Synthase. (It would be like pulling
the plug in a sink)
(4) (5) (6) The H+ rush out (going from High [ ]–>Low [ ]) allowing the ATP
Synthase to use the Kinetic E to turn ADP ATP in large
amounts by phosphorylation
This is another example of Energy Coupling – two processes
working together to make ATP . One process is Active transport
and the other is facilitated diffusion. Also known as
Chemiosmosis.
The Electron Transport Chain can make 34 or 32 ATP vii. Add it
all up now:
2 Net ATP From Glycolysis
2 ATP from the Kreb’s Cycle
34 OR 32 from the ETC
38 Maximum OR 36 Normal
V. If no Oxygen is present within the cell (“Anaerobic” means “without oxygen”):
A. Fermentation will occur to free up the electron carriers to keep at least Glycolysis going
making ATP .
1. Two types of fermentation can occur (It depends on the organism doing it.)
a) Alcohol Fermentation (This occurs in bacteria and Yeast –a fungus.)
(1) They convert the two Pyruvate to 2 molecules of Ethanol by
cutting off CO2 and filling the open bond with H from the
electron carriers. (This freed up the electron carrier to keep
Glycolysis going and thereby making some ATP to stay alive.)
(2) Beer, wine, and bread are made by this type of fermentation.
b) Lactic Acid fermentation (This occurs in animals mainly.
(1) Converts Pyruvate into Lactic Acid by breaking a double bond
with O2 and adding H. The H comes from the electron carrier.
Here again keeping the process of Glycolysis going to make a
little amount of ATP to keep the cells alive in the absence of
Oxygen.
(2) Cheese, yogurt, and muscle cramps (These force you to stop
exercising.) are all created by this type of fermentation.
VI. Facultative Anaerobes
A. These organisms can perform both Aerobic and Anaerobic Respiration but prefer oxygen
– because it produces more ATP .