Download Flip Folder 4 KEY - Madison County Schools

Flip Folder #4: Unit 3: Bioenergetics KEY
1. Enzymes
a. Function**
Speed up chemical reactions by lowering activation energy (biological catalysts).
b. Properties**
A. These molecules are Biological Catalysts.
1. Most are proteins that speed up and control the rate of a chemical reaction.
2. They are mostly composed of Amino acids, some are also pieces of RNA (Ribozymes).
B. They are reactivated; therefore, they are not consumed by the reaction. They remain present,
essentially.
C. Enzymes are selective in what they will work with. We used to say they had a “lock and key fit”
(old term); we now say it “fits like a glove or has an induced fit”. (New term)
1. This is like putting on a latex glove… it stretches to conform to the shape of your hand.
2. The hydrogen bonds of secondary structure enable this property of enzymes.
D. Enzyme names usually end with “ase”.
E. They are involved in just about every process that a cell can perform.
c. Active Site, Allosteric Site, Substrate, Induced Fit
Active Site - This refers to the location where the chemical reaction(s) is taking place between the enzyme and
substrate.
It is an Induced Fit which creates the Enzyme-Substrate Complex. (Complex meaning “more than one piece in the
unit”.)
The two parts are mainly held together by weak Hydrogen bonds, Ionic bonds, or Van der Waals Interactions
(Remember, temporary polarity qualities because of electron clumping on one side of an atom.)
The R-Groups of the Amino Acids (building blocks of proteins) perform all the work of the reaction. The “R” is
for reactive.
Allosteric Site
A. This site, on the enzyme, acts as an on/off switch for that enzyme.
B. It is a way to control the enzyme’s being used at any given time. (It is like a light switch that controls when there
is light in a room.)
An Inhibitor molecule – This turns the enzyme “off” by closing the active site.
An activator molecule– turns the enzyme “on” by opening the active site.
Substrate – The molecule being worked on by the enzyme.
Induced Fit - The active site of the enzyme is induced (caused) to change shape to fit the substrate perfectly once
the substrate binds.
d. Coenzymes
Coenzymes are small molecules. They cannot by themselves catalyze a reaction but they can help enzymes to do so.
In technical terms, coenzymes are organic nonprotein molecules that bind to the protein molecule (enzyme) to form
the active enzyme
e. Cofactors
Cofactors are like coenzymes, but they are inorganic (mostly ions).
f. Graph (labeled – Catalyzed vs. Non-Catalyzed Rxn)
i. Delta G
The change in free energy is not affected by the enzyme. In other words, the end result of energy gained or lost
is the same.
ii. Activation Energy
Energy needed to activate or start a reaction. Enzymes lower it by ORIENTING MOLECULES to make their
reactions easier to occur (GRAB-GRAB-PAIR OR GRAB-GRAB-TEAR). This reduces the amount of
HEAT ENERGY the body would have to put in otherwise to make the molecules move faster (and increase
the likelihood that they’ll bump into each other and do a reaction).
2. Enzyme Rate (how each affects rate of reaction) – The drawing for each of these should be a graph showing the
effect of each on the rate of reaction.
a. Optimal
The Optimal Conditions for most human enzymes:
I.
98.6˚F (35 - 40⁰C)
II.
pH usually between 6 – 8 (The human body’s pH of blood is an average of 7.4.)
III.
Remember, this is an unstable (dynamic) environment. There is an upper limit and a lower limit for
enzymes. Beyond the limits, bad things begin to happen. So it is basically, trying to stay between the limits,
as concentrations of molecules rise and fall. The limits of “life”.
IV. ALL of these factors mainly affect the SECONDARY folding of proteins, by altering the Hydrogen bonds.
They may sometimes be affected at the disulfide bonds of tertiary structure.
1. Remember, when proteins “unwind” that is denature. Enzymes will not function when this
occurs.
b. pH
pH can affect the secondary bonding of enzymes as well. Most human enzymes work best at a pH near neutral. This
obviously is not true for enzymes found in the stomach (which work best at acidic pH).
c. Temperature
Enzymes work slower when it is cold because the molecules involved move slower (and they stop working all
together at a certain low temperature because they’ll freeze). Enzymes work increasingly faster as temperature rises
(and the molecules move faster) until a certain point where the temperature becomes too high and the enzyme
denatures.
d. salinity
Enzymes denature once salinity levels become too high.
e. Enzyme Concentration
The reaction rate will increase as enzyme concentration increases (because the job of enzymes is to speed up
reactions). This is only true when there is an abundance of substrate. If there isn’t a surplus of substrate then the
reaction rate will eventually level out because there isn’t enough substrate for the enzymes to continually work on
(they would spend some time just waiting on around on a substrate to work with).
f. Substrate Concentration
The reactions rate increase as the substrate increase because the enzyme has more material to work with (it
doesn’t have to wait on another substrate to react with after finishing with one). Remember enzymes are
reusable so when they finish one reaction they are automatically ready to do another. Eventually the reaction
rate reaches a peak because the enzyme is going as fast as it can go (so if you add more enzyme it won’t
matter because it already is going as fast as possible – there is no wait time).
g. Competitive Inhibitor
Competitive is shaped like the substrate and competes for the active site. It slows down reaction rate by
blocking the substrate from getting to the active site.
h. Non-Competitive Inhibitor (Allosteric)
Non-competitive is not shaped like the substrate so it does not compete for the active site. It binds to another
site (called the allosteric site) which causes the enzyme’s active site to change shape so that it can no longer
bind with the substrate.
3. Energy
a. Metabolism**
Metabolism refers to any chemical reaction in your body (essentially, the breaking down of your food by catabolism
and the building of your body by anabolism.
b. Anabolic
To build up using dehydration; requires energy; Remember by anabolic steroids build muscle OR build up like
an ant.
c. Catabolic
To break down using hydrolysis; gives off energy; Remember by: tear down like a cat.
d. Exergonic/Endergonic Reactions
Endergonic – Requires energy (i.e. anabolism and dehydration)
Exergonic – Gives off energy (i.e. catabolism and hydrolysis)
e. Energy Coupled Reactions
Cells make endergonic reactions happen by powering them with the energy released by an exergonic reaction. The
majority of the body’s processes using the exergonic, catabolism of ATP to ADP to power endergonic, anabolic
reactions.
4. Metabolic Rate and Homeostasis
a. Basal Metabolic Rate (BMR) vs Standard Metabolic Rate (SMR)**
Standard metabolic rate (SMR) - The minimum metabolic rate needed to sustain life at a specified temperature.
The SMR is measured in organisms that are resting in a post-absorptive state and in darkened conditions.
Basal metabolic rate (BMR) - Minimum amount of energy required by the body to sustain basic life processes,
including breathing, circulation, and tissue repair. It is calculated by measuring oxygen consumption. Metabolic rate
increases above BMR during physical activity or fever, or under the influence of some drugs (including caffeine). It
falls below BMR during sleep, general anaesthesia or starvation. BMR is highest in children and decreases with age.
b. Metabolic rate related to body size**
Small-bodied organisms tend to have higher mass-specific metabolic rates than larger-bodied organisms.
Furthermore, organisms that operate at warm temperatures through endothermy or by living in warm environments
tend towards higher metabolic rates than organisms that operate at colder temperatures.
b. Positive vs Negative Feedback
Negative Feedback - These stop a process already occurring and get it going in the opposite direction. Think of a
thermostat. If it gets too hot, the air kicks on to cool it down. If it gets too cold, the heat kicks on to warm it back
up. Anything involved in homeostasis. The body has a set point for all of your body’s components. Negative
feedback loops keeps them at this level.
Positive feedback - These enhance a process that is already occurring. If the variable goes above the set point, then
the body kicks in to keep pushing it even further past the set point.
Cervix dilation during pregnancy. Once a woman goes into labor, she releases hormones that make her cervix dilate
more and more until the baby is born.
Clonal selection during immune response. Once the body finds the right type of B and cytotoxic T cells to make, it
continues making them more and more until the pathogen is destroyed.
c. Ectotherm vs Endotherm
Ectotherm = cold blooded (must use the environment to regulate its temperature). Pros = requires less energy. Cons
= dependent upon the environment
Endotherm = warm blooded (uses its metabolism to regulate its temperature). Pros = not dependent upon the
environment. Cons = requires more energy
1. Vasoconstriction vs. Vasodilation
Vasodilation means the smooth muscles in your blood vessel walls relax causing them to widen. This widening
results in less vascular resistance, thus the blood flowing through the dilated vessel increases. Vasodilation may
occur locally or system wide.
Some basic health benefits resulting from vasodilation include:
lowering blood pressure
assists in eliminating excess metabolic produced heat
enhances clotting factor & leukocyte entry into damage tissue
increases delivery of oxygen & nutrients during energy consuming activities
Vasoconstriction means the smooth muscles in your blood vessel walls contract causing them to narrow. This action
results in blood flow through your vessels to be restricted. Some health benefits of vasoconstriction are:
retain heat in cold climates
reduce excessive blood loss
prevent orthostatic hypotension
2. Countercurrent Heat exchange
During periods of cold, temperature is control by counter-current heat exchange. This uses the water in the
circulatory system to help transfer heat from the internal body coming out in arteries to inward flowing blood in
veins. The heat is transferred; not the water. Remember water can absorb heat. Metabolism and shivering can also
help increase body temperature.
3. Shivering/Sweating
Shivering – The movement of your muscles increases the usage of ATP. This is a catabolic, exergonic reaction that
releases heat. The more you shiver, the more heat you release.
Sweating - Water from the body is used to remove heat. Remember water acts as a heat “trapper” therefore it can be
used to remove excess heat quicker. This “warm” water is the moved to the surface and released. The wind (air
movement) removes the water as it evaporates. This is referred to as evaporative cooling.
5. Free Energy
st
a. 1 and 2nd Law of Thermodynamics**
I.
The study of Heat E (Thermo) and its properties (dynamics).
II.
First Law of Thermodynamics (Also called the Principle of the Conservation of Energy)
A. Energy cannot be created nor destroyed ONLY transformed or transferred.
III.
Second Law of Thermodynamics
A. Every Energy transfer increases the entropy of the universe.
1. Entropy- means “disorder”; unable to do work because it is in a LOW state of order
B. Sunlight(high quality E) going in and heat (low quality E) coming out; it can’t do work
C. Conception to birth to death is how life relates to the second law.
1. You are at your most organized state as a single cell; as you “progress” you go move
toward a state of entropy (death).
b. Gibbs Free Energy Equation**
A. ΔG=ΔH-TΔS (This is the formula for calculating Free E.)
G- Free E (This amount goes from positive to negative as catabolism of food occurs.)
T- Temperature constant (Measured in Kelvin, ⁰C +273.)
Gibbs Free E (represented as “G”)
A. It is referred to as “free” because E is available to perform work. It’s mainly for helping to make ATP
or GTP in a cell. These are the molecules capable of doing work with in cells, remember.
B. Not all energy is available. (Some is lost as waste…like when we defecate…same goes for cells too.)
1. MOST energy is lost as Heat as a byproduct of the bonds being broken.
c. Enthalpy**
H- Total usable E in the system. (Starts large but becomes smaller as food is broken down.)
Total Useable energy in the system is referred to as Enthalpy.
d. Entropy**
S- Amount of Entropy (Starts at 0 but becomes larger as the reaction continues to produce heat and the highly
organized food molecules are broken apart more and more.)
e. Spontaneous Rxn
A. ΔG = G(f) – G(i)… The change in free E is equal to the final amount minus the initial amount.
B. Exergonic.
C. If ΔG is negative, then there is E available “free” to perform work. (It is Spontaneous.)(It is
Exergonic.)
2. This is the result of Cellular Respiration and Digestion. It is a Catabolic processes that
releases free E.)
f. Non-Spontaneous Rxn
Endergonic.
C. If ΔG is positive, then there is E that is not available because it is “locked up” and can NOT
perform work. (It is Non-Spontaneous.)(It is Endergonic.)
3. Photosynthesis is a good example. It is an Anabolic processes that stores free E.
g. When a protein unfolds to its denatured state, the change in Enthalpy is 46,000 joules/mol. Also the change
in Entropy is 178 joules/mol. At a temperature of 20⁰C, calculate the change in Free Energy ΔG, in j/mol.
Is this spontaneous or non-spontaneous?
ΔG=ΔH-TΔS
= 46,000 – (20+273)*178
= 46,000 – 52,154
= -6154
Negative delta G so it is spontaneous.
6. ATP
a. Structure
Structure is the same as the RNA nucleotide Adenine, but it has 3 phosphates instead of 1. So it has 3 phosphates,
ribose sugar, and adenine base.
b. Function**
Phosphates are negative. The phosphate-phosphate bonds repel each other. ATP has 3 phosphates so they all
push each other away (and is very unstable). It breaks and releases energy very easily. It breaks into ADP (2
phosphates) which does not have lots of energy because the phosphates can bend so that their negative
charges do not repel as much.
c. Phosphorylation
The attaching of an unstable phosphorus ion to another molecule to make it unstable and thereby able to perform
work. Take the phosphorus off and it quits working.
d. ATPase/ATP Synthase
This enzymes is located in mitochondria (on the inner membrane – cristae folds) and chloroplast (thylakoid
membranes). It phosphorylates ADP to make ATP as H+ ions flow through it. It is powered by the Electron
Transport Chain which will be described later.
7. Cellular Energy (Mitochondria and Chloroplasts)
a. Mitochondria structure and function of each part
Inner membrane – Site of oxidative phosphorylation (Electron Transport Chain and Chemiososmosis)
Cristae = Folds of inner membrane to increase surface area
Matrix = site of Kreb’s Cycle
b. Chloroplast structure and function of each part
Thylakoid space
Green pancake = thylakoid. Green because this is where photosystems (and chlorophyll A) are located.
Responsible for the Light reactions.
Stack of pancakes = grana. Increase surface area of thylakoids to allow more light to be absorbed (and more
photosynthesis to occur).
Syrup (sugar water) = stroma. Sight of Calvin Cycle (which is why it is “sugar” water).
c. REDOX reactions
i. Which gains/loses electrons?**
L.E.O. (lose electrons oxidized) the Lion says G.E.R. (gain electrons reduced)
O.I.L. (oxidation is losing) R.I.G. (reduction is gaining)
ii. Which shows a gain/loss of energy?**
Electrons are the source of energy for living things. Since reduction is gaining electrons then it is gaining energy.
Oxidation is losing electrons so it is losing energy.
iii. Oxidizing vs. Reducing agent**
The “agent” means that it causes that particular reaction in the other reactant. That means if a molecule is oxidized
then it is the reducing agent. This is because it is personally oxidized (loses electrons) but the Law of the
Conservation of Matter says that these electrons can’t just disappear; therefore, another reactant will have to accept
the electrons (thus becoming reduced). This means that the molecule being oxidized is the reducing agent because it
causes the other reactant to be reduced.
8. Photosynthesis
a. Equation
i. Summary
ii. Purpose of each reactant/product**
Reactants
• Light = Original source of energy
• CO2 = gains hydrogens to become glucose (sugar)
• H20 = take hydrogens to provide electrons, release oxygen as byproduct
Products
• C6H12O6 (glucose) = sugar (energy).
• O2 = byproduct (not used)
• Heat = imperfect energy conversion (2nd law of thermodynamics)
iii. What is oxidized/ reduced? Tell what product they become.**
CO2 is reduced (gains electrons) to become Glucose.
Water is oxidized to become oxygen.
b. Pigments, Chlorophyll**
There are several pigments that absorb light in plants. They are grouped in clusters called photosystems with
chlorophyll A at their center.
c. Photosystem I and II - ETC, NADPH
Step 1: Sunlight hits the water in the stroma and also the Photosystems I and II at the same time.
A.
The water in the stroma, using the high quality E of sunlight, lyses into O gas (a waste product), 2
H+ ions (these stay in the stroma), and 2 free electrons. (These will be used to replace the 2
“excited” electrons lost from the Mg atom of Chlorophyll A in Photosystem II.)
B.
The Photosystem II Mg atom loses two electrons due to absorbing all of the E being funneled into
Chlorophyll A from Chlorophyll B and the Carotenoids. (These 2 excited electrons are collected
by a primary acceptor protein, also in the Thylakoid membrane, and moved toward Photosystem I
along the primary electron transport chain. They will be replaced by the 2 electrons from water
lysing. This keeps the process going.)
C.
The Photosystem I Mg also loses two electrons due to absorbing all that E from the Chlorophyll
and carotenoid molecules. (These are also collected by another primary acceptor protein and
moved toward NADP+ along the secondary electron transport chain. These will be replaced by the
2 electrons coming down the chain from Photosystem II in the primary electron transport chain.)
Step 2: Excited electrons travel down the electron transport chains. (This is a series of Redox reactions. A redox
reaction is basically two molecules exchanging electrons. One molecule receives them [called Reduction] and the
other molecule loses them [called Oxidation]. Hence the combined name of Redox.) This is associated with the Law
of Conservation of Mass…” Mass is neither created nor destroyed; only transferred and transformed.” As the excited
electrons go down the electron transport chain, by going through these series of Redox reactions, their excited
kinetic E (also called Free E) is being used to power the proteins called Proton pumps. As the electrons go down
their transport chain, their excited kinetic E decreases.
A. Ph
1. Free E of the electrons is used to actively transport H+ ions (a.k.a. called protons) into the inner
thylakoid space The H+ ion concentration [H+] goes up inside the space. This causes the pH to
decrease and become more acidic. The [H+] goes down in the stroma. The stroma becomes more
basic. As this is occurring a concentration gradient is created. A concentration gradient is a source
of potential E now. (It would be like blowing air into a balloon. The pressure builds as more air is
blown inside the balloon. This is also an example of potential E.)
B.
NADP+.)(This is the ending point for nonPhotosystem I) This would be for cyclic electron flow. Remember this makes extra ATP.
C.
Cytochrome C is an important molecule as ALL organisms possess it in their membrane that is
used for energy production. This supports common ancestry among ALL organisms.
1.
Mitochondria and Chloroplast INNER membranes in eukaryotic organelles.
2.
The plasma membrane of Prokaryotic cells.
Step 3: The trapped H+ ions, inside the Thylakoid, are released through the ATP Synthetase Complex. This is a
group of enzymes in the Thylakoid membrane that helps make ATP, by Anabolic Phosphorylation. Just look the
be like the
air coming out of the blown up balloon and turning a pinwheel.
A. This Kinetic movement of H+ ions produces a LARGE AMOUNT OF ATP.
B. This is an example of Energy Coupling (Two processes working together and involving energy.)The
first process was Active transport to pump the H+ ions into the confined space of the Thylakoid, using the
Proton pump proteins, to make the concentration gradient. The second process is diffusion, The H+ ions
going from high [ ] to low [ ]. The kinetic movement of the H+ fuels the production of ATP
1.
This form of energy coupling, for making ATP, is referred to as Chemiosmosis.
Step 4: ATP and NADPH will now be used to power the fixing of CO2 into sugar in Calvin Cycle.
d. Calvin Cycle (Light Independent Reactions)
A. This part uses the ATP and NADPH, of light reaction, to perform Carbon fixation. (Making
sugar using CO2.)
B. It has three steps:
Step 1: CO2 molecules enter the leaf through the open stomata. Then the CO2 molecules
diffuse into the cells by crossing the phospholipid portion of the plasma membrane. Once
inside the cell, the CO2 molecules diffuse across the phospholipid portion of the
chloroplast membrane. Once in the stroma of the chloroplasts, 3 molecules of CO 2
combine with 3 RuBP molecules using the enzyme Rubisco. (RuBP is a 5 Carbon
molecule.)
A. The resulting three 6 carbon molecules are unstable and break into two 3 carbon
molecules of 3 phosphoglycerate. (Six total carbon molecules still, just in two groups
of three.)
Step 2: Use 6 ATP and 6 NADPH (1 ATP and 1 NADPH /molecule of 3 phosphoglycerate)
to “bend” each molecule twice into G3P. (G3P is half of a Glucose molecule.)
Step 3: Take out 1 G3P and recycle the other 5 G3Ps back into the original 3 RuBPs using
3 extra ATP (Remember, from the cyclic electron flow.) This process basically takes 1
Carbon away from two G3Ps (remember, there are 5 G3P left) and thus creating 2 two
carbon molecules. Then one of the two 2 carbon molecules is paired with one of the three
remaining three Carbon molecules.
3 +2 = 5. The two single Carbons are added to the last G3P molecule to have 5
carbons again.
(3 + 1 +1 =5)So we end up with 3 five Carbon molecules of RuBP again. Thus,
we have started and ended at the same point… a cycle.
a. 1 G3P used to make glucose (So the cycle must go around TWICE to make 1
glucose molecule. So repeat steps 1-3 to make the second half.)
C. Total Numbers needed: For each turn of the cycle – 9 ATP and 6 NADPH are needed.
: To make 1 glucose molecule (2 turns) – 18 ATP and 12 NADPH are
needed.
D. These sugars will be needed to feed the whole plant or algae. Or they will be stored in the form of
starch, a complex carbohydrate. The sugars will be consumed in the process of cellular respiration.
They could also be utilized in the making of plant cell walls.
9. Photorespiration
a. What is this? When/Where does it occur?**
b. C3 plants
In C3 plants – RuBPs are broken down to make G3Ps like normal. (This can eventually cause death to
the plant because there will not be enough Carbons to recreate the necessary RuBPs if they are slowly
being taken out to make sugar. It would go 15C  12C  9C 6C 3C  Death. The plant needs
the 3 CO2 to replace the THREE Carbons in G3P that were taken out to make sugar.)
i. Examples**
Most crops used as food. Rice, barley, wheat, rye, etc.
ii. Locations**
Temperate environments.
c. C4 plants
i. Examples**
Corn, maize, sugarcane
ii. Location**
Tropical or semi-tropical. High light intensity. Drought conditions.
iii. Modification to C3 photosynthesis**
C3 plants do Light Reactions and Calvin Cycle in mesophyll cells. C4 plants perform the Calvin Cycle in bundle
sheath cells. Oxygen can’t move into the bundle sheath cells so rubisco cannot fix oxygen. Requires extra energy
because G3P has to be converted to another intermediate to be moved into the bundle sheath cells but saves water.
d. CAM plants
i. Examples*
Pineapples
ii. Location**
Desert
iii. Modification to C3 photosynthesis**
Stomata open at night. Even so, the Calvin Cycle must occur during the day when the products of the Light
reactions are available. CO2 would diffuse back out of the stomata if it was not converted to another form; therefore,
CAM plants convert CO2 to Crassulacean Acid (hence the name Crassulacean Acid Metabolism). Requires extra
energy for this conversion but saves water.
10. Cellular Respiration
a. Equation
i. Summary
ii. Purpose of each reactant/product**
Glucose provides the hydrogens to power cellular respiration (making ATP)
Oxygen is the most biologically electronegative element. It is at the end of the Electron Transport Chain so it can
run longer (and make more ATP).
CO2 is the byproduct once the hydrogens have been removed from glucose.
Water is created once oxygen receives the electrons and eventually hydrogens.
iii. What is oxidized / reduced. Also tell what product they become.**
Glucose is oxidized (loses energy) to becomes CO2.
Oxygen is reduced (gains energy) to become water.
b. Glycolysis, anaerobic, pyruvate
I.
The Process of Glycolysis (Breaking of Glucose)
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.
1. Glucose is said to be oxidized, as it is losing electrons in the breakdown.
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.) (The enzyme, Phosphofructokinase, puts the SECOND phosphate on
the Glucose molecule; it is the “ON/OFF Switch” for the WHOLE process. If it does
NOT put the second phosphate on the Glucose molecule, the Glucose WILL NOT
break in half.)
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. Remember this process occurs with or without O2 present in the cell.
D. ALL organisms can do it as it occurs in the cytoplasm of a cell. Therefore, this process must have
been one of the earliest processes to evolve within organisms to harvest energy from molecules
present within the earth’s earliest environments. Even before free oxygen was present in the
atmosphere.
c. Krebs Cycle, NADH, FADH2, electron acceptors, acetyl co-a
I.
If Oxygen is present within the Eukaryotic cell (“Aerobic” means “with Oxygen”), the cell can
perform the other two parts of Cellular Respiration – Kreb’s Cycle and Electron Transport Chain.
A. In order to enter the inner mitochondrial space, where the Kreb’s 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. This Pyruvate Conversion involves three steps:
a. Step 1: Removal of CO2from each molecule of Pyruvate. (Remember there are 2.)
b. Step 2: NAD+ or FAD+ (Both can perform this act as they are both electron carriers.)
becomes reduced by accepting the 2 e- from the broken bond. This allows for
a H+ ion to attach and make NADH or FADH2. (Remember these are
Oxidizing Agents because they are receiving electrons.)
c. Step 3: To the open bond, Coenzyme A is attached using sulfur as the connecting link.
2. 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 inner mitochondrial space where there is room to work.)
Remember, the main purpose of the Kreb’s cycle is to make electron carriers. See
how many it makes per Acetyl Coenzyme A put into the cycle.
1. EACH Acetyl Coenzyme A that goes through the cycle will produce:
a. 3 NADH (electron carrier) So 2 molecules X 3 = 6 NADH electron carriers
b. 1 FADH2(electron carrier)  So 2 molecules X 1 = 2 FADH2 electron carriers
c. 1 ATP  So 2 molecules X 1 = 2 ATP
d. 2 CO2 (A waste product.)  So 2 molecules X 2 = 4 CO2 that diffuse out of the cell.
d. Oxidative Phosphorylation, Chemiosmosis, ETC – electrochemical gradient
Electron Transport Chain
a. This occurs on the inner mitochondrial membrane.
i. This membrane is folded (THE FOLDS INCREASES SURFACE AREA;
MORE ATP CAN BE PRODUCED AS THERE IS ROOM FOR MORE
ELECTRON TRANSPORT CHAINS.)
b. Electrons move by a series of Redox reactions using increasing electronegativity.
i. Move 2 at a time DOWN the chain toward OXYGEN, making H2O at end.
c. NADH drops its two electrons off at FMN “first molecule at top of chain”. (In doing
so, the pair of electrons will pass through 3 protein Proton Pumps. If three
protons, H+ ions, are pumped into the space BETWEEN the membranes 3 ATP will be
able to be produced.)
d. FADH2 drops its two electrons off at Q, which is a lipid.
(These pairs of electrons will only pass through two Proton pumps; therefore only 2
protons, H+, will be pumped into the space between the membranes and thereby only
2 ATP will be able to be produced.)
e. Remember the Cytochromes indicated common ancestry for ALL organisms, as
ALL electron transport chains will possess these proteins.
f. Cyanide kills by replacing Oxygen at the chain and stopping the flow of electrons.
g. Free Energy, from the electrons, fuels the active transport of H+ ions into the inner
mitochondrial space between the membranes.
i.
H+ (ions/protons) are pumped into the confined space between the
membranes using the Free E released from electrons as they go down
the chain.
ii.
The concentration of H+ ions builds inside the space (like blowing up a
balloon) to create a concentration gradient. High[ ] in between and
low [ ] in the center.
iii.
The H+ ions are released using ATP Synthesizing Complex. (It
would be like pulling the cork in the sink.)
iv.
The H+ ions rush out (going from High [ ]–>Low [ ]) allowing the
ATP Synthesizing Complex to use the Kinetic E to turn ADP  ATP
in large amounts by phosphorylation.
v.
vi.
vii.
This is another example of Energy Coupling – two processes working
together and involving energy. (Same as it was in Photosynthesis.) One
process is active transport and the other is diffusion.
This type of energy coupling, for making ATP, is referred to as
Chemiosmosis.
The Electron Transport Chain can make 34 or 32 ATP. It depends on
which electron carrier showed up in the Pyruvate conversion. If it was
NAD+, the process makes 34. If it was FAD+, the process makes 32.
FAD+ usually shows up because NAD+ is too busy in the Kreb’s
cycle.)
e. ATP produced in each stage and method of phosphorylation (oxidative or substrate-level)
2 Net ATP From Glycolysis (substrate-level phosphorylation)
2 Net ATP from the Kreb’s cycle (substrate-level phosphorylation)
34 OR 32 Net ATP from the Electron Transport Chain using all the NADH andFADH2. (oxidative
phosphorylation)
38 Maximum OR 36 Normal Total
Picture of substrate level phosphorylation
f. Fermentation, Lactic Acid and Alcoholic (how they differ)
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.)
i. They convert the two Pyruvate molecules to 2 molecules of Ethanol by cutting
off CO2 and filling the open bond with H from the electron carriers. This frees
up the electron carrier to keep Glycolysis going and thereby making some ATP
which is needed to stay alive.
ii. Beer, wine, and bread are made by this type of fermentation.
b. Lactic Acid fermentation (This occurs in animals mainly.)
i. Converts Pyruvate into Lactic Acid by breaking the ketone, the double bonded
Oxygen in the middle, 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.
ii. Cheese, yogurt, and muscle cramps (These force you STOP exercising.) are
all created by this type of fermentation.
Facultative Anaerobes
A. These organisms can perform both Aerobic and Anaerobic Respiration, but prefer to use oxygen –
because it produces more ATP than by using fermentation.
11. Carbon Cycle
a. Movement of Carbon inorganic to organic and back
Essentially, photosynthesis converts inorganic CO2 to organic glucose. Cellular respiration uses organic glucose and
releases inorganic CO2 back out.