What is Cellular Respiration
The process of converting chemical energy stored in organic molecules into ATP
Cellular Respiration equation
C6H12O6 + 6O2 > 6CO2 + 6H2O
Cellular Respiration stated in words
Organic compound + oxygen -> carbon dioxide + water + energy
Photosynthesis and Cellular Respiration coupled
light energy > photosynthesis > glucose + oxygen > cellular Respiration > ATP production (released as heat energy) > CO2 + H2O > back to photosynthesis
types of catabolic pathways
- fermentation
- aerobic respiration
fermentation
- a catabolic pathway that produces a limited amount of ATP from glucose without the use of an electron transport chain (oxygen) and that produces either ethyl alcohol or lactic acids
products of fermentation
ethyl alcohol
lactic acid
aerobic respiration
type of catabolic pathway that produces ATP by consuming O2 and using an electron transport chain where O2 is the final electron acceptor
AKA Cellular Respiration
products of aerobic respiration
ATP
Fermentation versus anaerobic respiration
- anaerobic respiration still uses the electron transport chain and has a final respiratory electron acceptor, but it's just not oxygen.
- Fermentation does not use the electron transport chain. It doesn't have a final respiratory electron acceptor
Cellular Respiration is an (endergonic/exergonic) reaction because it's delta G - free energy- is (positive/negative), which indicates that the reaction (doesn't occur spontaneously/occurs spontaneously), which means it (does need energy/ doesn't need ene
Cellular Respiration is an exergonic reaction because it's delta G is negative, which indicates that the reaction occurs spontaneously, which means it doesn't need energy.
How do catabolic pathways that breakdown glucose or other organic molecules yield energy
transfer of electrons; the relocation of electrons releases energy stored in organic molecules
redox-reactions
A chemical reaction involving the partial or complete transfer of electrons from one reactant to another.
oxidation
loss of electrons, loss of hydrogen
reduction
gain of electrons, gain of hydrogen
reducing agent
electron donor
oxidizing agent
electron acceptor
Potential energy and electrons
as electrons are transfered, Potential energy is lost (released)
in cellular respiration what becomes oxidized? reduced?
oxidized: glucose
C6H12O6 -> 6CO2
reduced: oxygen
6O2 -> 6H2O
reducing agent in cellular respiration
glucose
oxidizing agent in cellular respiration
oxygen
why does glucose yield energy ?
because it becomes oxidized, which means it loses electrons and when something loses electrons, it releases potential energy
in redox reactions, the electrons travel with a ____, which can also be called a _____
proton; hydrogen
NAD+
- electron carrier
- electron acceptor
- oxidizing agent (because it accepts electrons)
- coenzyme
reduced acronym for NAD is ... because
NADH
because reduction means an adding of an electron and since electrons travel with hydrogens, the NAD gains a hydrogen
oxidized acronym for NAD is.... because
NAD+
because the positive sign attracts a negative sign, meaning it's acting as an electron acceptor
how does NAD+ trap electrons
hydrogenases removes a pair of hydrogens from glucose (2 electrons 2 protons).
2 electrons and one proton are added to NAD+, neutralizing it.
The other proton is lost as an ion
NADH symbolizes
- trapped energy (from electrons accepted) that can be "tapped" later to create ATP when it is given to oxygen
How does NADH reach oxygen
by using an electron transport chain
what is the importance of the electron transport chain
breaks the "fall" of electrons, to prevent them from giving off too much energy all at once.
electron transport chain
a sequence of electron carriers molecules (membrane proteins) that shuttle electrons down a path through a series of redox reactions that release energy used to produce ATP
explain what happens in the electron transport chain in terms glucose and oxygen
1. glucose loses two hydrogens (2 electrons 2 protons)
2. 2 electrons and a proton are carried in NAD+
3. NAD+ > NADH
4. the lone proton is lost as a hydrogen ion (H+)
5. NADH travels to the top of the electron transport chain
6. O2 is at the bottom where
NADH losing electrons to oxygen is (exergonic/endergonic)
exergonic, release of electrons, comes with a release in p.e.
map out the "downhill" path taken by an electron in cellular respiration
glucose > NADH > electron transport chain > O2
Cellular Respiration steps
1. Glycolysis
2. Pyruvate oxidation +Citric Acid Cycle
3. Oxidative Phosphorylation
General overview of what occurs in the three steps
1. Glycolysis= breaks down glucose > pyruvate
2.
A. Pyruvate oxidation= pyruvate > Acetyl CoA
B. Citric Acid Cycle = Acetyl CoA > CO2
3. Oxidative Phosphorylation= electrons given off from the first two stages as NADH are given off to oxygen forming water
Which of the following give off electrons to NAD+ to be transported to the electron transport chain?
1. Citric Acid Cycle
2. Glycolysis
3. Pyruvate oxidation
1 & 2
oxidative phosphorylation
- production of ATP from the redox reactions that occur in the electron transport chain
electron transport chain + chemiosmosis =
oxidative phosphorylation
which of the three steps accounts for the most ATP production
oxidative phosphorylation
substrate-level phosphorylation
- enzyme catalyzed production of ATP by direct addition of a phosphate to ADP by an intermediate substrate in catabolism of glucose.
(T/F) The citric acid cycle and glycolysis do NOT produce ATP
FALSE.
The citric acid cycle and glycolysis do produce small amounts of ATP through substrate-level phosphorylation
oxidative phosphorylation versus substrate-level phosphorylation
- oxidative produces more ATP than substrate
- Oxidative adds an inorganic phosphate to ADP whereas substrate-level adds a phosphate to ADP from an organic (intermediate) molecule that resulted from the catabolism of glucose in glycolysis
1 molecule of glucose produces ____ ATP
32
&&& so it begins...... GLYCOLYSIS
...
glycolysis means
sugar splitting
What happens in glycolysis
1. glucose a 6 carbon molecule is split into 2 three carbon molecules
2. the three carbon molecules become oxidized (losing electrons and hydrogens)
3. Formation of 2 pyruvate
Glycolysis can be divided into two parts:
energy investment
energy payoff
Glycolysis: energy investment
2 ATP molecules are used to start glycolysis
Glycolysis Energy investment: phase 1
Hexokinase adds a phosphate to the end of the glucose molecule
(-1ATP)
Glycolysis Energy investment: phase 2
glucose -> Fructose 6- Phosphate
Glycolysis Energy investment: phase 3
phosphofructokinase binds another phosphate to the fructose 6- phosphate.
(-2ATP)
Phosofructokinase : activators? repressors?
...
Glycolysis Energy investment: phase 4
Adolase cleaves the Fructose 1- 6 bisphosphate into 2 three carbon molecules (isomers)
Glycolysis Energy investment: phase 5
cleavage results in Di----phosphate and Glyceraldehyde 3 phosphate (which is used in the energy payoff phase)
Glycolysis Energy investment: products
(-2ATP)
2 three-carbon molecules (G3P) Glyceraldehyde 3 phosphate
Glycolysis: energy payoff
- ATP is produced through substrate level phosphorylation
- NAD+ -> NADH because of the electrons released through oxidation of glucose
Glycolysis Energy payoff: How is ATP made
- ATP is made through oxidation reactions
1. Phosphates are added when the glucose molecule is oxidized
2. the electrons lost in oxidation create NADH
3. Enough energy is released to attach a phosphate to the end of the three carbon molecule
4. That same
Glycolysis: one glucose molecule can make...
ATP = 2 (net 4-2)
NADH = 2
Pyruvate = 2
H2O = 2
Glycolysis: (T/F) Glycolysis can only occur in the presence of oxygen.
False. Glycolysis can occur in the absence of oxygen, but if there is oxygen present, it then proceeds through pyruvate oxidation , citric cycle, oxidative phosphorylation.
IF No oxygen is present -> Fermentation
end of Glycolysis ********
Pyruvate Oxidation begins now
Pyruvate molecules make
2 ATP
1 H2O
1 NADH
Pyruvate oxidation occurs in the _____ and is the process between the ___ and ___
mitochondria
glycolysis and citric acid cycle (Krebs)
Pyruvate oxidation starting molecule:
Pyruvate oxidation ending molecule:
Pyruvate
Acetyl CoA
What are the products of Pyruvate oxidation all together (2 pyruvates, not one)
2 Acetyl CoA
2 NADH
2 CO2
end of pyruvate oxidation *******
Citric Acid Cycle begins now
Citric acid cycle is also called ....
krebs cycle
tricarboxylic acid cycle
The electron carriers in citric acid cycle are
NAD+
FAD
FAD is (oxidized/reduced) when turned to FADH2
reduced
FAD accepts how many electrons ? how many protons?
2 electrons
2 protons
it keeps the two H+ protons unlike NADH
Products of the Citric Acid Cycle per pyruvate
1 ATP
2 CO2
1 FADH2
3 NADH
All together (2 pyruvates) what are the prodcuts from the citric acid cycle
2 ATP
4 CO2
2 FADH2
6 NADH
Citric Acid Cycle: Step 1
Acetyl CoA + Oxaloacetate= citrate + CoA
1. 2 carbons from Acetyl CoA bind with oxaloacetate
2. Oaxloacetate + Acetyl form citrate
3. release CoA
Citric Acid Cycle: Step 2
Citrate > isocitrate
Citric Acid Cycle: Step 3
Isocitrate is oxidized,
1. makes one NADH first
2. Then makes a CO2
Citric Acid Cycle: step 4
1. CO2 is lost
2. oxidation occurs again, producing NADH
3. CoA is attached to the unstable molecule
Citric Acid Cycle: step 5
1. phosphate group replaces CoA (released)
2. Phosphate turns GDP into GTP
3. GTP has the ability of producing ATP
(1 ATP is made here)
GDP> > _____>_____>ATP
GDP > GTP > ADP > ATP
Citric Acid Cycle: step 6
1. oxidation of succinate
2. 2 hydrogens are added to FAD making FADH2
Citric Acid Cycle: step 7
water is added, rearranging the molecule
Citric Acid Cycle: step 8
oxidation occurs, NAD+ > NADH
- oxaloacetate is regenerated
where does the krebs cycle take place
matrix of mitochondria
how many ATP molecules have been made so far and where do they come from?
4:
2 from Glycolysis
2 from citric acid cycle
end of citric acid cycle *****
oxidative phosphorylation begins now
where is the ETC located
membrane of a mitochondria (cristae)
as electrons travel down the ETC what happens to the free energy
it drops
ETC runs from
uphill to downhill
ETC explanation
uphill> downhill:
electrons from an uphill molecule(reducing agent) are donated to a downhill molecule (oxidizing agent) because the uphill molecule is less electronegative than the one at the bottom.
The same happens until the electrons reach an oxygen t
what's the big idea of the ETC
The ETC shows how ATP is not made directly. Instead of energy from glucose going straight to ATP (which would cause a great loss of energy), the ETC uses electron carries (NADH & FADH2) to break the fall of energy into smaller steps which releases energy
How does the mitochondria use energy released from the ETC to produce ATP ?
through chemiosmosis
ATP synthase
an enzyme that produces ATP from ADP and an inorganic phosphate
Chemiosmosis
an energy coupling mechanism in which H+ concentration gradient energy is used to drive the synthesis of ATP through ATP synthase.
basically: ATP Synthase + electron transport chain (H+ gradient) = ATP
Electron transport chain + Chemiosmosis =
oxidative phosphorylation
electron transport chain + ATP synthase =
chemiosmosis
the production of ATP is (endergonic/exergonic)
endergonic
how many ATP can an NADH molecule make
2.5
how many ATP can an FADH2 molecule make
1.5
how much ATP is produced in oxidative phosphorylation
bout 28
how much ATP is produced in oxidative and substrate- level phosphorylation
(28 oxidative phosphorylation + 4 substrate- level phosphorylation) = 32
or 30
(T/F): Since in the electron transport chain, ATP is produced because of the highly electronegative oxygen pulling the electrons down, if no oxygen was present, then no ATP would be produced.
False. It's true that the oxygen is highly electronegative and pulls down the electrons in the electron transport chain, but ATP can still be produced through fermentation ( NO ETC) or anaerobic respiration (ETC)
anaerobic respiration uses another respiratory molecule called
sulfate ion
anaerobic respiration produces.... instead of H2O
hydrogen sulfide (H2S)
(T/F) Glycolysis produces 2 ATP regardless of the presence of oxygen or not
True
How does fermentation occur without the use of an electron transport chain or oxygen ?
oxidizing glucose does not need to involve an oxygen because all oxidizing means is losing electrons to an electron acceptor.
So in order for fermentation to occur, it has to oxidize the NADH to become NAD+ to continue using that same NADH.
the electrons
OK. one last time state what fermentation is
1. fermentation includes glycolysis plus the regeneration of NAD+ by giving the electrons from NADH to pyruvate.
2. then NAD+ can go back to oxidizing glucose without the use of oxygen
3. The pyruvate is then turned into either alcohol or lactic acid
Types of fermentation
lactic acid fermentation
alcoholic fermentation
Alcohol fermentation
pyruvate is converted into ethyl alcohol in two steps
1. release of CO2--> acetaldehyde
2. Acetaldehyde is reduced by NADH to ethyl alcohol
Alcohol Fermentation process
Pyruvate > release of CO2 > makes acetaldehyde > NADH releases hydrogens and electrons to acetaldehyde> ethyl alcohol > NAD+ oxidizes glucose > Pyruvate
example of alcohol fermentation occurs in
yeast
Lactic Acid Fermentation
pyruvate is reduced directly by NADH which makes lactate , with no release of CO2
Final electron acceptor in Fermentation? Aerobic respiration? anaerobic respiration?
- Alchohol Fer (acetaldehyde)
- Lactic Acid Fer (pyruvate)
- Aerobic (oxygen)
- Anaerob (ion sulfate)
what is common for fermentation, anaerobic, and aerobic?
- all go through glycolysis
- 2 ATP production in glycolysis
- electron carrier is NAD+
- go through substrate- level phosphorylation
why is phosphofructokinase so important
- (Remember) phosphofructokinase is used to catalyze fructose 6- phosphate into fructose 1, 6-bisphosphate with the use of ATP.
- when this happens, the glucose HAS to go through glycolysis. (irreversible)
- it's an allosteric enzyme, which can be used to
what is a stimulus to phosphofructokinase?
AMP (from ADP)
inhibitors of phosphofructokinase?
- ATP (from pyruvate, citrate, or ETC)
- citrate (citric acid cycle)
What is DNP ?
...
need to know step one and step three of citric acid cycle
...
when ATP is made there's a (low/high) concentration of H+ protons, which means the PH level is (low/high) or (acidic/basic)
high/ low / acidic
fatty acids go through
fermentation bc no oxygen ? or anaerobic? (C-H-C-H body)
one turn of the citric acid cycle means what
using only one pyruvate
purpose of citric acid cycle
produce reduced electron carriers
how many hydrogens are needed to make one ATP
3
how is a hydrogen concentration established
when electron carriers pass through ETC complexes, hydrogens are released.
Oxygen (O2) is used directly in which part of cellular respiration?
ETC
In eukaryotic cells, the enzymes controlling reactions of Krebs Cycle (citric acid cycle) are located:
mitochondrial matrix
The direct product of glycolysis reactions must be converted to which molecule before it can enter the Krebs Cycle?
Acetyl-CoA
Which is the best description of ATP use and production in glycolysis?
There is an initial cost of 2 ATP per glucose
In eukaryotic cells, the enzymes controlling reactions of glycolysis are:
in the cytoplasm
The main pupose of cellular respiration is to
produce ATP