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Cellular respiration
Catabolic process that uses energy stored in glucose to produce ATP
About what percent of the energy from glucose is found in ATP?
34%
What happens to the rest of the energy?
It is lost as heat
What type of process is the breakdown of glucose into carbon dioxide?
Exergonic - release energy
What type of process is the phosphorylation of ADP into ATP?
Endergonic - requires energy
What drives cellular respiration?
Energy from the transfer of electrons in redox reactions
Redox reactions
Reactions that transfer electrons from one molecule to another
In redox reactions, electrons release energy as they are pulled toward a more…
electronegative atom
Oxidation
loss of an electron
Reduction
gain of an electron - molecules become more negative, reducing the charge on the molecules
e-
electron
Electron acceptor - gain electrons
is reduced
oxidizing agent
has a high electronegativity
Oxidizing agent
causes other molecules to be oxidized
Electron donor - give up electrons
is oxidized
reducing agent
has a low electronegativity
Reducing agent
causes other molecules to be reduced
What atoms are often used in redox reactions
hydrogen atoms
Hydrogen atoms have ___ proton and ___ electron
1, 1
H →
H+ (proton) + e- (electron)
Aerobic Respiration
Uses sugar and oxygen to produce ATP
C6H12O6 + 6O2 →→→ 6CO2 + 6H2O + 30-32 ATP (Net equation for cellular respiration) Know for quizzes and tests
Oxygen is inhaled during breathing and carbon dioxide is exhaled during breathing
In redox reactions in aerobic respirations, glucose is broken down into what?
CO2 and H
H binds to O2 to form what?
H2O
Energy that is released from glucose is used to phosphorylate what?
ADP into ATP
What does 30-32 ATP represent?
About 34% of energy in one glucose molecule
In aerobic respirations, if all of the energy in fuel is released at once, how much work is accomplished?
little
Therefore, the energy in glucose must be released in a series of..
steps
Dehydrogenase enzymes remove electrons from molecules and transfer them to what?
electron carrier molecules
Electron carrier molecules accept ____-_____ electrons and transfer those electrons, along with most of their energy, to other molecules
high-energy
NAD+
Coenzyme derived from vitamin B
NAD+ + 2H → NAD+ + H + H + e- → NADH + H+
FAD
FAD + 2H → FADH2
2 Ways to Produce ATP
Substrate phosphorylation and Oxidative phosphorylation
Substrate phosphorylation
an enzyme transfers a phosphate group from an organic molecule to ADP to form ATP
Oxidative phosphorylation
uses energy from redox reactions in the electron transport chain to phosphorylate ADP into ATP
In Glycolysis, glucose is broken down into what?
pyruvate
Then, it produces some ATP and NADH and releases some what?
water
Where does glycolysis occur?
cytoplasm
In the oxidation of pyruvate, pyruvate is broken down into what?
acetyl CoA
Some what is then released?
CO2
Where does oxidation of pyruvate occur
In the inner membrane and matrix of the mitochondria
In the Citric Acid Cycle (Krebs cycle), Acetyl CoA is broken down into what?
CO2
What is then produced?
NaDH and FaDH2
Where does the Krebs Cycle occur?
In the matrix of the mitochondria
In oxidative phosphorylation, energy is used from electron transport chain and H+ gradient to produce what?
ATP
Electron transport chain
uses energy from redox reactions to create H+ gradient
H+ gradient
H+ are actively transported into the intermembrane space
contains a large amount of potential energy
Chemiosmosis
uses energy from H+ gradient to produce ATP
In Glycolysis, Glucose (6-carbon molecule) is broken down into how many pyruvates (3-carbon molecules)
2
This releases hydrogens, uses 2 ATP, and releases 2 what?
H2O
2 NAD+ are converted to 2 NADH
2NAD+ + 4H → NADH + 2H+
NADH goes to electron transport chain
H+ goes to the H+ gradient
4 ATP are produced by what?
substrate-level phosphorylation
This means that 2 ATP are used to produce pyruvate and there’s a net gain of how many ATP?
2
In the Oxidation of Pyruvate, pyruvate is broken down into what?
acetate (2-carbon molecule) and CO2
The acetate bonds with coenzyme A to form acetyl CoA, which enters what?
The citric acid cycle. CO2 is released
In the Oxidation of Pyruvate, NAD+ is converted to NADH using hydrogens released from what?
pyruvate
The NADH goes to the _______ ________ chain while H+goes to the __ gradient
electron transport, H+
In the Citric Acid Cycle, Acetyl CoA is broken down into what?
acetate and coenzyme A
The coenzyme A goes back to oxidizing what?
pyruvate
The acetate binds to an oxaloacetate to form what?
citrate
Citrate is converted back to oxaloacetate and what is released?
CO2
In the Citric Acid Cycle, 3 NAD+ are converted to
3 NADH and 3 H+
The NADH goes to electron transport chain while H+ goes to the..
H+ gradient
Continually, ATP is produced by what?
substrate phosphorylation
The FAD is converted to what?
FADH2, which goes to the electron transport chain.
In Oxidative Phosphorylation, the electron transport chain is composed of a series of..
multi-protein complexes labeled I - IV
Each complex has prosthetic groups, which are
nonprotein components and are essential to the catalytic function of the molecules
Many of the complexes in the electron transport chain contain what?
cytochromes - molecules with an iron group
Molecules further down the chain increase in what?
electronegativity
What is the most electronegative molecule in the electron transport chain?
O2
In the process of the electron transport chain, NADH contributes 2 electrons to what complex?
Complex I
The NADH is converted back to what?
NAD+
H+ is released, and NAD+ goes back to what?
glycolysis, oxidation of pyruvate, or citric acid cycle.
In the process of the electron transport chain, FADH2 contributes 2 electrons to what complex?
Complex II
The FADH2 is converted back to what?
FAD
2 H+ are released, and FAD goes back to the
citric acid cycle
Electrons move down the chain through a series of _____ reactions and energy is released at each step
redox
In Oxidative Phosphorylation, oxygen combines with electrons and H+ to form what?
water.
O2 + 4H+ + 4e- → 2H2O
water is released
In the H+ gradient, the energy from the electron transport chain is used to pump H+ from the matrix into the..
intermembrane space
Proton motive force
energy from the H+ gradient can be used to perform work
In Chemiosmosis, ATP synthase is a
protein complex that produces ATP
H+ diffuses down the concentration gradient and binds to..
ATP synthase
ATP synthase uses energy released by H+ to phosphorylate ADP into
ATP
Chemiosmosis produces how many ATP?
28
Sometimes energy from proton motive force is used to do other types of work
uptake of pyruvate
often produces only 26 ATP
In aerobic respiration, carbohydrates are converted to ___________ and are used in glycolysis
monosaccharides
Fats are broken down into
glycerol and fatty acids
Glycerol is used in..
glycolysis
Fatty acids are broken down into 2-carbon molecules and converted to..
acetyl CoA, which enters the citric acid cycle
1g of fat produces twice as many ATPs as 1g of what?
carbohydrate
Proteins are broken down into
amino acids, which are then converted to intermediates in glycolysis
What are amino acids converted to in glycolysis, oxidation of pyruvate, or the citric acid cycle?
intermediates
Anaerobic respiration
uses a different final electron acceptor in the electron transport chain, such as sulfate
Fermentation
uses only substrate-level phosphorylation to produce ATP
Two types of fermentation
Lactic acid fermentation and alcohol fermentation
In glycolysis, glucose is broken down into pyruvate and produces how many ATPs?
2 ATP’s, much less ATP than aerobic respiration.
It produces NADH, which must be recycled to
NAD+
Glycolysis occurs in both
lactic acid and alcohol fermentation
In lactic acid fermentation, pyruvate is converted to what?
lactate.
It also recycles NADH to
NAD+
Lactic Acid Fermentation occurs in what cells?
human muscle cells
It occurs in some fungi and some prokaryotes and is used to produce what
cheese and yogurt