Compare and contrast aerobic and anaerobic respiration
Both processes include glycolysis, the citric acid cycle, and oxidated phosphorylation. In aerobic respiration the final electron acceptor is molecular oxygen O2; in anaerobic respiration the final electron Accceptor is a different substance.
Describe the difference between the two processes in cellular respiration that produce ATP: oxidative phosphorylation and substrate-level phosphorylation
Most of the ATP produced in cellular respiration come from oxidative phosphorylation, in which the energy released from redox reactions in an electron transport chain is used to produce ATP.
In substrate level phosphorylation, an enzyme dirctly transfers
During the redox reaction in glycolysis, which molecule acts as the oxidizing agent? Which molecule acts as the reducing agent?
NAD+ acts as the oxidizing agent in step 6, accepting electrons from G3P, which thus acts as the reducing agent
During the redox reaction in glycolysis, Which molecule acts as the reducing agent?
G3P
What processes in your cells produce the CO2 that you exhale
CO2 is released from the pyruvate that is the end product of glycoloysis, and CO2 is also released during the citric acid cycle
The Citric Acid Cycle begins ___; occurs ____;
with glycolysis by oxidyzing acetyl CoA (derived from pyruvate) to carbon diozide; within the mitochondrion in eukaryotic cells and in the cytosol of prokaryotes
Which process or processes return carbon to the atmosphere?
Cellular Respiration
What are the 4 major steps of cellular respiration?
1.Glycolysis- (occurs in the cytosol)
2. Pyruvate Oxidation - Formation of Acetyl Co-enzyme A (occurs in the mitochondrion)
3. Citric Acid Cycle
4. Oxidative phosphorylation - Electron Transport Chain and Chemiosmosis - (occurs in the inner membrane of th
In the Cellular Respiration Process, which coenzymes is an electron carrier?
NADH and FADH2
How many ATP are produced by the citric acid cycle for each molecule of glucose?
2
What is the correct sequence of steps as energy is extracted from glucose during cellular respiration.
glycolysis ? acetyl CoA ? citric acid cycle ? electron transport chain
Which of the part of the cellular respiration process takes place in the cytosol of a eukaryotic cell?
Glycolysis
How would you describe glycolysis?
This process splits glucose in half and produces 2 ATPs for each glucose.
Which part of a eukaryotic cell is involved in cellular respiration?
Mitochondria
Glucose and _______ are consumed during cellular respiration
Oxygen
In a eukaryotic cell, most of the ATP derived from glucose during cellular respiration is produced by ...
The Electron Transport Chain
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
H+ concentration across the membrane holding ATP synthase.
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
oxygen.
Most CO2 from catabolism is released during
the citric acid cycle
In the overall process of glycolysis and cellular respiration, _____ is oxidized and _____ is reduced.
glucose ... oxygen
(In cellular respiration, electrons and hydrogen are removed from glucose and added to oxygen.)
Oxygen gas (O2) is one of the strongest oxidizing agents known. The explanation for this is that _____.
The oxygen atom is very electronegative.
The function of cellular respiration is to _____.
Extract usable energy from glucose.
A small amount of ATP is made in glycolysis by which of the following processes?
Transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation
Where do the reactions of glycolysis occur in a eukaryotic cell?
the cytosol
Most of the NADH that delivers electrons to the electron transport chain comes from which of the following processes?
The citric acid cycle
(Both NADH and FADH2 are produced during the citric acid cycle.)
Why is the citric acid cycle called a cycle?
The four-carbon acid that accepts the acetyl CoA in the first step of the cycle is regenerated by the last step of the cycle.
In the citric acid cycle, for each pyruvate that enters the cycle, one ATP, three NADH, and one FADH2 are produced. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH2 are produced in the citric acid cycle?
two ATP, six NADH, two FADH2
Where do the reactions of the citric acid cycle occur in eukaryotic cells?
The matrix of the mitochondrion
(The citric acid cycle, which takes place in the mitochondrial matrix, completes the degradation of glucose.)
How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen?
Four
(There is a net gain of two ATP from glycolysis and one per each molecule of acetyl CoA oxidized in the citric acid cycle for a total of four per glucose.)
What is the major (but not the only) energy accomplishment of the citric acid cycle?
The formation of NADH and FADH2
(Each turn of the citric acid cycle releases carbon dioxide, forms one ATP by oxidative phosphorylation, and passes electrons to three NAD+ and one FAD.)
After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of _____.
NADH (The citric acid cycle produces three NADH per turn of the cycle)
during the conversion of pyruvate to acetyl CoA before the citric acid cycle there is a release of _____ and synthesis of _____
...
In glycolysis in the absence of oxygen, cells need a way to regenerate which compound?
NAD+
Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step _____.
enables the cell to recycle the reduced NADH to oxidized NAD+
During respiration in eukaryotic cells, the electron transport chain is located in or on the _____.
inner membrane of the mitochondrion
Which of the following is the source of the energy that produces the chemiosmotic gradient in mitochondria?
Electrons moving down the electron transport chain
describe the electron transport chain
Electrons are passed from one carrier to another, releasing a little energy at each step.
During aerobic respiration, molecular oxygen (O2) is used
at the end of the electron transport chain to accept electrons and form H2O
Light Reactions
reactions which occur on the thylakoid membranes of the chloroplast convert solar energy to the chemical energy of ATP and NADPH and release oxygen in the process (The first of two major stages in photosynthesis... happens before the calvin cycle)
Calvin cycle
The second of two major stages in photosynthesis (following the light reactions), involving fixation of atmospheric CO2 and reduction of the fixed carbon into carbohydrate.
NADP is an electron ______ that as NADPH stores _____ _______ produced during the _____ _____
acceptor; energized electrons; light reactions
Photophosphorylation
The process of generating ATP from ADP and phosphate by means of chemiosmosis, using a proton-motive force generated across the thylakoid membrane of the chloroplast or the membrane of certain prokaryotes during the light reactions of photosynthesis.
Carbon Fixation
The initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote).
Glyceraldehyde 3-phosphate (G3P)
A three-carbon carbohydrate that is the direct product of the Calvin cycle; it is also an intermediate in glycolysis.
What are the three phases of The Calvin cycle?
Carbon Fixation, Energy Consumption and Redox, Release of G3P; Regeneration of RuBP
Which of the following sequences correctly represents the flow of electrons during photosynthesis?
H2O ? NADPH ? Calvin cycle
autotroph vs. heterotroph
Autotrophs can nourish themselves with CO2 and inorganic nutrients
The light reactions of photosynthesis supply the Calvin cycle with
ATP and NADPH.
What provides electrons for the light reactions?
H2O (Electrons are stripped from water in the light reactions of photosynthesis. Light provides the energy to excite electrons.)
What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle?
Carbon dioxide (CO2)
(Carbon dioxide provides the carbon atoms that are incorporated into sugars in photosynthesis. Carbon dioxide initially combines with RuBP, and RuBP is regenerated to continue the Calvin cycle.)
What transports electrons from the light reactions to the Calvin cycle?
NADPH (NADPH is an electron carrier that picks up electrons in the light reactions and releases them in the Calvin cycle. An electron transport chain conveys electrons from one photosystem to the other within the light reactions.)
The light reactions take place in the _________ and the Calvin cycle takes place in the _________.
thylakoids; stroma
(Within the chloroplast, the light reactions take place in the flattened sacs called thylakoids and the Calvin cycle takes place in the thick fluid called the stroma.)
Where does the Calvin Cycle take place?
the stroma
Describe Carbon Fixation in the Calvin Cycle
Three molecules of carbon dioxide are added to three molecules of a five-carbon sugar abbreviated RuBP. These molecules are then rearranged to form six molecules called 3-PGA, which have three carbons each.
The reaction A --> B + C + heat is released in a(n) _____ reaction.
exergonic
In cells, what is usually the immediate source of energy for an endergonic reaction?
ATP
(The hydrolysis of ATP provides the energy needed for an endergonic reaction.)
The reaction ADP + P --> ATP is a(n) _____ reaction.
endergonic
The energy for an endergonic reaction comes from a(n) _____ reaction.
exergonic (the energy released by an exergonic reaction can be used to drive an endergonic reaction = energy coupling)
What is the fate of the phosphate group that is removed when ATP is converted to ADP?
It is acquired by a reactant in an endergonic reaction
What is energy coupling?
the use of energy released from an exergonic reaction to drive an endergonic reaction
How many NADH are produced by glycolysis?
2
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation (A phosphate group is transferred from glyceraldehyde phosphate to ADP.)
In glycolysis there is a net gain of _____ ATP.
2 (It takes 2 ATP to produce 4 ATP.)
Substrate-level phosphorylation occurs within a metabolic pathway where sufficient energy is released by a given chemical reaction to drive the synthesis of ATP from ADP and phosphate. In which of the following metabolic pathways is substrate-level phosph
in both glycolysis and the citric acid cycle
The reactions of pyruvate processing, the citric acid cycle, and the electron transport chain occur within the _____ in the cell.
mitochondria
In the citric acid cycle, ATP molecules are produced by _____.
substrate-level phosphorylation
products of the citric acid cycle
NADH, H+, ATP, CO2, FADH2
Following glycolysis and the Krebs cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at
NADH
_____ and _____ are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce __ to _____ in the final step of electron transport. However, the amount of ATP made by electrons from an _____ molecul
NADH; FADH2; O2; water; NADH; FADH2 (because fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor)
Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops. In the absence of oxygen, _____ _______ stops. ____ is no longer converted to _____, which is needed for the first three stages of cellular respiration.
electron transport stops; NADH; NAD+
The energy of electron transport serves to move (translocate) protons to the outer mitochondrial compartment. How does this help the mitochondrion to produce energy?
The translocation of protons sets up the electrochemical gradient that drives ATP synthesis in the mitochondria.
In fermentation _____ is reduced and _____ is oxidized.
pyruvate ... NADH
lactate ... ethanol
NAD+ ... pyruvate
NADH ... lactate
lactate ... NADH
pyruvate ... NADH
Which molecule is most often metabolized in a cell to produce energy for performing work?
Glucose
Which step of the cellular respiration pathway can take place in the absence of oxygen?
Glycolysis
Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?
Carbon dioxide
____ and _____ donate their electrons in the electron transport chain
NADH and FADH2
Which stage of glucose metabolism produces the most ATP?
Electron transport and chemiosmosis
When ATP is _____ into ADP and inorganic phosphate, a large amount of energy is released.
hydrolyzed
In cellular respiration, glucose is _____ and oxygen is _____.
oxidized, reduced
_____ is the three-carbon sugar that is produced as an end product of glycolysis.
Pyruvate
A substrate-level phosphorylation occurs in the Krebs cycle when _____.
GDP is phosphorylated to produce GTP
How do allosteric regulation and competitive inhibition compare?
Competitive inhibition involves binding of a regulatory molecule to the active site; in allosteric regulation a regulatory molecule binds to a different location
Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?
pyruvate, ATP, and NADH
Why is ATP production during cellular respiration characterized as indirect?
ATP is not produced directly by the ETC but instead via the proton gradient generated during electron transport through the ETC.
Why are fermentation reactions important for cells?
They generate oxygen.
They regenerate NAD+ so that glycolysis can continue to operate.
They allow the cell to conserve oxygen for the Krebs cycle.
They produce alcohol which enhances the permeability of
They regenerate NAD+ so that glycolysis can continue to operate.
what is the ultimate electron donor in the calvin cycle?
water (donates new electrons and chlorophyl passes them on all the way to the sugar)
in photosynthesis, the electron transport proteins are in the
thylakoid membranes
carbohydrate synthesis takes place in the
stroma
does a re-oxidation reaction produce ATP
no, it provides ADP+ so glycolysis can continue
chemiosmosis
use of energy of the flow of H+ ions down their gradient (electron transport chain to ATP synthesis)
during chemiosmosis ____ is oxidized to ___ which then goes back and picks up a H from all three of the pathways
NADH; NAD+;
during chemiosmosis, the hydrogen ions are pumped as a result of the electron flow from the ____ to the _____ and therefore the hydrogen ion concentration inside the cell _____
matrix; inter membrane space; decreases
how do we use exergonic flow of electrons?
The free energy from electron flow is used to move hydrogen ions across a membrane against their gradient
in the absence of CO2, which pathways shut down?
the citric acid cycle, electron transport pathway, and production of acetyl CoA (aka oxidation of pyruvate)