Chapter 9 - Cell Respiration Flashcards
Aero
= air
An
= not
Chemi
= chemical
Glyco
= sweet
Lysis
= split
Acetyl CoA
The entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to a coenzyme.
Aerobic
Containing oxygen; referring to an organism, environment, or cellular process that requires oxygen.
Alcohol Fermentation
The conversion of pyruvate to carbon dioxide and ethyl alcohol.
Anaerobic
Lacking oxygen; referring to an organism, environment, or cellular process that lacks oxygen and may be poisoned by it.
ATP Synthase
A cluster of several membrane proteins found in the mitochondrial crista that function in chemiosmosis with adjacent electron transport chains. using the energy of a hydrogen ion concentration gradient to make ATP.
ATP Synthasees provide a port through which hydrogen ions diffuse into the matrix of a mitochondrion.
Cellular Respiration
The most prevalent and efficient catabolic pathway for the production of ATP, in which oxygen is consumed as a reactant along with the organic fuel.
Chemiosmosis
An energy-coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP.
Citric Acid Cycle
A chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules to carbon dioxide; occurs within the mitochondrion.
The second major stage of cellular respiration.
Electron Transport Chain
A sequence of electron carrier molecules(membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP.
Fermentation
A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.
Glycolysis
The splitting of glucose into 2 pyruvate. Occurs in all living cells, serving as the starting point for fermentation or aerobic respiration.
Lactic Acid Fermentation
The conversion of pyruvate to lactate with no release of carbon dioxide.
NAD+
Nicotinamide adenine dinucleotide, a coenzyme present in all cells that helps enzymes transfer electrons during the redox reactions of metabolism.
Oxidation
The loss of electrons from a substance involved in a redox reaction.
Oxidative Phosphorylation
The production of ATP using energy derived from the redox reactions of an electron transport chain.
Proton-motive Force
The potential energy stored in the form of an electrochemical gradient, generated by the pumping of hydrogen ions across biological membranes during chemiosmosis.
Redox Reaction
A chemical reaction involving the transfer of one of more electrons from one reactant to another; also called oxidation-reduction reaction.
Reducing Agent
The electron donor is a redox reaction.
Reduction
The addition of electrons to a substance involved in a redox reaction.
Substrate-level phosphorylation
The formation of ATP by directly transferring a phosphate group to ADP from an intermediate substrate in catabolism.
Goal of cell respiration
A series of chemical reactions aimed at breaking down large, energy rich macromolecules to release the stored energy in order to make many ATP molecules which can each be used to power cell jobs.
Is cell respiration Catabolic or Anabolic?
Catabolic
Redox(oxidation-reduction) summed up
Important to cell respiration.
- oxidation is the loss of electrons (oxidized and reducing agent)
- reduction is the gain of electrons(reduced and oxidizing agent)
Oxidation released energy from chemical bonds while reduction stores energy
Cell respiration summary formula(multiple steps)
C6H12O6+6O2 -> 6CO2+6H2O+ATP+Heat
3 major steps of cell respiration(in order)
- Glycolysis
- Citric Acid Cycle
- Electron Transport Chain
Glycolysis location
In cytoplasm outside of mitochondria
Glycolysis process
- Breaks glucose into 2 molecules of pyruvate
- Initial series of endergonic reactions requiring ATP.
- Second series of exergonic reactions makes a net 2 molecules of ATP for every glucose
- ATP is made by substrate level phosphorylation
- Some electrons from glucose are also transferred to electron shuttle NAD+
- reduces to NADH with the help of dehydrogenase.
Citric Acid Cycle location
- inside the mitochondrial matrix
Pre-Citric Acid Cycle
Between Glycolysis and Citric Acid Cycle.
- Pyruvate is converted to Acetyl Co-A
- a molecule of CO2 is produced
- More electrons are transferred to NAD+ to make NADH
- Co-enzyme A helps formation of Acetyl Co-A
Citric Acid Cycle process
- Joins Acetyl Co-A to a 4 carbon molecules(oxaloacetate) to form the 6 carbon molecule Citrate.
- Series of rxns converts citrate back into oxaloactate but in the process:
- More CO2 produced
- More electrons to NADH and FADH2(reduced from FAD+)
- Some ATP is made by substrate level phosphorylation.
- By end of citric acid cycle, all the original energy of glucose has been released either to make ATP in glycolysis or the citric acid cycle or carried in the electrons shuttled by FADH2/NADH
Electron Transport Chain location
Carrier molecules embedded in inner membrane of mitochondria.
Electron Shuttles NADH and FADH2(in electron transport chain)
Both drop off their electrons(becoming oxidized NAD+ and FAD) and reduce carrier molecules.
- In a series of reactions:
- carrier molecules pass the electrons down the chain until they are received by the final electron acceptor, Oxygen
- Oxygen + electrons + H+ = H2O
- the role of this oxygen is the reason aerobic organisms need to breath oxygen!
Redox Reactions in the electron transport chain
- Each redox in the chain allows some energy to be released which can be used to pump H+ from the matrix to the intermembrane space
- build up of H+ stores potential energy
- H+ ions are allowed to flow back down their concentration gradient, through the inner membrane into the matrix but only through the enzyme ATP SYNTHASE
- ATP Synthase can then be powered to make ATP from ADP and inorganic phosphate groups by OXIDATIVE PHOSPHORYLATION
Chemiosmosis and electron transport chain
The process of building up of the H+ gradient in order to do a job - the job in this case is the making of ATP.
Where is the vast majority of ATP made?
In the electron transport chain(~30 molecules).
Glycolysis(~2 molecules) and Citric Acid Cycle(~2 molecules) very little ATP creation in comparison.
Fermentation
When oxygen is not present, glycolysis can still take place, making pyruvate and 2 molecules of ATP, enough to power single cell organisms such as bacteria.
NAD+ and Fermentation
NAD+ is reduced to NADH but without the ETC, the NADH can not be oxidized back to NAD+ to continue the process of glycolysis.
How is NADH oxidized in fermentation?
- Alcohol Fermentation and 2. Lactic Acid Fermentation
Alcohol Fermentation
- Pyruvate is first converted to acetaldehyde which produces CO2.
- Acetaldehyde is then converted to ethanol by oxidizing NADH to NAD+
Lactic Acid Fermentation
- Pyruvate is directly converted to lactic acid by oxidizing NADH to NAD+
Summary Equation for Cell Respiration
Glucose + Oxygen -> CO2+H2O+Energy(ATP and Heat)
Oxidation and Reduction
Oxidation - Loss of electrons
Reduction - Gain of electrons
Glucose is oxidized to CO2 as electrons are taken away from it and given to oxygen which is reduced.
3 main stages of cellular respiration and location
- Glycolysis: Cytoplasm
- Citric Acid Cycle: Mitochondrial matrix
- Electron Transport Chain: Within inner mitochondrial membrane
Glucose(Stage utilized)
Glycolysis: Used
Pre-Citric: N/A
Citric: N/A
ETC: N/A
Oxygen(stage utilized)
Glycolysis: N/A
Pre-Citric: N/A
Citric: N/A
ETC: Used
Carbon Dioxide(Stage utilized)
Glycolysis: N/A
Pre-Citric: Produced
Citric: Produced
ETC: N/A
Water(Stage utilized)
Glycolysis: Produced
Pre-Citric: N/A
Citric: N/A
ETC: Produced
ATP(Stage utilized)
Glycolysis: Produced and Used
Pre-Citric: N/A
Citric: Produced
ETC: Produced
ADP + Pi(Stage utilized)
Glycolysis: Produced and Used
Pre-Citric: N/A
Citric: Used
ETC: Used
NADH(stage utilized)
Glycolysis: Produced
Pre-Citric: Produced
Citric: Produced
ETC: Used
NAD+(Stage utilized)
Glycolysis: Used
Pre-Citric: Used
Citric: Used
ETC: Produced
Describe role of NAD+ and FAD in cellular respiration
Molecules serve as electron shuttles.
They oxidize more complex molecules, such as glucose, and take those electrons to the ETC in order to allow the extraction of energy in a slow, controlled manner which makes the maximum amount of ATP molecules.
Why is the Citric Acid Cycle a cycle?
4 carbon sugar Oxaloacetate begins the cycle by combining with the 2 carbon Acetyl CoA molecule to form the 6 carbon sugar Citrate. CO2 and high energy electrons are produced(several steps). NAD+ and FAD take electrons to ETC and ATP is made by substrate level phosphorylation.
Eventually, the products of these steps regenerates Oxaloacetate to be used again as the cycle turns again.
What is Chemiosmosis and its role with ATP by oxidative phosphorylation
Chemiosmosis is a general term used to describe when a proton(H+) gradient is developed and then allowed to do some type of work.
The gradual passing of electrons between carrier molecules embedded in the inner membrane of the mitochondria that allow the protons to be pumped into the inner membrane space.
Once there is a strong proton gradient, protons “leak” back into the mitochondrial matrix via ATP synthase. The energy gained from protons going down their concentration gradient is used to make ATP by oxidative phosphorlyation.
the “work” of chemiosmosis is the making of ATP in cellular respiration.
What is cellular respiration and why is it important to living organisms?
Organisms energy needs are very large and require the building of larger molecules against their concentration gradients. These activities require an energy payment, such as energy in glucose.
1 glucose molecules would be far too much(wasted) energy for any specific cellular job.
Cellular respiration is a process that allows the gradual breakdown of all the bond energy in glucose and turns it into many, smaller packets of more usable energy(ATP molecules).
