8.2 Cell Respiration Flashcards
Link reaction: reaction
Pyruvate -> Acetyl CoA (+ NADH, CO2)
Give an example of a catabolic pathway.
Cellular respiration
Functions of outer membrane (mitochondria)?
Separates the content of the mitochondrion from the rest of the cell; contains appropriate transport proteins for shuttling pyruvate into mitochondria
Steps of glycolysis (simple).
- Phosphorylation - Lysis - Oxidation - ATP formation
Functions of inner membrane (mitochondria)?
Contains the carriers for the electron transport chain and ATP synthase for chemiosmosis; folded into cristae to increase surface area for electron transport chain
Give an example of an anabolic pathway.
Photosynthesis
First step of glycolysis.
Phosphorylation: Two molecules of ATP are used to begin glycolysis. The phosphates from the ATPs are added to form fructose 1,6-bisphosphate.
What is chemiosmosis?
* The hydrogen carriers donate electrons via oxidation to electron carriers on the inner membrane (cristae)
* The electrons lose energy as they are passed along an electron transport chain
* This energy is utilized to pump protons (H+ ions) into the intermembrane space
* The build-up of protons creates a proton motive force (electrochemical gradient)
* The protons return to the matrix via a transmembrane enzyme (ATP synthase)
Krebs cycle: Reaction
Acetyl CoA -> CO2 (x2), ATP, NADH (x3), FADH2
What is oxidative phosphorylation?
* In chemiosmosis, protons diffuse through ATP synthase to generate ATP
* In order to maintain the electrochemical gradient, de-energized electrons must be removed from the transport chain
* Oxygen is the final electron acceptor and binds with free protons in the matric to form water (this maintains the H+ gradient)
* As protons were produced by oxidative processes, this method of ATP synthesis is called oxidative phosphorylation.
What is the link reaction?
The link reaction functions to connect the anaerobic process of glycolysis to the aerobic activities of the mitochondria.
* Pyruvate (from glycolysis) is transported from cytosol to mitochondrial matrix
* Pyruvate is decarboxylated (CO2 is produced) to form an acetyl compound that is then attached to coenzyme A (form acetyl CoA)
* Pyruvate is also oxidized to produce on reduced hydrogen carrier (NADH + H+)
End result of glycolysis.
Four ATPs, two NADPs, two pyruvates molecules (an ionized form of pyruvic acid)
Oxidation vs. reduction
Oxidation: * Loss of electrons * Gain of oxygen * Loss of hydrogen * Results in many C-O bonds * Results in a compound with lower potential energy Reduction: * Gain of electrons * Loss of oxygen * Gain of hydrogen * Results in many C-H bonds * Results in a compound with higher potential energy
What is the electron transport chain?
The electron transport chain utilizes chemiosmosis to synthesize ATP via oxidative phosphorylation.
What is the Krebs cycle?
The Krebs cycle describes a series of oxidation reactions that occur within the mitochondrial matric. (6C -> 5C -> 4C -> 4C).
* Acetyl CoA (link reaction) combines with a 4C compound to form a 6C compound
* Via oxidation/decarboxylation reactions, the original 4C compound is reformed
* These reactions result in the formation of carbon dioxide (x2), ATP (x1) and multiple hydrogen carriers (x3 NADH and x1 FADH2)
Functions of intermembrane space (mitochondria)?
Proton accumulation (maximize gradient)
Where does the Krebs cycle occur?
Mitochondrial matrix
Oxidation and reduction =
Redox reactions
What is phosphorylation and what does it do?
Phosphorylation is the chemical addition of a phosphoryl group to an organic molecule. It creates a less stable molecule.
Third step of glycolysis.
Oxidation and ATP formation: When the two G3P molecules are formed, they enter an oxidation phase involving ATP formation and the production of the reduced coenzyme NAD. Each G3P undergoes oxidation to form a reduced molecule of NAD+, which is NADH. During the formation of NADH, released energy is used to add inorganic phosphate to the remaining 3-carbon compound which results in a compound with two phosphate groups. Enzymes then remove the phosphate groups so that they can be added to ADP to produce ATP.
Functions of cristae (mitochondria)?
Increases the surface area for oxidative phosphorylation
Where does the link reaction take place?
Mitochondrial matrix
Cellular respiration equation
C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy
What do catabolic pathways result in?
The breakdown of complex molecules into smaller ones
Summary of glycolysis
* Two ATPs are used to start the process * Four ATPs are produced; a net gain of two ATPs * Two molecules of NADH are produced. The pathway involves substrate-level phosphorylation, lysis, oxidation, and ATP formation * The pathway occurs in the cytoplasm
How many ATPs are produced in cellular respiration?
36 ATP
Second step of glycolysis.
Lysis: The less stable 6-carbon phosphorylated fructose is split into two 3-carbon sugars called glyceraldehyde-3-phosphate (G3P).
Cellular respiration involves the…
oxidation and reduction of electron carriers. They occur together because one compound’s loss is another compound’s gain.
Where does glycolysis occur?
Cytoplasm/cytosol
Mitochondria diagram
What do anabolic pathways result in?
The synthesis of complex molecules from smaller ones
Where does the electron transport chain take place?
In the fold of the inner membrane of the mitochondria (the cristae)
Functions of matrix (mitochondria)?
Contains the enzymes necessary for the link reaction and the Krebs cycle
What is glycolysis?
= ‘sugar splitting’. It uses no oxygen and occurs in the cytosol and proceeds efficiently in both aerobic and anaerobic environments and occurs in both prokaryotic and eukaryotic cells.
