8.2 (Energy Metabolism) Flashcards
Outline oxidation and reduction reactions in terms of movement of electrons, hydrogen or oxygen atoms
- Oxidation involves the loss of electrons from an element through the gain of oxygen or the loss of hydrogen.
- Results in a compound with lower potential energy
- Reduction involves the gain of electrons through the addition of hydrogen or the loss of an oxygen molecule.
- Results in a compound with higher potential energy
Define “electron carrier.”
Electron carriers are molecules that can accept or donate electrons.
State the name of the electron carrier molecule used in cellular respiration.
The main electron carrier in cellular respiration is NAD+ (nicotinamide adenine dinucleotide)
NAD, FAD and the components of the electron transport chain?
Define phosphorylation
The addition of a phosphate group, typically from ATP. (catalysed by kinases)
State the consequence of a molecule being phosphorylated.
The molecule becomes less stable (and therefore more likely to react).
ATP has 2 functions
1) energy currency by releasing energy when hydrolyzed to ADP
2) transfer phosphate to other molecule, less stable and more reactive.
Outline the glycolysis reaction, including phosphorylation, lysis and energy harvest.
Firstly, ATP is used to phosphorylate the sugar. Causes sugar to become unstable and breaks into TP
Then each TP gets oxidized and becomes GP. Hydrogen is removed and gets accepted by NAD+ to make NADH+H
In the last phase, the phosphate group is transferred to ADP to produce more ATP and pyruvate.
State that glycolysis occurs in both anaerobic and aerobic respiration.
Glycolysis in cellular respiration is not oxygen-dependent, thus it can happen in both anaerobic or aerobic.
Define decarboxylation and oxidation.
Decarboxylation is the removal of a carbon atom, which forms a carbon dioxide molecule from pyruvate (once glucose)
Oxidation is the removal of hydrogen atoms from pyruvate. Hydrogen election carriers NAD+ and FAD+ accepts electrons and passes it to the ETC.
Summarize the reactant and products of the link reaction.
The LINK reaction is named because it links product of glycolysis with aerobic processes of the Mitochondria.
Pyruvate is transported into the mitochondria
State that decarboxylation of glucose occurs in the linking reaction and Krebs cycle of aerobic respiration.
Aerobic respiration involves the breakdown of glucose in the presence of oxygen to produce water and carbon dioxide
Aerobic respiration involves three main types of reactions – decarboxylation, oxidation and phosphorylation
State that electron tomography enables scientists to view the dynamic nature of mitochondrial membranes.
Electron tomography is a technique by which the 3-dimensional internal structure of a sample can be modeled
Used to create a 3-D image of active mitochondria
Show cristea are connected to intermembrane space
Show shape and volume changes of cristae in active mitochondria.
State evidence that suggests mitochondria were once free living prokaryotes.
- 70S ribosomes and a naked loop of DNA are found within the mitochondrial matrix.
- outer membrane:
- impermeable to H+s,
- facilitates diffusion of pyruvate,
- shuttles 2 e-s from glycolytic NADH + H+
to inside of mitochondrion
- inter-membrane space:
- low pH = high concentration of H+s from ETS/proton pump
inner membrane:
folded into cristae, increasing SA for ETS and ATP synthetase;
permeable to H+s
matrix:
contains enzymes for oxidative decarboxylation and Krebs cycle
- low pH = high concentration of H+s from ETS/proton pump
Outline how mitochondria structure could evolve through natural selection.
there is often a clear relationship between the structures of the parts of living organisms and the functions they perform. This can be explained in terms of natural selection and evolution.) if mitochondrial structure varied, those organisms with the mitochondria that produced ATP most efficiently would have the advantage. They would have an increased chance of survival and would tend to produce more offspring. These offspring would inherit the type of mitochondria that produce ATP more efficiently. If this trend continued, the structure of mitochondria would gradually evolve to become more and more efficient.
State that that formation of water in the matrix at the end of the electron transport chain helps to maintain the hydrogen gradient between the intermembrane space and the matrix.
formation of water in the matrix at the end of the electron transport chain helps to maintain the hydrogen gradient between the intermembrane space and the matrix.
State that oxygen is the final electron acceptor in aerobic cellular respiration.
In order for ETC to continue, the de-energized electrons must be removed. Oxygen removes the de-energized electron to prevent the chain from becoming blocked.
Define oxidative phosphorylation and chemiosmosis.
- Oxidative phosphorylation is where energy originally released from the oxidation of glucose is used to produce ATP from ADP and Pi.
- Chemiosmosis is the use of the energy held within the proton gradient (created by the transport of electrons by the electron transport chain) to produce ATP.
State that the movement of electrons through electron carrier proteins in the electron transport chain is used to pump protons (H+) across the inner mitochondrial membrane into the intermembrane space.
the movement of electrons through electron carrier proteins in the electron transport chain is used to pump protons (H+) across the inner mitochondrial membrane into the intermembrane space.
State that NADH and FADH2 carry electrons to the electron transport chain on the mitochondrial inner membrane.
ETC will release energy stored within the reduced electron carriers to synthesize ATP
- NADH and FADH2 are oxidized to release high-energy electrons and protons
- Electrons are transferred to ETC which consists of carrier protons.
- As electrons pass through the chain they lose energy which is used to pump H+ from matrix to intermembrane space.
- Accumulation of protons within intermembrane space creates electrochemical gradient
State that FAD is reduced to become FADH2 in the Krebs cycle.
Energy released from the oxidation of the acetyl groups is transferred to electron carriers NAD and FAD to form NADH and FADH2.
State that NAD+ is reduced to become NADH in the link reaction and Krebs cycle.
Energy released from the oxidation of the acetyl groups is transferred to electron carriers NAD and FAD to form NADH and FADH2.
Outline the events of the Krebs cycle, referencing the formation of NADH and FADH2, formation of ATP and decarboxylation of acetyl groups.
Each acetyl group enters the Krebs cycle, therefore there are two rotations of the Krebs cycle per glucose molecule. There are two decarboxylations and four oxidations per cycle**
Step 1 - In the first stage of the Krebs cycle, the acetyl group from acetyl CoA is transferred to a four carbon compound. This forms a six carbon compound.
Step 2 - This six carbon compound then undergoes decarboxylation (CO2 is removed) and oxidation (hydrogen is removed) to form a five carbon compound. The hydrogen is accepted by NAD+ and forms NADH + H+.
Step 3 - The five carbon compound undergoes decarboxylation and oxidation (hydrogen is removed) again to form a four carbon compound. The hydrogen is accepted by NAD+ and forms NADH + H+.
Step 4 - The four carbon compound then undergoes substrate-level phosphorylation and during this reaction it produces ATP. Oxidation also occurs twice (2 hydrogens are removed). The one hydrogen is accepted by NAD+ and forms NADH + H+. The other is accepted by FAD and forms FADH2. The four carbon compound is then ready to accept a new acetyl group and the cycle is repeated.
The carbon dioxide that is removed in these reactions is a waste product and is excreted from the body. The oxidations release energy which is then stored by the carriers when they accept the hydrogen. This energy is then later on used by the electron transport chain to produce ATP.
