Answer:
A. NADH and FADH2 both donate electrons at the same location.
Explanation:
In the respiratory chain, four large protein complexes inserted into the mitochondrial inner membrane transport NADH and FADH₂ electrons (formed in glycolysis and the Krebs cycle) to oxygen gas, reducing them to NAD⁺ and FAD, respectively.
These electrons have great affinity for oxygen gas and, when combined with it, reduce it to water molecules at the end of the reaction.
Oxygen gas effectively participates in cellular respiration at this stage, so its absence would imply interruption of the process.
NADH and FADH₂ electrons, when attracted to oxygen, travel a path through protein complexes, releasing energy in this process.
The energy released by the NADH and FADH₂ electrons in the respiratory chain in theory yields <u>34</u> <u>ATP</u>, however, under normal conditions an average of 26 ATP molecules is formed.
If we consider that these 26 molecules are added to the two ATP formed in glycolysis and two ATP formed in the Krebs cycle, it can be said that cellular respiration reaches a maximum yield of 30 ATP per glucose molecule, although theoretically this number was 38 ATP per glucose molecule.
Answer:
Astrocytes
Explanation:
Astrocytes are the most abundant cells in the central nervous system that twine around nerve cells supporting the brain and spinal cord. They perform many functions; such as providing the nuerons with nutrients, control the blood brain barrrier and blood flow. Astrocytes are basically responsible for maintaining the central nervous system homeostasis.
During the repolarization phase of an action potential which of the following is the primary activity in the membrane of the post-synaptic cell?
A) Sodium ions are flowing out of the cell.
B) Sodium ions are flowing into the cell.
C) Potassium ions are flowing into the cell.
D) Potassium ions are flowing out of the cell.
Answer:
D) Potassium ions are flowing out of the cell.
Explanation:
The threshold opens both voltage-gated Na+ channels and the voltage-gated K+ channels. The voltage-gated K+ channels are very slow in opening. Therefore, they open when the voltage-gated Na+ channels are closing. The opened voltage-gated K+ channels are responsible for the repolarizing phase.
During this phase, the inflow of Na+ becomes less as the responsible channels are inactivated. The opened K+ channels allow the K+ to move out of the post-synaptic cell. It results in the generation of negative charge inside the cell membrane as the membrane potential reduces +30 mV to −70 mV.
