Answer:
The alveolar membrane- is where gas exchange between the blood and the atmosphere takes place. The gas molecules must diffuse across the alveolar epithelium and the capillary endothelium. ... Thus, the alveolar surface (as well as the respiratory bronchioles) have no cilia or mucus layer.
Explanation:
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Answer: Endocytosis brings materials to the inside of the cell while exo takes them out. Exoocytosis has the vesicle being formed in the golgi apparatus which then fuses with the membrane, while endo has the vesicle. formed from the cell membrane which then gets into the cytoplasm.
The answer is D. Both a and c
Answer:
The purine ring is built onto ribose-5-phosphate of PRPP for its de-novo nucleotide biosynthesis, while the ring structure of the pyrimidine bases are synthesized separately and then coupled to ribose-5-phosphate via the C-N glycosidic bond.
Explanation:
In the de novo synthesis of nucleotides, their metabolic precursors such as aminoacids, ribose-5-phosphate, CO₂ and NH₃ are used as starting materials.
In purine nucleotide synthesis, the ring structure is built up on ribose-5-phosphate of PRPP by addition of one or a few atoms one at a time starting with the amino group donated by glutamine until the first intermediate inosinate is synthesized.
In pyrimidine ring synthesis, orotate is first synthesized from carbamoyl phosphate and aspartate, and then is attached to ribose-5-phosphate of PRPP, before it is then converted to the common pyrimidine nucleotides starting from uridylate.
