Microorganisms that are involved in the nitrogen cycle are able to break the triple of elemental nitrogen using special enzymes that they have developed and make ammonium. Other organisms like plants are unable to break the triple bond and therefore rely on these microorganisms so that they can absorb the ammonia
Answer:
E) Improve membrane fluidity
Explanation:
Cholesterol constitutes the basic structural element of the skeleton of cell membranes. Without their reinforcement, the membranes would become extremely fluid and lose their consistency. Cholesterol is found in the esterified membranes in its hydroxyl group (OH): with fatty acids, mainly oleic and linoleic, or as cholesterol sulfate. The cholesterol-sulfate polar group is disposed on one of the faces of the membrane that interacts with other polar groups in that area, while its bulky hydrophobic portion is embedded between the apolar parts of the lipids that form the membrane skeleton and They fulfill many other functions, among which the reduction in the permeability of protons and sodium ions, and their participation in signal transmission. Cholesterol is also essential in phagocytosis processes carried out by cells to capture many nutrients and, in general, for the function of cleaning up organic waste produced by macrophages.
The membranes must have a fluid structure so that the integrated proteins can move "horizontally" to interact with their ligands and with other proteins. The fluidity is given by unsaturated fat. With the excess of saturated fat, the membranes become rigid, but only with the necessary unsaturated fat the membranes are extremely fluid and very sensitive to temperature changes. Cholesterol stabilizes the structure of the membranes; In order for them to have the correct structure, they must have the correct proportions of saturated, unsaturated fats and cholesterol. The membranes produced in the laboratory without cholesterol are unstable to temperature changes, drastically modifying their fluidity against the small temperature changes that occur in the physiological range.
In addition to its functions in cell membranes, cholesterol is an important product that metabolism uses as a raw material to make other compounds:
*Bile salts
*Sex hormones
*Hormones of the adrenal cortex (corticosteroids)
*Vitamin D (Calciferol)
Answer:
a) 28 cases
b) 3 cases
Explanation:
a) From the table of genetic codes, there are 28 codons that specify more than one amino acid assuming only the first two nucleotides are considered. In these cases, one cannot outrightly specify the amino acid the genetic codes are coding for without knowing the last nucleotide of the codes. <em>For example, UU can be for Phenylalanine or Leucine, CA can be for Histidine or Glutamine, etc. </em>
b) From the table of genetic codes, the first two nucleotides of Arginine can be either of CG or AG, that of Serine can be either of UC or AG while that Leucine can be either of CU or UU. Only in these <u>3 cases</u> would one fail to know which are the first two nucleotides assuming the name of the amino acids are given.
<em>See the attached image for the genetic code.</em>
Oxygen is the correct answer !
