Answer:
Nucleic Acids
Explanation:
Nucleic acids are DNA and RNA and they are the molecules responsible for containing the genetic material of all living beings. Thus, DNA and RNA are the molecules responsible for establishing the variability and different characteristics between dog breeds, through the genetic information that each of them houses.
In this case, among the options given in the question above, we can confirm that if Allen has studied the genetic material of dogs to better understand why there are so many different breeds, he must have studied nucleic acids.
Answer:
C) Because apoptosis genes kill cells, natural selection is seldom involved in apoptosis pathways.
Explanation:
Apoptosis is a natural process taking in the cell which causes the physiological and biochemical changes in the cell which could cause the death of the cell.
The apoptosis is controlled at the genetic level therefore apoptosis is also known as the programmed cell death.
The studies have shown that the process is involved in the development of the finger and the toes in humans and the sequences controlling the process has been conserved during the evolution in a different organism.
This shows that humans and nematode have the same conserved sequence of apoptosis but the natural selection does not control the apoptosis.
Thus, the selected option is the correct answer.
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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)
