Answer:
The fewer number of T cells a person has, the more chances to be affected by an opportunistic infection. When the number of T cells reaches 200 cells/µl, the person is at risk of being infected by other infections.
Explanation:
The whole immune system of a person who is infected with HIV infection seems to be severely affected. When the person is not treated or the disease is in a very advanced stage, the depletion of the T- cells turns to be very sharped, especially CD4+ T cells. At this point, the immune system can not resist the attack of other microorganisms. The <em>lower is the number of CD4+ T Cells, the higher possibility the person has to be attacked by opportunistic infections. </em>
Classically, it has been suggested that opportunistic infections appear after the CD4 + T lymphocytes reach very low levels, such as 200 cells/µl. The number of circulating T cells can be used as an indicator and a measure of global "immune competence", and the previously mentioned amount of CD4 + T cells is an accepted universal reference used to predict the risk of having one of these opportunistic infections.
I agree because an ecosystem and a host are basically the same thing.
Answer:
a. The directionality of the complementary strand is antiparallel. The double-stranded DNA is antiparallel comprising two strands, which run alongside each other, however, point in reverse directions. In a double-stranded molecule of DNA, the 5 prime ends of one strand align with the 3 prime ends of the other strand, and vice versa.
b. The mediation of base pairing is done by non-covalent hydrogen bonds. It is reversible, that is, the strands can separate and can come combined again without any chemical modification.
The specificity of base pairing is illustrated by hydrogen bonds that is, the first strand produces hydrogen bonds only with a particular base in the second strand, and these two bases produce a base-pair.
c. The interaction or association of non-covalent type, that is, hydrophobic interaction and hydrogen bonding. Collectively, they both are strong. In the process, one base associate with the other base on the complementary strand.
d. The phosphate backbone possesses the tendency to associate with water on the outside of the molecule, and this is favorable chemically as both the strands are held together by hydrogen bond and hydrophobic interaction.
The polar molecules of sugar can produce hydrogen bonds with the surrounding molecules of water. The negatively charged phosphate group associate with the positively charged ions. The nonpolar nitrogen bases are found within the molecule and associate favorably through stacking interactions.
1st one, fats/phospholipids/steroids.
2nd one, cholesterol and saturated fats.
