A cell membrane has consists of phospholipids. They are lipids with a phosphate group such as (PO3/4). They are hydrophilic meaning that they allow water to pass through proteins well some at least- but it might be needed to move molecules throughnthe membrane as well. But basically it's just a composed bilayer of phospholipids with hydrophobic acid tails so that they could all meet with one another. The form complexes into function to describe or to identify the cells to anothers cells.
Hope this helps.
I am going to assume you are working on a test or a quiz. Please provide your answer choices becuase I might have taken the same test or quiz as you recently. (:
Answer:
Having considered how an appropriate primary immune response is mounted to pathogens in both the peripheral lymphoid system and the mucosa-associated lymphoid tissues, we now turn to immunological memory, which is a feature of both compartments. Perhaps the most important consequence of an adaptive immune response is the establishment of a state of immunological memory. Immunological memory is the ability of the immune system to respond more rapidly and effectively to pathogens that have been encountered previously, and reflects the preexistence of a clonally expanded population of antigen-specific lymphocytes. Memory responses, which are called secondary, tertiary, and so on, depending on the number of exposures to antigen, also differ qualitatively from primary responses. This is particularly clear in the case of the antibody response, where the characteristics of antibodies produced in secondary and subsequent responses are distinct from those produced in the primary response to the same antigen. Memory T-cell responses have been harder to study, but can also be distinguished from the responses of naive or effector T cells. The principal focus of this section will be the altered character of memory responses, although we will also discuss emerging explanations of how immunological memory persists after exposure to antigen. A long-standing debate about whether specific memory is maintained by distinct populations of long-lived memory cells that can persist without residual antigen, or by lymphocytes that are under perpetual stimulation by residual antigen, appears to have been settled in favor of the former hypothesis.
