The human immunodeficiency virus (HIV) that causes the disease known as aids selectively infects helper T cells (CD4+).
This retrovirus also infects macrophages and dendritic cells. When CD4+ T cell numbers decrease below a critical level (due to the killing of this cells with different mechanisms), cell-mediated immunity is lost. As a result, the body becomes progressively more susceptible to infections, leading to the development of AIDS.
<span> HIV can be transmitted only via body fluids like blood, semen, pre-seminal fluid, rectal fluids, vaginal fluids, and breast milk, which means that people usually get or transmit HIV through sexual behaviours and use of the needle. For HIV infection, these fluids must come in direct contact with a mucous membrane or damaged tissue. Another way is to be directly injected into the bloodstream (from a needle for example).</span>
Answer: it is called sorting or in other words sequence order
Explanation: Already Learned This In Class
Answer:
1) To form a multicellular organism, a zygote must divide into 16 cells which produces ball structure called a morula. After that, morula is converted into a structure called blastula.
2) Adult stem cells are responsible for the maintenance of tissues and repair the damage tissues in the body. It is also called somatic stem tissue. It increase in number through cell division.
Acylhomoserine lactones used in quorum sensing regulate their own synthesis by an autoinduction system.
- Numerous bacteria use acyl homoserine lactones (acyl-HSLs), significant intercellular signaling molecules, to track the density of their population for quorum-sensing control of gene expression. The LuxI family of proteins produces the signals in question.
- A lot of proteobacteria use quorum-sensing signals from acyl-homoserine lactones.
- Cells create a baseline amount of signal at low population densities, and when enough signal has accumulated in the environment, it binds to its receptor and activates quorum-sensing-dependent genes.
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