T cells. When HIV arrives in the lymph nodes – around 24 to 48 hours after exposure – they activate other immune cells, such as CD4 t-cells, HIV's primary target.
Would not be to distinguish between labeled DNA and amino acids.
It is the serous membrane
It radiates light and heat, or solar energy, which makes it possible for life to exist on Earth. Plants need sunlight to grow. Animals, including humans, need plants for food and the oxygen they produce. Without heat from the sun, Earth would freeze.