Answer:
Immune system of the body helps in fighting with the infectious agents that are foreign for the body. So the immune system protects us from infection.
When any foreign substance(antigen) comes in the body B-lymphocyte recognize it by binding the antigen through its receptor. After recognizing the antigen, B cell divides into antibody-producing plasma cell and memory cell.
Antibodies produced by plasma cells help in destroying the antigen by getting the antigen recognized by phagocytic cells or by complement activation.
B cells are antigen-presenting cell which present antigen to T cell and then T cell activates and produce chemicals that kill the antigen. Therefore the immune system has many immune cells that activate when an antigen comes in the body. This is how the immune system functions.
Answer:
tetracycline
Explanation:
When the DNA insert is ligated in Pstl site, the ampicillin gene is disrupted while <em>tetracycline gene is still intact</em>.
- If the bacterial colony is growth in a medium with only ampicillin, only the cells that contains the plasmid with the insert will grow.
- If the bacterial colony is growth in a medium with only tetracycline, the cells which have incorporated the plasmid will survive. We cannot distinguish between cells with plasmid + insert and plasmid alone.
- If the bacterial colony is growth in a plate with ampicillin + tetracyclin, only the cells with the plasmid without the insert will grow.
Therefore, to ensure that the cells of a bacterial colony contains the plasmid, they have to be seeded in a plate with tetracycline.
Answer:
Part of the extracellular matrix secreted by osteocytes. (Ans. B)
Explanation:
Cells which are present on bones are known as osteocytes. Bone is composed of extracellular matrix, and cells. There are three types of cells which are present in the bones:
1) Osteoprogenitor cells.
2) Osteoblast.
3) Osteocyte.
Extracellular matrix is composed of organic matrix consisting glycoproteins, proteoglycans, osteocalcin also known as calcium binding proteins, and osteonectin which anchors bone mineral to collagen.
