What are the two types of defence mechanism? Non-specific and specific
What are some examples of a non-specific defence mechanism?Physical barrier, like
the skin or the stomachs HCl<div>Phagocytosis </div>
What are some examples of a specific defence mechanism? The cell-mediated
response of T cells<div>The humoral response of B cells</div>
What are antigens? Proteins on the surface of cells that help the immune
system identify if they are self cells or foreign cells
How do lymphocytes recognise self cells? In the foetus, there are millions of
lymphocytes each with difference receptors that are capable of detecting and
recognising different kinds of cells.<div>These cells are colliding with the cells
of the foetus all the time. These are all self cells.</div><div>The lymphocytes
that have receptors complementary to self cells are terminated, meaning the only
remaining lymphocytes are those with receptors complementary to foreign
antigens </div>
Which kind of white blood cell performs phagocytosis? Phagocytes
How does phagocytosis work? The phagocyte is attracted to the bacteria due to the
trail of chemicals it leaves. it moves towards the pathogen along a concentration
gradient of these chemicals in a process known as chemotaxis<div>The phagocyte
binds to the antigens on the surface of the pathogen and engulfs it</div><div>The
phagocyte forms a vesicle around the pathogen, known as phagosome</div><div>The
lysosomes in the phagocyte fuse with the phagosome, releasing lysozymes that break
down the pathogen, except its antigens.</div><div>The products of the hydrolysis of
the pathogen are absorbed by the phagocyte, and the antigens are presented on the
surface of the phagocyte </div>
Where do B cells mature? The bone marrow
Where do T cells mature? The thymus
What kind of cell does cell mediated immunity involve? T cells
How does cell-mediated immunity work? T cells complementary to the pathogen
invading are stimulated by antigen presenting cells<div>They divide rapidly into T
helper cells and cytotoxic T cells </div><div>The T helper cells go on to
either serve as memory cells, so that the immune system is ready to respond to a
future infection from the same pathogen, or to stimulate B
cells</div><div>Cytotoxic T cells use a protein called perforin to make holes in
the cell membrane of other cells/particles of the pathogen, thus destroying
it</div>
What kind of cell does humoral immunity involve? B cells
How does humoral immunity work? When a B cell encounters an antigen that it has
receptors complementary to, the antigen enters the B cell by
endocytosis <div>The B cell processes these antigens and displays them on its
cell membrane</div><div>Stimulated T helper cells bind to the processed antigen,
causing the B cell to become stimulated</div><div>The stimulated B cell divides
rapidly- this is called clonal selection theory, as only B cells that will produce
complementary antibodies divide</div><div>The B cell divides into two kinds of
cell- plasma cells and memory cells</div><div>Plasma cells produce monoclonal
antibodies that are specific to the pathogen- this is the primary
response</div><div>Memory cells stay in the blood and tissue fluid, waiting for re
infection, upon which they rapidly divide in clonal selection theory again for a
rapid immune response- the secondary response </div>
What kind of protein structure do antibodies have? Quaternary structure
What kind of bonds hold together the different polypeptide chains in antibodies?
Disulphide bridges
When antibodies bind to antigens, what is it called? An antibody-antigen
complex
What is the structure of an antibody? """<img src=""""image-
66708641bbe84304f2efe97635abf7340c342f33.png"""">"""
How do antibodies kill pathogens? They cause agglutination of bacterial cells,
meaning phagocytes can engulf them more easily<div>They can mark pathogens for
destruction by phagocytes</div>
What is a monoclonal antibody? One that is specific to a single antigen
What are some examples of a non-specific defence mechanism?Physical barrier, like
the skin or the stomachs HCl<div>Phagocytosis </div>
What are some examples of a specific defence mechanism? The cell-mediated
response of T cells<div>The humoral response of B cells</div>
What are antigens? Proteins on the surface of cells that help the immune
system identify if they are self cells or foreign cells
How do lymphocytes recognise self cells? In the foetus, there are millions of
lymphocytes each with difference receptors that are capable of detecting and
recognising different kinds of cells.<div>These cells are colliding with the cells
of the foetus all the time. These are all self cells.</div><div>The lymphocytes
that have receptors complementary to self cells are terminated, meaning the only
remaining lymphocytes are those with receptors complementary to foreign
antigens </div>
Which kind of white blood cell performs phagocytosis? Phagocytes
How does phagocytosis work? The phagocyte is attracted to the bacteria due to the
trail of chemicals it leaves. it moves towards the pathogen along a concentration
gradient of these chemicals in a process known as chemotaxis<div>The phagocyte
binds to the antigens on the surface of the pathogen and engulfs it</div><div>The
phagocyte forms a vesicle around the pathogen, known as phagosome</div><div>The
lysosomes in the phagocyte fuse with the phagosome, releasing lysozymes that break
down the pathogen, except its antigens.</div><div>The products of the hydrolysis of
the pathogen are absorbed by the phagocyte, and the antigens are presented on the
surface of the phagocyte </div>
Where do B cells mature? The bone marrow
Where do T cells mature? The thymus
What kind of cell does cell mediated immunity involve? T cells
How does cell-mediated immunity work? T cells complementary to the pathogen
invading are stimulated by antigen presenting cells<div>They divide rapidly into T
helper cells and cytotoxic T cells </div><div>The T helper cells go on to
either serve as memory cells, so that the immune system is ready to respond to a
future infection from the same pathogen, or to stimulate B
cells</div><div>Cytotoxic T cells use a protein called perforin to make holes in
the cell membrane of other cells/particles of the pathogen, thus destroying
it</div>
What kind of cell does humoral immunity involve? B cells
How does humoral immunity work? When a B cell encounters an antigen that it has
receptors complementary to, the antigen enters the B cell by
endocytosis <div>The B cell processes these antigens and displays them on its
cell membrane</div><div>Stimulated T helper cells bind to the processed antigen,
causing the B cell to become stimulated</div><div>The stimulated B cell divides
rapidly- this is called clonal selection theory, as only B cells that will produce
complementary antibodies divide</div><div>The B cell divides into two kinds of
cell- plasma cells and memory cells</div><div>Plasma cells produce monoclonal
antibodies that are specific to the pathogen- this is the primary
response</div><div>Memory cells stay in the blood and tissue fluid, waiting for re
infection, upon which they rapidly divide in clonal selection theory again for a
rapid immune response- the secondary response </div>
What kind of protein structure do antibodies have? Quaternary structure
What kind of bonds hold together the different polypeptide chains in antibodies?
Disulphide bridges
When antibodies bind to antigens, what is it called? An antibody-antigen
complex
What is the structure of an antibody? """<img src=""""image-
66708641bbe84304f2efe97635abf7340c342f33.png"""">"""
How do antibodies kill pathogens? They cause agglutination of bacterial cells,
meaning phagocytes can engulf them more easily<div>They can mark pathogens for
destruction by phagocytes</div>
What is a monoclonal antibody? One that is specific to a single antigen
