3.2.4 Cell Recognition And Immune System Flashcards
What are the 2 types of defence?
Non- specific:
Response is immediate and same for all pathogens
Examples- physical barriers(skin), phagocytosis
Specific :
Response is slower and specific for each pathogen
Examples- cell meditated cells(T lymphocytes), humoral response(B lymphocytes)
Differences in non-specific to specific response?
Specific targets specific pathogens and is slower (T+B lymphocytes)
What is a self antigen?
Antigen on your own cells
What is an antigen?
Any party of an organism or substance that is recognised as non-self(foreign) by the immune system and stimulates the immune system
What are molecules that would trigger an immune responses?
Pathogen(HIV)
Non-self material(protein on foreign cell)
Cancerous cell antigens
Toxins
Explain phagocytosis
Phagocyte move towards pathogen (it’s attracted to the pathogens chemicals)
Phagocyte recognises the antigens on the pathogen and binds to it
Phagocyte engulfs pathogen in a phagocytic vesicle
Lysosome(containing lysozyme) fuses with pathogen vesicle. Pathogen is hydrolysed
Phagocyte presents the pathogens antigens to active other immune cells
(Becomes an APC - antigen presenting cell)
Differences between Band T lymphocytes?
B lymphocytes mature in the bone marrow and are part of the humoral response which produces antibodies
T lymphocytes mature in the thymus glands and are part of cell mediated response
What does a helper T cell do after finding an APC?
A helper T cell with compliments shaped receptors bind to the antigen
The helper T cell is activated and divides by mitosis
After a T cell divides what happens?
Some develop into memory T cells
Some stimulate phagocytes to engulf pathogens
Some work as helper T cells that stimulate B cells to divide
Some activate cytotoxic T cells
ALL CLONES HAVE THE SAME RECEPTORS
What do cytotoxic cells do?
Destroy infected cells by punching holes in the cell surface membrane using a protein called perforin(drains the cytoplasm)
What is an antibody?
A protein produced by the immune system (B cell) in response to the presence of the appropriate antigen
Describe and antibody
Has 2 antigen binding sites in the tips of the Y
Variable region just below the binding site
The light chains(short one) is one of the angled lines (/)
There is a disulphide bonds between the 2 straight lines (|-|) and each of those straight lines are heavy chain
Receptor binding site at the bottom
From the bottom to the variable region is the constant region
Does an antibody have a Quaternary structure?
What type of molecule is an antibody?
Yes and it’s made by more than one polypeptide chains
Globular proteins called immunoglobulins
How do antibodies bind to antigens?
The antigen binding site has a compliments shape to a specific antigen. They bind to form an antibody antigen complex
How are antibody’s prepared for destruction?
3 ways:
1) agglutination- clumping together of bacteria so phagocytes can easily engulf them
2) attach to bacteria cells and act as marks for phagocytes to engulf cells
3) neutralisation binding to critical parts of the pathogen preventing functioning
