Section 2 - Cell recognition and the immune system Flashcards
How can tumour cells be destroyed in the immune system?
It is a foreign antigen
T-Cells will bind to faulty foreign protein
T-Cells will stimulate clonal selection of B cells
Release of antibodies against faulty protein
What is an antigen?
Cell-surface molecule which stimulates an immune response
What 4 things do protein molecules allows the immune system to identify?
Pathogens
Abnormal body cells
Non-self material
Toxins
What are the 2 types of white blood cell?
Phagocytes
Lymphocytes
What are phagocytes?
Ingest and destroy the pathogen by phagocytosis before it causes harm
What are the 2 types of lymphocyte?
B lymphocytes: associated with humoral immunity
(antibodies)
T lymphocytes: associated with cell-mediated immunity
(body cells)
What is the process of phagocytosis?
- Phagocyte engulf pathogens with any foreign antigen
- Lysosomes fuse with the phagosome releasing the lysosome onto the pathogen
- The lysozyme hydrolyses the pathogen
- Some of the antigens from the pathogen are represented on the surface of the phagocyte.
It becomes an antigen presenting cell.
What are the 3 types of T cells associated with the cell-mediated response?
Helper T cells - activate phagocytes, B cells, Tc cells
Cytotoxic T cells- destroys infected body cells
Memory T cells- provide long term immunity
What are 2 differences between a specific and non-specific defence mechanism?
Specific mechanism: distinguishes between different pathogens but responds more slowly
Non-specific: treats all pathogens, responds more rapidly
Why does it take the body’s immune system a couple of days to control a pathogen after it gains entry?
Lymphocytes need to build up their number
What is the process of the cell-mediated response?
- Receptors on a specific helper T cell bind to an antigen presenting cell
- Attachment activates T cell to divide by mitosis forming clone of genetically identical cells
- Clones T cells develop into memory cells, stimulate phagocytes, stimulate B cells and activate Tc cells
How do cytotoxic T cells kill infected cells?
Protein is produced called perforin
Makes holes in cell-surface membrane
membrane becomes freely permeable to all substances and dies
What are 2 similarities between T cells and B cells?
Both are types of white blood cell
Have a role in immunity
Produced from stem cells
What are 2 differences between T cells and B cells?
T cells mature in thymus gland
B cells mature in bone marrow
T cells involved in cell-mediated immunity
B cells involved in humoral immunity
What is the humoral response controlled by?
B-lymphocytes
What is the role of plasma cells?
To secrete antibodies
What are memory cells responsible for?
The secondary immune response
What is the process of the humoral response?
- Surface antigens are taken up by a B cell and placed on B-cell surface
- Helper T cells attach to antigens activating B cell which divide by mitosis to give a clone of plasma cells
- Cloned plasma cells produce specific antibody
- Antibody attaches to antigen on the pathogen and destroys them
- Some B cells develop into memory cells
What 3 organelles would you expect to find in large quantities in plasma cells that produce 2000 protein antibodies each second?
Rough endoplasmic reticulum- to make and transport proteins
Golgi apparatus- to sort and process proteins
Mitochondria- to release the energy needed for such antibody production
What are antibodies?
Proteins with specific binding sites synthesised by B cells.
What is the structure of an anitbody?
4 polypeptide chains (2x heavy, 2x light)
Binding site: binds to complementary antigen
Disulphide bridge: holds antibody together
Constant region: attaches to phagocyte
Hinge region: movement, improves efficiency
How do antibodies lead to the destruction of a pathogen?
Formation of antigen-antibody complex results in agglutination which enhances phagocytosis
What are monoclonal antibodies?
Antibodies produced from a single clone of B cells.