Immune system

• Active immunity - resistance to a disease resulting from the activities of an individuals own immune system whereby an antigen induces plasma cells to produce antibodies
• Antibiotic - a substance produced by living organisms that can destroy or inhibit the growth of microorganisms
• B cells (B lymphocytes) - type of white blood cell that is produced and matures within the bone marrow (humoral) - clones = memory cells and plasma cells which produce antibodies
• Antibodies - respond to foreign antigens
• Antigens - non-self foreign protein that triggers an immune response by lymphocytes
• Phagocyte - type of white blood cell that carries out phagocytosis it's found in the blood and in tissues
• T cells - lymphocytes that ate matured in the thymus gland (cellular)has receptor proteins on its surface that bind to complementary antigens presented to it by phagocytes stimulates other Tc cells
• Helper t cells - release chemical signals that activate/ stimulates phagocytes
• Cytotoxic t cells - kills abnormal/foreign cells by releasing the enzyme perofin which makes the host cell freely permeable
• Primary response - symptoms show and it's slow
• Secondary response - involves memory cells making it faster
• Active immunity - takes a while for protection to develop can be natural (immunity after contracting a disease) or artificial (vaccination)
• Passive immunity - immediate protection with no memory cells. The protection is short term and the antibodies are broken down. Natural (baby- breastmilk/placenta) or artificial (tetanus jab)
• Herd immunity - 90% of population vaccinated which protects those that have it but also those that haven't had it as it reduces the occurrence of the disease/those who have been vaccinated don't show symptoms
• Antigenic variation - antigens present on the virus mutate and are no longer complementary to the antibodies so not antigen-antibody complex can be formed so the primary response has to happen again
• Phagocytosis - 1- phagocyte attracted to the pathogen via it's chemical products the phagocyte then recognises the pathogens antigen as non-self and causes the phagocyte to bind to the pathogen 2- phagocyte engulfs the pathogen and seals it into a phagosome
• Phagocytosis (2) - 3-the lysosome fuses with the phagosome and releases lysozymes which destroys the pathogen 4- the soluble products from the breakdown are absorbed into cytoplasm the antigens from the pathogen are then expressed on the phagocytes cell membrane turning it into an APC
• ELISA test - Enzyme-Linked ImmunoSorbant Assay
• ELISA test - direct test = uses only one antibody 1- add the sample containing the target protein 2- add antibody specific to target protein then wash out to remove any unbound antibodies add a solution containing substrate to the well the enzyme attached to the antibody and will act on the substrate causing a colour change the indirect test = uses two antibodies
• Monoclonal antibodies uses - diagnoses of disease(bind to specific cells to identify infected cells), treatment of disease (specific cells - bringing therapeutic drugs with them), pregnancy testing (pregnancy hormone) and detecting certain cancers
• HIV replication - 1- attachment proteins on the HIV attach to receptors on a helper T cell 2- HIV releases it's RNA into the helper T cell 3- reverse transcriptase concerts this RNA into DNA 4- the viral DNA is inserted into the helper T cells genome
• HIV replication (2) 5- the helper T cells DNA is translated to make viral proteins 6- the proteins are used to assemble new HIV particles 7- fully assembled HIV particles bud off the cell in order to infect other cells killing the T cell
• HIV structure - genetic material= 2 single strands of RNA - enzymes= reverse transcriptase - capsid= layer of protein molecules that surrounds and protects genetic material - envelope= outer layer of phospholipids - glycoproteins= also known as attachment proteins
• Antibody structure - 2 short light chains each individually bonded to long heavy chains which are joined together by a disulfide bridge. All antibodies have the same constant region allowing them to bond to receptor of self cells by they have a unique variable region that's complementary to an antigen
• B lymphocytes - B cells mature in bone marrow, circulates through bloodstream and lymphatic vessels, binds to antigens using their surface immunoglobulin, when activated undergo clonal expansion and differentiate into plasma cells