Immunity

• What is the definition of an Antigen?

  cell-surface molecule which stimulates an immune response
• What are the two types Defence Mechanisms?

  non-specific & specific
• What are features of non-specific Defence Mechanisms?

  does not recognise between pathogens & response is immediate
• What are features of specific Defence Mechanisms?

  distinguishes between different pathogens & less rapid responses
• What are features of a phagocyte?

  white blood cell & large & has a nucleus & vesicles
• What is the definition of Pathogen?

  any organism which can cause disease
• Where do B cells mature?

  bone marrow
• Where do T cells mature?

  thymus glandes
• What is the definition of Cytoxic Cells?

  produce protein perforin & is freely permeable to all substances causing cells to die as a result
• What is the definition of Perforin in Cytoxic Cells?

  makes holes in cell surface membrane
• What is the first step of Phagocytosis?

  phagocytes attracted to pathogen by chemoattractant of pathogen
• What is the second step of Phagocytosis?

  phagocytes have several receptors on its cell surface that attach to chemicals on the surface of pathogens
• What is the third step of Phagocytosis?

  lysosomes within phagocytes migrates towards the phagosome by engulfing the bacterium
• What is the fourth step of Phagocytosis?

  lysosomes release lysozyme into phagosomes where they hydrolyse bacterium
• What is the fifth step of Phagocytosis?

  hydrolysis products of bacterium are absorbed by phagocyte
• What does the structure of Antibodies contain?

  glycoproteins & 4 polypeptide chains & antigen antibody complex & chains together by disulphide bridges
• What is the definition of Agglutination?

  stick together so are unable to move
• What are 4 key points of H.I.V?

  .viral RNA converted into DNA by reverse transcriptase,

  .viral DNA inserted into T helper cells DNA,

  .transcriptase of DNA into mRNA,

  .translation of MRNA into amino acids
• What is the first step of H.I.V Replication?

  glycoproteins molecule on virus surfaces bind to CD4 receptors on the surface of T helper cells & allow envelope surrounding virus to fuse with the T helper cell
• What is the second step of H.I.V Replication?

  capsid released into cell where it releases the RNA and reverse transcription
• What is the third step of H.I.V Replication?

  reverse transcriptase is used to make DNA from H.I.V RNA template
• What is the fourth step of H.I.V Replication?

  DNA inserted into the cells DNA, this gets replicated when the cell replicates
• What is the fifth step of H.I.V Replication?

  DNA used to make H.I.V RNA and proteins at host ribosomes
• What is the sixth step of H.I.V Replication?

  virus particles are assembled which bud off from the cell membrane and go on to infect other cells