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Revision Themed structured questions - Coggle Diagram
Revision
Themed structured questions
Example 1
Innate immunity
Name 5 different soluble proteins that prevent infection and explain their function
Lysozyme - enzymatically breaks down bacterial cells
Defensins - small antimicrobial peptides produced by neutrophils
Surfactants - blocks peptides produced by neutrophils
C reactive protein acts as opsonin
Mannose-binding lectin - act as opsonin
Identify the different cell types that are involved in phagocytosis and how these cells recognise microbial pathogens
Monocytes/Macrophages
Neutrophils
Dendritic cells
These cells have Toll-like receptors
Recognise pathogen associated molecular patterns that are repeated and common and vital to many microbes
Briefly describe the inflammatory response
Following tissue injury or infection, mast cells produce mediators
These make capillaries leaky and dilated
This allows plasma proteins and cells to enter tissue
Thus fighting injury/infection
Identify 2 mechanisms by which microbes invade the innate response
Make a capsular polysaccharide that inhibits phagocytosis
Make inhibitors that block convertases
Name the 3 complement pathways and briefly describe three main functions of complement
Classical pathway
Alternate pathway
Mannose-binding lectin pathway
Acts as an opsonin to coat microbes and promote phagocytosis by phagocytes
Are chemo-attractants for neutrophils and macrophages
Complement proteins make a membrane attack and complex that punches holes in the microbial membranes
Example 2
Antibody
Describe the structure of an Immunoglobulin antibody molecule with a diagram
Monomer
4 polypeptide chains
Disulphide bonds
2 light chains - 25kDa
2 heavy chains - 50kDa
heavy chains of different classes differ
symmetrical molecule
2 identical Fab regions :
2 antigen binding sites
single fc region
Describe four main differences in the structure of IgA, IgE, IgM and IgG
IgA
IgA1
Monomer
2 light chains
2 heavy chains
IgA2
Dimer
two Ig molecules joined together by J-chain
additional protein - 'secretory piece'
IgM
Pentamer
5 units joined together by disulphide links between fc regions
Additional protein J chain
IgG
Monomer
4 polypeptide chains held by disulphide bonds
IgE
Monomer
2H and 2L chains
4 C domains
IgM has ten antigen binding sites per molecule, whereas IgG only has two.
Would it bind five times as many antigenic sites as IgG?
IgG = 2 binding sites = 2 Ag
IgM = 10 binding sites 10 Ags
IgM can bind more than 5 antigen molecules but perhaps not five times more
conformational restraints - flexibility of hinge region
steric hindrance - congestion caused by Ag molecules
You have identified a B cell lymphoma that has made non productive rearrangement for both heavy chain alleles. What is the arrangement of its light chain DNA?
Why?
the kappa chain DNA must have the germ line configuration because a productive heavy chain rearrangement must occur before the light chain kappa DNA can begin to rearrange
Describe four human diseases or conditions where antibodies are being developed or used as treatment
Antibodies are used in the treatment of:
snake bites
neutralisation of snake venom
viral infections (antibody infusion for covid19)
neutralisation of virus
cancer
antibody dependent cellular cytotoxicity
Example 3
Cell mediated immunity
Describe the developmental journey of T lymphocytes
T cell precursors migrate from the bone marrow to the thymus where they mature
Mature T cells exit the thymus, enter the circulation and travel through secondary lymphoid organs
Describe the structure and functions of MHC class I and class II molecules
MHC I
α chain with 3 domains α1, 2 and 3
peptide binding site for foreign antigens between outermost domains
α1 and 2 are polymorphic
MHC II
Peptide binding site for foreign antigens between outermost domains
α and beta chains with 2 domains each α1, 2, β1 and 2
α1 and β1 are polymorphic
What lymphocyte cell types recognise MHC class I and class II molecules and how do they recognise them
Cytotoxic T cell
class I MHC protein
Helper T cell
class II MHC protein
Name the five different types of effector CD4+ T helper cells and briefly describe their functions
TH1 CD4+ cells
Defence against intracellular microbes
Macrophage activation
TH2 CD4+ cells
Defence against parasitic worms
TH17 CD4+ cells
Neutrophil activation
Monocytic inflammation
Tfh CD4+ cells
B cell differentiation
Antibody production
T reg CD4+ cells
Suppress immune response
Describe how cytotoxic T lymphocyte kills virally infected cell
Can recognise antigens on infected cells, bind to antigen and induce apoptosis