Neisseria Meningitidis is A Gram-negative Diplococcus That Is One Of The Most Common Causes Of Bacterial

Leukocyes (WBCs) & Defence

A summary

Neutrophils -  non-specific defence against bacteria and fungi

Eosinophils -Defence against parasites; dampen allergic response

Basophils  - Anaphylactic & inflammation response

Monocytes - Mature into macrophages, engulf foreign substances;  remove aged RBCs and other debris

Lymphocyes - Recognise antigens, various roles

how am i always so behind in my work ??

(i do know the answer to this, it’s called procrastination lmao)

Staphylococcus epidermidis is a coagulase negative, Gram-positive coccus. The organism uses sophisticated regulatory networks to adapt its metabolism to suit varying environmental conditions. S. epidermidis relies on biofilm formation to protect cells from the host immune system and other anti-microbial molecules.

Antibodies (Human)

The ‘foot’ (bottom) of the antibody is known as the Fc fragment - binds to cells, binds to complement = effector function (kills or removes antigen)

The top (antigen binding) is the Fab fragment

Chains are held together with disulphide binds

Associated molecules allow intracellular signalling 

Normally 3X constant heavy chain domains per chain and a hinge region (except μ and ε which have 4 and no hinge region)

Classes of Immunoglobulins

The five primary classes of immunoglobulins are IgG, IgM, IgA, IgD and IgE,  distinguished by the type of heavy chain found in the molecule. 

IgG - gamma-chains

IgMs - mu-chains

IgAs - alpha-chains

IgEs - epsilon-chains

IgDs - delta-chains.

Differences in heavy chain polypeptides allow different types of immune responses. The differences are found primarily in the Fc fragment. There are only two main types of light chains: kappa (κ) and lambda (λ), and any antibody can have any combination of these 2 (variation).

IgG 

monomer

Gamma chains

70-85% of Ig in human serum. 

secondary immune response 

only class that can cross the placenta - protection of the newborn during first 6 months of life

principle antibody used in immunological research and clinical diagnostics

21 day half life

Hinge region (allows it to make Y and T shapes - increasing chance of being able to bind to more than one site)

Fc strongly binds to Fcγ receptor on phagocyte - opsono-phagocytosis

Activates complement pathway

IgM

Serum = pentamer 

Primary immune responses - first Ig to be synthesised

complement fixing 

10% of serum Ig 

also expressed on the plasma membrane of B lymphocytes as a monomer - B cell antigen receptor

H chains each contain an additional hydrophobic domain for anchoring in the membrane

Monomers are bound together by disulfide bonds and a joining (J) chain.

Each of the five monomers = two light chains (either kappa or lambda) and two mu heavy chains.

heavy chain = one variable and four constant regions (no hinge region)

can cause cell agglutination as a result of recognition of epitopes on invading microorganisms. This antibody-antigen immune complex is then destroyed by complement fixation or receptor mediated endocytosis by macrophages.

In humans there are four subclasses of IgG: IgG1, IgG2, IgG3 and IgG4. IgG1 and IgG3 activate complement.

IgD 

B cell receptor

<1% of blood serum Ig

has tail pieces that anchor it across B cell membrane

forms an antigen specific receptor on mature B cells - consequently has no known effector function (don’t kill antigens, purely a receptor) (IgM as a monomer can also do this)

IgE 

Extra rigid central domain

has the most carbohydrates

IgE primarily defends against parasitic invasion and is responsible for allergic reactions.

basophils and tissue mast cells express very high affinity Fc receptors for IgE - mast cells then release histamine

so high that almost all IgE is bound

sensitizes (activates) mucosal cells and tissues 

protects against helminth parasites

IgE’s main purpose is to protect against parasites but due to improved sanitation these are no longer a prevalent issue across most of the world. Consequently it is thought that they become over activated and over sensitive while looking for parasites and start reacting to eg pollen and causing allergies.

IgA

Exists in serum in both monomeric (IgA1) and dimeric (IgA2) forms (dimeric when 2 Fcs bind via secretory complex)

15% of the total serum Ig.

4-7 day half life

Secretory IgA2 (dimer) = primary defense against some local infections

Secreted as a dimer in mucous (e.g., saliva, tears)

prevents passage of foreign substances into the circulatory system

Isotype: class of antibody (IgD, IgM etc)

Allotype: person specific alleles 

Idiotype: (hyper) variable region - antibody specificity 

Bacterial strain X is resistant to Ampicillin and sensitive to Gentamycin. Bacterial strain Y is resistane to gentamycin and sensitive to Ampicillin. Bacterial strain X and Y are grown in mixed culture in medium without antibiotics, then the culture is plated on medium containing both ampicillin…

Yesterday’s notes featuring actual winter sunshine!!

This one’s about bugs

Guys, I love ID. I really hope I get to do an ID rotation on Medicine. If you remember, I once posted the mnemonic I swear by for viruses. Well here is the bacteria counterpart. Also your micro mantra should be: sketchy is life. Love Andrew like I do (this part’s not the mantra, I just love Andrew).

Let me know if you have any questions or need clarification. This is a perfect example of a “not aesthetically pleasing tumblr study post” because sometimes your handwriting sucks and you aint got that kinda time in my life for pretty arrows and banners and I just wanna finish this shit so I can leave the library when will Step 1 even be over why is this my liiiiiife

Microbiology Genetics

Transformation

Conjugation:  F+ –> F-  &  Hfr –> F-

Transposition 

Transduction: Generalized   &  Specialized