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black and white checklist for sketchy micro

Archaea

Archaeans are single-celled and join bacteria to make up the Prokaryotes.  The Archaea classification is a very recent discovery, due to the similarities in appearance and behaviour to bacteria they weren’t separated until the late 1970′s. They mostly live in extreme environments and can be sub grouped: 

Methanogens - produce methane gas as a waste product of their “digestion,” or process of making energy.

Halophiles - live in salty environments.

Thermophiles - live at extremely hot temperatures.

Psychrophiles — those that live at unusually cold temperatures.

Like bacteria, archaea lack a true nucleus. Both bacteria and archaea usually have one DNA molecule suspended in the cell’s cytoplasm contained within a cell membrane. Most, but not all, have a tough, rigid outer cell wall.

use a variety of substances for energy, including hydrogen gas, carbon dioxide and sulfur. 

many archaea thrive in conditions mimicking those found more than 3.5 billion years ago. [eg oceans that regularly reached boiling point — an extreme condition not unlike the hydrothermal vents and sulfuric waters where archaea are found today]

April Background

I created this new background for April! A reminder to all the great girls out there who are awesome human beings!

For a high quality foto, check out the link in my previous post!

Eukaryotes of microbiology

What is Acute or Subacute Bacterial Endocarditis?

Acute or Subacute Bacterial Endocarditis is an infection of the heart’s endocardium. The endocardium is the inner lining of the heart muscle, which also covers the heart valves. Bacterial Endocarditis can damage or even destroy your heart valves. The difference between acute and subacute bacterial endocarditis is acute bacterial endocarditis is a sudden onset, whereas subacute bacterial endocarditis is a gradual onset.

Acute endocarditis most often occurs when an aggressive species of skin bacteria, especially a staphylococcus (staph), enters the bloodstream and attacks a normal, undamaged heart valve. Once staph bacteria begin to multiply inside the heart, they may send small clumps of bacteria called septic emboli into the bloodstream to spread the infection to other organs, especially to the kidneys, lungs and brain. Intravenous (IV) drug users are at very high risk of acute endocarditis, because numerous needle punctures give aggressive staph bacteria many opportunities to enter the blood.If untreated, this form of endocarditis can be fatal in less than six weeks.

Subacute endocarditis is caused by one of the viridans group of streptococci (Streptococcus sanguis, mutans, mitis or milleri) that normally live in the mouth and throat. Streptococcus bovis or Streptococcus equinus also can cause subacute endocarditis, typically in patients who have some form of gastrointestinal cancer, usually colon cancer. Subacute endocarditis tends to involve heart valves that already are damaged in some way, and it usually is less likely to cause septic emboli than acute endocarditis. If untreated, subacute bacterial endocarditis can worsen for as long as one year before it is fatal.

Cysteine Growth Requirements

MICROBIOLOGY MNEMONIC

BoyFriend Lost Penis

B rucella

F rancisella

L egionella

P asteurella

or….

The four sisters “Ella” worship in the “cystein” chapel

Brucella

Francisella

Legionella

Pasteurella

My assistant

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 

This bedroom is soooo pretty, this colour palette is everything.