Lets learn some shit.

My first microbiology exam is TOMORROW and thus, I've decided to do a small thing.

The shit we're learning about in microbio is divided into two main categories...living shit and non-living (infectious agent) shit. 

Living shit falls into two subcategories: Prokarya and Eucarya

Non-Living shit's categories are: Viruses, Viroids, and Prions (the really fucking scary ones)

Eucarya gets people like: Algae, Protozoa, Fungi (yeasts and molds), and Helminths (rounds and shit like that)

Some relative sizes of shit. Viruses are obviously the smallest, maxing out at 100nm (usually less). Bacteria & Archaea are relatively the same size, different things have told me different sizes, but on average of 1-5 or 1-10 micrometers (10^-6). Eukaryotes are bigger at 10-100micrometer cell sizes.

As far as Eukaryotes go, they mostly come single and multicelled with exception of protozoa which are always going to be single-celled organisms. 

These terrifying motherfuckers.

Viruses have DNA, RNA and a protein coat while viroids (mostly infect plants) and have only RNA, no protein coat.

Prions are misfolded proteins and can cause neurodegenerative disease, mostly from eating prion-infected tissue. They're resistant to any possible form of killing, so they're scary as shit.

Some words on bacteria. Since they're prokaryotes (something dealing with pre-real nuclear membrane structure), they have no membrane bound nucleus or organelles. Their cell walls are made out of peptidoglycan (to be discussed later). 

This whole hypo-hyper tonic shit really confused me (and really still kind of does)

Bacteria live in hypotonic environments meaning their insides are hypertonic. Google defines this as "having increased pressure or tone", measuring osmotic pressure. So, they like not having pressure on their outsides, but their insides are pressurized? Things outside of them that can't come in cause pressure. Hypertonic environments will have a lot of crap in them (that's outside the cell), which makes water want to flow out of the cell to try to create equilibrium, which is unfortunate for the cell. The cell membrane ends up getting pulled away from the cell wall, resulting in plasmolysis. 

Just a few words about Archaea. What's crazy is that they're actually evolutionarily closer to us than they are to bacteria. Which I think is nuts. Most of them are extremeophiles, living in the arctic and deep sea vents. Their cells walls don't have the peptidoglycan crap that I'm going to talk about later.

Some staining methods we've done in the lab. Gram stains tell the difference between Gram positive cells and gram negative cells. This deals with how much peptidoglycan is in the cell walls, whether or not that cell wall will retain the dye. Crystal violet and iodine form a complex in the cell that when you decolorize with alcohol, doesn't wash out of gram positive cells. (These will be purple when you look at them under a microscope). Gram negative cells have a thin layer of peptidogylcan in their cell walls, and the decolorizer damages their outer membranes (not present in Gram+ cells). After you decolorize the G- cells, you counter-stain with safranin, making your G- cells look red/pink. 

The other stain we did in lab was the Acid Fast Stain which applies to microorganisms that don't take up dyes like G-/G+. A type of these are Mycobacteria...scary shit that causes TB and leprosy. The cell wall in these things have lots of waxy mycolic acids (which is why they don't take up dyes)

A HORRIBLE rendering of a G+ cell wall. The cell wall is on the outside, with techoic acids in it. They give the bacteria a negative exterior charge, sticking out above the peptidoglycan later (which, remember, is super thick in G+ cells). There's also lipotechoic acids somewhere in the cytoplasmic membrane (made of a lipid bilayer...my favorite thing).

If my "art" couldn't get any worse...it just did. Here's a G- cell wall structure. The cell wall has only a thin peptidoglycan layer but has a sick outer membrane (which is not present in G+ cells). The outer membrane has lipids and porin proteins inside of it and lipopolysaccharide (an endotoxin) on the outside of it. The LPS is what our immune system sees, and recognizes foreign crap. 

The LPS is made out of Lipid A and O Antigen. O Antigen is directed outside of the membrane, with Lipid A anchoring the LPS into the lipid bilayer... Lipid A is toxic. 

The outer membrane is why G- cells are less sensitive to antimicrobial things than G+ cells. 

I said I would talk about Peptidoglycan and now I will.

It's basically repeating units of N-acetylmuramic acids (NAM) and N-acetylglucosamine (NAG). Only bacterial cells have peptidoglycan in their cell walls. PEPGLY determines the strength of the cell wall...In G+ bacteria, there are peptide interbridges. 

Here's some interesting (and frightening) bacteria we have discussed thus far...

Yersinia pestis: I still remember this from a class called Marvelous Microbes I took at Rutgers. This shit is the black plague (from the 1300s).

Vibrio chloera: The cholera outbreak that happened in the 1850's in London, resulting from a contaminated water pump. Vibrio refers to a "curved bacillus" shape - basically a curvy rod bacterium. It's salt tolerant, which is scary as fuck, but luckily, not all Vibrio are human pathogens. 

Treponema pallidum: This shit is a pathogenic spirochete, basically an elongated curvy twisting rod like thing. Longer and twistier than a spirillum. This shit causes syphilis and can't be cultivated in the lab.

Neisseria gonorrhoeae: A G- diplococcus (another bacterial shape), which has the power to modify its lipopolysaccharide...this is really scary because that means it can keep "changing it's jacket" to confuse our immune systems. 

 Staphylococcus aureus and Staphylococcus epidermis: Two very different things. S. aureaus causes a whole HOST of terrifying shit from endocarditis to your SKIN FALLING OFF, depending on the site of infection and the strain it is. It affects about 25-30% of people...It's G+ cocci growing in grapelike clusters. Terrifyingly delicious. S. epidermis, on the other hand is part of your skin's normal microflora. Obviously, also a G+ coccus structure.

Streptococcus pyogenes: G+ bacteria causing anything from strep throat to, again, your skin falling off (impetigo?), and toxic shock syndrome...also necrotizing fasciitis. Do. Not. Want.

Bacillus and Clostridium: are two types of bacteria that make endospores, which can survive in high heat, high pressure, unfavorable conditions by slowing down or discontinuing their metabolic processes. B. anthracis is a G+ bacterium causing ANTHRAX while C. tetani's spores like to live in rust...giving me tetanus when I climb fences. 

Deinococcus radiodurans: is a really tough bacteria that doesn't form endospores but relies on a really good DNA repair mechanism. 

I have to go get ready for class now, so we'll continue this later tonight, after lab...