Lecture 7, 9-14-07 - Cell structure, Gram(+)(-)

Audio for today's lecture is available here.

• Linnaeus – one of Sweden’s top biologist. From Uppsala.
• First one to try and do classification – genus, species.
• More info about Linnaeus here.
  
• Typically use common names for viruses despite available classification system ex. HIV Epstein Bar Virus.
• Silvilvice and holmes
• Child bed fever a.k.a. puerperal fever caused by Streptococcus pyogenes (same thing that causes strep sore throat)
• Easily transferred diseases in the hospital due to doctors not disinfecting in between doing autopsies and caring for patients.
• General differences between Gram Positive and Gram Negative
• If you put stains in the media gram positive doesn’t grow, they are susceptible to dye in the media. Gram (-) grow fine.
• Sensitivity to lysozyme (Fleming discovered it).
• Lysosyme with a gram (+) all of the cell wall is removed leaving you with a protoplast. In a gram (-) it only takes out part of the cell wall. Lysosyme also known as a bacteria living enzyme. This experiment proved the difference between gram (+) and gram (-)
• Structural forms
• If you are looking at a round structure or spore forming rods it is probably gram (+).
• Non spore forming rods is gram(-). If you every run into a spiral (like syphilis) it will be gram (-)
• Toxins –
• not all gram (+) have exo-toxins. These ones do however: Botulism, Tetanus, diptheria.
• All gram (-) have an endo toxin which is part of the cell wall. Erwinia cartovora – classical plant pathogen. Find it on lettuce – causes spoilage.
• Septic shock a.k.a. Endotoxin shock - means a gram (-) in their blood.

• Erilick
• Salverzan – a magic bullet that took out psyphilis
• We have some leprosy in US. (Texas, Louisiana) Nearly 12 million in the world. Can’t grow leprosy, difficult to study.
• Acid Fast stain is used to diagnose TB and leprosy
• These two organisms have a very unique lipid that prevents them from staining well. You have to force the stain in by steaming it. Acid alcohol decolorizes it and counter stain it with blue. If it is acid fast it is stained red. All the others are blue. Acid fast organisms are usually in the genus mycobacterium.
• Giemsa - Intracellular organism staining – OIP’s
• Example of OIP’s - Chlamydia, rickettsia, viruses

• Staining works because of a charge - charge interaction. Organisms usually have a net negative charge. The dies have a positive charge.

• Prokaryotic Structures
• Cellular shapes and cellular arrangements
• Cocci: micrococcus, streptococcus
• Rods (more rods than anything else): bacillis subtilis, e. coli
• Spiral: borrelia, treponema
• Pleomorphic – many shapes (mycoplasma)
• Cellular arrangement: This was taught using an illustration in class. I will do my best to reproduce it here but some of the details could be “lost in translation”
• Coccus model used to illustrate cellular arrangement. A coccus divided in two by Binary fission (in one dimension) gives you diplococcus. Example of diploccoccus is niceria and Streptococcus pnemonea. If you do binary fission again you get a chain. This is typical of certain streptococci such as mutans, pyogenes, saliveria, lactis (sour cream).
• Division in two dimensions – ?Petrats?. Some micrococci are known for ?petrats?. (not sure if this is the word)
• 3 dimensions – grape like structure – stapholococci. Another formation is cuboidal cocci. You can also find some micrococci in this arrangement.
  
• Rods can be arranged as palisades or Chinese letters. Corynebacteria all have palisade arrangment. Diptheria is arranged in this way.
• Prokaryotic Cell Structure
• Many gram (-)’s are rod shaped.
• 1 to 2 micrometers is the size of an e. coli.
• What was the first organism sequenced (genome)? I found the answer here
• Our chromosomes are linear. Most prokaryotic cells have circular chromosomes.
• Rhibozomes – protein synthesis (translation)
• S value: 70 s in e. coli composed of 50 and 30
• S value: 80 s in humans composed of 60 and 40
• Prokaryotic granules are usually intracellular reserves. If e. coli makes too much of something it puts it into granules to use later. We do the same thing – glycogen granules
• Corynebacteria have volutin granules or metotomatic granules which is phosphorus storage.
• Sulfer granules are usually stored only in photosynthetic bacteria example: Chromatium okeii
• All Prakaryotic have nucleodes, rhibozomes and cytoplasm which supports the cell and filled full of water which they need to survive. Biological reactions don’t go on without water.
• “Endo”(within)spores – formed inside the cell. Free spores are the most resistant structure we know of. Bacteria have spores as a survival mechanism.
• Only some have spores: ex. bacillis and clostridium (obligate anaerobe)
• Spores have a unique substance called dipicolinic acid – lots of calcium (provides structure). They are also unique as they have very little water. This slows things down. We break down substances by a process called hydrolysis.