done by: mohammad haitham

Transcription

1 done by: mohammad haitham

2 "Anatomy" and Function of Prokaryotes: The pictures are very important, go back to the slide2! Last lecture we talked about the shape of the bacteria. Now the shape of the bacteria goes under genetic control, genes coded of the shape are presented on the chromosome, so the bacteria does not lose its shape regardless of the reason, coccus continue as a coccus, rod as a rod. Wouldn t be changed! -The basic three shapes of bacteria: 1.spherical coccus (plural:cocci). 2.Rod-shaped bacillus (plural:bacilli). 3.Spiral. There are another shapes of bacteria which is not considered as a basic shape of bacteria, only the three mentioned shapes are basic. -e.g: star shape, a rectangular. They are not very important because it is not pathogenic bacteria and it is kind of Archea (old bacteria) and it is found in salty environment like Dead sea or extreme environment which is suffer form high temperature or pressure. bacteria has many different arrangement: 1) coccusmay arrange in: 1. singlecoccus 2. diplococcus (each 2 toghether) When the single coccus divided, diplococcus is formed. * Bacteria is divided and regenerated by the Binary Fission. 2) Rod bacteria may arrange in : 1. Single rod (single bacillius) 2. Diplobacillius 3. Streptobacilli (they cluster like chain) *Although the Shape is very important, cell wall still more important since the gram stain depends on it. -Usually we do not use gram stain for spiral bacteria because it is already transparent (colorless). -Basically, spiral tests tend to be called serology, which is derived from serum, where serum usually contains anti-bodies, so the reaction that will occur during this test is Antigen-anti-body reaction. الضدمولد *Antigen: مضادةاجسام *Anti-bodies: -Some of the bacteria appears in non-basic shaped like: coccobacili, it also goes under genetic control -Plane of division: A) 1-diplococci

3 2-streptococci which causes tonsillitis. B) Tetrad (not very important in pathogenetic) *About 90% of tonsillitis is caused by streptococcus. Note that those that divide in two planes and remain in groups of four are known as Tetrads. - Those that divide in three planes and remain attached in cubelike groups of eight are called Sarcinae. - Those that divide in multiple planes and form grapelike dusters or broad sheets are called Staphylococci Spiral bacteria : 3 types: 1.vibrios 2.spirilla 3.spirochetes Vibrio. e.g: cholera (yellow fever) Yellow because diarrhea is occurred so that the feces color is yellow. Cholera causes dehydration about (20L) of fluids is lost per day. Spirilla and spirochetes both are helical shape, the difference between them that the spirochetes are flexible while the spirilla is rigid bodies. Spirilla and vibrios move by flagella. * vibrio cholera moves by polar flagella Spirochetes also have flagella but we call it axial filaments occurs between the cell wall and the sheath. Some bacteria presents in Pleomorphic shape which makes the diagnosis process more difficult (more than one shape) also this goes under genetic control. -Bacteria structure: (slide 8 and 9) *All bacteria types contain cell wall and plasma membrane *Some of them contain capsule (capsulated) *Capsulated bacteria more pathogenic than non capsulated because the function of capsulated is to resist phagocytosis so this is one of the main reasons why bacteria escapes from the immune system. *Inclusion body حبيبات may contains lipids, gas,enzymes, it is called granules storage,it can act as storage to store certain nutrient *Chromosome is not inside the nucleus. *Plasmid is also circular bilayers strains with an extra chromosome part and contains genes are not necessary used by the bacteria. *Fimbriae useful attachment. *Flagella for movement. The following things will be discussed later.. -Poly-B-hydroxybuterate source of lipid. Some type of bacteria like microbacteria metabolism its wall contains mycolic acid which it wax material like lipid

4 -cyanophycin (nitrogen granules) bacteria needs it, it is the main source of ATP nucleic acid -Carboxysomes contain enzyme ribulose 1.5 diphosphate carboxylase which is used by the photosynthesis bacteria to fix CO2. -Gas vacuoles(vesicles) contains gas that is useful for buoyancy so if the bacteria needs O2, it will easily float on the surface of the water to take O2. -polyphosphate granules (volutin) or metachromatic granules which is the source of inorganic phosphate on type of bacteria present in it corano bacteria diphtheria (bacteria responsible for diphtheria). -Magnetosomes inclusion serves as a source of iron oxide (Fe304). -Sulfur granules as a source of sulfur. -Ribosome: The dr talked about the ribosome in the previous lecture, I made sure that all the information which was mentioned in this lecture about the ribosome is included in the previous sheet. And it will be discussed later, -Plasma membrane or cytoplasmic membrane: It is composed of lipid bilayer. The head is polar hydrophilic,hydrophilic outside and hydrophobic inside. * Plasma membrane head (phosphateglyceriol), tail (fatty acid) Types of protein in the plasma membrane 1.integral protein,protein inside the plasma membrane. It forms pores-like to arrange the transportation of the materials to and out of the bacteria. -Cell wall: -this is very important part in the bacteria. In addition to giving the cell its shape and protection, it is important in diagnosis since it determines its stain type whether it is positive or negative. *Gram positive (purple) * Gram negative (red) Cell wall gram positive differs from gram negative: Gram positive contains a thick layer of peptidoglycan,also known as murein. -Components of peptidoglycane: one layers of peptidoglycan contains 2 subunits: 1.N-acetylglucosamine 2. N-acetylmuramic acid -Peptidoglycan in gram negative is one single layer while gram(+) approximately 70% of the dry whight of bacteria about 40 layers.

5 Gram negative make up for peptidoglycan with outer membrane,this outer membrane is composed of LPS act as endotoxin. In the gram negative there are 2 spaces one between plasma membrane and peptidoglycan and the other between peptidoglycan and the outer membrene,these 2 spaces known as periplasmic and it contains a gel-like components, and the most important enzymes which the bacteria needs in the metabolism. -To sum up, composition of: Gram positive cell wall: thick layer of peptidoglycan and teichoic acid. *teichoic acid is composed of: glycerol phosphate and ribitolphosohote. -Two types of this acid (slide 15): 1- lippoteichoic acid attached to the plasma membrane. 2- cell wall teichoic acid attached to the peptidoglycan layer The following things will be discussed in the future lectures,, Gram negative cell wall: thin layer of peptidoglycan and the outer membrane (LPS) and the distance between them periplasmic space. *Gram negative: Thin layer of peptidoglycan and outer wall (LPS). This outer membrane importance to the cell is the endotoxin of the gram negative bacteria. #Remember that the LPS is part of the gram negative since the gram positive does not have outer membrane. -There are 2 types of toxin: 1. endotoxin,part of the structure of the bacteria cell wall 2. exotoxin, secreted by extracellular we can collect it, while the endotoxin because it is part of the cell wall we can not collect it before the cell die. (will be discussed later) -LPS is composed of 3 different regions: 1.O polysaccharide (terminal) 2.Core polysaccharide 3.Lipid A Every one of them has function: 1.O polysaccharide : responsible for the antigenicity (act as antigen).

6 *What is the antigen? #Notice that not all the strange bodies are antigen. When antigen enters the body it stimulates the immunity system to produce antibodies. There are conditions of antigen have specific molecular weight, specific complexity -E.coil cause terrible diarrhea. -Core polysaccharide does not have any function. -Lipid A responsible for toxicity. -Now all the diseases which are caused by the gram negative bacteria have the same or similar symptoms while the gram positive does not, why? Because all Gram (-) bacteria have the same structure (all of them have LPS), while Gram (+) does not (each toxin of it has different causes and effects