Presentation on theme: "Bacterial Morphology Arrangement 1. Bacilli a.Streptobacilli b. Bacilli 2. Cocci a. Cocci b. Doplococci c. Streptococci d. Staphylococci e. Sarcina( 3D."— Presentation transcript:
Bacterial Morphology Arrangement 1. Bacilli a.Streptobacilli b. Bacilli 2. Cocci a. Cocci b. Doplococci c. Streptococci d. Staphylococci e. Sarcina( 3D ) f. Gaffkya( 2D )
Common Shapes & Arrangement
Bacterial morphologies (1)
Bacterial morphologies (2)
Bacterial morphologies (3)
Bacterial Morphology Arrangement 3 Spirl a. Vibrio b. Spirillum c. Spirochete
Bacterial morphologies (4)
Bacterial Cell Structures & Functions
Size relationships among prokaryotes
Bacterial Cell Structure Appendages - fdlagella, pili or fimbriae Surface layers - capsule, cell wall, cell membrane Cytoplasm - nuclear material, ribosome, mesosome, inclusions etc. Special structure - endospore
Bacterial Cell Structure
Appendages 1. flagella Some rods and spiral form have this. a). function: motility b). origin : cell membrane flagella attach to the cell by hook and basal body which consists of set(s) of rings and rods Gram - : 2 sets of ring and rods, L, P, S, M rings and rods e.g. E. coli Gram + : S, M rings and rods e.g. B. megaterium
Organ of bacterial locomotion
Structure of the flagellum
Flagella movement (1)
Flagella movement (2)
Flagella movement (3)
b).Origin (continued) – The structure of the bacterial flagella allows it to spin like a propeller and thereby propel the bacterial cell; clockwise or counter clockwise ( Eucaryotic, wave like motion. – Bacterial flagella provides the bacterium with mechanism for swimming toward or away from chemical stimuli, a behavior is knows as CHEMOTAXIX, chemosenors in the cell envelope can detect certain chemicals and signal the flagella to respond.
c). position monotrichous lophotrichous peritrichous d). structure protein in nature: subunit flagellin
2. Pili or Fimbriae Shorter than flagella and straighter, smaller. Only on some gram- bacteria. a). function: adhere. One of the invasive mechanism on bacteria. Some pathogens cause diseases due to this. If mutant (fimbriae) not virulent. Prevent phagocytosis.
pili - sex factor. If they make pili, they are + or donors of F factor. It is necessary for bacterial conjugation resulting in the transfer of DNA from one cell to another. It have been implicated in the ability of bacteria to recognize specific receptor sites on the host cell membrane. In addition, number of bacteria virus infect only those bacteria have F pilus.
b). Origin: Cell membrane c). Position: common pili, numerous over the cell, usually called fimbriae sex pile, 1-4/cell d). Structure: composed of proteins which can be dissociated into smaller unit Pilin. It belongs to a class of protein Lectin which bond to cell surface polysaccharide.
II. CELL SURFACE LAYER 1. Capsule or slime layer Many bacteria are able to secrete material that adheres to the bacterial cell but is actually external to the cell. It consists of polypeptide and polysaccharide on bacilli. Most of them have only polysaccharide. It is a protective layer that resists host phagocytosis. Medically important.
2. Bacterial Cell Wall General structure: mucopolysaccharide i.e. peptidoglycan. It is made by N- acetylglucosamine and N-acetylmuramic acid. tetrapeptide ( L-alanine- isoglutamine-lysine- alanine) is attached. The entire cell wall structure is cross linked by covalent bonds. This provide the rigidity necessary to maintain the integrity of the cell. N-acetylmuramic acid is unique to prokaryotic cell.
Cell walls of bacteria (2)
Cell walls of bacteria (3)
Cell walls of bacteria (4)
Cell walls of bacteria (1)
Structure of peptidoglycan (1)
Structure of peptidoglycan (2)
( a). Gram positive bacterial cell wall Thick peptidoglycan layer pentaglycin cross linkage. Teichoic acid: ribitol TA & glycerol TA Some have peptioglycan teichoic acid. All have lipoteichoic acid.
Function of TA: * Antigenic determinant * Participate in the supply of Mg to the cell by binding Mg++ * regulate normal cell division. For most part, protein is not found as a constituent of the G+ cell wall except M protein on group streptococci
Structure of the Gram-positive Cell Wall
(b) Gram - Thin peptidoglycan Tetrapeptide cross linkage A second membrane structure: protein and lipopolysaccharide. Toxicity : endotoxin on lipid A of lipopolysaccharide. glucosamine- glucosamine-long polysaccharide- repeated sequences of a few sugars (e.g. gal- mann-rham) n=10-20 O antigen
Structure of peptidoglycan (3)
Toxicity : endotoxin on lipid A of lipopolysaccharide. glucosamine- glucosamine-long FAFA FA FA polysaccharide- repeated sequences of a few sugars (e.g. gal- mann-rham) n=10-20 O antigen
Chemistry of LPS
The Gram-negative outer membrane (1)
The Gram-negative outer membrane (2)
2. Cell Membrane Function: a. control permeability b. transport e’s and protons for cellular metabolism c. contain enzymes to synthesis and transport cell wall substance and for metabolism d. secret hydrolytic enzymes e. regulate cell division. Fluid mosaic model. phospholipid bilayer and protein (structure and enzymatic function). Similar to eukaryotic cell membrane but some differs. e.g. sterols such as cholesterol in Euk not in Prok.
The cytoplasmic membrane
Functions of the cytoplasmic membrane (1)
Functions of the cytoplasmic membrane (2)
Classes of membrane transporting systems (1)
Classes of membrane transporting systems (2)
Classes of membrane transporting systems (3)
III. Cytoplasm 80% water, nucleic acids, proteins, carbohydrates, lipid and inorganic ions etc. 1. Bacterial chromosomes a single large circular double stranded DNA no histone proteins. The only proteins associated with the bacterial chromosomes are the ones for DNA replication, transcription etc. 2. Ribosome protein synthesis
The bacterial chromosome and supercoiling
3. Mesosomes A large invaginations of the plasma membrane, irregular in shape. a. increase in membrane surface, which may be useful as a site for enzyme activity in respiration and transport. b. may participate in cell replication by serving as a place of attachment for the bacterial chromosome.
4. Inclusions Not separate by a membrane but distinct. Granules of various kinds: * glycogen, *polyhydroxybutyric acid droplets (PHB) i.e. fat droplets * inorganic metaphosphate (metachromatic granules) - in general, starvation of cell for almost any nutrients leads to the formation of this to serve as an intracellular phosphate reservoir.
5. Chromatophores Only in photosynthetic bacteria and blue green algae. Prok. no chloroplast, pigment found in lamellae located beneath the cell membrane.
IV. Special Structure *Endospores Spore former: sporobactobacilli and sporosarcinae - no medical importance. bacillus and clostridium have medical importance. *Position: median, sub-terminal and terminal have small water, high calcium content and dipicolinic acid (calcium dipicolinate) extremely resistant to heat, UV, chemicals etc. may be due to many S containing A.A for disulfide groups.
After the active growth period approaching the stationary growth phase, a structure called forespore develops within the cells. It consists of coat, cortex and nuclear structure. The process of endospore formation