Bacteria cell structure Flashcards
Units of microorganis taxonomy
MICROBIAL WORD
1) Acellula
1. 1- Prions
1. 2- Virus and viroids
2) Celullar
2. 1- prokaryote
2. 2- eukaryote
How is done the Binary nomenclature?
(genus) 1 + (species) 2
Mycobacterium leprae
Constant elements of bacterial cell structure
1- cell wall 2- cytoplasm 3- plasma membrane 4- nucleoid 5- ribossomes 6- mesosomes
Incontanst elements of bacterial cell structure
1-Pili 2- Flagellae 3- Capsule 4- Spore 5- Plasmides 6- Inclusions
CELL WALL
Components: Peptidoglycan
Function: -protection -keep the microorganisms shape -prevention from osmotic swelling and cell rupture (do have pores)
FLAGELLAE
components: protein
functions: locomotion
PLASMA MEMBRANE
components: bilipid layer maid of phospholipids
functions:
- transport of chemicals throught the membrane (passive or active)
- keeps the chemicals concentration (cell potential)
- separates intracelullar from the outercellular environment .
MESOSOME
components: same as cell membrane
functions:
- center of respiratory activity of bacteria (Lateral mesosome- several in the cell)
- paticipates in cell division (Septal mesosome- only one in the cell)
- intracelullar metabolism
- coordination of enzyme system
CYTOPLASM
components: proteins, nucleic acids, carbs, lipids, minerals and water (80%)
functions:
- Is the medium for intracellular metabolism.
- Is where organelles are localized (ribosomes. nucleoid and inclusions)
NUCLEOID
components: double stranded DNA, haploid.
functions: Is the genetic material (1 chromosome only) of the bacteria
PLASMIDS
components:Extrachromosomal circular DNA segments
functions:
-Inheritance of aditional features like drug resistance, toxigenicity, etc.
RIBOSOMES AND POLYRIBOSOMES
components:Ribosomal RNA and protein
functions:
- protein synthesis
INTRACYTOPLASMATIC INCLUSIONS
functions:
- Spare nutrients
TYPES OF MESOSOME
- septal mesosome (one in the cell; cell division)
- lateral mesosome (several in the cell; respiratoty centers)
PILI (aka fimbriae)
components: protein (pillin)
functions:
* Common pili: For attachment to the substrate.
* sexual pili: Take part in the conjugation process, responsible for the genetic exchange between bacteria.
CAPSULE
components: polysaccharides, polypeptydes (2%) and water (98%)
functions:
- Protection (mostly chemical)
- Inhace the virulence
- Acts as an antigen
SPORE
- Is a resisnt and dorment form of the bacteria.
- It contains the genetic material.
- It is formed when the bacteria is in an environment which is not viable for living.
- The spore opens again when the bacteria is again in a favorable environment
Spore positions in bacteria
1-central
2-terminal
3- subterminal
Bacteria with LACK of cell wall
1- Spheroplasts
2-Protoplasts
3- L- form bacteria
4- Mycoplasma
SPHEROPLASTS
- derived from Gram - bacteria
- Partial loss of cell wall
- cannot reproduce
- Are unstabel (able to reverse the transformation)
PROTOBLASTS
- derived from Gram + bacteria
- Complete loss of cell wall
- Cannot reproduce
- Are unstable (able to reverse the transformation)
L-FORM
- Are strains of bacteria lacking cell wall
- Can reproduce (binary fission)
- Are divided in:
a) stable (cannot return to their original form)
b) unstabel (can return to their original form) - Their transformation can be spontaneous of forced.
- Their transformation happen uppon presence of a causative factor.
SPORE-forming pathogens
1- Bacillus anthracis 2- Chlostridium tetani 3- C. botulinum 4- C. Perfrigens 5- C. septicum 6- C. histolyticum
ENCAPSULATED pathogens
1- Klebsiella pneumoniae
2- K. ozaenae
3- K. rhinocleromatis
