Structure of prokaryotes

Structure of prokaryotes

1. features of a prokaryotic cell

   • Flagella
     • allow for the movement of the cell
       • clockwise rotation
         • cell tumbles
       • anticlockwise rotation
         • develops movement for cell
       • Allows for directional movement toward or away (Chemotaxis)
   • Frimbrie
     • The hairs of the cell
     • Allows the cell to stick to surfaces/adohernce e.g hard surfaces
     • Allows for Genetic transfer from one bacterium to another
   • Capsule
     • slimy layer on the cells surface
       • carbohydrate envelope of glycocalx
     • prevents the cell/organism to becoming dehydrated/dessicatted in non aqueous environments
     • resistance to phagocytosis (bacteria being indigested)
   • Ribosomes (Prokaryotic cell)
     • 50% smaller than ribosomes found in eurkarotic cells
     • allows for the synthesis of proteins
     • target site for some antibiotics to inhibit protein synthesis of the cell and therefore kill it
   • Nucleoid
     • Large strands of DNA (loop) not enclosed by a nuclear membrane
   • Plasmid
     • Small loops of extrachromosomal DNA
     • important in contributing extracelluar DNA in bacterium
     • V; Virulence (Can make organism cause diseases)
     • R; Can cause bacterium to become resistant to antibiotics
     • B; Bacteriocin (natural antibiotic produced by cell)
     • F; Fetility (transfer of genes)
   • Endospores
     • cells form spores during unfavourable conditions
     • condensation of nuclear material such as DNA
     • material is surrounded by two coats of protein
       • allows DNA to resits damage caused by Heat, Chemicals and desiccation

2. Establishing the difference between Gram Positive (+) and Gram negative (-)

   • Gram Postive
     • Thick outer layer of polytidglycon
   • Gram Negative
     • Thin layer of peptidoglycan
     • surrounded by two membranes. Outer Membrane and Plasma Membrane
   • peptidoglycan is a protein only found in bacteria therefore is a good indicator in determining Gram Positive and Negative bacteria
   • Gram Staining
     • the method used to determine Gram positive and negative bacteria
       • Use of two stains
         • treated with iodine to fuse the proteins of the peptidoglycan
           • colour of stain identifies type bacteria (positive or negative)
     • violet = positive
     • pink = negative

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