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• Morphology –

  Cocci – round shaped

  Vibrio – curved shaped

  Bacilli – rod shaped

  Spirochetes – spiral shaped
• Bacterial cells are prokaryotic. Multicellular cells are eukaryotic
• Prokaryotes have organelle that are not enclosed by a membrane

  All bacteria contains, cytoplasm, ribosome, plasma membrane and a nucleoid. . Almost all bacteria has cell walls.
• ultrastructure of bacterial cell

  A) Inclusion

  B) Pilus

  C) Capsule

  D) CYtoplasm

  E) Ribosomes

  F) Cell wall

  G) Plasma membrane

  H) Nucleoid containing DNA

  I) Plasmid

  J) flagella

  K) Fimbriae

  L) Plasma membrane

  M) Capsule

  N) Cell wall

  
• Cytoplasm – is a dense fluid inside the cell. Has ribosomes and storage granules. Ribosomes are similar to eukaryote with both large and small subunit. The storage granules have glycogen, lipids and phosphates.

  There are also metabolic enzyme for biochemical reactions.
• Nucleoid –serves the same function as the nucleus. In the cytoplasm. Has as single circular DNA double helix. DNA can fit inside the cell through supercoiling which can be done without histone proteins.
• Plasmid – small circular double helix strand of DNA. They carry genes apart from the main DNA. These genes help for the bacteria to adapt to different situations. Makes them resistant and becoming more harmful
• Fimbriae – help the bacteria to stick to surfaces. They are small bristle like short fibers on the surface of the bacteria. Found on both gram positive and negative bacteria.
• Pili – long hair like tubular structures of the surface which can help for mating. Only found in some gram negative bacteria. Involved in conjugation.
• Pili – hair like structures on bacteria which can be used for conjugation (genetic transfer between bacteria). This structure can also make the bacteria harmful as it helps the bacteria to stick to body surfaces which can increase their virulence and contribute to the severity of the infection caused.
• Flagellum – helps in propulsion and motility. Consists of 3 parts: hook, motor and filament
• Mucous capsule – This is an extra gelatinous layer made up of polysaccharides. These type of bacteria are more harmful and virulent and can easily avoid the immune system. These are hard to treat as the immune cells cant attack the bacteria due to its capusle which increases the risk of infections. It also reduces the chance of drying out in dry conditions.
• Mucuous capsule prevents phagocytosis and antibody blockage to surface of cells.
• Cell wall – gives support and protection to the cell. It is made up of peptidoglycan. Penicillin prevents peptidoglycan synthesis. More common in gram positive bacteria.
• Gram staining is a technique to see the behaviour of bacteria. There are 2 types of bacteria – gram-positive and gram-negative.

  Gram positive – has thick cell wall which is resitant to drying out. Have no flagella so no motility. (S.aureus)

  Gram negative - thin cell wall. More resistant to antibiotics and are present in damp situation. (E.Coli)
• Gram positive cell wall has thick peptidoglycan
• Gram negative cell wall has thin peptidoglycan between plasma membrane and outer membrane
• Gram positive will be purple and gram negative will be pink.
• Gram positive bacteria – Staphylcoccus, streptococcus, bacillus, clostridium

  Gram negative bacteria – salmonella, haemophillus, E.Coli, proteus.
• Bacterial reproduction is through binary fission.

  Transverse binary fission is the seperation of 2 cells through the formation of a septum.
• Bacterial DNA exchange is not the same as in eukaryotes. It can occur in 1 of 3 different ways.

  Transduction, conjugation and transformation.

  Transduction – bacterial DNA carried between cells by phage

  Transformation – intake of DNA fragments

  Conjugation – one cell grows a tube to the other cell and copies the plasmid DNA and gives it to the other cell (reciever)
• Conjugation (E.coli) - usually from male to female.

  Sex pili of donor cell attaches to the recipient cell

  Plasmid replication happens. The copy is then passed to the reciepent.
• Transduction – phage DNA penetrates bacterial cell

  Host DNA and phage DNA gets intergrated and forms a prophage

  New phages produced when prophage become lytic.

  Bacterial cell lyses and releases the phages. This infect other cells. Cycle is repeated again.