MBIO 1010 Lecture 9

• Cytoplasm is the material bounded by plasma membrane
• protoplasm is the plasma membrane and everything within

  • macromolecules - amino acids, nucleotides
  • soluble proteins
  • DNA and RNA (nucleoid)
• Proteins

  Serve many functions: enzymes - catalyze chemical reactions, transport proteins - move other molecules across membranes

  Structural proteins help determine the shape of the cell (involved in cell division)

  proteins are made of polypeptides

  polypeptides are a long polymer of amino acids joined by peptide bonds
• The nucleoid

  • region that contains the genome
  • the typical bacterial genome:
  • single circular double stranded DNA chromosome
  • may have one of more plasmids
  • smaller circular double stranded DNA
  • Self replicating
  • carry non-essential genes
  • selective advantage
  • genes for antibiotic resistance
  • DNA
  • Carries genetic info of all living cells
  • polymer of deoxybonucleotides
• Ribosomes

  site of protein synthesis

  70S ribosome

  2 parts

  • 30S subunit (small subunit)
  • protein
  • 16S rRNA
  • 50S subunit (large subunit)
  • protein
  • 23S and 5S rRNA
  • Cytoplasmic ribosomes
  • cytoplasmic proteins
  • PM associated ribosomes
  • membrane proteins
  • proteins to be exported from the cell
• Cell surface structure

  capsules and slime layers

  • composed of polysaccharide /protein layers
  • may be thick or thin, rigid or flexible
  • assist in attachment to surfaces or other cells
  • protect against phagocytosis
  • resist desiccation
• biofilms

  • little armies of bacteria can have one species or different
  • community of bacteria associated with a surface
  • for water - called pellicle
  • goal of biofilms is that they provide an advantage being synergistic community
  • capsules help with the biofilm production
  • if the bacteria doesn't express its capsule then phagocytosis can occur
  • capsules use a negative stain
• Fimbriae

  • filamentous protein structures
  • enable organisms to stick to surfaces or form pellicles
  • the short little hairs like is the fimbriae (looks like someone forgot to shave - goes all the way around the cell
• Pilli

  • filamentous protein structure
  • typically longer than fimbriae
  • assist in surface attachment
  • facilitate genetic exchange between cells (conjugation)
  • type 4 pili involved in twitching motility
• Vertical gene transfer

  • Genetic change in the starting bacteria that is carried through to the daughter cells (carried down)
• Horizontal gene transfer

  • Within the generation
  • Pass information between each other
  • This happens with conjugation
  • To get the good genes (adding the upgrades the add ons )
  • Some may happen unintentionally
• Twitching motility

  • Grappling hook
  • Attaches and moves
• cell inclusion bodies

  Visible aggregates in cytoplasm - can be seen in the cytoplasm

  might use it later - storage

  carbon storage polymers

  PHB: Liquid (Poly-beta-hydroxybutyric acid)

  glycogen: glycogen polymer

  polyphosphates: accumulations of inorganic phosphate

  sulfur globule: composed of elemental sulfur

  magnetosomes: magnetic storage inclusions
• Carbon storage polymers

  • Poly-beta-hydroxybutyrate (PHB)
  • Liquid storage
  • PHB is a common type of PHA
  • Try to keep carbon through liquids
  • can take up to 90% of the cells weight
  • glycogen granules
  • polymer of glucose
  • like starch
  • really good source of energy
• Inorganic inclusions

  • Polyphosphate granules - volutin
  • storage of phosphate and energy
  • sulfur globules
  • storage of sulfur used in energy generation
• Magnetosomes

  • magnetic inclusions
  • intracellular granules of iron oxides and iron sulfides
  • gives the cell magnetic properties
  • allows it to orient itself in a magnetic field
  • bacteria migrate along Earths magnetic magnetotaxis
• Taxis

  • directed movement
  • first part of the word will tell you where they are going
  • magnetotaxis are moving toward magnets
• Magnetosomes look like little dots
• inclusions look like chains
• Microarophiles

  • need a little bit of oxygen
  • follow magnetic field to prevent them to get too much oxygen - helps them thrive