Cytoplasmic (Cell) Membrane, Mesosome and Cytoplasm

1. Cytoplasmic (Cell) Membrane

1. 1. Located just inside the peptidoglycan layer.

1. 2. Phospholipid bilayer similar to eukaryotic membranes, but does not contain sterols (except Mycoplasma species).

1. 3. Functions:

• • • transport of molecules into cell
    • energy generation by oxidative metabolism
    • synthesis of cell wall precursors
    • secretion of enzymes, toxins, and other proteins
    • signal transduction

 

2. Mesosome

1. 1. Involved in cell division

 

3. Cytoplasm

1. 1. contains the nucleoid and ribosomes, nutrient granules, metabolites and plasmids.
      1. Ribosomes
         1. Differ in size and composition from eukaryotic ribosomes—selective target of several antibiotics that inhibit bacterial, but not eukaryotic protein synthesis.

2. Granules

1. 1. 1. 1. Several different types; stain characteristically and can be used to help identify some bacteria.

3. Nucleoid

1. 1. 1. 1. Location of bacterial DNA chromosome (~2000 genes, no introns)
            1. No nuclear membrane, no nucleolus, no mitotic spindle, no histones.

4. Plasmids

1. 1. 1. 1. Extrachromosomal double-stranded, circular DNA molecules.
         2. Replicate independently of bacterial chromosome.
         3. Found in Gram-positive and Gram-negative bacteria.

2. Transposons

 

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