* **Cell membrane** = semi-permeable barrier that regulates the passage of substances
* **Cell wall** = single, interlinked molecule that encloses the entire cell and is made up of peptidoglycan (provides structure to the cell) and 2 sugars: N-acetyl muramic acid (NAM) and N-acetyl glucosamine (NAG)
* Some have no cell wall
* Some are **pleomorphic** (have different shapes) and thus can pass through filters
* Some lose their cells walls making them more susceptible to changes and lyse
* **L-forms** = survive and reproduce despite lack of cell wall
* **Protoplast** = could mean a cell lost some or all of its cell walls but it can also refer to the cell membrane and the contents inside the cell
* **Spheroplasts** = specifically refer to a rod-shaped organism that loses peptidoglycan and starts to form a sphere
* **S-layer** = a self-assembling highly structured layer of proteins that are found in some bacteria, both gram + and -; it gives structure, protects the organism, and allows attachment
* **Glycocalyx** = coating of glycoproteins outside cell wall that help to protect the cell and also help with attachment
* Two types:
* **Capsule** - highly organized, tightly attached
* Not all bacteria have a capsule
* If it’s small or happy, bacteria would not want to make a capsule b/c it wants to conserve energy
* **Slime layer** - loosely organized and attached
* On most bacteria
* **Cytoplasm** = fluid inside the cell, acts as a solvent
* **Nucleoid** = DNA containing region of the bacterial cell
* Has **chromosomes** which are single, circular, double-stranded, and tightly coiled DNA that contains all the genetic info required by a cell
* **Plasmids** may become part of the chromosome → episome
* **Ribosomes** = 70s size and site of protein synthesis
* Specialized structures
* **Fimbriae** attach cells to surfaces; shorter and more numerous
* F (fertility) pili, or **sex pili**, facilitates the transfer of DNA between cells (conjugation)
* Some specialized cells have **stalks**
* Types of flagella
* **Monotrichous** = one end
* **Amphitrichous** = both ends
* **Peritrichous** = all around
* **Lophotrichous** = tuft at one end
* **Periplasmic flagella** = exist in a spirochetes’ periplasmic space