Bacteria anatomy Flashcards
Why is it important to study bacterial structures?
- Identification
- Determine pathogenicity and pathogenesis
- Targets for control
3 basic shapes of bacteria?
- Spherical (coccus)
- Rods (bacillus)
- Spirals or spirochets
What is a monomorphic shape?
Uniform shape and size
What is pleomorphic
Variable shape
What are three broad categories of bacterial structures?
- Cell envelope (cytoplasmic membrane and cell wall)
- Cytoplasmic structures
- Surface structures
What are bacterial cytoplasmic membranes made of?
Phospholipids and proteins but no sterols
What is one bacteria that does have sterols in their cytoplasmic membrane?
Mycoplasma
What is the function of cytoplasmic membrane?
- Selective barrier
- Contains enzymes
- Target for antibiotics and disinfectants
What is the purpose of the cell wall
- Complex and rigid
- Protects interior of the cell
- Contributes to virulence
- Determines gram stain
What are the steps of the Gram stain?
- Crystal violet
- Iodine (mordant)
- Alcohol (decolorizing agent)
- Safranin (counter stain)
What color is gram positive?
Purple
What color is gram negative?
Pink, colorless until you use the counter stain
What is the macromolecule cell wall are made of?
Peptidoglycan
What is the target for penicillin?
The cross linkage between tetrapeptides of peptidoglycans
What is the periplasm?
Space between peptidoglycan and cytoplasmic membrane
What is teichoic acid?
Polymer of glycerol or ribitol with phasphate. Only found in Gram +
What are the classes of teichoic acid?
- Lipoteichoic acid
- Cell wall teichoic acid
What is the function of teichoic acid
Transport cations
What is the biggest difference in cell envelope of Gram-
Very tin peptidoglycan wall
What is the outer membrane of gram - made of?
Lipopolysaccharide and protein
What is the cell envelope consist of in gram -
Cytoplasmic membrane (phospholipid), Peptidoglycan (thin), Outer membrane (phospholipid and lipid a)
What is lipopolysaccharide?
Endotoxin. Found in gram -. Main component is lipid A
What is in the cell wall of mycobacterium?
No peptidoglycan. Contains waxy lipid coat of mycolic acid
How can you stain mycobacterium?
Acid fast staining
What is extrachromosomal DNA?
Plasmid
Do bacteria have nuclear membranes?
No
What type of DNA do bacteria have?
Circular dsDNA
What type of ribosome do bacteria have?
70S. 16S rRNA 1500 NT
What are mesosomes?
Only found in Gram -. Folds of cell membrane in cytoplasm used for cell division
What are inclusions or storage granules?
Reserve materials stored in cytoplasm
What genes are found in plasmids?
Selective advantages to the cells not for growth or division
What is curing?
Elimination of plasmids either spontaneously or from treatment
What are spores?
Consists of thick spore coat and resistant to most things. Ensures that the DNA inside survives
What are actin-like proteins?
Cytoskeletons that give the cell its shape. Major ones is MreB in rods and spirals
What are the types of cell surface structures?
Capsule or slime. Most are polysaccharide
How do you stain capsule?
Negative stain. Stain everything but the capsule
What is the function of capsules?
- Protection
- Nutrition
- Antigenic determinant (K antigen)
- Mediates attachment
What is the biofilm
Group of bacterial cells embedded in a common matrix of the capsular polysaccharide
What is a flagella?
Originate from cytoplasmic membrane made from flagellin. Used for movement. Antigenic (H antigen)
What are pili or fimbriae?
Made from protein pilin and mediate attachment to cells. Sex pilus is used in conjugation (Transfer of DNA)
