Microbiology- Morphology/Fine Structure of Bacteria OBJECTIVES

Cocci

spherical

Bacilli

rod-like

Spirilla

spiral-shaped

Shape defined by

cocci, rods, spirilli

Arrangement determined by

type of bacteria

plane of divison

seperation or not

Diplococci

uniplanar—pairs

Streptococci

uniplanar—chains

tetracocci

biplanar—four cells

4 cocci in a square

staphylococci

triplanar—”bunches”

grape-like clusters

sarcinae

triplanar—cuboidal

vibrios

comma-shaped—modified spirilla

Size determined by

Surface area to volume ratio- the smaller things are, the more likely they are to reproduce.

Flagella

“tail” allows for mobility, found in bacilli and spirilla

Pili

Hair-like protein structures moslty found in Gram-negative bacteria, allows bacteria to attatch to other things 

Capsules

slime layer on the outside of the cell wall, act as protective covering, store food, and increase the infective capacity of the bacteria

Sheaths

in freshwater and marine bacteria, have metal compunds in them, act as protection 

Stalks

in freshwater and marine bacteria, semirigid adhesive appendage, help bacteria attach to things

Cell Wall

protective rigid outer layer than can withstand pressure, temperature, and severe conditions. It is essential for growth and cell division. Gram-positive or Gram-negative

General biochemical makeup of some fine structures of the bacterial cell explained:

Cell wall: made up of peptidoglycans (polymers). The structure of peptidoglycan is 2 alternating sugars, N-acetylglucosamine (AGA) and N-acetylmuramic acid (AMA). The strands have a helical shape and are crosslinked for strength. Can be Gram-positive which has thick peptidoglycan or Gram-negative which is more complex with a thin layer of peptidoglycan. 

Protoplasts

no cell wall, Gram Positive

Spheroplasts

no peptidoglycan, Gram Negative

Spores

metabolically dormant bodies

Bacterial exospores

external chains of spores

Bacterial endospores

highly resistant dormant spores that are used as a survuval mechanism