Bacterial Cell Flashcards
Macromolecules in Each Cell
proteins, polysaccharide, phospholipid, nucleic acid
protein
amino acid
3 architectural regions of a Bacterial cell
- Appendages (attachments to the cell surface}
- Cell envelope
- Cytoplasmic region
Appendages (attachments to the cell surface}
Flagella
Pili (or Fimbriae)
Cell envelope
Capsule
Q Cell wall
Q Plasma membrane
Cytoplasmic region
Nucleoid (DNA)
Q Ribosomes
Q Inclusions
Threadlike (filamentous) protein appendages extending
outward from the plasma membrane and cell wall
» Slender, rigid structures, about 20nm across and up to
15 or 20 um long
» Allows a cell to move (swimming movement)
Flagella
Flagellar distribution
Polar — one or more flagella arising from one or both
poles of the cell
o Peritrichous — flagella are spread fairly evenly over the
whole cell surface
Short, fine, hairlike protein structures on the surfaces of
prokaryotic cells but not involved in motility
pili/fimbria
— shorter and stiffer than flagella and slightly smaller in
diameter
- Most often involved in adherence of bacteria to surfaces,
substrates and other cells or tissues in nature.
fimbria
similar to fimbriae, but not typically longer and only one or
a few pili are present on the surface of a cell
- Important in facilitating genetic exchange between cells in a
process called conjugation
- For pathogenic bacteria: important in the adhesion to
specific host tissues that leads to invasion
pili
polysaccharide layers outside of the cell
capsule and slime layer
if the layer is organized in a tight matrix that
excludes small particles, such as india ink
capsule
less organized and is more easily deformed, does
not exclude small particles and is more difficult to see
slime layer
formed when encapsulated microorganisms bind to
solid surfaces in nature (soil/water}
biofilms
- Mediate adherence of the cells to surface
- Protect bacterial cells from engulfment by predatory protozoa,
or from attack by antimicrobial agents of plant or animal origin - Protect cells from drying or desiccation
Functions of Capsule