CHAPTER 2: Lesson 7: Bacterial Morphology and Fine Structure Flashcards
The size of most bacteria ranges from ________ to ________ and from _______ to ________.
0.2 μm (micrometer) to 2.0 μm in diameter
2.0 μm to 8.0 μm
Several shapes of bacteria
Cocci
Bacilli
Vibro
Spirilla
Spirochete
Usually round but can either be oval,
elongated, spherical or elliptical shape. Either they may remain as a single cell or
may aggregate together for various configurations.
Cocci: (singular: coccus meaning berries)
6 various configurations of Cocci
a. Monococcus
b. Diplococcus
c. Streptococcus
d. Tetracoccus
e. Staphylococcus
f. Sarcina
Represented by single, discrete round cell
Monococcus
The cell of this bacteria divides but the cells remain attached to each other.
Diplococcus
Here the cells divide repeatedly in one plane to form chain
of cells
Streptococcus
This consists of four round cells, which divide in two planes at
right angles to one another and remain in a group of four
Tetracoccus
Here the cells are divided into three planes forming a
structured like bunches of grapes giving an irregular configuration
Staphylococcus
These cells divide in three planes but they form a cube like
configuration consisting of eight or sixteen cells but they have a regular
shape.
Sarcina
These are rod shaped or cylindrical bacteria which either remain singly or
in pairs.
Bacilli
appear in pairs after cell division
Diplobacilli
occurs in chain after cell division
Streptobacilli
Oval shaped similar to cocci
Coccobacilli
3 type of Bacilli
Diplobacilli
Streptobacilli
Coccobacilli
curved, comma shaped bacteria and represented by a single genus
Vibro
Spiral or spring like with multiple curvature and terminal flagella with
fairly rigid bodies.
Spirilla
Helical and flexible which move by means of axial filaments
resembling flagella but contained within an external sheath.
Spirochete
Structures external to the cell wall
Glycocalyx
Flagella
Axial filaments
Fimbriae
Pili
These are viscous substances that surround the cell
composed of polysaccharide, polypeptide or both
Glycocalyx: (meaning sugar coat)
Functions of Glycocalyx
(1) enables bacteria
to survive by attaching to surfaces, example: Streptococcus mutans attaches to
the surface of the teeth and cause dental carries,
(2) bacterial source of energy
when supply is low, and
(3) protection to host cell by attaching to surface hence
preventing the movements of nutrients out of the cell during dehydration.
Two forms of Glycocalyx
a. capsule form
b. slime layer
form
The substance is organized, is firmly attached to
the cell wall, and clinically contributes to the virulence (ability to cause disease) of
bacteria due to its capacity to evade phagocytosis by host cells.
capsule form
The substance is unorganized and is loosely attached to the cell wall.
slime layer form
These are long filamentous appendages
that propels bacteria.
Flagella: (singular: flagellum, meaning whip)
Three basic parts of Flagella
(1) filament
(2) hook
(3)
basal body
Long outermost part that
contains flagellin arranged in helix.
filament
where filament is attached to
hook
It anchors the flagellum to the cell wall and plasma membrane. The
flagella move by rotating from this part either in clockwise or
counterclockwise direction.
basal body
The movement of the basal body is termed as _________.
motility
Motility can be
presented in different patterns: what are these patterns?
(a) run or swim
(b) tumbles
(c) swarm