Microbiology Topic 3: Cell Structure And Function (Chapter 4)

Front 1

Coccus

Back 1

Circular/spherical
Diplo and strepto (1 plane)
Tetrad (2 planes)
Sarcina (3 planes)
Staphylo (>3 planes)

Front 2

Bacillus

Back 2

Long, rod-shaped
Only divide in one plane, limited arrangements:
Diplo (2 bacilli joined together)
Strepto (chain of bacilli)

Front 3

Vibrio

Back 3

crescent-shaped

Front 4

Spirillum

Back 4

spiral

Front 5

Spirochaete

Back 5

tight spiral

Front 6

Glycocalyx

Back 6

High molecular weight polysaccharide &/or protein coat surrounding most bacterial species

Secreted; deposited outside cell wall

Slime layer (loosely attached/unorganized) or capsule (firmly attached/organized)

Front 7

Functions of glycocalyx capsule

Back 7

Can be a virulence factor: prevents cell from being washed away, capsule becomes part of biofilm/protects against chemical/antibiotic entry
Prevent desiccation
Source of nutrition
Evade immune cells

Front 8

Function of glycocalyx biofilm

Back 8

Difficult to remove; common way bacteria grow in nature
Protect cells against physical forces and chemicals
Allows for cell-cell communication

Front 9

Flagella

Back 9

Long, thin helical filament(s); one end attached to cell, other end free
Base of each filament contains rotary motor
Propels bacteria through liquid
4 arrachngements:
Monotrichous (one on end)
Amphitrichous (one on both ends)
Lophotrichous (multiple on one end)
Peitrichous (multiple, various locations)

Front 10

Axial filaments (endoflagella)

Back 10

Spirochaetes only:
-Borrelia burgdorferi
-Treponema pallidum

Bundles of flagella anchored at either pole
-winds around cell between CM and OM

Filament rotates, cell turns in corkscrew manner, cell propelled

Front 11

Fimbrae

Back 11

pilin protein
shorter than flagella
used for: attachment to surface, twitching motility

Front 12

Sex pili

Back 12

pilin protein
longer and fewer in number than fimbrae
used for Conjugation

Front 13

Gram positive cell wall

Back 13

thick peptidoglycan
teichoic acids
Lipoteichoic acids

No outer membrane

Front 14

Gram negative cell wall

Back 14

Thin peptidoglycan layer
Outer membrane: lipid bilayer, lipopolysaccharide (Lipid A, Core polysaccharide, O side chain), Porins

Gram negative cells have a periplasmic space

Front 15

Peptidoglycan structure

Back 15

Bacteria only
Function: rigidity
Contains sugars and peptides
2 sugars: NAM and NAG

Adjacent glycan chains connected by peptide cross link

Front 16

Peptide cross link

Back 16

Short peptides connecting NAMs in adjacent glycan chains
Consist of D and L amino acids
Differ between gram pos and gram neg

G neg: diaminopimelic acid (DAP), tetrapeptides linked by SINGLE peptide bond

G pos: no DAP, tetrapeptides linked by glycine interbridge

Front 17

The cell wall of a gram negative bacterium consists of a thin layer of peptidoglycan and an outer membrane. The outer membrane consists of:

Back 17

a lipid bilayer and porins.

The lipid bilayer consists of one layer of phospholipids and one layer of lipopolysaccharide (LPS): lipid A, core polysaccharide, and O side chain

Front 18

Teichoic acids

Back 18

Gram positive cell wall

phosphorylated alcohols (-)
unknown function, might facilitate transport of (+) charged substances into cell

Front 19

Lipoteichoic acids

Back 19

gram positive cell wall

teichoic acids with lipids bound to them
Function: anchor peptidoglycan to cell membrane

Front 20

Lipid bilayer

Back 20

Gram negative cell wall

two layers of lipids
Amphipathic (one hydrophilic end, one hydrophobic end) molecules build lipid bilayers

Front 21

O side chain

Back 21

gram negative cell wall

Contains sugars, varies among bacteria
Sugars have (-) charge, responsible for g(-) cells being neg charged
Function: attachment to surfaces

Front 22

Mycoplasma

Back 22

Atypical

Smallest independently producing bacteria
No CW
CM has sterols (strengthens/prevents osmotic lysis)

Front 23

Archaea

Back 23

Atypical

Often CW but NO peptidoglycan
no cell wall, thermoplasma
If cell wall, diverse gypes (ex: pseudopeptidoglycan)

Front 24

beta(1,4) bond

Back 24

bonds glycan chain, G-M bond

Front 25

mycobacterium

Back 25

atypical

cell wall = 60% mycolic acid (acid fast +)
Increased resistance to antibiotics and cell wall degrading components of the immune system

Front 26

Cytoplasmic membrane in bacteria

Back 26

Phospholipid bilayer (glycerol)
Proteins (phosphate group -> negative charge)
Hopanoids (sometimes--long chains of H-C, Hydrophobic)

Front 27

Peripheral proteins

Back 27

not embedded
attaches to CM via lipoprotein
Surface
Easily removed chemically w/o disrupting membrane

Front 28

integral proteins

Back 28

embedded in CM to some extent
must destroy membrane to remove

Front 29

Prokaryotic vs. Eukaryotic membranes

Back 29

usually no sterols in prokaryotic membranes
Many bacteria hopanoids instead (similar to sterols, embedded in CM, increase CM strength/rigidity)

Front 30

Archaea vs. Bacteria membranes

Back 30

Arachae:
ether-linked lipids (vs. ester-linked lipids in bacteria)
Isoprene units (vs. fatty acids in bacteria)
Some have lipid monolayers (vs. no monolayers in bacteria)

Front 31

Functions of cytoplasmic membrane

Back 31

selectively permeable
Anchors proteins
Generation of electrical gradient (i.e. proton motive force)