Cell Surface Structures, Inclusions, & How Bacteria Move

can capsules be stained by india ink? why or why not?

no — India ink is a negative stain, so it stains everything except bacteria

where are cell surface structures located?

outside of cell envelope

2 cell surface structures

1. capsules

2. slime layers

purposes of capsules

help bacterium attach to surfaces, form biofilms, and evade immune-recognition

capsules primarily contain _______

polysaccharides (CPS)

bacterial species can have multiple capsules, sometimes termed ________

K-antigens

even the same bacterium can switch b/w multiple __________

• think R and S experiment

capsules

slime layers

• loosely attached

• can contain proteins and lipids

• instead of CPS, contain exopolysaccharide (EPS)

purpose of capsule and slime layer

help prevent dehydration (bacteria can exist in the environment for a long time)

which cell surface structure is tightly bound to the cell wall?

capsule

which cell surface structure is loosely bound to the cell wall?

slime layer

fimbriae

short pili

purpose of fimbriae

mediate attachment to surfaces, both biotic (living) & abiotic (biofilms)

all gram _________ produce pili of some form

negative

functions of pili

• mediate attachment to surfaces

• transfer of genetic material b/w bacteria (conjugation)

• transfer of electrons/energy metabolism thru nanowires (long, up to 1cm)

which type of pili is involved in twitching motility?

Type IV

Type IV Pilus

• involved in twitching motility

• located only at poles of cell

hami/hamus

• similar to Type IV pilus

• has barbed hook to aid in attachment

what structure does carbon storage?

polyhydroxyalkonate

carbon storage polyhydroxyalkonate

• a lipid and/or poysaccharide

• almost all prokaryotes

• generated during itmes of excess carbon

what do carbon storage (polyhydroxyalkonate) vesicles look like in electron microscopy?

white blobs

polyphosphate

• used for ATP and ADP generation

• almost all prokaryotes

sulfur/sulfate storage

• primarily for anaerobic organisms & extremophiles

• for energy metabolism

• stored in periplasm

  ***ONLY GRAM NEGATIVE

do gram + or - bacteria have sulfur/sulfate storage?

negative

where are sulfur/sulfate storage vesicles located?

periplasm

***ONLY IN GRAM NEGATIVE (need to have 2 membranes)

cyanobacteria function

biomineralize carbonate (a source of CO2)

some cyanobacteria & archaea have _________ that allow them to float and control ________

gas vesicles / buoyancy

magnetosomes

bacteria that store iron oxides that generate a magnetic dipole

magnetotaxis

bacteria that can orient & travel along a magnetic field, the Earth’s or a more locally generated one

endospores

• dormant state of bacteria

• alive but not biologically active

• can withstand extreme heat (hours of boiling), radiation, chemical exposure, drying, and without most nutrients

• can remain dormant for 100-1000s of years

spores are found in 2 groups of gram _____ bacteria

+

spores are found in 2 groups of gram + bacteria: bacillales and clostridiales, many of these members are found in the ______ and __________ of animals

soil / digestive tract

spores have high concentrations of _________ and ___________ that help trap water and stabilize DNA

Ca2+ / dipicolinic acid (DPA)

spores have high concentrations of Ca2+ and dipicolinic acid (DPA) that help _______ and ____________

trap water / stabilize DNA

what stain is used to stain endospores green?

malachite green

list sporulation stages/steps

1. from vegatative cycle

2. asymmetric cell division, commitment to sporulation, septum formation

3. englufment: outer spore membrane formed

4. late sporulation; cortex & spore coat formed

5. maturation: dehydration of spore, Ca2+ uptake, SASPs, dipicolinic acid

6. mother cell lysis

7. free endospore enters germination

is spore formation random?

no → caused by event such as stress or nutrient limitation

germination of the spore occurs when _______ are present, such as bile salts

germinants

example of germinant

bile salts

what is germination of a spore?

when spore returns to vegetative cell growth

peritrichous

have multiple flagella randomly distributed

polar flagella

found at one or both ends of a bacterial cell

lophotrichous flagella

flagella are on one side — mix b/w polar and peritrichous

what determines how strong the rotation/speed of movement of flagella is?

strength of proton motive force (PMF)

what dictates what type of movement is possible/what directions a bacterium can travel (flagella)?

type of flagella

in twitching motility, bacteria tend to be ___________

closer together

in swimming motility, bacteria tend to be more _______

spread out

flagella

• ridged

• composed of proteins

• anchored into cytoplasmic membrane & cell wall

the motor portion of the flagella is composed of 25 proteins and can usually rotate _________

bidirectionally

export of downstream cytoplasmic external components is accomplished through a _______ secretion system located in the cytoplasm

Type-III

gliding motility

• smoth, nearly continuous process

• structures are all internal to the cell (cell rotates from inside)

• exact nature & operation of motility unknown

what type of bacteria use gliding motility?

bacteria w/o flagella/pilli

can gram (+) bacterium store excess sulfur?

no

• need periplasm → gram negative only

chemo-

towards/away a chemical (sugar molecule/nutrient etc.)

photo-

towards or away from light

aero-

towards/away from oxygen

magneto-

towards/away from a magnetic field