Module 2: Shape, arrangement and size Flashcards
what is bacteriology
subdivision of microbiology that studies the morphology, ecology, genetics and biochemistry of bacteria
what shape are bacteria cells
- come in limited assortment of shapes
- each species has a characteristic cell shape
what is a cocci
- round like a ball
what is a rod or bacilli
- tube like or sausage shaped
spirochetes
long cockscrew shaped rodes
- short and flexible in length
spirilla
- rigid spiral shaped cells
- usuall shorter
what are stalks
- bacteria cells form stalks to anchor them to solid surfaces
what is pleomorphic
no conistent cell shape
T/F smaller bacteria typically can increase their populations faster then larger cell species
True
plasma membrane
- the inner most layer
- encompasses the cytoplasm
- requirement for all living cells
- selective permeable memebrane (letting in certain things but not others)
- an anchor point - multiple receptors for detecting and responding to chemicals in the surrounding environment
- a lipid component of amphipathic lipids (hydrophilic and hydrophobic component)
- membrane proteins - loosely connected to the memebrane
Bacterial cell wall
- essential for all bacteria as it helps maintain shape and protects cell from osmotic lysis (popping)
- gram negative or gram positive
capsules
- well organized layers that are not easily washed off
- often composed of polysaccharides
- can be visualized by negative staining under light microscope
- are not required for growth in labroatory cultures
- can also protect against drying out
- can exclude viruses anf most hydrophobic toxic materials
slime layer
- zone of difused unorganized material that is removed easily
- usually composed of polysaccharides but not as easily seen
s layers
- extermal layers made by some species of bacteria that is made of protien or glycoproteins
- in gram negativve bacteria the s layer adheres noncovalently to the outer most layer where is is associated with the peptidoglycan surface of typical gram positive walls
- functions - protecting cell ahainst ion and pH fluctuations, osmotic stress, enzymes of predatory bacteria
- can also help maintain cell shape and regidity
- protect host defence for some pathogens
ribosomes
- cells machinery for protein synthesis and nearly each cell has a large number of them
- synthesize proteins to remain in the cell
- large and complex
- bacterial ribosomes are called 70S ribosomes and are comprised of two subunits
cytosol
- liquid component of bacterial cytoplams
- home to all the molecules dissolved within it
- holds inclusions, ribosomes and plasmids
- macromolecular crowding results in a viscosity about 10 times higher than water and affects physical and chemical processes
inclusions
- common in all cells
- formed by the aggregation of substances that may be organic or inorgnanic
- form granuals, crystals, globules or be amorphous in shape
- used for storage or to reduce osmotic pressure
- storage varies with the nutritional status of the cell and by species
nucleoid
bacterial chromosome is located within the nucleoid which is simply a zone within the cytoplasm where the DNA and numerous protiens resides
plasmids
- extrachromosomal DNA molecules
- relatively few genes
- both circular and linear plasmids have been documented but most known are circular
- plamids can carrt unimportant cells and cells that offer a selective advantage
episomes
cells that have the ability to exsists as integrated and as freely replicating in the cytoplasm
pili and fimbriae
thin, hair like appendages that stick out from the cell surface
flagella
- more motile bacteria move by the way of flagella
- threadlike locomotor appendages extending outward from the plasma membrane and cell wall
- attachment to surfaces or contribute to ability to cause disease ( virulence factors)
chemotaxis
- random movement of little advantage to a cell
- movement in response to the environment
- cell uses temporal sampling of the environmnet to decide if it wants to move or not
- if going favourable it goes straight
- non favourable has to spin around
ensopsores
- dormat cells that are formed within so call mother cell
- ## only in bacillus and clostridium (rods) and sporosarcina (cocci)
T/F bacterial spore formation is a reproductive strategie?
FALSE - its a survuval strategie during adverse conditions
- environmental stress = heat ultraviolet radiation, gamma radiation, chemical disinfectants and desiccation
Archaeal cells
- bacterial like cells that vary in size and shape
either free or clustered - can be either large or small
what kind of linkages make up isoprene
ether linkages
- joined to glycerol with the third carbon in the glycerol containing a charged head goup such as phosphate
lipid monolayer
- glycerol head attached to each end
- one hydrophobic tail taversing the hydrophibis region
what do archaea cell walls lack
peptidoglycan
do eukaryotic cells have walls
not always
- when they do its different from bacteria and crhaea
virons
nucleocapsid - nucliec acid (DNA or RNA) and virus coat = capsid
- virons covered in a lipid memebrane are enveloped viruses
lytic infection
replicating and bursting from its host cells
lysogenic
turn off its lytic pathway and remain silent within the infected cell
- gets into host chromosomes and remains undetected - able to shoot stresses into the host cell
can viruses replicate on their own?
- they cannot, susceptible host cell strain/line must be propagated and infected with the virus to allow more replication
- counting plaques which are distinct areas of killed or damaged cells created as the virus replicates
viroids
- small infections RNAs molecules that cause disease in plants
- do not code proteins
they RNA paring with mRNA of some essential gene
