lect2 Flashcards
(31 cards)
what is the size of bacteria and how do we visualize them?
the size is 1-10 um
via light microscopy following staining
or electron microscopy
what is the difference between electron and light microscopy?
electron– 100,00x, uses electrons instead of light, high resolution
light–1,000x, common & we always use stain
what are the 2 common shapes of bacteria?
what are theother shapes??
coccus– spherical
rod–cylindrical
vibrio— comma shape, curved rod
spirillum–rigid spiral, long rod
spirochete—flexible cell wall, long helical cells
pleomorphic–many
what are basic structure of bacterial cell?
cytoplasmic membrane
cell wall
capsule
filamentous appendages (flagella and pilli)
nuclei
plasmid
ribosome
in gram negative– extra outermsmbrane
what is the function of the internal structures:
chromosomes
plasmids
ribosome
chromosome: circular dsDNA, has all genetic info
- is in the cytoplasm or nucleotide
- single chromosome
plasmid: circular DNA
- can enhance survival –resistance genes, colonization factors, expresses virulence genes
ribosome: proefins and rRNA
-decodes mRNA and helps tRNA synthesize proteins
-different from eukaryotic
what does the cytoplasmic membrane do?
semi permeable barrier of cell
-prevents leaks
phospholipid bilayer—tails face in
- proteins that sensor and are selective gates
what is allowed to pass the permeability lipid layer of the cytoplasmic membrane?
- selectively permeable
gases & small hydrophobic mol
charged or large need transports
since most molecules need transport, what are the characteristics of these transporters?
span the membrane
very specific
most require energy –active transport
can have many proteins
bring molecules in or send them out
what is the cell wall made of and what does it do?
strong rigid, maintains structure & prevents lysis
peptidoglycan–mesh like, and is sugar and short peptide polymer
- only in backteria
what are the subunits in petidogtylcan that form glycan chains?
what links them?
N acetymuramic acid (NAM)
n acetylglucosamine (NAG)
short peptide chains
how do antibacterials works?
interfere with function of synthesis of petioglycan
-lysosome breaks bonds linking NAM and NAG
what does penicillin do?
prevent cross linking of glycan chains of the peptides— only on gram pos bacteria
Target peptidogylcan— which is only in bacteria
what is gram positive bacteria characteristics?
thick cell wall
multiple layers of peptidoglycan
Teichoic acids project out of the peptidogylcan
what is gram negative bacteria characteristics?
thin cell wall– few layers of peptidoglycan
second membrane outside cell wall –outer membrane
what are the compartments between the membranes in gram negative bacteria called?
periplasm
what is the make up of the in gram neg outermembrane?
what does it do?
unique outer leaflet
-contains lipopolysaccharide (LPS)
blocks entry and exit of many molecules
what are the parts of LPS in gram neg outermsmbrane?
Lipid A– 6 acyl chains
core poly sacc
O antigen
what are the porins in the outermembrane?
water filled channels
allowed for diffusion of small molecules in & out of periplasm
additional transport for macromolecules
what are the steps in gram staining for gram pos and neg?
crystal violet stain–both purple
iodine—both purple
alcohol— gram pos is purple , gram neg is colorless
safranin– gram pos is purple, gram neg Is pink
staining shows difference in cell wall*
in bacteria that has no cell wall, what does not affect is and what does the cytoplasmic membrane contain?
penicillin and lysozmye
sterols than increase length
what does the flagella and pili and fimbraie do?
flagella: propeller for motility
p&f: surface attachment, surface movement, connect bacteria (help DNA transfer)
how does the immune system sense pathogens?
PAMPS (pathogen associated molecular patterns)
-LPS, petidoglycan, teichoic acid, flagella
does gram pos or gram neg have more secretion systems?
gram neg
how does cell division in bacterial work?
what is generation time?
binary fission
one cell divided to 2–> 4
growth is exponential
time for population to double
