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microscopic bobo macroscopic hair > lecture 2 bacteria 1 > Flashcards

lecture 2 bacteria 1 Flashcards

1
Q

what are the three domains of life?

A

bacteria
arcaea
eukarya (protists, fungi, molds)

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2
Q

whats the most powerful microscopy tool?

A

xray crystollography

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3
Q

what are 4 morphologies of microbes and which are most common?

A

filamentous rods
rods
spirochetes
cocci in chains

common: rods and cocchi

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4
Q

what are the general features of a typical bacterial cell?

A

cell membrane
chromosomal dna that is concentrated in a nucleoid and extrachromosomal dna called plasmids
ribosomes
cell wall
some prokaryotic cells may have flagella pili fimbriae and capsules

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5
Q

differences between flagella, pilus, and fimbriae

A

flagella is for motility
pilus is for flexibility, four types, can be rigid
fimbriae are shorter more flexible and made of sugar. used to colonize and stick bacteria together or to surfaces.

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6
Q

what are the 5 functions of membrane proteins?

A

integral or peripheral proteins
transport
osmosis
energy
sensing
secretion

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7
Q

what is a hopanoid

A

chemical structurre of these are diverse but the role is the same as cholesterol as stabilizing agent for the membrane of bacteria

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8
Q

three functions of cytoplasmic membrane?

A

permeability barrier - prevents leakage and is gateway for transport of nutrients/waste into and out of the cell. polar and charged molecules must be transported.
protein anchor - holds transport proteins in place
energy conservation - generation of proton motive force

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9
Q

what are four types of lipids

A

cardiolipin
palmitic and oleic acid
cyclopropane fatty acid
hopanoids

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10
Q

describe function of cardiolipin
palmitic and oleic acid
cyclopropane fatty acid
hopanoids

A

cardiolipin= binds environmental stress proteins when the cell is under osmotic stress
palmitic= add fluidity to membrane in cold temperatures, saturated or unsaturated
cyclo= stiffens cell membrane by converting unsaturated fatty acids to cyclopropane
hopanoids= stabilize membranes like cholesterol does

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11
Q

how do prokaryotes protect the cell membrane?

A

cell envelope includes at least one structural supporting layer like the cell wall, helps keeps its shape and resist mechanical stress

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12
Q

describe gram positive bacteria

A

thick cell wall

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13
Q

describe gram negative bacteria

A

thin cell wall

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14
Q

how does cell wall protect against changes in osmotic pressure

A

because cell membrane is typically attached to the cell wall (which is s rigid sugar protein coat) which allows it to maintain its shape in different solutions

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15
Q

describe the structure of the cell wall

A

consists of a single interlinked molecule, like a mesh that is made up of peptidoglycan - 100 of them have been distinguished
long line of sugars ties together by beta 1,4 linkage
those sugars are tied through bridges of amino acids
that bind creates the mesh

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16
Q

what is the rigid layer of peptidoglycan structures typically made of

A

alternating modified glucose NAG or NAM
amino acids like L-ala D-ala D-Glu L-lys or DAP

17
Q

how can the peptidoglycan structure be destroyed

A

by lysozymes, which cleave the glycosidic bond between sugars and is found in human secretions, defense against bacterial infection

18
Q

whats the difference between peptidoglycan arrangement in gram + and gram -

A

gram + = have a bridge of pentaglysines that cross link the two peptidoglycan
gram - = have a direct cross link between 2 peptidoglycan

19
Q

what is unique about bacteria structure

A

peptidoglycan
can be used as a target for antibiotics (the enzymes responsible for its biosynthesis) like in penicillin or vancomyacin

20
Q

how do peptidoglycan structures grow

A

synthesis complex that extends the chains of amino sugars
penicillin binding proteins catalyze the formation of peptide cross bridges
extension as a whole is organized by protein complex that includes MreB which is an actin homologue

21
Q

what are 3 different places that bacterial species can synthesize new peptidoglycans

A

in dispersed zones
at the septum (middle)
at the poles

22
Q

whats the difference in the cell envelope between gram + and gram -

A

gram + = very thick peptidoglycan layer, will stain blue with gram stain
gram - = has thin peptidoglycan layer, will stain pink with gram stain. has LPS which needs to be cleared if used by humans

23
Q

describe in detail the structure of gram + bacterial cell wall

A

has multiple layers of peptidoglycan threaded by teichioc acids
techoic acid is negatively charged, a glycopolymer that helps with ridigity and protects against high temperatures and high salt conditions, and antiobiotics
only small things go through the cell wall so the bacteria has to secrete enzymes to break down bigger molecules
lipoteichoic acid are teichoic acids covalently bound to membrane lipids

24
Q

describe in detail the structure of gram negative bacteria cell wall

A

LPS consists of core polysaccacharide -> O polysaccacharide and lipid A
different sugars form the LPS and the lipid A part is the thing that anchors sugars to outer membrane
it also is the thing that makes the immune system react, as it sees it as toxic
outer membrane -> LPS stuff attached
peptidoglycan layer middle
inner membrane
braun lipoprotein is a transmembrane protein spanning the outer membrane to peptidoglycan layer

25
Q

explain how the gram stain works

A

crystal violet stain is used first
then a counterstain is added like fuschsine or safranin
so then gram + will stay blue and gram - will retain the red of the safranin
in gram + the thick layer stays blue and then in the gram - the thing layer sandwiched between the membranes will be stained pink -> presence of membrane

26
Q

what are 3 other differential stains

A

acid fast stain that use carbofuchsin to stain mycobacterium species
spore stain that use malachite green to detect spores of bacilus and clostridium
negative stain that colours backgrounds to make capsules more visible

27
Q

****explain acid fast bacteria

A

resist decolourization
final colour of pink or red
mycobacterium example

28
Q

what do antimicrobials target

A

cell structures and processes

29
Q

what are antibiotics and antimicrobrials used for

A

antibiotics for bacteria only
antimicrobials for drugs against viruses fungi and parsites

30
Q

bactericidal vs bacteriostatic

A

bactericidal kills bacteria
bacterostatic inhibits growth

31
Q

what is a nosocomial infection

A

infection acquired in hospital care

32
Q

how does antibiotic resistance happen

A

organisms genome changed, genetic material is shared with other microbes to resist toxic effects of antibiotics

33
Q

difference between resistance and persistance

A

resistance= have something changed in genetic code or adding to genetic code to resist change to particular stress, done for genetic advantages
persistance= able to respond to stress and survive the stress

microscopic bobo macroscopic hair (3 decks)

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