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Micro 186 > Lecture 2 - Bacteriology > Flashcards

Lecture 2 - Bacteriology Flashcards

1
Q

What types of doman bacteria are there?

A

Autotrophs - Photosynthetic bacteria (can produce energy from light + CO2), Chemosynthetic bacteria (can produce energy from inorganic chemicals such as hydrogen sulfide, methane, etc

Heterotrophs - 4 common groups (gram+ cocci and bacilli, gram - cocci and bacilli)
3 less common (spirochaetes, rickettsia, mycoplasma

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2
Q

how can you describe bacteria?

A

morphology
size - of individual cell
arrangement
if gram stain available, include if gram pos or neg

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3
Q

Describe the cocci morphology

A

spheres, always give diameter

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4
Q

Describe bacilli morphology

A

rods, can be filamentous (long and thin; almost string-like)

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5
Q

describe coccobacilli morphology

A

short, plump rods; almost ovals in appearance

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6
Q

Describe vibrios morphology

A

comma shapped, curved rod, singular

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7
Q

describe spirilla morphology

A

rigid helix, flagella for motility, singular, less commonly found in short chaings

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8
Q

Describe spirochetes morphology

A

corkscrew (telephone cord), move using flagella to wind by or spring-type creeping, singular

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9
Q

What is pleiomorphism

A

Having more than one shape or form, refers to variability in shape

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10
Q

How do you describe size in bacteria?

A

always measure individual cells in microns
most bacteria are 0.5-3 microns in width
Rods - give diameter
Cocci - give WxL of individual cell
Filamentous, spirilla, spirochetes - give length while curved/folded
slight pleomorphism - describe most commonly represented size

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11
Q

How large is 1 micron?

A

1 mm = 1000 micron

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12
Q

Describe each arrangement of cocci and what their names are/what they look like

A

Coccus – singular
Diplococci – pairs
Streptococci – chains
Staphylococci – grape-like
clusters
Tetrads – 4 cocci in a square
Sarcinae – 8 cocci in cube13

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13
Q

Describe each arrangement of bacilli and what their names are/what they look like

A

Bacillus – singular
Diplobacilli – pairs
Streptobacilli – chains; 3 or
more arranged end-on-end
Palisades – picket-fence;
arranged side-by-side; least
common

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14
Q

What is a bacteria colony?

A

a discrete mound of bateria cells visible to the naked eye
all cells in mound derived from a single bacteria cell
can exist in vitro or in vivo

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15
Q

What is an in vitro bacteria colony

A

diff bacteria produce colonies with distinct shapes and colors when grown in vitro under specific growth conditions

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16
Q

What is a colony forming unit?

A

A SINGLE colony is created frm a SINGLE bacterium that replicates many times until there are enough cells to see with the naked eye

A CFU refers to the single bacterium that started the colony because all cells within the colony are identical

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17
Q

Describe the cytoplasmic membrane of a bacteria

A

aka cell membrane, plasma membrane
phospholipid bilayer
contains diff types of proteins, carbs, cholesterol,
surrounds contents of EVERY living cell
thin, flexible, selectively permeable

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18
Q

What are the different types of proteins a cytoplasmic membrane can have? (6)

A

Channels + transporters
signal receptors
metabolic proteins
attachment proteins
Surface antigens

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19
Q

What are channels and transporter proteins in regards to the cytoplasmic membrane?

A

Move substances ( nutrients, toxins, waste) in/out of cells
Some antibiotics are designed to only target bact cells using these transporters to move into cell

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20
Q

What are signal receptors proteins in regards to the cytoplasmic membrane?

A

proteins that bind to “signals” from outside enviro
tell bact to: start/stop replicating, move from harm, prod enzymes to metab nutes, prod enzyme req to inactive specific antibiotics

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21
Q

What are metab proteins in regard to the cytoplasmic membrane?

A

bact have no mitochondria
energy prod machinery loc along folds/invagination in cytoplasmic membrane (mesosomes)

22
Q

What are attach proteins in regard to the cytoplasmic membrane?

A

bact use these proteins to attach to specific cells in host animal
certain bact only attach to certain cells
essential for infection

23
Q

What are surface antigens proteins in regard to the cytoplasmic membrane?

A

any protein or portion of a protein on the surface of a bact cell that can be recognized by the animals immune system
antigens = molecular ID tags found on all cells
diff bact have hiff surface antigens (used as methods of ID diff strains of same species)

24
Q

What are the fuctions of the cytoplasmic membrane

A

encloses the cytoplasm
barrier prot
regulates movement of molecules in/out of cell
inter. w/ enviro via signal receptors
site for energy prod
attachment - part of infect process

25
Q

What is cytoplasm?

A

Fluid or gel that fills the cel
60-70% water
cytoskeleton - molecular scaffold
metabolically active - biochem reactions

26
Q

What are ribosomes?

A

complex structures consisting of protein and ribosoma RNA
sit of protein synthesis where the RNA is read and used to assemble proteins in translation

27
Q

What is chromosomal DNA

A

A single strand of DNA contains all essential genes
fewer genes than in eukaryotic cells
Strand of DNA organized by DNA binding proteins and super coiled into tight bundle
bundled chromosomal DNA loc in the nucleoid
immune system can recog bact DNA

28
Q

What are plasmids?

A

“extra”, sm, circular pieces of DNA containing 1 or 2 genes
NOT part of chromosomal DNA
loc outside of nucleoid
Genes on plasmid not essential to life, but beneficial to survival by evolutionary advantage
-proteins that provide antibiotic resist (ex beta-lactamase enzyme)
-genes for specific toxins or attachment proteins
genes that enable the bact to prod capsules
can have none, one or more than one diff plasmid

29
Q

How do plasmids replicate?

A

replicate independently of the chromosomal dna
once a bact aquires a plasmid, it will duplicate itself inside the cell until there are 100s-100000s of copies per cell
very resist to degration - may remain stable in the enviro after bact cell has died

30
Q

What are the three ways plasmids are transferred btw cells?

A

during replication
transformation
bacterial conjugation

31
Q

Describe plasmids replicating through replication

A

any time the bact cell divides, plasmids also duplicate and an equal # of plasmids are transferred to the daughter cell

32
Q

Describe plasmids being transferred through transformation

A

Process where the cell membrane opens up and allows the bact cell to take up a plasmid from the enviro

33
Q

describe plasmids being transferrred thru bacterial conjugation

A

process where there is direct contact btw 2 bact cells thru creation of a temp cytoplasmic membrane bridge to allow plasmid transfer

34
Q

What are the external structures of bact?

A

cell wall, periplasmic space, flagella, fimbriae and pilli, capsules, slime layers

35
Q

Describe the cell wall

A

All bact (except mycoplasma) have a cell wall
rigid -surrounds cytoplasmic memb
categories - Gram +/-, acid fast
necessary for survival

36
Q

What is the func of the cell wall in bact?

A

maintain bact shape
protect cell from lysis due to osmotic pressure
helps protect from toxi materials (inc. antibiotics, sm molecules (<2nm) can diffuse btw peptidoglycan chains; lg molecules excluded)
helps w/ attachment
prevents phagocytosis by WBC in immune system

37
Q

How can you break down the bact cell wall?

A

lysozymes - enzyme found in tears/saliva
beta-lactams - class of antibiotics (inc penicillins + cephalosporins) prevents proper synthesis of the cell wal

38
Q

What are the two components of the bact cell wall?

A

Peptidoglycan layer
peptide cross-links

39
Q

What is gram staining? What use does it server?

A

A method of staining bact
separates most bact genera into 2 groups based on diff in cell walls structure
whether bact are gram +/- is important for certain growth req, pathology + tx during infection

40
Q

Gram pos cell wall

A

thicc - 40-90% of total cell mass
20-80 layers of peptidoglycan, layers joined by peptide cross-links
enzyme called transpeptidase is req to make the cross links
Teichoic acid
may have additional teichoic acids on surface of cell wall that help bact to attach to other bact and/or animal cells

41
Q

What is teichoic acid?

A

long molecules that help embed the cell wall to the cytoplasmic membrane

42
Q

What is the relationship between gram + cell wall and beta-lactam antibiotics

A

gram + bact are suspectible to the beta-lactam class of antibiotics
beta-lact antibiot binds to and block funct of the transpeptidase enzyme to prevent formation of peptide cross links btw peptidoglycan strands
w/o cross-links, cell wall cannot withstand osmotic pressure and cell lyses

43
Q

Describe the gram - cell wall

A

Thin, roughly 10% of total cell mas
multiple layers
peptidoglycan layer - closest to the cytoplasmic membrane (1-2 layers)
outermembrane - complex, composed of 2 layers. 1 - inner layer is single sheet of phospholipids. 2 - outer layer is single sheet of lipopolysaccharide (LPS)
periplasmic space - space bwn the cytoplasmic plasma membrane and outer membrane

44
Q

What is LPS?

A

Lipopolysaccharide
molecule that makes up the outmost layer of gram - cell walls, outer membrane layer
important to bact for establish infection: important to host while fighting off an infection
3 parts - O antigen, core polysacc, lipid a (endotoxin)

45
Q

What is the O antigen of LPS?

A

repeats of polysacc units
“smooth” bact with long O chains
“rough” bact with very short or lacking O chains
hydrophilic
certain species or strains are distinguished by the specific sugar molecule in their O chain

46
Q

What are O antigen’s of LPS important for? How can they help the cel:

A

Imp for back to estab infection
WBC are unable to grab smooth bac; WBC can easily phagocytose rough cells
o-anti take part in attach to epithel cells
some bact can alter sugars to make up o-anti, variation over time allows bact to evade the immune system
immune system uses o antigen when trying to fight off infection
sometimes, immune system can recog sugars in chain and target these cells for destruction
presence of o chain will trigger non=specific inflam

47
Q

what is the lipid a portion of LPS?

A

endotoxin
“tail” made up of lipid chains
same in all gram neg bact
hydrophobic
fuct to hold the lps molecule in place
normally hidden from enviro- if gram neg bact dies, sm amount is released into enviro
one of the strongest activators of inflam

48
Q

What is endotoxic shock?

A

Condition in body where overwhelming inflam causes vasodilation- drops BP -systemic shock
caused by sudden release of lg amounts of lipid a during gram ned infect
lipid a enters circulation and turns on systemic inflam
can be fatal if not treated immediately

49
Q

What are some bacteria that do not gram stain?

A

acid-fast bacteria + mycoplasma

They do not have the cell wall structures like gram +/-

50
Q

What is acid-fast bact?

A

cell wall structure is vry sim to gram + but contain lg numbers of mycolic acid (waxy molecules) in the cell wall. ex mycobacterium

51
Q
A

Micro 186 (5 decks)

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