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VETM 423 > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

the 3 main domains of life are

A

bacteria
archea
eukaryota

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2
Q

what are the main differences between prokaryotes and eukaryotes in regards to:
- cell membrane lipids
- peptidoglycans in cell walls
- ribosome size
- transcription and translation coupled
- organelles
- chromosome topology
- number of chromosomes
- nuclear membrane

A

prokaryotes:
- have mostly saturated or monounsaturated cell membrane lipids
- have peptidoglycans present in the cell walls
- have smaller ribosome size
- transcription and translation are coupled
- do not have membrane bound organelles
- have one chromosome that is circular
- do not have nuclear membrane

eukaryotes:
- have mostly polyunsaturated cell membrane lipids
- do NOT have peptidoglycans in cell wall
- have larger ribosomes
- transcription and translation are NOT coupled
- have membrane bound organelles
- have multiple linear chromosomes
- have a nuclear membrane

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3
Q

for bacteria, the basic taxonomic entity is the ______. A ____ is a collection of species with related properties.

A

species
genus

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4
Q

how are bacteria named?

A

genus and then species and the name needs to be italicized. you can also abbreviate the genus word to the first letter, ex) B. anthracis

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5
Q

other than subspecies, what are 4 other ways bacteria are taxanomically divided?

A
  1. genotypes based on genetic makeup
  2. serovars or serotypes based on antigenic properties
  3. pathovars or pathotypes based on pathologic properties
  4. phage types based on ability to be lysed by specific bacteriophages
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6
Q

what are 3 ways in which you can identify a pathogenic bacteria?

A
  1. miscroscopic identification
  2. cultural biochemical characterization of pathogens
  3. identification by immunological or molecular methods
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7
Q

breifly explain koch’s postulates

A
  1. the pathogen must be found in every case of disease and not in healthy animals
  2. the pathogen can be isolated and grown in pure culture
  3. a healthy animal infected with the pathogen must develop the same disease signs and symptoms of disease as in the postualte
  4. pathogen must be re isolated from the new host and must be identical to the first
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8
Q

what are the 3 morphological forms of bacteria?

A

coccus, bacillus, spirochaete

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9
Q

what are the names for cocci in pairs, four together in a cube structure, grape cluster, sube packet of 8 cocci, and arranged into chains?

A

diplococci, tetracocci, staphylococci, sarcina, streptococci

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10
Q

for rod type bacteria, what is the name for a classic rod vs a rod shape that tapers at the ends, sort of like an oval sape?

A

classic rod: bacilli
tapering: coccobacillus

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11
Q

what do diplobacilli, palisades, and streptobacilli mean?

A

diplobacilli: two bacilli in a pair
palisades: fence like form
streptobacilli: in chains

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12
Q

for spirochaetes, there are 3 different categories based on their shapes. Name the 3 and what they look like?

A

vibrio (a comma or an eyebrow)
spirillum (like a worm, snake, or bird)
spirochete (like arby’s curly fries)

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13
Q

why do are there so many different bacteria shapes and why should I care HUH????

A

selective forces are driving bacteria to change their shapes, it’s all about survival and competition, so if a different shape gives the bacteria a competitive edge, that is a big deal! the shape of the bacteria helps us to know in what specifc ways they cause disease/why they succeed the way they do

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14
Q

why does B. anthracis look different in pure culture vs infected tissue?

A

bacteria will change the way they grow/colonize based on their environment (stress vs optimal conditions for that specific bacteria). in this example, in the infected tissue the bacteria are in shorter chains and are surrounded by polypeptide capsules

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15
Q

true or false: all bacterias can be cultured

A

false! some bacteria species like treponema species cannot be cultured and do not grow unless inside host cells

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16
Q

BRIEFLY describe the 4 steps of a gram stain

A
  1. crystal violet: stains cells purple/blue
  2. iodine: makes dye stick to cell walls, cells stay purple/blue
  3. decolorizer: washes away the stain from gram neg cell walls, gram positive stays purple/blue and gram negs lose color
  4. safranin: stains the remaining gram negs, gram positive are still purple/blue and gram negs are pink/red
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17
Q

in regards to the cell wall, what are the main differences between gram negative and gram positive bacteria?

A

gram + have a thick layer of peptidoglycan in their cell walls, stains blue/purple
gram - have a thin layer of peptidoglycans with way more lipid content so it stains pink/red

gram + do not have outer membranes but gram - do have an outer membrane

see slide 35 of lecture 1 for more detail

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18
Q

what are the 5 bacterial cell surface components?

A
  1. capsule
  2. cell wall
  3. cell membrane
  4. flagellum
  5. pilus
19
Q

what consists of the “cell envelope” of a bacteria?

A

the capsule, the cell wall, and the cytoplasmic membrane

20
Q

what is the function of the “cell envelope” of a bacteria?

A

protection, nutrient transportation, and virulence

21
Q

what is/are major functions of the capsule of a bacteria?

A

the capsule is variable between species are some do not have them at all. it is made of extracellular polymeric material. usually has to do with virulence and therefore mediate adherence, protects the bacterial cells from engulfment by either WBCs or protzoa, and the capsule helps them resist environmental stress

22
Q

the “slime layer” or “glycocalyx” is refering to what bacterial structure?

A

the capsule

23
Q

what are major functions of the cell wall of a bacteria?

A

essential for bacterial structure/shape, contains adherence ligands and receptors (important for antibiotics), plays a role in virulence and can cause symptoms of disease in animals, provides distinction among strains using serotyping, prevents osmotic rupture

24
Q

what is the major component of a cell wall in a bacteria that provides strength and determines the shape?

A

peptidoglycan

25
Q

what is LPS and why do I care

A

lipopolysaccharide, a unique component of the outer membrane in gram - bacteria. it is an endotoxin, it is heat stable, toxic to most animals, and will be released when the cell wall ruptures. it is responsible for many toxic effects of infections with gram - bacteria and can cause endotoxic shock (uncontrolled activation of the immune system and massive production of inflammatory mediators)

26
Q

what portion of LPS is toxic?

A

the lipid A on the very end of the chain following the O antigen and the core

27
Q

compare exotoxins and endotoxins in regards to the following categories:
- source
- composition
- effect on host
- heat stability
- LD50

A

source: endotoxins are from gram -, exotoxins are from gram +
composition: endotoxins are made of lipid A from LPS origin, exotoxins are proteins
effect on host: endotoxins create general systemic symptoms of inflammation and fever, exotoxins do specific damage depedning on receptor mediated targeting of cells
heat stability: endotoxins are heat stable, exotoxins are sensitive to heat (mostly)
LD50: endotoxins have a high LD50, exotoxins and a low LD50

28
Q

botulinum toxin is an example of

A

an exotoxin

29
Q

list 3 functions of the cytoplasmic membranes of bacteria

A
  1. similar to the cell membranes of eukaryotes: lipid bilayer with embedded proteins, selectively permeable
  2. site of respiration, secretion, photosynthesis
  3. contains sensing proteins, enzymes, transport proteins
30
Q

what is the function of flagella/fimbriae?

A

flagella: motility, common in gram -
fimbriae: play a role in conjugation and adhesion, also common in gram -

31
Q

why is coupled transcription and translation advantageous?

A

it allows bacteria to make lots of protein very quickly and it also allows translation to prevent transcriptional pasuing, backtracking, and termination

32
Q

why is it useful to know that bacteria ribosomes are much different than mammalian ribosomes?

A

it makes them a good target for antibiotics, the drugs can inhibit protein synthesis at the ribosome

33
Q

what are the 3 ways in which bacteria can exchange DNA?

A

transformation: uptake of new DNA like a plasmid and encorportating it into the bacteria’s DNA
transduction: obstaining new DNA material from a lysogenic bacteriophage
conjugation: DNA is transferred from one cell to another via a mating bridge that connects the two cells

34
Q

what are the two types of bacteriopahges?

A

lysogenic phages: major mobile genetic elements
lytic phages: phage therapy

35
Q

what kind of genes can bacteria obtain from bacteriophages?

A

antibiotic resistance genes, virulence genes, and others that benefit bacterial growth and persistence

36
Q

conjugation requires

A

an F plasmid

37
Q

what is binary fission?

A

asexual reproduction in bacteria

38
Q

what are the two things you can use to assess bacterial growth on a culture?

A

turbidity: optical density
viable cell counts/colony counts

39
Q

what are the four phases of bacterial growth in a closed system?

A
  1. lag phase
  2. exponential growth phase
  3. stationary phase
  4. death phase
40
Q

what is generation time?

A

the time it takes for the bacterial population to double. many factors affect this

41
Q

what are the 3 main genera of spore forming bacteria?

A

bacillus, clostridium, alicyclobacillus

42
Q

what are spores and why are they significant?

A

they are produced by bacteria in response to stress to conserve it’s genetic material, they can survive very harsh environments, and have 7 layers/are very thick and tough

43
Q

spores do not form in host tissues unless________

A

the infected body fluids are exposed to air

VETM 423 (9 decks)

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