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microscopic bobo macroscopic hair > lecture 3 bacteria 2 > Flashcards

lecture 3 bacteria 2 Flashcards

1
Q

what are glycocalyces

A

umbrella name for other structures that have a similar function like capsule and slime

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2
Q

describe the features of capsules

A

Tightly attached, tight matrix; visible if treated with India ink

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3
Q

describe the structure and functions of the slime layer

A
  • loosely attached, easily deformed (e.g., Leuconostoc)
  • assist in attachment to surfaces
  • role in development and maintenance of biofilms
  • virulence factors: protect against phagocytosis
  • prevent dehydration/desiccation
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4
Q

what are the similarities between capsules and slime layer

A
  • both are sugars, capsule is more structured and tighter, whereas slime is more soft loose and less well defined
  • both protective and adhere to different surfaces which can help the bacteria
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5
Q

what is the s-layer and where is it found. what does it help the cell with

A

an additional protective layer commonly found in free-living Gram positive and Gram negative bacteria and archaea

may contribute to cell shape and help protect the cell from osmotic stress

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6
Q

what is the s-layer composed of

A

crystalline layer of thick subunits consisting of protein or glycoprotein

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7
Q

what are fimbriae and pili

A

filamentous protein structures ~2-10 nm wide

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8
Q

what is the function of fimbriae

A

Fimbriae enable organisms to stick to surfaces or form pellicles (thin sheets of cells on a liquid surface).

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9
Q

name the two types of pili and what they do

A

conjugative/sex pili facilitate genetic exchange between cells (conjugation).

type IV pili adhere to host tissues and support twitching motility (e.g., Pseudomonas and Moraxella).

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10
Q

how many fimbriae are found per cell, how many pili are found

A

many fimbriae, only 1/a few pili

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11
Q

what are 9 structural features of the cytoplasm . which are the 3 not usually found in eukaryotes

A
  1. nucleoid
  2. extra chromosomal dna
  3. enzymes
  4. regulatory factors
  5. ribosomes
  6. cell inclusions
  7. gas vesicles
  8. magnetosomes
  9. cytoskeleton

7,8,9

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12
Q

what kind of shape does FtsZ give the cell

A

spherical

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13
Q

what shape does MreB give the cell

A

rod

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14
Q

what shape does crescentin give the cell

A

virbroid shape

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15
Q

what is the ParM protein and how does it help chromosomes divide

A

at the origin of replication, theres a protein called Par, binds on to origin, as chromosome divides, the two proteins are dragged to poles of cells. doing that bc between it is a build of cytoskeletal protein, and pushes the two proteins that are bound to the origin to the poles of cells, thereby segregating them to split them up

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16
Q

do bacteria undergo mitosis and meiosis

A

no

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17
Q

how do bacteria cells divide and what does it require

A

through fission

bacterial cell division, or fission, requires highly coordinated growth and formation of all the cell’s parts

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18
Q

what is the bacterial DNA replication coordinated with

A

bacterial DNA replication is coordinated with the cell wall expansion and ultimately the separation of the two daughter cells

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19
Q

explain how the process of septation works. what does it form?

A

as DNA synthesis terminates, the cell divides by a process called septation, the formation of the septum

the septum grows inward from the sides of the cell, at last constricting and sealing off the two daughter cells

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20
Q

how does FtsZ direct septal growth in the bacterial cell

A

FtsZ subunit assembly circles around the septum in a treadmilling pattern, stepwise around the cell, that directs septal growth

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21
Q

what does septation require? what is it managed by

A

Septation requires rapid biosynthesis of all envelope components, including membranes and cell wall.

the overall process of septation is managed by a protein complex called the divisome

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22
Q

what is the difference in dna organization between eukaryotic and prokaryotic cells

A

Eukaryotic cells have a well-defined nucleus delimited by a nuclear membrane

prokaryotic cells have a nucleoid region that extends throughout the cytoplasm and is not enclosed by a membrane

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23
Q

what is dna attached to in bacterial cells

A

in most bacterial species, the DNA is attached to the envelope at the origin of replication, on the cell’s equator

24
Q

explain how translation is prokaryotes is coupled to transcription

A

the ribosomes bind to mRNA and begin translation even before the transcription of the mRNA strand is complete

25
Q

explain the four steps of cell division in bacterial cells

A
  1. in prokaryotes, a circular chromosome begins to replicate at its origin, or ori site
  2. two replication forks are generated, which proceed outward in both directions. at each fork, DNA is synthesized by DNA polymerase, with the help of accessory proteins, this protein complex is called the replisome.
  3. as the termination site is replicated, the two forks separate from the DNA
  4. completion of replication triggers Z-ring formation
26
Q

what is the name of the protein complex that helps synthesize dna in bacterial cells

A

replisome

27
Q

how do bacterial cells efficiently divide

A

it starts to replicate again, before it divides in the 4th picture. so this happens if the bacteria is in a nutrient rich environment, its an efficient system to divide rapidly. they havent finished replicating the whole genome buy they have already started a new replication.

28
Q

what are the two types of daughter cells bacteria can generate

A

some bacteria generate two kinds of daughter cells: one stationary (sessile) and one mobile (swarmer)

29
Q

what form does the cell have to be in to divide? how can a swarmer cell divide?

A

in order to be able to divide, this cell has to be in the sessile form. swimmers can go to good areas to divide, ditch its flag, grow a stalk, stick itself to a surface, then on the top side of the bacteria it will grow a whole new cell that is a swarmer cell (with a flagella)

30
Q

what is polar agining increased by

A

stress

31
Q

what is a major form of asymmetrical growth

A

endospore formation

32
Q

what does the process of cell division determine about the poles in bacteria

A

the actual process of cell division itself determines that the poles of each daughter cell differ chemically from each other

33
Q

what are the 3 functions of vesicles

A
  • attractors of partner hetertrophs
  • phage decoys
  • vehicles for DNA transfer
34
Q

what are contained in the membrane vesicles that microbial cells export

A

surprisingly, isolated microbial cells continually export bits of cytoplasm in membrane vesicles. these carry proteins and nucleic acids

35
Q

what are nanotubes? what do they allow for

A

nanotube have cell membrane that connects two cells. allows for cells to contain protein and mra, a way to exchange information between the two

these nanotubes allow bacteria to directly share proteins and mRNA useful under hostile conditions, such as when exposed to antibiotics

36
Q

what are thylakoids

A

thylakoids: extensively folded intracellular membranes found in photosynthetic bacteria

37
Q

what are carboxysomes

A

carboxysomes: polyhedral bodies packed with the enzyme Rubisco for CO2 fixation

38
Q

what are gas vesicles

A

Gas vesicles: protein-bound gas-filled structures that increase buoyance

39
Q

what are magnetosomes

A

allow bacteria to orient themselves across a magnetic gradient

40
Q

what is an inclusion body and what is their function

A

inclusion bodies come out of the bacteria is because their are being produced in too high volumes

inclusions function as energy reserves, carbon reservoirs, and/or have special functions

41
Q

what are inclusion bodies enclosed by, what do they reduce

A

thin membrane, osmotic stress

42
Q

what kind of storage polymers do cell inclusions have

A

glycogen: glucose polymer
poly-β-hydroxybutyric acid (PHB): lipid polymer, stored as lipid droplets

43
Q

what are the 4 arrangements of flagella in bacteria

A

polar, lophotrichous, amphitrichous, peritrichous

44
Q

describe the structure of flagella

A

helical in shape
consists of several components
filament composed of flagellin
increase or decrease rotational speed relative to strength of proton motive force

45
Q

what does ccw rotation of the flagella result in? what is this movement called? what is it caused by?

A
  • CCW rotation
    • flagella bundle together
    • push cell forward
    • “run”
46
Q

what does cw rotation of the flagella result in? what is this movement called? what is it caused by?

A
  • repellents (or absence of attractants) cause CW rotation
    • flagellar bundle falls apart
    • “tumble”
      • bacterium briefly stops, then changes directions
47
Q

what is a biased random walk

A

biased random walk is when you are moving towards a signal

48
Q

what is a random walk

A

random walk is when they are moving not with a signal and not towards a attractant

49
Q

what are the 5 types of taxis

A
  • chemotaxis: response to chemicals
  • phototaxis: response to light
  • aerotaxis: response to oxygen
  • osmotaxis: response to ionic strngth
  • hydrotaxis: response to water
50
Q

what does an endospore do?

A

endospores essentially protect the bacterial genome in a dormant state when environmental conditions are unfavorable

51
Q

what are 4 characteristics of endospores

A
  1. resistant to extreme temperatures and radiation
  2. do not absorb gram stain, only special endospore stains
  3. dehydrated; no metabolic activity
  4. dormant; no growth or metabolic activity
52
Q

what are 5 structural features of an endospore

A
  • many layers: exosporium (outermost), spore coats, cortex, core wall
  • contains dipicolinic acid and is enriched in Ca2+ both form the calcium-dipicolinic acid (DPA) complex
  • DPA complex help the cells to cope with dehydration and stabilize DNAdehydration and stabilize DNA
  • Core contains small acid-soluble spore proteins (SASP), which bind and protect DNA and function as carbon and energy source for outgrowth.
  • Core also contains the cytoplasmic membrane, cytoplasm, ribosomes and other cellular essentials.
53
Q

when are endospores formed

A

Formed during endosporulation or sporulation

54
Q

where are endospore present? where are they not present?

A

Present only in some gram-positive bacteria, (e.g., Bacillus and Clostridium), none in archaea, suggesting this process evolved in bacteria after split.

55
Q

what kind of dispersal are endospores ideal for?

A

Ideal for dispersal via wind, water, or animal gut

56
Q

name the 6 steps from dna from forming to releasing an endospore

A
  1. dna replicates
  2. membranes form around the dna
  3. forespore forms additional membranes
  4. protective cortex forms around the spore
  5. protein coat forms around the cortex
  6. spore is released.

microscopic bobo macroscopic hair (3 decks)

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