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Microbiology > Lecture 6: Microbial Physiology > Flashcards

Lecture 6: Microbial Physiology Flashcards

1
Q

What do bacteria have instead of membrane bound organelles?

A

they have internal organization

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2
Q

What gives bacterial cytoplasm/cytosol a gelatinous consistency?

A

very high concentration of protein, nucleic acid, carbohydrates, and ions

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3
Q

What shape is bacterial genome?

A

Circular with a few exceptions

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4
Q

What is genome?

A

chromosomes plus plasmids

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5
Q

What are plasmids?

A

small circular self replicating DNA strands

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6
Q

What is a chromosome?

A

one long DNA chain

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7
Q

What does bacteria do instead of having a cell nucleus?

A

may partition genetic material to different parts of the cell

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8
Q

Where does DNA partition when bacterial cells divide?

A

partitions to plasma membrane on either side of the division plane

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9
Q

What are ribosomes?

A

the structures
responsible for translation of mRNA

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10
Q

What do ribosomes do?

A

converts gene sequence to polypeptide

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11
Q

What are ribosomes made of?

A

RNA (called rRNA or ribosomal RNA) and protein

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12
Q

What are the subunits of ribosomes?

A
  • 50S (bacterial)
  • 30S (bacterial)

(40, 60, and 80 are for eukaryotes)

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13
Q

What is the final ribosome?

A

70S

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14
Q

What does S mean?

A
  • Svedberg Unit
  • sedimentation rate
  • how long it takes for a particular piece to end up where it belongs
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15
Q

What does the kind of ribosome tell you?

A

the target of a number of antibiotics

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16
Q

Are ribosomes present in every cell?

A

Yes, they are in every cell of every kind. Cells cannot function without them

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17
Q

carboxysomes

A

contain ribulose 1,5
diphosphate carboxylase enzyme for CO2 fixation by photosynthetic bacteria

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18
Q

What do metachromatic granules do?

A

store inorganic phosphate (volutin) in Corynebacterium diphtheriae

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19
Q

Forms of nutrient storage

A
  • carboxysomes
  • metachromatic granules
  • polysaccharide granules
  • sulfur granules in thiobacillus
  • lipid inclusions (PHB)
20
Q

PHB

A

polyhydroxy butyric acid

21
Q

Functional inclusions

A
  • ex: take energy from iron and use it for themselves?
  • magnetosomes from magnetospirillum magneticum
  • cyanobacterial gas vacuole
22
Q

How do some bacteria respond to stress/heat/fryness/freezing/radiation?

A

by forming hardy endospores that are resistant to the stresses

23
Q

why sterilize things with an autoclave?

A

because the heat can kill the bacteria

24
Q

What kind of bacteria produces endospores?

A

gram positive
- clostridium and bacillus primarily

25
Q

what do vegetative cells do in response to stress?

A

start sporulation (takes several hours)

26
Q

What is sporulation?

A

spores form inside vegetative cell and then the cell body breaks apart, leaving the spore intact

27
Q

How to get rid of spores?

A

special sterilization techniques are needed

28
Q

what components of bacteria are good targets for antibiotics? What properties of a bacterial cell component make it a good antibiotic target?

A
  • peptidoglycan, cell, ribosomes (different), DNA/RNA replication, transcription, gyrase (unwind DNA in bacteria)
  • essential to cell viability and replication
  • is common in many/all bacteria
  • not present in human cells
29
Q

Biofilm physiology

A
  • Heightened
    resistance to antibiotics
    – Catheter infections
  • Very strongly adherent to surface
  • Plaque on teeth
  • Highly differentiated substructure
  • Anaerobic regions
  • Nutrient micropores
30
Q

Bacteria that is harmless on your skin, but dangerous if it gets on your heart? (for example)

A

Staphylococcus Epidermis

31
Q

How does biofilm cause cavities?

A

Bacteria at the bottom of the biofilm are not exposed to oxygen, so when they are exposed to sugars, they ferment and produce acids that degrade the teeth

32
Q

What are some significant morphological changes that species of bacteria go through?

A

Biofilm formation
- fruiting body formation (myxobacteria)
- caulobacter crescentus (stalked/swarmer transition)

33
Q

Most bacteria in the world are in… (about 90%)

A

biofilms (mostly mixed species biofilms)

34
Q

What are myxobacteria?

A

predatory bacteria
- fruiting body formation that is controlled by cell-cell contact, response to starvation
- individual cells also undergo morphogenesis into spores

35
Q

Caulobacter crescentus

A

great model for programs of cell differentiation

36
Q

cell cycle in bacteria

A
  • stalked cell attaches to a surface
  • elongates (pre-divisional cell)
  • asymmetrically divides
    -produces a cell without a stalk, but a single polar flagellum (swarmer cell)
  • swarmer uses flagellum to move on and attach somewhere else
  • turns into a stalked cell to continue the cycle

(swarmer never makes swarmer and stalked never makes stalked)

37
Q

What is quorum sensing?

A

coordinated behavior

38
Q

What bacteria have virulence quorum sensing?

A

S. aureus

39
Q

What bacteria have symbioses quorum sensing?

A
  • vibrio fischeri (that squid “Tom Kleindinst”)
  • euprymna scolopes
40
Q

What bacteria have horizontal gene transfer quorum sensing?

A
  • agrobacterium (crown gall - a cancer in plants)
  • enterococcus
41
Q

quorum sensing - autoinducer

A

Gram negative:
- lux I: makes the signal
- Lux R: site of binding to make a dimer?
- amphipathic ring with a fatty acid tail

Gram positive:
- peptides cant go across membranes so ComQ/X gives a way to send the signal across the surface?
- ComP auto-phosphorylates comA, activating transcription

42
Q

What things does the bacterium need to
do before and during division?

A
  • Divide cytoplasm in two
  • Replicate DNA
  • Partition critical cellular proteins, cofactors,
    substrates
  • Invaginate membrane(s), divide into two separate cells
43
Q

DNA replication in bacteria

A
  • circular genome
  • has an origin of replication
  • bidirectional replication
  • DNA pol III (dominant)
  • DNA pol I – okazaki
    fragments (dominant)
  • Topoisomerase - unwind DNA (gyrase for bacteria, also good for antibiotic target cause all bacteria have it)
44
Q

Binary fission

A
  • DNA replicates
  • partitioning of daughter strands
  • septum formation
    –FtsZ: related to eukaryotic tubulin
    – ring structure at nascent division site
  • membrane invagination
45
Q

fts

A

filamentous temperature sensitive

46
Q

What does mutagenesis result in?

A

FTS mutants

Microbiology (16 decks)

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