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PHGY - Midterm > MICRO - Week 1 > Flashcards

MICRO - Week 1 Flashcards

1
Q

Thiomargarita magnifica
Significance:
Size:
Fact:

A

Thiomargarita magnifica
Significance: Is the largest known bacaterium
Size: up to 2 cm in length
Fact: has chromosomes in membrane-bound organelles
> 500 000 genome copies per cell

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2
Q

What defines prokaryotes?

A

Bacteria and Archaea = Prokaryotes
- DNA in cytoplasm
- Lack membrane-enclosed organelles
- Single-celled

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3
Q

What defines Eukaryotes?

A
  • Eukarya
  • DNA surrounded by a nuclear membrane
  • Membrane-bound organelles (ER, Golgi …)
  • Single celled or multicellular
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4
Q

What region of a prokaryotic cell contains DNA?

A

The Nucleoid is a region of the cytoplasm that contains DNA

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5
Q

What is one key way that a bacterium structure differs from a eukaryote?

A

Cell wall

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6
Q

What are some structural features of a prokaryotic cells?

A
  • Capsule (in many)
  • Cell wall (in all)
  • Ribosomes
  • Plasma membrane
  • Nucleoid
  • Flagellum (some)
  • Inclusion bodies (All)
  • DNA
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7
Q

Archaea vs Bacteria
Similarities vs Differences

A

Similarities:
- structure
- metabolism

Differences:
- cell wall components
- types of lipids in the membrane
- transcriptional and translational components

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8
Q

What are some specifications of binomial nomenclature?

A
  • written Genus then species
  • name is italicized
  • capitalize the first letter
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8
Q

What is the key molecule is the bacterial cell wall?

A

peptidoglycan

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9
Q

Define: Strain

A

Strain: descendants of a single pure microbial culture
- have genetic differences

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10
Q

Define: Bacterial species

A

Bacterial species: a group of strains with similar properties

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11
Q

Can strains be different

A
  • Strains can have genetic differences
    Ex. E.coli can be safe, or it can cause foodborne illness
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12
Q

How can you identify prokaryotes?

A
  • Morphology or composition
  • Metabolism
  • Ecology (where they’re found)
  • Nucleotide sequences (16S rRNA, whole genomes)
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13
Q

What is the average size of a prokaryote?

A

1 um diameter

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14
Q

What is needed for light microscopy?

A

staining

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15
Q

Can you see prokaryotes macroscopically?

A

no, average prok is 1 um, human eye can see 0.1 mm

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16
Q

Staining
Simple vs Differential

A

Simple: size, shape, arrangement

Differential: differentiates based in type of cell wall (gram staining), other structures (capsules, flagella)

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17
Q

Why are there gram differences in gram staining

A

gram differentiation is due to the permeability differences in cell walls

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18
Q

Describe the process of gram straining?

A
  1. Crystal Violet - sticks to all cells
  2. Iodide - enhances the binding of the dye
  3. Alcohol - de-stains some of the cells
  4. Safranin - stains the de-stained cells

Results:
Gram positive = stained crystal violet
Gram negative = Stained by safranin

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19
Q

Provide examples of very large bacteria, and some benefits to being large?

A

Thiomargartia magnifica
- has long filaments up to 2cm

Thiomargartia namibiensis
- diameter: 100-750 um
- grows in linear chains

Large size may offer:
- more storage space
- less predation

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20
Q

Vey small bacteria
- name one
- diameter
- good/bad

A

Saccharibacteria
- 0.2 um in diameter

Parasitic
- live on other bacteria
- small genome, can’t make aa or vitamin

Common in oral cavity
- may protect against periodontal disease

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21
Q

Name and describe, provide example:
Morphology and Arrangements of bacteria

A

Cocci - spherical
- staphylococcus aureus

Bacilli - rods
- legionella pneumophila

Spirals
- campylobacter jejuni

Arrangements:
diplococci - two together
streptococci - chains
staphylococci - blobs

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22
Q

What impact does shape have on bacteria:

A

Shape impacts:
- motility
- pathogens
- ability to evade predators/immune system

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23
Q

What bacteria was used as an example for importance of shape…why?

A

Campylobacter jejuni
- has a helical shape that is important for motility
- demonstrated with a mutation that made it rod shaped - no longer infectious

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24
Q

Can bacteria change shape over time?

A

yes

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25
Q

What example of bacteria was given for changing shape?

A

uropathogenic E.coli
- lives inside the bladder
- can change from non-motile rods to mobile filament

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26
Q

What are bacteria that live in hot temperatures called?

A

Hyperthermophiles

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27
Q

Geogemma barossi - Significance

A

Example Hyperthermophile = geogrmma barosii
- grows at 120
- survives 10h in autoclaving
- unable to grow < 80

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28
Q

How to hyperthermophiles cope with the intense heat?

A

Membranes
- more viscous
- branched saturated fatty acids
Proteins
- more intermolecular interactions

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29
Q

What is bacteria called that lives in cold environments?

A

Psychrophiles: grow at low temperatures

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30
Q

Describe psychrophiles in terms of proteins and membrane?

A

Proteins
- makes cryoprotectants, antifreeze proteins (prevents ice from forming, protects membranes)
- proteins are more flexible (fewer H bond and ionic interactions)

Membranes
- have more unsaturated fatty acids

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31
Q

What is bacteria called that lives in acidic environments?

A

Acidophiles: grow at low pH

32
Q

Picrophilus torridus - significance

A

Picrophilus torridus
- is an acidophile
- can grow at pH 0

33
Q

How do acidophiles survive?

A
  • they keep their cytoplasm near neutrality, use a proton pump to get H+ out of cell
  • surface proteins are acid stable
34
Q

What are bacteria that live at a high pH called?

A

Alkaliphiles: grow at high pH, basic conditions

35
Q

Natronomonas pharaonis - Significance

A

Natronomonas pharaonis
- is an alkaliphile
- grows at pH 11

36
Q

What strategies do alkaliphiles use?

A
  • They keep their cytoplasm near neutral by increasing H+ uptake and retention
  • They produce acidic metabolites
  • Their extracellular enzymes work at high pH
37
Q

How many microbes does the average adult have?

A

10^13

38
Q

Define: Commensalism

A

Commensalism: one benefits, the other is not benefitted/harmed

39
Q

In what ways do microbes living in the human body benefit us?

A
  • Nutrient absorption
  • Vitamin production
  • Maintain immune system
  • Colonization resistance
40
Q

What is an intercellular habitat?

A

When bacteria lives within other cells

41
Q

What is an example of a bacterium that live intercellularly

A

Listeria monocytogens

42
Q

Define: Culturing

A

Culturing: The deliberate controlled growth or microbes

43
Q

What are the types of media that bacteria can be cultured in

A

Liquid media - ex. broth
Solid media - ex. agar

44
Q

What % of media can be cutured?

A

Approx. 1% of bacterial species can be cultured. Limited to what bacteria we can grow in the lab bc we don’t know what the cultures need to grow.

45
Q

Define: Pure Cultures

A

Pure Cultures: contain only one strain

46
Q

How can you isolate a pure culture?

A
  • Have a liquid mixed media culture
  • Put on solid media agar plate
  • Take pure colony you want and put it in a liquid growth media
47
Q

What is a colony derived from

A

Each colony is derived from a single cell

48
Q

Define: synthetic growth media
Benefits

A

Synthetic: of known composition
- can use to study nutritional needs
- less batch to batch variability

49
Q

Growth Media: Complex Media
Descibe

A
  • contains complex products from other organisms that are hard to define in terms of composition
  • can support many species
  • useful for bacteria with unknown nutritional requirements
50
Q

WTF is LB

A

LB = a common complex growth medium
contains:
- peptone
- yeast extract
- sodium chloride

51
Q

Define: differential growth media
Give example

A

Differential growth media: distinguishes between different kinds of bacteria
- doesn’t favor or disfavor certain species

Ex. Blood agar
- used to detect hemolytic bacteria
- hemolysis is a defining feature of some pathogens

52
Q

Define: selective media

A

Selective media: supports certain species, or inhibits certain species

53
Q

Tell me about MacConkey agar

A

MacConkey agar

Selective for Gram-negatives
- bile salts, crystal violet inhibits Gram-positives

Differential
- bacterial the ferment lactose make acidic products that turn the pH indicator red

54
Q

What disease is the leading cause of death?

A

Diarrheal

55
Q

Define: Growth

A

Growth: increase in number of cells

56
Q

What are the steps of binary fission? (Simple)

A
  1. Chromosome is replicated
  2. Cell elongates
  3. Septum forms, chromosomes partitioned
  4. Daughter cell forms
57
Q

What is FtsZ

A

FtsZ is a tubulin like protein that forms the Z ring in the middle of the cell. It’s involved in binary fission

58
Q

What is the divisisome?

A

Divisome: is a complex that forms at the Z ring during binary fission. The Z ring constricts invaginating the membrane, and the divisome makes septum (peptidoglycan)

59
Q

Name 2 other bacterial reproductive strategies aside from binary fission?

A
  • Budding (Listeria monocytogenes)
  • Spore formation (strept0momyces)
60
Q

Define: Generation time
What factors impact?

A

Generation time: time it takes a population to double

  • condition dependent
  • depends on species
61
Q

Define: Batch culture

A

Batch culture: closed vessel, single batch of medium deliberate growth of bacteria (medium is inoculated with bacteria)

62
Q

What are the 4 phases of growth in a batch culture

A

Lag Phase: metabolic activity is increasing, cells prepare to replication, and they adapt to the nutrients present in their environment

Log Phase: Exponential growth, grow as fast as possible

Stationary Phase: growth is off set by death

Death Phase: little nutrients and lost of waste, drives evolution bc only the strongest survive

63
Q

What is the y axis on a growth graph?

A

The y-axis is the log of viable cell count

64
Q

In the Log phase of cell division, cells divide as fast as possible according to:

A
  • species/strain
  • growth medium
  • conditions
65
Q

What are you counting in direct counting methods

A

Cells/mL

66
Q

Plate Counting - Define

A

Plate counting: add sample to agar plate, then count the number of colonies

67
Q

TF
1. Plate count only counts viable cells
2. Plate count counts individual cells
3. Plate counts give smaller counts than direct counts

A

TF
1. T - Plate count only counts viable cells
2. F - Plate count counts individual cells (Plate count counts colony forming units)
3. T - Plate counts give smaller counts than direct counts

68
Q

Name some of the plate count anomalies

A
  • plate counts give smaller counts than direct counts
  • Living vs dead
  • viable but not culturable
  • many species can’t be grown in lab
69
Q

If your sample is too dense to count what technique can you use?

A

Serial dilutions

70
Q

Growth (G) vs Cell mass (M)
indicate which is measured:
1. Cell mass
2. Dry weight
3. # genomic copies
4. Metabolic activity
5. Turbidity
6. Spectrometer

A
  1. Cell mass (G)
  2. Dry weight (M)
  3. # genomic copies (G)
  4. Metabolic activity (G)
  5. Turbidity (M)
  6. Spectrometer (M)
71
Q

How do cells cope with hypertonic conditions?

A
  • plasmolysis conditions cause membrane damage
  • dehydration slows growth
  • some bacteria make compatible solutes, to draw water in
72
Q

How do cells respond to hypotonic conditions

A

Mechanoselective channels: regulated by stretching of the cytoplasmic membrane
- when stretched the channel opens and solutes leave, this decreases the osmotic pressure

73
Q

Name the classification of bacteria based on the pH:
pH< 5.5
pH 5.5-8
pH> 8.0

A

Acidophile = pH< 5.5
Neutrophiles = pH 5.5-8
Alkaliphiles = pH> 8.0

74
Q

How do cells cope with pH changes?

A

They import or export protons

75
Q

There are 5 classifications of bacteria based on the temperature they live in…name them from coldest to warmest?

A

Psychrophiles
Psychrotrophs
Mesophiles
Thermophiles
Hyperthermophiles

76
Q

What is the name for bacteria that grows at the temperature of the fridge

A

psychrophiles

77
Q
A

PHGY - Midterm (10 decks)

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