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MBIO 1010 > Lecture 1: What is Microbiology? > Flashcards

Lecture 1: What is Microbiology? Flashcards

What is Microbiology?

1
Q

What is Microbiology?

A

Study of organisms too small to be seen with the naked eye
(bacteria, viruses, single-celled eukaryotes, fungi, algae)

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2
Q

the oldest form of life
largest mass of living material on Earth
carry out major processes for biogeochemical cycles
can live in places unsuitable for other organisms
other life forms require ______ to survive

A

microbes!

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3
Q

all cells have what things in common?

A

cytoplasmic membrane
cytoplasm (contains macromolecules, ions, proteins)
ribosomes (site of protein synthesis)

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4
Q

______:
membrane bound nucleus
membrane bound organelles
complex internal organization
divides by mitosis/meiosis

A

eukaryotes

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5
Q

what are the two major groups of eukaryotic microbes?

A

protists (unicellular or multi-cellular without differentiation into tissues)
fungi

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6
Q

what are the four types of protists?

A

protozoa (animal-like
microorganisms)
algae (photosynthetic plant-like microorganisms)
slime molds and water molds (filamentous)

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7
Q

what are the three forms of fungi?

A

yeasts- unicellular
molds- filamentous
mushrooms- multi-cellular

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8
Q

_________:
No membrane bound nucleus or organelles
Generally smaller (approx 1 µm diameter)
Simple internal structure
Divide by binary fission
Most are unicellular (if they’re multicellular, they’re not differentiated)

A

prokaryotes

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9
Q

what is advantageous about prokaryotes not having compartmentalization?

A

they’re smaller- so they’re super efficient!

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10
Q

what are the two major groups of prokaryotic microbes?

A

bacteria and archaea

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11
Q

_______:
Genetically diverse
Extremely diverse metabolic styles
Includes both pathogens and non-pathogens

A

bacteria

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12
Q

true/false: bacteria can change from a non-pathogen to a pathogen easily and fast

A

true! they change often and very quickly- think about the amount of division taking place (mutations)

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13
Q

_______:
Genetically and biochemically distinct from bacteria
Also have diverse metabolism
Never pathogenic
Most famous for living in extreme environments

A

Archaea

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14
Q

true/false: archaea are eukaryotes with some sort of adaptation

A

false! they’re often prokaryotes with some sort of adaptation

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15
Q

________:
Acellular infectious particles
Extremely small
Obligate intracellular parasites
Lack independent metabolism
* No ribosomes
* No ribosomal RNA
* Cannot be classified with other microbes

A

viruses

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16
Q

because viruses don’t have _____ they defy normal classifications schemes (how we compare/contrast other organisms)

A

ribosomal RNA

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17
Q

First anaerobic life appeared between
3.8 and 3.9 billion years ago

Photosynthetic bacteria oxygenated the Earth about 2 billion years ago
(Allowed the evolution of modern _______)

First plants and animals appeared about 0.5 billion years ago

A

eukaryotic microorganisms

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18
Q

how do we classify organisms based on evolutionary relationships?

A

by comparing small subunit (SSU) rRNA genes

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19
Q

_____: have 70S ribosomes,
16S SSU rRNA <- what’s compared!

A

prokaryotes

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20
Q

there are TWO protein subunits and they are NOT _____

A

additive

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21
Q

prokaryotes have 2 ribosomal subunits: ___S and ____S

A

30S and 50S, NOT additive (like a shoebox)

22
Q

_____: have 80S ribosomes,
18S SSU rRNA <- what’s compared!

A

eukaryotes

23
Q

eukaryotes have 2 ribosomal subunits: ___S and ____S

A

40S and 60S

24
Q

rRNA genes change ___ over time, we look at differences to identify/compare things that have evolved

A

slowly

25
Q

sequencing rRNA genes:
Step 1:
DNA is collected from a _____ culture

Step 2:
The SSU rRNA gene is amplified using the polymerase chain
reaction (PCR)

Step 3:
The gene is sequenced

Step 4:
Sequence is aligned with sequences from other organisms

A

pure

26
Q

______– a technique used to synthesize many identical copies of a short sequence
of DNA

A

PCR

27
Q

when sequencing rRNA genes- the number of ______ is used to calculate evolutionary distance

A

differences

28
Q

________ – A graphic representation of the evolutionary distance
between organisms

A

Phylogenetic tree

29
Q

the Tree of Life is a…

A

Phylogenetic tree based on 16S or 18S ribosomal DNA sequences

30
Q

what three groups can all organisms be assigned to within the Tree of Life?

A

Bacteria, Archaea, Eukarya
the 3 distinct domains of life

31
Q

Microorganisms are far more genetically diverse than plants and
animals, why?

A

they’re so simple that they can make more changes, they evolve faster and have more mutations

32
Q

what is a species?

A

Phylogenetic species concept:

“A group of strains that share certain diagnostic traits, are genetically cohesive and have a unique recent common ancestor”

33
Q

In practice, species of ____ and ______ should have:

Most (but not all) characteristics in common

Greater than 97% sequence similarity in the 16S rRNA gene

High degree of genome similarity
* DNA-DNA hybridization
(2 DNA strands from different organisms should anneal)

A

Bacteria and Archaea

34
Q

microbiologists use _____ classification

A

hierarchical, groups of organisms are placed in successively larger groups (species, genus, phylum typically used)

35
Q

5 rules for classification and nomenclature:

A
  1. Names are latinized
  2. Italicized or underlined
  3. Genus capitalized, epithet (species) is not
  4. Genus name may be abbreviated the second time it’s used: E. coli
  5. Trivial names can be used, but do not follow these rules
36
Q

_______:
The first to describe eukaryotic microbes

Used a compound microscope – uses 2 lenses
to magnify the image

Allowed magnification up to 30x

Used it to observe:
* Cells in cork
* Bread mold filaments – 1st microbe
* Beginning of cell theory – all living things are composed of cells

A

Robert Hooke

37
Q

_______:
Built microscopes that magnified specimen by 50-300x

Observed single celled microorganisms – called them “animalcules”

First discovery of bacteria (prokaryotic cells!)

A

Antoni van Leeuwenhoek

38
Q

________:
Studied wine and beer production

Yeasts convert sugar to alcohol in the absence of oxygen

Fermentation– “La vie sans air”

Bacteria can sour wine by converting alcohols to acid

A

Louis Pasteur

39
Q

Louis Pasteur developed a method of gentle heating to kill unwanted bacteria:

A

Pasteurization

40
Q

Pasteur tested Spontaneous Generation of cells-

Prepared meat infusions inside of long swan-necked flasks

Boiled the infusion to sterilize it

As long as the flask remains upright, dust and microbes cannot
enter, and the infusion remains sterile

Led to the development of methods for controlling the growth of
microorganisms (aseptic technique)

A

proved that cells CANNOT derive spontaneously, disproved the Spontaneous Generation theory

41
Q

______:
Studied anthrax– responsible for epidemics in livestock

He isolated bacteria from the carcass of a diseased animal –
Bacillus anthracis

Injected healthy animals with the bacterium

Animals became ill with anthrax

Re-isolated B. anthracis from the test subjects and showed that it was identical

A

Robert Koch

42
Q

Robert Koch established a set of criteria for relating a specific microbe to a
disease, they were called what?

A

Koch’s postulates

43
Q

Koch realized that ___ media provided a simple way to obtain pure cultures

A

solid

44
Q

Koch’s solid media was:
Broth medium solidified with agar
* Polysaccharide derived from _____
* Melts at ~ 97°C and polymerizes (solidifies) at ~ _____
* Cannot be degraded by most microorganisms
* Typical ______ = nutrient broth medium + 1.5% agar

A

marine algae
43°C
Petri plate

45
Q

nutrient agar contains:
______ (organic digest)- 5 g/L
______ (nutrience for bacteria)- 3 g/L
______ (ion gradience)- 5 g/L
______ (seaweed polysaccharide)- 15 g/L
then brought up to 1L with distilled water

A

Peptone
Beef extract
NaCl
Agar

46
Q

The _______ technique:
* One edge of a plate is inoculated with a
concentrated sample of bacteria

  • Sample is diluted by streaking it across the
    surface of the plate
    (To deposit individual cells on the plate)
  • Plate is incubated
  • Individual cells grow to form colonies
A

streak plate

47
Q

______ – a mass of cells that (ideally) arose from
one single cell
* Can be used to create a pure culture

A

Colony

48
Q

The ______ and ________ Techniques:

Sample is diluted before plating

Diluted sample can be spread over the surface of the plate with a sterile spreader
(Separate cells grow into colonies on the surface
of the plate)

Or can be mixed with molten agar (~ 45°C)

Colonies form embedded inside the plate

A

Spread Plate and Pour Plate

49
Q

Standard Plate Count:
Spread and pour plates allow you to calculate the concentration of
bacteria in a population (bacterial titre)

What is the formula?

A

titre= (# of colonies)/(volume)(dilution)

expressed in cfu/mL

cfu= colony forming unit

50
Q

through what range do we consider something a countable plate?

A

30-300 colonies
under 30= not statistically sig.
over 300= inaccurate counts

calculate titre and average all countable plates

MBIO 1010 (12 decks)

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