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microbio > lecture 1 > Flashcards

lecture 1 Flashcards

1
Q

What are the types of microbial cells?

A

bacteria archaea and eukerya

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2
Q

how was the orgins of life identified?

A

Carbon dating
Fossils
Molecular fossils - hopanes

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3
Q

what was the oxygen revolution?

A
  • Caused the extinction of some prokaryotes
    Some groups survived anaerobic environments
    Others adapted using cellular respiration to harvest energy - endosymbiosis
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4
Q

how do the three domains increase diversity?

A
  • Eukaryotes increase diversity through sexual reproduction
  • Bacteria and archaea increase the gene pool through horizontal gene transfer
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5
Q

what was endosymbioisis?

A
  • Endosymbiosis is when one organism lives inside another, which leads to the formation of mitochondria, chloroplasts, and hydrogenosomes
  • These organelles have DNA and ribosomes similar to bacteria, showing they evolved from bacteria that were absorbed by larger cells.
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6
Q

What are the characteristics of Domain bacteria?
- single or multi-celled?
- what structure do most bacteria have?
- what cellular features do bacteria lack?
- what environment do they live in?
- effects?
- the typical structure of chromosomes?
- common lipid found?

A
  • usually single celled
  • Most have cell walls with peptidoglycan
  • Most lack a membrane-bound nucleus
  • Live in extreme environments (including our bodies - microbiome)
  • Both disease-causing and non-disease causing exist
  • Chromones - usually one circular chromosomes that have a single origin of replication, some are polyploid
  • ester linked phospholipids
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7
Q

What are charchteristics of Archea?
- What distinguishes this group from bacteria at the molecular level?
- What type of environments do many organisms in this group inhabit?
- Do organisms in this group cause diseases in humans?
- What is the structure of the chromosomes found in these organisms?
- What is one unusual characteristic of the metabolism of some organisms in this group?
- plasma membrane?
-

A
  • Distinguished from bacteria by unique rRNA sequences
  • Have unique membrane lipids
  • Some have unusual metabolic characteristics
  • Many live in extreme environments
  • Do not directly cause disease in humans
  • One circular chromosome, some have chromosomes with multiple origins of relocations, some are polyploid
  • Plasma membrane lipids: glycerol diethers and diglycerol tetraethers
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8
Q

What are the characteristics of Eureka? Two types?

A
  • membrane-enclosed nucleus
  • Larger and more morphologically complex
  • Chromosome: multiple and linear with multiple origins of replication - usually a diploid
  • Plasma membranes - ester-linked phospholipids and sterols
  • protest and fungi
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9
Q

What are the characteristics of protists?
- cellular type?
- two types?

A
  • unicellular, generally larger than bacteria and archaea
  • Protoza- animal-like metabolism
  • Algae - photosynthetic
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10
Q

what are the characteristics of fungi?
- cellular type? examples?

A
  • Unicellular (yeast) or multicellular (molds and mushrooms)
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11
Q

what is the use of 16s rRNA gene sequence analysis?

A
  • It is responsible for the initiation of protein synthesis and stabilization of correct codon to anticodon pairing
  • Carl Woese pioneered the use of RNA nucleotide sequences to classify and identify organisms
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12
Q

why do we use 16s rRNA?

A
  • It is a highly conserved genetic sequence in bacteria and archaea and is present in all strains
  • Can find where certain species have diverged by aligning sequences and finding small differences
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13
Q

what did robert hooke do?

A
  • made a compound microscope and illumination system
  • made the word cell
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14
Q

Who created the term animalcules?

A

Dutch biologist Antin van Leeuwenhoek (observed single-cell organisms)

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15
Q

What is sponentenous generation?

A
  • that living organisms can develop from nonliving or decomposing matte
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16
Q

Who were the scientists that tried to discredit spontaneous generation?

A
  • Francesco Redi - showed maggots decorating meat came from fly eggs by comparing three jars (corked, gauze, open)
  • Lazzaro Spallanzani - discredited Needham observations - Proved that the hay itself did not make microorganisms if in a sealed environment
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17
Q

Which scientist approved of spontaneous generation?

A
  • john needham
  • Based on observations that boiled hay gave rise to microorganisms, he stated that some extracts have what it takes to confer life from nonliving material
18
Q

Which scientist conducted the swan neck experiment?

A
  • Louis Pasteur
  • disapproved spontaneous generation
  • a flask with the broth was heated (sterile), broke the neck of one, and left one intact
  • the broken neck had growth and intact did not have growth
19
Q

What did Louis Paster discover?

A
  • microorganism cause fermentation and disease
  • pasteurization
  • vaccine for anthrax and rabies
20
Q

What did Robert koch do?

A
  • founded modern biology
  • evidence for the germ theory (susceptibility - infecting agent, environment, host)
21
Q

What was Koch’s experiment?

A

1.) microbe has to be in every case and not in healthy organisms
2.) microbe is isolated and grown on pure culture
3.) has to cause the same disease when added to a healthy host
4) has to be isolated from the diseased host

22
Q

what were limitations of koch experiment?

A
  • Some organisms cannot be grown in pure culture because they rely on host cells
  • Possible lack of an animal model - can’t use human subjects
23
Q

edward jenner

A

vaccine for smallpox

24
Q

Joseph lister

A
  • indirectly said microbes caused disease
  • antiseptic surgery system
  • lactic fermentation -> milk souring
25
Q

Alexandr fleming

A

pencilin

26
Q

First microscope?

A
  • light microscope which magnified objects through a lens
27
Q

bright-field microscope

A
  • Dark image on a light background
  • Used to examine both stained and unstained species
28
Q

dark field microscope

A
  • Light image on a dark background
  • For living, unstained preparations. Used to observe internal structures of eukaryotic cells
29
Q

Phase contrast microscope

A
  • Deviated and undeviated light are combined in a condenser to generate a more detailed image
  • Can see microbial movement and detect structures
  • Can observe living cells no fixing or staining required
30
Q

Differential interference contrast (DIC) microscope

A
  • Adds contrast to look at cell walls, endospores, granules, vacuoles and nuclei
31
Q

fluorescence microscope

A
  • Labeled probes are added to specific cell constituents
  • Produced image by exciting a specimen with a wavelength of light that triggers the object to emit fluorescence light
  • Can show localization of specific proteins in cells
32
Q

Confocal microscope

A
  • Uses a laser beam to illuminate a fluorescently labeled specimen
  • Creates a sharp composite 3D image of specimens’ special aperture that eliminates stray light
  • Can be used to study biofilms
33
Q

what is fixiation in terms of Preparation of specimens ?
heat fixation?
chemical fixation?

A
  • Preserves internal and external structures by inactivating enzymes that can disturb cell morphology
  • Heat fixation - preserves overall morphology but destroys subcellular structures
  • Chemical fixation - protects fine cellular substructures and morphology
34
Q

what is Staining?
fixing?

A
  • Increases visibility and detect the presence or absence of structures
  • preserve on slide
35
Q

Electron microscopy

A
  • Uses electrons as a beam to see very small organisms
  • The wavelength is 100,000 shorter than visible light making a higher resolute image
  • Allows for microbial morphology to be studied
36
Q

Scanning electron microscopy

A
  • Uses a stream of electrons excited from the surface of a specimen p to create a details image, and it makes a realistic image inthe 3D form of a surface image
  • gives information about the sample surface and its composition
37
Q

transmission electron microscopy

A
  • A focused beam of electrons passes through the specimen to form the image
    -clearer image
  • information on the inner structure of the sample
38
Q

Cyro-electron microscopy

A

Samples are rapidly frozen, and images are captured at different angles to make a 3D image
- visualize biomolecules (proteins) and generate high resolution structures

39
Q

Scanning probe microscopy

A
  • Measures surface features of an object by moving a sharp probe over the surface of an object
  • Can view atoms on the surface of a solid
40
Q

Atomic force microscopy

A
  • Up and down movement of the sharp probe as it maintains constraint distance from the specimen
  • The deflection of a laser beam that strikes the level holding the probe is measured
41
Q

selective media vs differential media

A
  • allows the growth of a particular microbe while inhibiting the growth of others (McConkey agar test)
  • distinguish among different groups of microbes and identify based on bio characteristics

microbio (5 decks)

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