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Microbiology 265 > Week 1- Intro to Microbiology > Flashcards

Week 1- Intro to Microbiology Flashcards

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1
Q

Microorganisms split into how many groups ?

A
  1. Acellular : Don’t replicate independently

2. Cellular : Replicate independently and have DNA in a membrane

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2
Q

Acellular

A

Viroids- smallest infectious material. They are short circular RNA
Viruses: Protein rich with RNA or DNA
Prions: Infectious proteins

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3
Q

What are the two types of cellular microroganisms ?

A

Prokaryotes : Have no nuclear membrane. Archaea and Bacteria

Eukaryotes: DNA is in a nuclear envelope. Algae, Protozoa, Fungi

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4
Q

Fungi

A

Eukaryote.

Yeast, molds, and mushrooms. Very diverse

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5
Q

Algae

A

Eukaryote.

Photosynthetic aquatic organisms.

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6
Q

Protozoa

A

Eukaryote.

Free living or parasitic microorganisms that feed on organic matter.

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7
Q

Archaea

A

Prokaryotes.

Similar in size and shape to bacteria, the transcription/translation/metabolism is similar to eukaryotes.

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8
Q

Bacteria

A

Prokaryotes.

Most have a peptidoglycan cell wall and nucleoid ( ball of DNA)

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9
Q

Components of a Prokaryotic Cell

A
  • Cell wall
  • Cytoplasmic membrane
  • nucleoid
  • cytoplasm
  • plasmid
  • ribosomes
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10
Q

Components of a Eukaryotic Cell

A
  • Cell wall
  • Cytoplasmic membrane
  • Mitochondria
  • Nuclear Membrane
  • Nucleus
  • Ribosome
  • Endoplasmic Reticulum
  • cytoplasm
  • Golgi Complex
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11
Q

What is a cell and its defining features ?

A
  1. Structure : All cells have a cytoplasmic membrane, cytoplasm, a genome, and ribosomes.
  2. Metabolism: Use info in DNA to make RNA and protein. All cells take up nutrients and turn it into energy. (Anabolic and Catabolic)
  3. Growth: Cells can self-replicate and divide to grow. Proteins do the work.
  4. Evolution: Can evolve and mutate based on the environment.
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12
Q

Special properties of some cells

A
  1. Differentiation: Cells can take on different forms, or form new structures.
  2. communication: Cells interact with each other by chemical messengers.
  3. Motility: Some cells can self-propel.
    4 Horizontal Gene Transfer: Can share DNA/ Nucleic Acids.
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13
Q

Cell Size and Visualization with a microscope

A

0.2 nm –> electron microscope
0.2 um –> light microscope
100 um –> Visible microscope

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14
Q

Bacterial Cell Shape

A 
Cocous (sphere)
Rod(s) 
Spirillum
Spirochete
Stalk/Hypha 
Filamentous
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15
Q

What is a Unicellular organism ?

A

An organism that performs all of life’s functions for itself.

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16
Q

What is a Multicellular organism?

A

An organism that depends on other cells for survival.

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17
Q

Origin of Life

A

Life started with self-replicating RNA, the RNA also acted as an enzyme which was used to catalyze reactions.
The RNA ended up in a lipid bilayer which created the first type of cells.

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18
Q

RNA World Theory

A

life started with self replicating RNAs and liposomes ( creating prehistoric cells)

the cells developed into DNA containing bacteria
archeoeukarya were made
some archeoeukarya developed an endosymbiotic relationship with mito, which lead to the separation of archaea and eukaryotes.

19
Q

Endosymbiotic Theory

A

-How mitochondria and chloroplasts evolved.
The larger bacteria engulfed smaller bacteria, mitochondria came from bacteria which used O2 for energy and chloroplasts came from bacteria which used sunlight for energy.

20
Q

Endosymbiotic Theory: Evidence

A
  1. Mitochondria and chloroplasts have their own DNA and ribosomes which are similar to that of bacteria
  2. Mitochondria and chloroplasts replicate on their own, in a similar way that bacteria do.
21
Q

Spontaneous Generation

A

The sudden appearance of bacteria when there was none before.

22
Q

Disproving spontaneous Generation

A

Louis Pasteur
Poured a non-sterile liquid into a flask, he heated the neck of the flask with a flame to kill all the bacteria. He also heated up the liquid in the flask to kill all the bacteria. If he left the flask up right and the liquid did not touch the neck no bacteria grew. If the flask was tipped over the liquid was contaminated with the dust and bacteria that collected in the neck.

23
Q

Disproving Spontaneous Generation Explained

A

The upright flask had no bacteria grow because the liquid was not contaminated by the microorganisms that got trapped in the neck. in the flask that was tipped over the liquid was contaminated by the microorganisms in the neck. The microorganism were not spontaneously generated or else we would have seen them in the liquids in both flasks.

24
Q

Germ Theory of Disease

A
  • Evidence that bacteria cause a disease.
  • states that many diseases are caused by specific bacteria.
  • Koch’s postulates establish a causal link between the organism and disease.
25
Q

Koch’s Postulates

A
  • focused on growing the organism
    1. The microorganism should be found in all infected organisms but not in healthy organisms
    2. The microorganism must grow when isolated on agar (pure culture)
    3. Cells from the culture should cause the same disease when injected into a healthy animal
    4. The microorganism has to be re-isolated and re-grown in pure culture and look the same as the original plate.
26
Q

Modified Koch’s Postulates

A
  • focused on nucleic acid
    1. The nucleic acid sequence of the pathogen should be found in affected hosts and not in healthy hosts.
    2. There should be no nucleic acid sequence found in hosts without disease.
    3. When healed there should be little to no trace of the nucleic acid sequence, but if the disease occurs a second time then the opposite occurs.
    4. ???
    5. Similar microorganisms should cause similar diseases.
    6. ???
    7. The sequence based evidence should be reproducible
27
Q

Taxonomic Classification

A

Life, Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

28
Q

16S Ribosomal RNA

A

This is an important part of the ribosome and it is conserved across all organisms. There are variable regions which change based on the organism.

29
Q

Robert Hooke

A

-Wrote the first book dedicated to microscopic observations in 1665, mostly on fruiting structure of molds.

30
Q

Antoni van Leeuwenhoek

A

first person to see bacteria using a microscope

31
Q

Magnification

A

Degree to which an image is enlarged

32
Q

Resolution

A
  • Ability to distinguish adjacent objects as separate and distinct.
  • It is affected by the wavelength of light, the longer the wavelength the lower the resolution.
  • Limit for light microscopy is 0.2 um
33
Q

Contrast

A

Ability to see an object distinct from it surroundings

34
Q

Steps involved in Staining

A
  1. Prepare culture: Spread culture thin, and air dry
  2. Heat fixing & Staining: Use flame to heat fix and denature proteins so they stick to the slide. Add in liquid stain.
  3. Microscopy: Look at the slide
35
Q

Steps in Gram Staining

A
  1. Heat fixed cells are flooded with crystal violet which penetrates the cell and makes them all purple.
  2. iodine is added, which helps the CV form crystals/structures to help the cells stay purple
  3. Alcohol is added to wash away the colour. Gram negative bacteria are Colourless due to the thin peptidoglycan layer and Gram positive bacteria stay purple due to the thick peptidoglycan layer.
  4. Safranin is added as a counterstain it turns all the Colourless (gram negative) bacteria a pink colour
36
Q

Dark Field Microscopy

A

Light comes from the side, and the specimen reflects light into the objective lens

  • observes motility
  • has a dark background
  • better resolution than light microscope
37
Q

Phase contrast Microscopy

A

Light passing through a cell differs in phase than light passing through the surrounding liquid, the difference in phase is amplified by the phase ring which gives a dark image on a light background.

  • usually have a grey background
  • can be used to view motility because the bacteria are not heat killed
  • no, need to stain, best for transparent specimen
  • can see some internal structure
38
Q

Bright field/ Light Microscopy

A

Light source shines on the specimen from the bottom

  • has a light background
  • uses a stain to view specimen
  • cant see movement because the proteins are denatured
39
Q

Fluorescence Microscopy

A

Photons are absorbed and this causes electrons to become more excited and they move to a higher energy state, when the electrons relax they emit a photon called fluorescence.

  • a dark background with many colors
  • DAPI is used to stain DNA (nucleoids)
  • kind of messy due to the light emitting at the 3D image
40
Q

Confocal fluorescence Microscopy

A

A laser scans the specimen in different planes, and the planes can be assembled into a 3D image. The cells struck by the laser will fluoresce.

  • a better resolution, as the images are taken in different planes
  • images from different planes can be put together to create a 3D image
41
Q

Electron microscopy

A
  • uses electrons rather than light
  • electrons have a shorter wavelength than light
  • shorter wave length = higher resolution, 1000X better than light microscopes
  • electrons are larger than photons
  • electrons can’t penetrate large objects so it’s able to visualize proteins but not cells.
42
Q

Scanning electron microscopy

A

Detector is at the side, and the electrons come form the side

  • used to view cells
  • specimen get coated with gold
43
Q

Transmission electron microscopy

A
  • cells are sliced thinly to view
  • used to view proteins
  • thin sections get stained
  • can view outside of cells w/o cutting
  • can see structures at the molecular level
  • detector is at the bottom

Microbiology 265 (7 decks)

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