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1

Microbe

An organism that is a single cell for most or all of its life

2

Approximately how many microbes are on earth?

9.2 x 10^29 - 3.2 x 10^30

3

How many species of microbes have been described to date?

5000

4

What is the Human Microbiome Project?

34 trillion microbes live in and on us - in 2008, we tried to classify them by what attributes they give us health-wise

5

How many species of microbe are associated with the health of an individual?

10,000

6

Who utilized the "modern" microscope? And why was it modern?

Robert Hooke
It was modern because it was compound

7

What book did Robert Hooke publish?

Micrographia

8

What was Antony van Leeuwenhoek's microscope? What type of microscope did he use?

A simple microscope- very small, with 50-300x magnification
He used dark-field illumination

9

What did Tyndall find?

That bacteria can be carried on dust, and it can be highly heat resistant

10

What did Ferdinand Cohn discover?

Bacterial endospores
-Found that they were highly heat resistant and had implications for human health

11

Who developed early culture techniques and a classification system for bacteria?

Ferdinand Cohn

12

What did Redi, Needham, and Spallanzi look at? How did their experiments differ?

They all looked at spontaneous generation
Redi: Maggots do not spontaneously arise on meat
Needham: Looked at microorganisms- Boiled mutton, cooled flasks, and stoppered them tightly
Spallanzi: Stopped flasks before boiling

13

What are some main contributions Louis Pasteur made?

Sterilization (Pasteurization), Vaccine for rabies, anthrax, and cholera, contributions to wine and silk industry

14

When was disease still considered supernatural?

Before the 1800's

15

Who realized pathogens can be passed between people?

Semmelwise
-Realized that mothers giving birth via doctor contracted more streptococcal infections that via midwife

16

Who introduced aseptic surgery techniques?

Lister

17

Who was Robert Koch? What did he contribute?

Established Bacillus cause anthrax
Established Mycobacterium cause tuberculosis
Nobel prize 1905
Koch's Postulates

18

What are Koch's postulates?

1. Pathogen must be present in all cases
2. Pathogen must be purely cultured
3. Pathogen from pure culture must cause disease in healthy animals
4. Pathogen must be isolated and cultured from the newly infected/sick animal again

19

What are some cellular organisms studied by microbiologists?

Fungi, Protists, Bacteria, Archaea

20

What are some acellular organisms studied by microbiologists?

Viruses, Viroids, Virusoids, Prions

21

What are properties that ALL cells have?

Metabolism, Growth, and Evolution

22

What are properties of SOME cells?

Differentiation, Communication, Genetic exchange, Motility

23

What are the 3 domains?

Eukaryotes, Archaea, Bacteria

24

What is the pseudonym for DKPCOFGS?

Dear King Philip Came Over From Great Spain

25

What is the mnemonic order of taxonomy?

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

26

Bacteria

Usually single celled
Lack internal structures
No true nucleus

27

Archaea

Unique membrane composition- Lacks peptidogylcan
Initially grouped with bacteria
Extremophiles
rRNA sequences led to the separation

28

Eukarya

Organelles
Protists and fungi
Larger than most bacteria

29

LUCA

Last Universal Common Ancestor

30

Who came up with the endosymbiont hypothesis?

Lynne Margulis, 1967
Interaction between 2 organisms where 1 lives inside the other

31

How do we define specific microorganisms?

Collection of strains sharing many properties that differ significantly from other groups of strains

32

What are the 4 different types of strains?

Biovar, Morphovar, Serovar, and Pathovar

33

Biovar

Physiological properties

34

Morphovar

Morphological properties

35

Serovar

Can be detected by antibodies

36

Pathovar

Cause different diseases in different places

37

When were microbes first visualized?

1600's

38

Human eye resolution

200-300 um

39

Light microscope resolution

200 nm

40

Bacteria

1-3 um

41

Atom

0.1 nm

42

Animal cell

50 um

43

How do you define the limit of resolution?

When 2 dots are distinctly 2 dots (just distinct)

44

What is the formula for resolution?
*Keys of microscopy are resolution and magnification*

0.61 wavelength / NA
NA= numerical aperture= nsinø, where n is the refractive index

45

When were spectacles first used?

13th century

46

Who built the first compound microscope?

Janssen

47

Pros and cons of bright field microscopy?

Pro: Can be alive
Con: Can stain structures

48

Pros and cons of dark field microscopy?

Pro: Improved observation of internal structures b/c direct light does not enter the eyepiece

49

Phase contrast microscopy

Shift the phase of light 1/2 wavelength out of phase to exaggerate difference in light
-gives a look at many dimensions within the cell
-3D

50

Fluorescent microscopy

Specimen is stained or tagged with F.
First filter removes short wavelengths, light hits the specimen, emit long wave rads, and dichromatic mirror lets through the longer wavelengths and reflects shorter ones

51

Confocal microscopy

Allows you to focus on 1 plane of the specimen

52

Electron microscopy

Specimens must be dead, it is expensive, and a lot of preparation, but MUCH higher resolution: 0.2nm

53

Scanning electron microscope

Excellent depth of field
Resolution: 10nm

54

What is STEHM?

Scanning Transmission Electron Holography Microscope

55

Cocci bacteria

-Spherical
-Clusters or single
-How they cluster is used for identification

56

Rod (Bacilli) bacteria

-Pairs, chains, or clusters
-Shape of the end varies
-Ex: E.Coli

57

Vibrios

-Comma shaped
-Similar to rods
-Indicative of cholera

58

Spirilla

-Spiral shaped
-Have tufts of flagella

59

Spirochetes

-Spiral shaped
-Internal bacteria

60

Budding/Appendages

-Long processes or appendages of the cell

61

Filamentous

-Bacteria form long filaments called hyphae
-They are pleomorphic (can form other structures)

62

Why is small size important for bacteria?

To maintain a good Surface Area : Volume ratio

63

Extrachromosomal DNA

-Some bacteria have DNA outside their nucleus
-We can manipulate this DNA

64

Plasma Membrane

-Defines the cytoplasm
-Barrier to molecules
-Lipid bilayer
-Has some proteins embedded (integral membrane proteins)
-Some proteins attached (peripheral membrane proteins)
-Fluid mosaic model

65

Lipids

-Amphiphilic (1 hydrophobic, 1 hydrophilic)
-Phospholipids based on glycerol
-Polar head groups exposed to aqueous environment

66

Plasma membrane function

-Permeability
-Protein anchor
-Energy conservation

67

Simple diffusion

-Concentration gradient (high to low)

68

Facilitated diffusion

-Concentration gradients via protein transport

69

Cell envelope

-Plasma membrane & all external layers
-Innermost membrane
-Selectively permeable
-Fluid mosaic model
-Large # of metabolic processes associated with this

70

Bacterial cell wall

-Determines shape of cell & protects against osmotic cell
-May contribute to pathogenicity
-Target of many antibiotics
-Differentiates gram positive and negative

71

Peptidoglycan structure

-Found in gram + and - cells
-Built from identical subunits

72

Gram negative peptidoglycan layer is _____ nm thick

2-7

73

Gram positive peptidoglycan layer is _____ nm thick

20-80

74

Peptidoglycan subunits

-Long string of NAG-NAMs w/ lots of peptides sticking out
-Cross-linking between NAG-NAMs (covalent bonds) - Used to classify organisms

75

Gram positive cell walls

-Thick cell walls - mainly peptidoglycan
-Rich in teichoic acids
-Glycerol/Ribitol linked via phosphoral groups to other acids
-Peptidoglycan layer is porous
-Narrow periplasmic space

76

Bacterial intra-cytoplasmic membrane

-Some bacteria have it
-Inclusions are aggregates- organic/inorganic material that can be membrane bound or free in the cytoplasm
-Inclusions often used to store molecules

77

Poly-b-hydroxybutyrate (PHB)

-Way to store energy
-Method of storing carbon
-Repeating building blocks
-Bacteria can use these to store carbon and energy
-Monomer units linked by ester bonds

78

Bacterial flagella

-Motility
-Secretes proteins
-Consists of basal body, hook, and hollow filament
-External components through filament
-Can spin and move at rapid rates
-Can't see them without adding a flagella stain

79

Gram negative cell walls

-Very thin layer of peptidoglycan
-Very thick periplasm
-Phospholipids, proteins, lipoproteins, and lipopolysaccharides

80

Lipopolysaccharides

-3 parts:
-Core polysaccharide
-O-specific polysaccharide
-Lipid A
-Negatively charged
-Protects cells from host invasion

81

Archaeal flagella

-Not hollow
-No secretory system

82

Motility

-Move towards food & away from danger
-Movement can be directional, up/down a gradient, or either an attractant or repellent
-Can develop signalling
-Flagellum is a rigid helix that rotates & allows for movement

83

Chemotaxis

-Chemo-sensing system linked to signalling pathway
-May respond to signals present in nM concentrations

84

Twitching motility

-Short, jerky motions
-Cells must be in contact with one another

85

Gliding motility

-Sliding, smooth
-Lays down a slime & slides against it

86

Gram staining

-Type of differential staining
-Differentiate organisms by thickness of peptidoglycan layer (thick in +, thin in -)

87

Acid-fast staining

-Stain is driven into cells with heat
-For acid-fast cells, acidified alcohol cannot wash away the stain

88

Endospore staining

-Stain is driven in with heat, the decolorization, then counterstaining with safranin

89

Capsule staining

-Cells with a polysaccharide capsule will not take up India ink

90

Flagella staining

-Increase the thickness of flagella so that they can be seen under a microscope

91

S layers

-Layer made of protein or glycoprotein
-Binds to outer membrane in gram negative cells
-Binds to peptidoglycan surface in gram positive cells
-Protection, shape maintenance

92

Fimbriae and Pili

-Proteins that extend from the outer membrane
-Roles in DNA uptake, motility, and conjugation

93

Bacterial endospores

-Gram + bacteria
-Exist within cells
-Peptidoglycan layer becomes cortex
-Not all endospores successfully germinate
-Formed through asymmetric replication
-Have no activity - everything it needs is inside it

94

Asymmetric replication

-2 different types of cells
-Mother cell gets one copy of DNA and then dies
-Get 1 cell in the end

95

Nucleoid

-Irregularly shaped region that contains the chromosome and associated proteins (no membrane)

96

Plasmids

Extrachromosomal, linear, or circular
-Cells may contain multiple copies or even types of these
-Replicate autonomously (don't contain DNA essential to the host)
-Metabolic function and antibiotic production

97

Eukaryotic microbes

-Chromosomes are membrane-bound
-Organelles allow internal compartmentalization
-Divided into protists and fungi
-Fungi are monophyletic, while protists are not
-Nucleus is composed of a double membrane and is quite large

98

Microtubules

-Composed of alpha (-) and beta (-) tubules
-Maintain cell shape
-Cell motility
-Role during cell division

99

Microfilaments

-Composed of actin
-Cell shape and motility

100

Intermediate filaments

-Fibrous keratin
-Cell shape and organelle position