Microbiology First Exam

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Microbiology
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Hooshdaran
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1

What benefits do microorganisms provide?

Decompose organic wastes

Producers in the ecosystem by photosynthesis

Produce industrial chemicals (ethyl alcohol and acetone)

Produce fermented foods such as vinegar, cheese and bread

Food preservation, flavor, biochemical recycling, vitamins

2

What harm do microorganisms cause?

Disease

Food blights

Spoilage

3

What is genus?

The first name in the scientific bi-nomenclature that is capitalized.

4

What is specific epithet (species)?

The second name in the scientific bi-nomenclature that is not capitalized.

5

Who established the system of scientific nomenclature?

Carolus Linnaeus in 1735

6

What does a scientific name tell us about the organism for which it is named?

It may be descriptive of the organism or it may honor a scientist.

7

What are the main groups of microorganisms?

Prokayotes

Viruses

Eukaryotes

8

Who identified the 3 domains of microorganisms and when?

Carl Woese in 1978

9

By what method are microorganisms classified in the 3 domains?

It is based on ribosome RNA (protein factory).

10

What are the characteristics of bacteria?

Prokaryotes

Peptidoglycan cell walls

Binary fission

Use organic chemicals or photosynthesis for energy

11

What are the characteristics of archaea?

Prokaryotic

Lack peptidoglycan

Live in extreme environments

Include: methanogens, extreme halophiles, extreme thermophiles

12

What are the characteristics of fungi?

Eukaryotes

Chitin cell walls

Use organic chemicals for energy

Includes molds, mushrooms and yeast

13

What is mycelia?

Multiple hyphae

14

What is hyphae?

The filaments that make up mycelia.

15

Which type(s) of fungi have mycelia?

Molds and mushrooms

16

What are the characteristics of protozoa?

Eukaryotes

Absorb or ingest organic chemicals

May be motile via pseudopods, cilia, or flagella

17

What are the characteristics of algae?

Eukaryotes

Cellulose cell walls

Use photosynthesis for energy

Produce molecular oxygen and organic compounds

18

What are the characteristics of viruses?

Acellular

Consist of DNA or RNA core

Core is surrounded by a protein coat

Coal may be enclosed in a lipid envelope

Are replicated only when they are in a living host cell

19

What is classified under domain eukarya?

Protists

Fungi

Plants

Animals

20

Who described "little boxes" or "cells" and is credited with the beginning of the cell theory of life (all living things are composed of cells)?

Robert Hooke in 1665

21

Who was the first to observe live mircroorganisms 'animalcules" and is called the "Father of Microbiology"?

Antoni van Leeuwenhoek in 1673

22

Who heated broth in open flasks with s-shaped necks disproving the spontaneous generation theory?

Louis Pasteur in 1861

23

What is biogenesis?

All cells arise only from preexisting cells.

24

What is aseptic technique?

The most important techniques that all microbiologists use. The methods that prevent contamination by unwanted microorganisms.

25

What is Pasteurization?

Heating which kills pathogens but does not damage the food (milk). This application of a high heat for a short time.

26

What is the difference between sterilization and Pasteurization?

Sterilization kills the pathogen and the host; Pasteurization only kills the pathogen.

27

Who showed that a silkworm disease was caused by a fungus?

Agostini Bassi in 1835

28

Who believed that another silkworm disease was caused by a protozoan?

Louis Pasteur in 1865

29

Who advocated handwashing to prevent transmission of puerperal fever from one OB patient to another?

Ignaz Semmelwise in 1840s

30

Who used a chemical disinfectant to prevent surgical wound infections after looking at Pasteur's work showing microbes are in the air, can spoil food and cause animal disease?

Joseph Lister in 1860s

31

Who provided proof that a bacterium causes anthrax and provided the experimental steps used to prove that a specific microbe causes a specific disease?

Robert Koch in 1876

32

What are Koch's postulates?

Pathogen must be present in all cases of disease

Pathogen must be isolated and grown in lab in pure culture

Pathogen from pure cultures must cause disease when inoculated into healthy, susceptible lab animals

Same pathogen must be isolated from the diseased lab animal

33

Why are Koch's postulates used?

To look for the cause of a specific disease

34

Who inoculated a person with cowpox virus and as a result, the person was protected from smallpox.

Edward Jenner in 1796

35

What is the protection from a disease called?

Immunity

36

Who discovered the first antibiotic?

Alexander Fleming in 1928

37

What is the name of the first antibiotic?

Penicillin - made from the fungus Penicillium

38

When was penicillin tested clinically and mass produced?

In the 1940s

39

What is total magnification?

Objective lens x ocular lens

40

What is resolution?

The ability of the lenses to distinguish two points.

41

In a microscope, what is either reflected, refracted or absorbed?

Light

42

Why is immersion oil used?

To keep light from bending

43

What kind of microscope has only one lens?

A simple microscope

44

In which type of microscope is the image magnified by the objective lens and then again by the ocular lens?

A compound microscope

45

What type of microscope shows a dark image against a brighter background?

A Bright-field mircroscope

46

True or false. In the bright field microscope, light reflected off the specimen does not enter the objective lens.

True

47

Which concept accentuates diffraction of the light that passes through a specimen and where direct and reflected light rays are combined at the eye?

Phase-Contrast Microscopy

48

Which concept uses UV light and cells may be stained with fluorescent dyes (fluorochromes)?

Fluorescence Microscopy

49

Where is fluorescence microscopy used regularly?

In the hospital

50

Using the fluorescent microscopy, how can you tell if a Syphilis test is positive or negative?

Green means positive and yellow means negative

51

What does an electron microscope use for illumination?

Electrons because they have shorter waves lengths and allow for greater resolution.

52

What are the two types of electron microscopes?

TEM (Transmission Electron Microscope) and SEM (Scanning Electron Microscope)

53

Which electron microscope displays an image produced by electrons which are emitted from the surface of the object creating a 3 dimensional structure?

Scanning Electron Microscope

54

Which electron microscope have electrons that pass through a thin section of the specimen?

Transmission Electron Microscope

55

Which electron microscope can view specimens that have been stained with heavy metal salts and show a two dimensional structure?

Transmission Electron Microscope

56

What is fixation?

A process by which internal and external structures of a cell are preserved.

57

What is heat fixation?

Fix an air-dried thin film (smear) by passing through a flame

58

Why is fixation used?

To attach the microbes to the slide and to kill the microbes

59

In an ionic stain, basic dyes have a chromophore that is a ______.

Cation

60

In an ionic stain, acid dyes have a chromophore that is an _________.

Anion

61

When only one staining agent is used, this type of staining is called ________.

Simple staining

62

How do differential stains work?

It divides bacteria into separate groups based on staining properties.

63

What type of stain traps crystal violet-iodine complex due to a thick layer of peptidoglycan cell wall?

Gram positive

64

When lipids in the cell wall are dissolved by the ethanol, allowing crystal violet-iodine complex to escape, what type of stain does it depict?

Gram negative

65

What is the most important staining procedure and who is it named for?

Gram stain, Dr. Christian Gram in 1884

66

In the Gram Stain, which is the primary stain?

Crystal violet

67

In the Gram Stain, which is the counterstain?

Safranin

68

In the Gram Stain, which is the mordant?

Iodine

69

In the Gram Stain, which is the decolorizing agent?

Alcohol-acetone

70

Name the steps in the Gram Stain

1. Crystal Violet - 1 minute 2. water 3. Iodine - 1 minute 4.Alcohol - 10-20 secs 5.water 6.Safranin - 1 minute 7.water 8.Dry lens - DO NOT RUB!

71

In Gram+, what is the color stain after the mordant is applied?

Purple

72

In Gram-, what is the color stain after the counterstain is applied?

Red

73

Why is an acid-fast stain used?

To stain Mycobacterium, which have high mycolic acid content (waxy)

74

What is the counterstain used in acid-fast staining?

Methylene blue

75

What are cells called that retain a basic stain in the presence of acid-alcohol?

Acid-fast

76

What is the evolutionary history of a group of organisms?

Phylogenesis

77

In the Three-Domain system, what does bacteria have that the other domains do not have?

Mitochondria and chloroplast

78

What does the fossil record tell us?

Eukaryotic relationships

79

What does rRNA sequencing tell us?

Prokaryotic relationships

80

In Eukarya domain, which type is multicellular but has no cell wall and is chemoheterotrophid?

Animalia

81

Which Eukarya is multicelluar but with a cellulose wall and usually phototutotrophic

Plantae

82

Which kingdom is unicellular or multicellular; has chitin cell walls and may develop from spores or hyphal fragments?

Fungi

83

Which kingdom is considered the "catch all" for eukaryotic organisms that don't fit in any other kingdom?

Protista

84

What is a clone?

When a population of cells are derived from a single cell

85

What characteristics do all cells have in common?

Basic shape - spherical, cubical, cylindrical

Internal content - cytoplasm, surrounded by a membrane

DNA Chromosome(s), ribosomes, metabolic capabilities

86

What are the two basic cell types?

Eukaryotic and Prokaryotic

87

What are the characteristics of a prokaryote?

One circular chromosome, not in a membrane

No histones

No organelles

Peptidoglycan cell walls

Binary fission

88

What are the characteristics of a eukaryote?

Paired chromosomes, in a nuclear membrane

Histones

Organelles

Polysaccharide cell walls

Mitotic spindle

89

What are the basic shapes of a cell?

Spherical, cubical and cylindrical

90

What are the arrangements of cells?

Pairs: diplococci. diplobacilli

Clusters: staphylococci

Chains: streptococci, streptobacilli

91

What are the unusual shapes of cells?

Star-shaped (Stella)

Square (Haloarcula)

92

Are most bacteria monomorphic or pleomorphic?

Monomorphic, only a few are pleomorphic

93

What is a glycocalyx?

A capsule, slime layer, or extracellular polysaccharide) is a gelatinous polysaccharide and or polypeptide covering

Outside cell wall

Usually sticky

A capsule is neatly organized

A slime layer is unorganized and loose

Extracellular polysaccharide allows cell to attach

94

What does the glycocalyx (capsules) do?

Prevent pahgocytosis

Enable adherence to surfaces

Prevent desiccation (dryness)

95

Which are more likely pathogen, much more virulent and more stable to create more bacteria?

Cells with capsules or glycocalyx

96

Explain the movement of motile cells?

Clockwise - toward food

Counterclockwise - away from toxins

97

What is fimbriae?

Fine, proteinaceous, hair-like bristles from the cell surface

Function in adhesion to other cells and surfaces

98

What are pili?

Pili are used to transfer DNA from one cell to another called conjugation

Found only in Gram negative cells

99

What is conjugation?

The transferring of DNA via pili

100

What is the function of the cell wall?

Prevents osmotic lysis

Made of peptidoglycan (in bacteria)

Give shape to bacteria

Protection of the cell

101

What is peptidoglycan?

Polymer of disaccharide (NAG) & (NAM)

Linked by polypeptides

102

Describe Gram-positive cell wall

Thick peptidoglycan

Teichoic acids: Lipoteichoic acid links to plasma membrane; Wall teichoic acid links to peptidoglycan

In acid-fast cells, contains mycolic acid

May regulate movement of cations

Polysaccharides provide antigenic variation

103

Describe the Gram-negative cell wall

Thin peptidoglycan

No teichoic acids

Outer membrane

104

In which type of cell wall can the glycin bridge be found?

Gram-Positive cell walls

105

Describe the Gram-Negative Outer Membrane

Lipopolysaccharides, lipoproteins, phospholipids

Forms the periplasm between the outer membrane and the plasma membrane

Protection from phagocytes, complement, antibiotics

O polysaccharide antigen

Lipid A is an endotoxin

Porins (proteins) form channels through membrane

106

What is endotoxin?

Part of the cell structure; happens once the cell dies

107

What is exotoxin?

Excretes some toxin, the bacteria must be alive

108

What is the Gram Stain Mechanism?

Crystal violet-iodine crystals form in cell

Gram-positive - Alcohol dehydrates peptidoglycan; CV-I crystals do not leave

Gram-negative - Alcohol dissolves outer membrane and leaves holes in peptidoglycan; CV-I washes out

109

What is the periplasmic space?

The space between peptidoglycan and cell membrane in Gram+ (also outer membrane in G-)

110

What are two examples of atypical cell walls?

Mycoplasmas (cause walking pneumonia) - lack cell walls; sterols in plasma membrane

Archaea - wall-less or walls of pseudomurein (lack NAM and D amino acids)

111

What is Gram+ treated with lysosome and have their cell wall entirely removed?

Protoplasts

112

What is Gram- treated with lysosome and have their cell wall only partially removed?

Spheroplasts

113

What digests disaccharide in peptidoglycan?

Lysosome

114

Where can lysosome be found?

It is in every fluid in the body.

115

What inhibits peptide bridges from forming in peptidoglycan?

Penicillin

116

What do all live cells have and are only differentiated by protein?

Phospholipid bilayer

117

What does selective permeability mean?

Allows passage of some molecules ( H2O, gas (O2, CO2), small molecules)

118

What are the two types of movement across membranes?

Simple diffusion and Facilitative diffusion

119

What is simple diffusion?

Movement of a solute from an area of higher concentration to an area of lower concentration

120

What is facilitative diffusion?

Solute combines with a transporter protein in the membrane; does not need ATP; moving from higher concentration to lower concentration

121

What type of solution has no net movement of water?

Isotonic

122

What type of solution causes water to move into the cell and may cause the cell to burst if the wall is weak or damaged?

Hypotonic (osmotic lysis)

123

What type of solution causes water to move out of the cell, causing its cytoplasm to shrink?

Hypertonic (plasmolysis)

124

What does active transport of substances require?

A transporter protein and ATP

125

What does group translocation of substances require?

A transporter protein and PEP

126

50s and 30s subunits makes what type of rbosome?

70s which is prokaryotic

127

50s and 40s subunits makes what type of ribosome?

80s which is eukaryotic

128

What are endospores?

Resting cells

Resistant to desiccation, heat, chemicals

Bacillus, Clostridium

129

What is sporulation?

Endospore formation

130

What is germination?

Return to the vegetative state

131

What is phagocytosis?

Eating solids; cell eating

132

What is pinocytosis?

Send toxin inside cell to kill it

133

What do sterols make?

Antibiotics

134

What is endocytosis?

Phagocytosis: Pseudopods extend and engulf particles

Pinocytosis: Membrane folds inward bringing in fluid and dissolved substance

135

What is cytoskeleton?

Microfilabments, intermediate filaments, microtubules

Gives shape to non-cell wall; movement

136

What is the sum of all chemical reactions within the cell?

Metabolism

137

What is the breakdown of complex organic molecules into simpler ones; energy is released?

Catabolism

138

What is the building of complex organic molecules from simpler ones; energy is used?

Anabolism

139

What is an enzyme?

A type of protein which catalyzes reactions in the cell by lowering the activation energy.

140

What is a substrate?

The compound being acted upon by the enzyme.

141

What is turnover number?

The maximum number of substrate molecules an enzyme can convert to product each second.

142

Enzymes are

All proteins except RNAse

Catalysts

Specific to a substrate

Can have many turnovers (generally 1- 10,000 molecules per second)

Has an active site that is shaped to match a specific substrate

143

Co-factors are

Mainly metal ions

144

Summarize the enzymatice action

1. Substrate binds to active site on the surface of the enzyme

2. Temporary intermediate complex forms - enzyme-substrate complex

3. Substrate transformed (other molecule added, molecule rearranged, bond broken, etc.)

4. Transformed substrate (product or products) no longer conform to the active site, is released.

5. Unchanged enzyme is ready to react with more substrate molecules

145

Which factors influence enzymes?

Temperature - Low, high, (optimum minimum, maximum)

pH - optimum, effects on amino acids

Substrate concentration - saturation

146

Which reaction is where one substrate loses electrons (oxidation) and the other gains elctrons (reduction)?

Oxidation-reduction reactions

147

Which reaction often includes the transfer of both the electron and the accompanying proton (hydrogen atom)?

Dehydrogenation reactions

148

What is oxidation?

The removal of electrons

149

What is reduction?

The gain of electrons

150

What is an oxidation reaction paired with a reduction reaction?

Redox reaction

151

True or False: Oxidation and reduction are always together in a reaction.

True

152

What is the removal and addition of electrons to molecules?

Oxidation-Reduction

153

What is phosphorylation?

Adding a phosphate group - storing energy

154

What is dephosphorylation?

Removing a phosphate group - releasing energy

155

What is generated by the phosphorylation of ADP?

ATP

156

What is losing or gaining a phosphate?

Energy

157

What does the oxidation of glucose to pyruvic acid yield?

ATP and NADH

158

What is glycolysis?

The oxidation of glucose to pyruvic acid

159

In respiration, how many ATP are gained?

36-38 ATP

160

In fermentation, how many ATP are gained?

2 ATP

161

What is fermentation?

The partial oxidation of glucose in the absence of oxygen where the final electron acceptor is an organic molecule.

162

What is respiration?

The process by which molecules are oxidized and the final electron acceptor is an inorganic molecule.

163

In aerobic respiration, the final electron acceptor is

Molecular oxygen

164

In anaerobic respiration, the final electron acceptor is

Inorganic molecule other than oxygen (or rarely, an organic molecule)

165

What is chemiosmosis?

The generation of ATP using a proton gradient; yield of ATP high

166

What is the electron transport chain?

A series of carrier molecules located in a membrane which are capable of oxidation and reduction. Energy of electrons used to establish a proton gradient

167

What is lipid catabolism?

The breakdown of lipids (uses enzyme CoA); some components enter the Krebs cycle

168

What is protein catabolism?

Some can also enter the Krebs cycle

169

What is carbohydrate catabolism?

Energy produced from complete oxidation of one glucose using aerobic respiration.