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BIOLOGY STRUCTURED > 10. Microbiology > Flashcards

10. Microbiology Flashcards

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1
Q

What is microbiology?

A

Microbiology is the study of organisms that are too small and are not visible clearly to the naked eye or un-aided eye when they exist individually

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2
Q

What are microorganisms?

A

organisms that are too small and are not visible clearly to the naked eye or un-aided eye when they exist individually

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3
Q

What do microorganisms include?

A

Bacteria
Archaea
Cyanobacteria/Blue green bacteria (BGB)
Fungi
Protists
Mollicutes such as mycoplasmas and phytoplasmas
Viruses
Viroids
Prions

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4
Q

What is the size of microorganisms?

A

Generally less than 0.1 mm in size and cannot be observed with a unaided eye

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5
Q

Why are microorganisms observed with a microscope?

A

Because they cannot be observed with a unaided eye

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6
Q

How are the structural components of microorganisms measured?

A

In micrometers and nanometers

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7
Q

Why are some microorganisms more readily visible than the others?

A

Because of their larger size

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8
Q

Why are microorganisms ubiquitous?

A

because they are found in water, soil, air and interior and exterior surfaces of other organisms

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9
Q

What do marine and freshwater microorganisms form?

A

The basis of food chains in oceans and freshwaters

Some of them do photosynthesis and are primary producers in aquatic environments

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10
Q

What do soil microorganisms help?

A

Recycling of chemical elements between soil, water, air and living organisms

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11
Q

How are microorganisms suspended in the air?

A

as bioaersols

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12
Q

How do bioaersols spread?

A

They have the opportunity to travel long distances with the wind current and precipitate

Pathogenic bioaerosols cause opportunities for disease spreading

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13
Q

What microorganisms are pathogenic?

A

Only a minority of microorganisms that associate with other organsims such as plants, animals and humans are pathogenic

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14
Q

What percentage of microorganisms are advantageous or harmless?

A

A majority

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15
Q

Are all viruses harmful to the organisms they’re attached to?

A

yes

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16
Q

What are some microorganisms capable of inhabiting?

A

Extreme environmental conditions that are unfavorable or even lethal for other organisms

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17
Q

What are the microorganisms capable of inhabiting extreme environmental conditions that are unfavorable or even lethal for other organisms?

A

Extremophiles

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18
Q

Where are extremophiles found?

A

inside the earth’s crust

deep sea at high pressures

extreme acidic/basic conditions

hydrothermal vents

frozen sea water

anaerobic conditions

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19
Q

How are extremophiles classified?

A

According to the conditions in which they grow in

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20
Q

What are the different types of extremophiles?

A

Thermophiles

Psychrophiles

Acidophiles

Alkaliphiles

Halophiles

Barophiles

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21
Q

What conditions are Thermophiles found?

A

High temperatures

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22
Q

What conditions are Psychrophiles found?

A

Low temperatures

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23
Q

What conditions are Acidophiles found?

A

Acid pH

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24
Q

What conditions are Alkaliphiles found?

A

Basic pH

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25
Q

What conditions are Barophiles found?

A

High pressure

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26
Q

What extreme environments consist of more than one extreme condition?

A

Many hot springs are acidic or alkaline in nature at the same time

Deep seas are cold and remain in high pressure

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27
Q

How do microorganisms live in environments consisting of more than one extreme condition?

A

They’re adapted to live with more than one extreme condition

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28
Q

Describe the rate of growth and reproduction of microorganisms

A

Its high

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29
Q

What do microorganisms possess due to their smaller size?

A

A high surface area/volume ratio

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30
Q

What does having a high surface area/volume ratio mean?

A

They have a large surface area available for exchange of materials from external environment

As a result, flowing rate of materials into the inside of cells and the exist of waste materials to the outside of the cells increases and results in high metabolic rate

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31
Q

What is the result of microorganisms possessing a high surface area/volume ratio?

A

Flowing rate of materials into the inside of the cells and the exit of waste materials to the outside of the cells increases and results in a high metabolic rate

Therefore, average generation time, or the time required to double the population of microorganisms is relatively less

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32
Q

Describe the forms of microorganisms

A

they possess diverse morphological forms

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33
Q

Describe the shapes of bacteria

A

they possess diversity in their shapes, basically 3 distinct shapes
rod shape/bacillus
spherical shape/coccus
monococcus, diplococcus, streptococcus, staphylococcus, tetrads and sarcinae

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34
Q

How are bacillus bacteria arranged?

A

they may be arranged in to either diplobacillus or streptobacillus

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35
Q

How are spiral bacteria arranged?

A

Into either vibrio or spirillum or spirochete

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36
Q

Describe the shapes of cyanobacteria

A

They exhibit a great variety of shapes and arrangements, unicellular to long multi-cellular filaments

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37
Q

How do multicellular cyanobacteria appear?

A

As either filamentous or non-filamentous

Filamentous appear as chains and non-filamentous appear as clusters or colonies forming spherical, cubical, square or irregular shape

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38
Q

What are the morphological varieties of viruses

A

There are 2 morphological varieties found in viruses based on their symmetry of protein coats; icosahedral and helical

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39
Q

Describe the shape of fungi

A

Some of them are unicellular and others multicellular, consisting of a mass of fine tubular branching threds known as hyphae, collectively forming mycelium

Hyphae might be septate or aseptate

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40
Q

What are prions?

A

They are smaller proteinaceous particles

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41
Q

Describe the morphology of unicellular protists

A

They possess a wide range of morphological diversity

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42
Q

Describe the nature of mollicutes

A

They are pleomorphic (variable shapes)

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43
Q

How are the nutritional types of microbes classified?

A

Based on the sources of carbon and energy

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44
Q

What are the 4 major nutritional types seen among microorganisms?

A

Chemoautotrophs
Chemoheterotrophs
Photoautotrophs
Photoheterotrophs

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45
Q

How are microorganisms classified into 4 physiological groups?

A

Based on the utilization of O2(g)

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46
Q

What are the 4 physiological groups of microorganisms?

A

Obligate aerobes
Obligate anaerobes
Facultative anaerobes
Microaerophiles

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47
Q

What physiological diversity do some microbes capable of fixing atmospheric molecular nitrogen show?

A

Free-living nitrogen fixing microbes
Symbiotic nitrogen fixing microbes

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48
Q

What are bacteria?

A

They are single-celled prokaryotic organisms

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49
Q

What is the morphological form of bacteria?

A

They show different morphological forms and arrangements

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50
Q

What is the most obvious structural feature of bacteria?

A

The shape of individual cells

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51
Q

What are the 3 basic shapes of bacteria?

A
  1. spherical; coccus
  2. rod shaped; bacillus
  3. spiral shape
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52
Q

What happens during the cell division of bacteria?

A

Cells can remain attached to each other and form different forms of cell arrangements

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53
Q

Write the form of cell arrangement of coccus bacteria

A

Cells divide in one plane.

Divided cells detach from each other after cell division

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54
Q

Write the form of cell arrangement of diplococcus bacteria

A

Cells divide in one plane.

Divided cells remain in pairs

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55
Q

Write the form of cell arrangement of streptococcus bacteria

A

Cells divide in one plane

Divided cells remain attached in chain like pattern

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56
Q

Write the form of cell arrangement of tetrad bacteria

A

Cells divide in two planes producing 4 cells remain attached together

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57
Q

Write the form of cell arrangement of sarcinae bacteria

A

Cells divide in 3 planes and remain attached in groups of 8 cells

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58
Q

Write the form of cell arrangement of staphylococcus bacteria

A

Cells divide in multiple planes and form grape like clusters of cells

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59
Q

How do bacilli divide?

A

Across their short axis. Therefore, there re a few cell arrangement forms

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60
Q

What is the cell arrangement of single bacillus bacteria?

A

Single rod

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61
Q

What is the cell arrangement of diplobacillus bacteria?

A

Remain in pairs after cell division

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62
Q

What is the cell arrangement of streptobacillus bacteria?

A

occur in chains after cell division

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63
Q

Describe the cell arrangement of spiral bacteria?

A

They have one or more twists, they are never straight

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64
Q

What is the form of cell arrangement of vibrio bacteria

A

Bacteria look like curved rods

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65
Q

What is the form of cell arrangement of spirillum bacteria

A

Helical shape, like a corkscrew and rigid body

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66
Q

What is the form of cell arrangement of spirochete bacteria

A

Helical shape, flexible body

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67
Q

What is the source of energy of photoautotrophs

A

Light

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68
Q

What is the source of energy of photoheterotrophs

A

Light

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69
Q

What is the source of energy of chemoautotrophs

A

inorganic chemicals

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70
Q

What is the source of energy of chemoheterotrophs

A

organic chemicals

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71
Q

What is the source of carbon of photoautotrophs

A

Carbon dioxide (inorganic carbon)

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72
Q

What is the source of carbon of photoheterotrophs

A

Organic carbon

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73
Q

What is the source of carbon of chemoautotrophs

A

Carbon dioxide (inorganic carbon)

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74
Q

What is the source of carbon of chemoheterotrophs

A

Organic carbon

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75
Q

Give examples for photoautotrophs

A

Purple sulfur
Green sulfur bacteria

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76
Q

Give examples for photoheterotrophs

A

Purple non sulfur bacteria

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77
Q

Give examples for chemoautotrophs

A

Nitrobacter
Nitrosomonas
Thiobacillus trioxidanes

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78
Q

Give examples for chemoheterotrophs

A

most bacteria

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79
Q

Describe obligate aerobic microorganisms tolerance to oxygen

A

These bacteria require oxygen for their survival. They generate energy by oxidative phosphorylation

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80
Q

Describe obligate anaerobic microorganisms tolerance to oxygen

A

They cannot survive in the presence of oxygen. These microorganisms generate energy by fermentation

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81
Q

Describe facultative anaerobic microorganisms tolerance to oxygen

A

These microorganisms prefer to grow in the presence of oxygen producing energy by oxidative phosphorylation, but they can also grow in anaerobic environments using fermentation

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82
Q

Describe microaerophilic microorganisms tolerance to oxygen

A

These microorganisms can grow only in oxygen concentrations lower than those in the air

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83
Q

Give examples for obligate aerobic microorganisms

A

Acetobacter sp

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84
Q

Give examples for obligate anaerobic microorganisms

A

clostridium sp.

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85
Q

Give examples for facultative anaerobic microorganisms

A

Escherichia coli

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86
Q

Give examples for microaerophilic microorganisms

A

Lactobacillus sp

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87
Q

What microorganisms show diversity in nitrogen fixation?

A

Free living nitrogen fixing bacteria (Azotobacter sp)

Symbiotic nitrogen fixing bacteria (Rhizobium sp. with legume root)

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88
Q

How do microorganisms reproduce?

A

Mostly bacteria undergo asexual reproduction by binary fission, and in some occasion, fragmentation or budding.

In rare occasions, bacteria of two strains share a portion of genetic material through the process of ‘conjugation’

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89
Q

What is the process of conjugation?

A

In rare occasions, bacteria of two strains share a portion of genetic material through the process of ‘conjugation’

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90
Q

How are cyanobacteria named?

A

They’re named for their characteristic blue-green (cyan) pigmentation

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91
Q

What kinds of shapes and cell arrangements do cyanobacteria exhibit?

A

They exhibit a great variety of shapes and cell arrangements, unicellular to colonial forms

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92
Q

Describe the unicellular form of cyanobacteria

A

Here, cells separate after cell division. However, in nature majority of unicellular forms stay together by copious secretion of mucilage by daughter cells.

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93
Q

In nature, how to majority of unicellular forms stay together?

A

by copious secretion of mucilage by daughter cells

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94
Q

Describe the colonial form of cyanobacteria

A

Cells remain attached by walls or held in a common gelatinous matrix forming a colony of cells.

Colonies may either be non-filamentous or filamentous.

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95
Q

Describe the non-filamentous colonial form

A

Depending on the plane of division and direction there are different arrangements such as spherical, cubical, square or irregular shape.

Filamentous colonial form is the result of cell division in a single plane and a single direction forming a chain or thread like structure

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96
Q

Describe the nutrition of cyanobacteria

A

They are photoautotrophs that carry out oxygenic photosynthesis similar to plants and algae

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97
Q

Write what organisms cyanobacteria are similar to in terms of nutrition

A

plants and algae

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98
Q

What are many cyanobacteria capable of?

A

Fixing atmospheric nitrogen

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99
Q

Give ex. for free living nitrogen fixing cyanobacteria

A

Nostoc sp.

Anabaena-azolla symbiotically fix nitrogen with its partner, Azolla sp. (water fern)

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100
Q

In most cases, where does nitrogen fixation take place?

A

In special cells called heterocyst

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101
Q

What enzyme is nitrogen fixation catalyzed by?

A

Nitrogenase in the heterocyst

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102
Q

Where is enzyme nitrogenase located?

A

In the heterocyst

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103
Q

What is nitrogenase sensitive to?

A

Oxygen

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104
Q

Why do heterocyst carry thick cell walls?

A

To protect nitrogenase from oxygen that could diffuse from neighboring photosynthetic cells and from air or water

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105
Q

Aside from heterocyst, what are the other specialized cell type cyanobacteria carry?

A

akinete

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106
Q

What are akinete?

A

They are thick walled resting spores with stored food

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107
Q

What are akinete resistant to?

A

drought and high temperature

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108
Q

As a result of akinete being resistant to drought and high temperature, what occurs?

A

Akinete is able to survive during unfavorable environmental conditions although vegetative cells dries out

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109
Q

How do cyanobacteria reproduce?

A

Only by asexual methods

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110
Q

What do single unicellular and colonial non-filamentous types undergo?

A

Simple cell division

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111
Q

How do colonial filamentous and colonial unicellular forms reproduce?

A

By fragmentation

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112
Q

Describe fungi

A

Fungi are eukaryotes. They may be unicellular (yeast) ot multicellular (molds)

Some multicellular fungi form mushrooms

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113
Q

What do molds form?

A

Visible masses called mycelia, which are composed of long filament like structures called hyphae

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114
Q

What do many molds contain?

A

Cross-walls called septa (singular, septum)

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115
Q

What do septa do?

A

Divide hyphae into distinct single nucleate cell-like units

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116
Q

What are coenocytic hyphae?

A

Some molds do not contain septa in their hyphae resulting in long continuous cells with many nuclei

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117
Q

Where are coenocytic hyphae found?

A

The cottony growths are sometimes found on bread and fruit are mycelia of molds

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118
Q

Describe the nutrition of fungi

A

They are chemoheterotrophs and acquire food by absorption

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119
Q

What is the main mode of nutrition of fungi?

A

Saprophytic mode of nutrition

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120
Q

What do fungi play an important role in?

A

In the food chain by decomposing dead plant materials by secreting enzymes and thereby recycling vital elements

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121
Q

What other modes of nutrition can be found in fungi?

A

Parasitic (plant and animal pathogens) and mutualistic (lichens and mycorrhizae) modes of nutrition

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122
Q

How do unicellular fungi reproduce?

A

By fission or budding

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123
Q

How do filamentous fungi (molds) reproduce?

A

Asexually and/or sexually by producing spores

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124
Q

Describe the shape of unicellular protists?

A

They are pleomorphic, vary in their shapes and possess locomotive structures such as pseudopods, cilia or flagella

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125
Q

What locomotive structures do unicellular protists possess?

A

locomotive structures such as pseudopods, cilia or flagella

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126
Q

How do unicellular protists exist?

A

either individually or form colonies. some join together and form filaments

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127
Q

What modes of nutrition are found among protists?

A

Photoautotrophic, heterotrophic, and mixotrophic modes of nutrition

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128
Q

What are the respiratory modes of protists?

A

Aerobic, anerobic, facultative anerobic respiratory modes

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129
Q

How do some algae contribute to symbiotic interactions?

A

With lichens

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130
Q

How do protists reproduce?

A

Sexually by gametes and asexually by fission

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131
Q

What are mollicutes?

A

They are prokaryotes included in domain bacteria.

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132
Q

Why are mycoplasma and phytoplasma considered unique?

A

Due to their absence of cell walls

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133
Q

Describe the shape of mycoplasma

A

They are pleomorphic, vary in shape from spherical to filamentous

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134
Q

What is the smallest prokaryotic group of organisms invisible under light microscope?

A

Mycoplasma

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135
Q

What don’t mycoplasma contain?

A

Flagella

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136
Q

What are almost all mycoplasma parasites of?

A

Humans and animals

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137
Q

What in high amounts do mycoplasma require?

A

Organic Growth Factors

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138
Q

How do mycoplasma reproduce?

A

By budding and binary fission and do not produce spores

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139
Q

What are the respiratory modes of mycoplasma

A

Aerobic or facultative anerobic

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140
Q

How do phytoplasma resemble mycoplasma?

A

They are similar in size

Both can only be seen under an electron microscope

Shape varies from spherical to filamentous

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141
Q

Describe the nature of phytoplasma

A

They only infect plants and are generally present in phloem sap.

They cannot grow in artificial media

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142
Q

How are phytoplasma mostly transmitted?

A

By leafhoppers

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143
Q

Where do phytoplasma reproduce?

A

In both leafhoppers as well as plant body

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144
Q

How do phytoplasma reproduce?

A

By budding and binary fission

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145
Q

What are the modes of respiration of phytoplasma?

A

Aerobic of facultative anaerobic

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146
Q

What are the characteristic features of viruses

A

They are neither prokaryotes nor eukaryotes and do not show any cellular organization

They do not possess any metabolic activity or reproduction when they are out of living host cells. Thus, they are not considered as living organisms.

However, once they get into the host cells, they multiply and cause infection through various metabolic pathways, shows characteristics of living organisms. Since they can only multiply within living host cells, they are called obligate parasites.

They are very small and can only be seen through an electron microscope

They possess simple structures, usually composed of a central core of a nucleic acid and surrounded by a protein coat called the capsids made up of a fixed number of protein subunits called capsomeres.

Viruses may have either DNA or RNA as their genetic material.

They do not have protein synthesis machinery such as additional RNAs or enzymes for protein synthesis. Therefore, they depend on host cell’s protein synthesis machinery.

RNA viruses consist of reverse transcriptase enzymes for reverse transcribing RNA into DNA

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147
Q

Why are viruses not considered living organisms?

A

Because they do not possess any metabolic activity or reproduction when they are out of living host cells

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148
Q

Why are viruses called obligate parasites?

A

Since they can only multiply within living host cells, they are called obligate parasites.

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149
Q

Describe the structure of viruses

A

They possess simple structures, usually composed of a central core of a nucleic acid and surrounded by a protein coat called the capsids made up of a fixed number of protein subunits called capsomeres.

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150
Q

On what basis can two basic morphological symmetries be identified?

A

On the basis of capsid architecture

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151
Q

What are the 4 types of morphological forms?

A

helical
polyhedron
complex
enveloped

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152
Q

What are helical viruses?

A

They are long rigid or flexible rods

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153
Q

Give ex. for helical viruses

A

Rabies virus

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154
Q

What kind of symmetry do icosahedron/polyhedral viruses show?

A

Icosahedron symmetry

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155
Q

What kind of symmetry do complex viruses show?

A

They exhibit more than one form of symmetry with additional structures

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156
Q

Give ex. for icosahedron/polyhedral viruses

A

Adeno virus

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157
Q

Give ex. for complex viruses

A

bacteriophage

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158
Q

What kind of symmetry do enveloped viruses show?

A

Roughly spherical, capsid covered by envelopes

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159
Q

Give ex for enveloped viruses

A

Herpes simplex virus

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160
Q

What is the multiplication of viruses?

A

A single virus can give rise to thousands of similar viruses in a single host cell.

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161
Q

What is the result of virus multiplication?

A

Therefore, viruses cause serious damages to their host leading to severe diseases in plants, animals and bacteria.

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162
Q

What are bacteriophages capable of?

A

They’re a typical group of viruses capable of infecting bacteria

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163
Q

How do bacteriophages multiply?

A

Lytic cycle or lysogenic cycle

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164
Q

What is difference between the lytic cycle and lysogenic cycle?

A

It involves with the lysis of the host cells whereas the lysogenic cycle allows viral DNA incorporating into host DNA and multiply without causing lysis of the host cell

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165
Q

What are the 5 distinct steps of the lytic cycle?

A

Attachment
Penetration
Biosynthesis
Maturation
Release

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166
Q

Describe the attachment step of the lytic cycle

A

The first step is the attachment of virus to a matching receptor site on the bacterial cell

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167
Q

Describe the penetration step of the lytic cycle

A

After attachment, bacteriophage injects its DNA into the bacterial cell. This is facilitated by an enzyme which breaks down the bacterial cell wall

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168
Q

Describe the biosynthesis step of the lytic cycle

A

The next step is biosynthesis of viral DNA and proteins in the host cytoplasm using host resources. This stage induces degradation of host cell DNA

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169
Q

Describe the maturation & assembly step of the lytic cycle

A

Once bacteriophage DNA and proteins and synthesized, DNA and capsid are assembled to form complete virus particles. This is called maturation

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170
Q

Describe the release step of the lytic cycle

A

Finally, bacteriophage induce bacterial cell to break open (lyse). Newly produced bacteriophages are released from the host cell. These released bacteriophages can start another lytic cycle in cells in the vicinity

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171
Q

What do viroids consist of?

A

They consist only of short piece of naked RNA with no protective layer such as protein coat

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172
Q

How can viroids multiply?

A

They can only multiply within a living host cell using host cell resources. However, viroids do not contain any gene and only carry signals for their multiplication

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173
Q

What do viroids infect?

A

Plants, but no other life forms till to date

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174
Q

What are prions?

A

They are proteinaceous infectious particles. Their size is smaller than virus.

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175
Q

How do prions replicate?

A

Although prions lack nucleic acid they can replicate with the help of a host’s gene that encodes the prion protein

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176
Q

What is the size of prions

A

Their size is smaller than virus

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177
Q

Where are prions found?

A

in disease causing agents in some birds and mammals.

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178
Q

What kind of diseases are caused by prions?

A

Neurological diseases

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179
Q

Give ex. for the neurological diseases caused by prions

A

Transmissible Spongiform Encephalopathies (TSEs)

Mad cow disease

Creutzfeldt-Jacob Disease (CJD)

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180
Q

Describe Transmissible Spongiform Encephalopathies (TSEs)

A

Large vaculoes develop in the brain giving a sponge-like appearance

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181
Q

When did mad cow disease emerge in cattle?

A

In 1987

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182
Q

What is a human disease caused by prions?

A

Creutzfeldt-Jacob Disease (CJD)

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183
Q

Why is it essential to culture microorganisms on artificial media?

A

For the study of morphology and biochemical properties of microorganisms

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184
Q

What are the basic laboratory techniques to be followed in culturing of the microorganism of interest without any contamination?

A

Preparation of artificial culture media

Sterilization techniques

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185
Q

What is sterilization?

A

It is the process of removal or destruction of all forms of microbial life, including endosperms

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186
Q

What are the 2 types of sterilization?

A

Physical sterilization
Chemical sterilization

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187
Q

What are some physical methods used in sterilization?

A

Sterilization by moist heat, dry heat, filtering using membrane filters, exposure to UV radiation

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188
Q

What is moist heat sterilization?

A

Here, moist heat is used to destroy the microorganisms present in the desired materials such as culture media, temperature labile reagents/fluids and various laboratory utensils

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189
Q

How is moist heat sterilization done?

A

By denaturing proteins by high temperature and pressure

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190
Q

Give an example for denaturing proteins by high temperature and pressure?

A

Autoclaving
Pressure cookers can also be used

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191
Q

Explain autoclaving

A

In an autoclave, steam with 121c temperature at pressure of 1atm/ 15 psi is used for sterilization.

Extending the above condition for 15 minutes is sufficient to kill all microorganisms (except prions) and their endospores.

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192
Q

What condition is sufficient enough to kill all microorganisms and their endospores?

A

Extending the above condition for 15 minutes is sufficient to kill all microorganisms (except prions) and their endospores.

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193
Q

What is autoclaving used for?

A

sterilizing culture media, solutions, syringes and needles, healthcare instruments and various other items that can withstand high temperatures and pressure.

Glassware can also be sterilizaed with an autoclave if care is taken to ensure that the steam contacts all surfaces

194
Q

What is dry heat sterilization?

A

Here, dry heat is used to destroy the microorganisms present in the desired materials such as glasswares, petridishes, pipettes, inoculation loops, inoculation needles, scalpels, etc

195
Q

What is direct flaming?

A

It is a simple method of dry heat sterilization used in laboratories to sterilize inoculating loops, inoculating needles and scalpel blades by heating them on the flames of bunsen burners/ hot spirit lamps until they reach red hot

196
Q

What is incineration?

A

It is mostly done in an incinerating oven. It is used to sterilize hospital waste. Microorganisms are burned to ash during direct flaming and incineration

197
Q

Where is incineration mostly done?

A

In incinerating ovens

198
Q

What is hot-air oxidization?

A

Microorganisms are killed by oxidization. Items to be sterilized are heated to about 170c and maintain for 2 hrs in a dry air oven.

199
Q

Where is hot-air sterilization used?

A

To sterilize glassware such as petri dishes, flasks, beakers bottles and glass pipettes

200
Q

What is pasteurization?

A

Louis Pasteur found spoilage of beer and wine can be prevented by applying mild heat that kills organisms causing spoilage without seriously damaging the taste, texture, and nutritional content of the product.

Later, the same principle was applied to milk products, now known as pasteurized milk

201
Q

What are the objectives of pasteurization?

A

Eliminating pathogenic microorganisms and reduce microbial number which prolongs milk quality under refrigeration

202
Q

What is High temperature short-time pasteurization (HTST)

A

It uses temperature of at least 72c for 15 seconds

203
Q

What is Low Temperature Long Time (LTLT) pasteurization?

A

It uses temperature of at least 63c for 30 minutes

204
Q

What are the 2 main methods of pasteurization

A

HTST
LTLT

205
Q

Name another method milk can be sterilized by?

A

Ultra high temperature (UHT) pasteurization. Here, milk is heated to about 140c in less than 5 seconds by flashing steam and this milk can be stored for several months without refrigeration

206
Q

What is boiling?

A

Boiling the materials such as surgical instruments to 100c. Most pathogenic microorganisms are killed at boiling temperature

207
Q

What is filtration used for?

A

It is used to sterilized heat sensitive liquids such as solutions containing enzymes, vitamins, antibiotics, vaccines and some culture media

208
Q

How is filteration done?

A

Material to be sterilized is passed through a filter by using vacuum. Filter retains microorganisms and the liquid is passed through the filter.

209
Q

Give ex for filtration and the reasons they are used?

A

Membrane filters are widely used to sterilize heat sensitive solutions.

Pores of membrane filters are from 0.01 um to 0.45 um size, retain almost all the microorganisms including viruses and some large protein molecules

209
Q

Give ex for filtration and the reasons they are used?

A

Membrane filters are widely used to sterilize heat sensitive solutions.

Pores of membrane filters are from 0.01 um to 0.45 um size, retain almost all the microorganisms including viruses and some large protein molecules

210
Q

What does UV radiation do?

A

It kills microorganisms that faills into direct exposure, either through destruction or damaging DNA

211
Q

What is a major disadvantage of UV?

A

Radiation doesn’t penetrate through solid surfaces and coverings such as paper, glass and textile, so anything to be sterilized should have direct contact with radiation

212
Q

Where is UV radiation commonly used?

A

It is commonly used to sterilize air in hospital rooms such as operating theatres and nurseries

213
Q

What are the chemical methods are currently used in sterilization?

A

A few chemicals such as ethylene oxide and chlorine dioxide (both are gases) are currently used as chemical sterilizing agents

214
Q

How do the majority of chemical agents sterilize?

A

By reducing microbial populations to safe levels or removing vegetative forms of pathogens

215
Q

What is the function of ethylene?

A

Ethylene oxice kills microorganisms and endospores.

216
Q

Where is ethylene oxide used?

A

It is highly penetrative. Therefore ethylene oxide is used to sterilize mattresses in hospitals.

217
Q

What is chlroine dioxide used for?

A

It has been used to fumigate enclosed building areas contaminated with endospores of Bacillus anthracis

218
Q

Where is chlorine dioxide used?

A

It is most commonly used in water treatment prior to chlorination

219
Q

How are microorganisms studied?

A

Since they cannot be studied in their natural habitat such as soil, water or air, we need to bring them to the laboratory and provide similar conditions for their growth and reproduction

220
Q

What is a culture medium?

A

A nutrient material prepared for providing nutrition and anchorage essential to the growth of microorganisms at the laboratory condition is called a culture medium

221
Q

What are non-culturable microorganisms?

A

Some microorganisms cannot be grown on a laboratory culture media, They are non-culturable microorganisms

222
Q

What kind of medium is required for microorganism growth?

A

Some microorganisms grow well on any culture medium whereas other microorganisms require a special medium

223
Q

What should the culture of microorganisms present in a certain soil sample contain?

A

Necessary nutrients, sufficient moisture and suitable pH

224
Q

What should the medium initially be?

A

Sterile; it should not contain any living microrganisms

225
Q

How should the culture media initially be sterile?

A

When preparing a culture medium, all glassware and liquid nutrient solutions should be sterilized

226
Q

What are the 2 general media commonly used to grow bacteria and fungi respectively

A

Nutrient agar (NA)
Potato dextrose agar (PDA)

227
Q

What is nutrient agar made up of?

A

Peptone
Meat extract
Sodium chloride
Agar
Distilled water

228
Q

What is PDA made up of?

A

Potato
Glucose
Agar
Distilled water

229
Q

What is used as a solidifying agent in culture mediums?

A

Agar

230
Q

What does agar solidify?

A

Temperatures below 40C, which means a culture medium containing agar is a solid medium

231
Q

For growing microorganisms, where is solid culture medium usually contained in?

A

Petri dishes
Test tubes

232
Q

Why do we have to prepare microrganisms for observation?

A

Because most microorganisms appear almost colorless when viewed through a standard light microscope

233
Q

How are microrganisms prepared?

A

By staining (coloring the microorganisms with a dye)

234
Q

What must be done before microorganisms stain?

A

They must be fixed (attached) to the microscope slide

235
Q

What is a simple stain?

A

An aqueous or alcohol solution of a single basic dye

236
Q

What is the primary purpose of a simple stain?

A

To highlight the entire microorganism so that cellular shapes, cell arrangements, and basic structures are visible

237
Q

What are some simple stains commonly used in laboratories?

A

Methylene blue
Crystal violet
Safranin

238
Q

How are microorganisms in humans during birth like?

A

Generally, humans are free of microorganisms at birth

239
Q

Where do newborns get in contact with microorganisms first?

A

At the vagina of the mother

240
Q

What are the bacteria newborns get in contact with at first?

A

Lactobacilli (they colonize the intestine of the newborn)

241
Q

After birth where does microbial populations begin to establish?

A

The inside or on the body surface. These are called normal microbiota of the human body

242
Q

What part of a healthy human body are free from microorganisms?

A

Internal tissues of a healthy human body

243
Q

Where does a part of microorganisms colonize?

A

On skin

244
Q

Where does majority of microorganisms colonize?

A

On inner surfaces such as mucous membranes of nose, throat, upper respiratory tract, intestinal tract and genitourinary tract

245
Q

How many microrganisms does a healthy human have?

A

A large no. of microorganisms

It has been estimated that the human body consists of 1 x 1014 microbial cells for 1 x 1013 total body cells, which means a 10 times more microbial cells than human cells

246
Q

How are the majority of microorganisms like in the body?

A

They are generally harmless or even beneficial

247
Q

Give an ex for an organisms beneficial to the body

A

Minimal colonization of Escherichia coli at large intestine prevent colonization of pathogenic bacteria such as salmonella typhi E coli
at large intestine prevent the colonization of pathogenic bacteria such as Salmonella typhi E coli. in large intestine synthesizes vitamin K and some B vitamins that are absorbed into the bloodstream and used by body cells

248
Q

What has led to the study of probiotics?

A

Recent interest in the important of bacteria to human health

249
Q

What are probiotics?

A

Live microbial cultures

250
Q

Give ex. for probitoics

A

Yoghurt exerts a beneficial effect

251
Q

What has studies shown about the ingestion of certain lactic acid bacteria?

A

It can alleviate diarrhea and prevent colonization of Salmonella enterica during antibiotic therapy

252
Q

What are opportunistic pathogens?

A

Although majority of human microbiota are harmless, some of them may change their interactions with the human body under certain conditions and cause infections. Those microorganisms are called opportunistic pathogens

253
Q

Give an ex. for opportunistic pathogens

A

E.coli is generally harmless as long as it remains in the large intestine. However they may cause diseases if they enter other body parts (urinary bladder- urinary tract infection, lungs- pulmonary infection)

254
Q

What is a pathogen?

A

An orgnaism or entity (non living entities such as virus and prions) capable of causing disease

255
Q

What is a host?

A

An organisms within which the infected pathogens live on or in and multiply

256
Q

What is pathogenicity?

A

The ability of a pathogen to cause disease in the host by overcoming the host’s defense

257
Q

What is a parasite?

A

An organism or entity living on or in another living organism (host) and obtain nutrients and other resources from the host

258
Q

What are the characteristics of pathogenic microorganisms?

A

Having optimal growth conditions (ex: temperature) that corresponds to the body conditions of the host

Having a structure to adhere to the host cells and protect against the host’s defense mechanisms (ex: capsule, pilli)

Produce toxins; endotoxins or exotoxins

Having enzymes for invasiveness such as phospholipase, lesithinase and hyaluronidase

Having enzymes such as DNase to alter the host’s metabolic processes

259
Q

How do microbes express their pathogenicity?

A

By means of their virulence

260
Q

What is virulence?

A

It is the degree of pathogenicity of the pathogen

261
Q

How the virulence of pathogens vary?

A

Some pathogens are highly virulent (chicken pox virus) whereas some are less virulent/ non virulent

262
Q

What are virulence factors?

A

A few genes of pathogenic microorganisms express factors which provide them the ability to infect their host and cause disease. such factors are called virulence factors

263
Q

Describe the relationship between a host and a pathogen

A

It is dynamic, each modifies the activities and functions of the other

264
Q

What is the result of the host and a pathogen having a dynamic relationship?

A

As a result, the outcome of such a relationship depends on the virulence of the pathogen and the effectiveness of the host defense mechanism

265
Q

What do virulence factors enhance?

A

The pathogenicity and allows pathogens to invade and colonize hose tissues and disrupt normal body function

266
Q

What are the 2 major mechanisms pathogens use for pathogenicity

A

Invasiveness
Toxigenicity

267
Q

What is invasiveness?

A

It is the ability of pathogens to invade tissues by overcoming the host’s defense mechanisms and multiply for colonizing

268
Q

What are the extracellular enzymes produced by pathogens contributing to their invasiveness?

A

Phospholipase - Destroy animal cell membranes
Lesithinase - Hydrolyzes the lecithin component of the lipid in the cell membrane
Hyaluronidase - Destroys the body tissue by breaking down the hyaluronic cid which is a cementing substance between cells

269
Q

Write the functions of phospholipase

A

Destroy animal cell membranes

270
Q

Write the functions of Lesithinase

A

Hydrolyzes the lecithin component of the lipid in the cell membrane

271
Q

Write the functions of Hyaluronidase

A

Destroys the body tissue by breaking down the hyaluronic cid which is a cementing substance between cells

272
Q

How do pathogenic microorganisms enter passively?

A

Through various portals or natural openings such as wounds on the skin, respiratory, gastrointestinal and genito-urinary tracts

273
Q

What is toxigenicity?

A

The ability of microorganisms to produce biochemical substances known as toxins that disrupt the normal functions of cells These proteins or lipopolysaccharides produce specific harmful effects on the hose, and thus are called biological poisons

274
Q

Why are toxigenic microorganisms referred to as biological poisons?

A

These proteins or lipopolysaccharides produce specific harmful effects on the hose, and thus are called biological poisons

275
Q

Give ex. for toxigenic microorganisms

A

Endotoxins
Exotoxins

276
Q

Write the features of endotoxins

A

They are lipopolysaccharides

These are thermos-stable toxins which are part of the microbial cell.

Toxins are released when the bacteria die and the cell wall breaks apart

All endotoxins cause the same signs of symptoms regardless of the species of pathogen.

These symptoms include chills, fever, weakness, generalized by ached and sometimes shock and death

Endotoxins are produced only by gram-negative bacteria

277
Q

Give ex. for endotoxins

A

Lipopolysaccharides of the cell walls of salmonella typhi

278
Q

Write the features of exotoxins

A

Exotoxins are produced inside bacterial cells as part of their growth and metabolism are are secreted or released to the surrounding environment after cell lysis.

Exotoxins are proteins. Majority of them are enzymes.

Dye to their catalytic nature even a small amount of toxin is quite harmful.

These are thermo-labile protein toxins, being inactivated by boiling.

Exotoxins are most commonly produced by gram-positive bacteria and a few gram-negative bacteria

279
Q

What are the 3 types of exotoxins

A

Neurotoxins

Enterotoxins

Cytotoxins

280
Q

Write the features of neurotoxins

A

Interfere with normal transmission of nerve impulses

281
Q

Give ex. for neurotoxins

A

Toxins produced by Clostridium tetani

282
Q

Write the features of enterotoxins

A

Stimulates the cells of gastrointestinal tract in an abnormal way

283
Q

Give ex. for enterotoxins

A

Toxins produced by Vibrio cholera

284
Q

Write the features of cytotoxins

A

Kills host cells by enzymatic attack

285
Q

Give ex. for cytotoxins

A

Toxins produced by corynebacterium diptheriae

286
Q

What does microbial disease start with?

A

From the avoidance and prevention of opportunities of getting infection to treatment or curative methods after infection

287
Q

What is the best method to avoid infectious diseases?

A

Good hygienic practices in day to day life

288
Q

What plays an important role in the prevention of infections?

A

Antiseptics, disinfectants and immunization

289
Q

What are antiseptics and disinfectants?

A

The chemical substances that are used to kill or reduce microbial population in order to prevent infection

290
Q

What microorganisms are antiseptics and disinfectants not effective against?

A

some microorganisms like polio virus, tuberculosis bacterium, spores of bacteria and fungi are not destroyed by most antiseptics and disinfectants

291
Q

What is the major difference between antiseptics and disinfectants?

A

Antiseptics can be safely and directly applied to the human body, whereas disinfectants cannots.

Therefore, antiseptics are used in disinfection of living surfaces like skin. Disinfectants are used in disinfecting non-living surfaces such as operation theatres, bathing areas, sinks, kitchen tops, cutlery, drains, etc

292
Q

Where are antiseptics used?

A

antiseptics are used in disinfection of living surfaces like skin

293
Q

Where are disinfectants used?

A

disinfecting non-living surfaces such as operation theatres, bathing areas, sinks, kitchen tops, cutlery, drains, etc

294
Q

How are antiseptics and disinfectants generally formulated?

A

As liquids

295
Q

How does the effectiveness of antiseptics and disinfectants vary?

A

with concentration, duration of exposure, temperature and presence of organic matter

296
Q

Give ex. for antiseptics

A

ethanol
isopropanol
chloroxylenol

297
Q

Give ex. for disinfectants

A

phenol
hypochlorites (calcium hypochlorite and sodium hypochlorite)

298
Q

When the body’s defense fails to protect the body from the infection or overcome the disease, how is it treated?

A

Chemotherapy with antimicrobial drugs

299
Q

What do antimicrobial drugs do?

A

They kill or interfere with the growth of microorganisms without damaging the host

300
Q

What are antibiotics effective against?

A

They are effective antimicrobial drugs against bacteria

301
Q

What are broad spectrum antibiotics?

A

Some antibiotics affect against a broad range of bacteria and they are termed as broad-spectrum antibiotics

302
Q

What are narrow-spectrum antibiotics?

A

Other antibiotics affect only against a specific group of bacteria and they are narrow-spectrum antibiotics

303
Q

What are the various modes of action antibiotics show?

A

Inhibition of cell wall synthesis - Penicillin

Inhibition of protein synthesis - Erythromycin, Tetracycline

Disrupting plasma membrane - Daptomycin

Inhibition of RNA/DNA synthesis - Rifampin

304
Q

What antibiotic helps in the inhibition of cell wall synthesis?

A

Penicillin

305
Q

What antibiotic helps in the inhibition of protein synthesis

A

Erythromycin, Tetracycline

306
Q

What antibiotic helps in the Disrupting of plasma membrane

A

Daptomycin

307
Q

What antibiotic helps in the Inhibition of RNA/DNA synthesis

A

Rifampin

308
Q

What is a vaccine?

A

A suspension of weakened pathogens or fractions of organisms that is used to induce immunity is a vaccine

309
Q

What are vaccines used to control?

A

They are frequently used to control diseases caused by viruses because there is no other control methods once infected

310
Q

What are the different types of vaccines?

A

Live attenuated vaccines
Inactivated vaccines
Subunit vaccines

311
Q

What are live attenuated vaccines?

A

Vaccines which contain live pathogens which were deliberately weakened for its pathogenicity

312
Q

What do live attenuated vaccines mimic?

A

An actual infection

313
Q

Why do live attenuated vaccines provide lifelong immunity?

A

Since the pathogen is active inside the host, such vaccines provide lifelong immunity.

314
Q

Is a booster required for live attenuated vaccines?

A

no

315
Q

Give ex. for live attenuated vaccines

A

Measles, mumps and rubella (MMR)
Chickenpox

316
Q

What are inactivated vaccines?

A

Pathogenic microorganism is inactivated or killed in the vaccine

317
Q

What do inactivated vaccines require compared to live attenuated viruses?

A

Repeated booster doses

318
Q

What do inactivated vaccines require compared to live attenuated viruses?

A

Repeated booster doses

319
Q

What diseases are inactivated vaccines used for?

A

Virus diseases such as rabies, influenza, polio
bacterial diseases like cholera

320
Q

What are subunit vaccines?

A

Subunit vaccines contain only the antigenic fragments of a pathogen that can induce immunity in the recipient

321
Q

What is the best ex. for a subunit vaccine that have been used for a long time?

A

Toxoid vaccines

322
Q

What do toxoids contain

A

They contain inactivated toxins derived from a pathogen

323
Q

Give ex. for toxoid vaccines

A

Vaccines for tetanus, diphteria, etc

324
Q

How are subunit vaccines produced presently?

A

using genetic engineering

325
Q

Give ex. for subunit vaccines produced using genetic enginnering

A

Hepatitis B vaccines

326
Q

What do subunit vaccines require to obtain full immunity?

A

repeated booster dose

327
Q

How have microorganisms been exploited long before their discovery?

A

Babylonian and Sumerian civilizations used yeast to make alcohol as early as in 6000 BC

328
Q

How were microorganisms used after their discovery?

A

Pure cultures of microorganisms are being used in food production

329
Q

What did pure cultures of microorganisms being used in food production help?

A

This increases the understanding of microorganisms, their processes and their products.

330
Q

At present, what are various industries based on?

A

Selected microorganisms and their qualities are in operation

331
Q

Write the advantages of using microbial processes over chemical processes

A

simple nutritional requirements are sufficient for their growth

They are able to convert (metabolize) a wide range of raw materials

They are able to convert cheap raw materials into industrially important products

Due to higher gowth rate, they can convert the raw materials into products within a short period of time

Their growth conditions can be controlled to obtain desired end products

332
Q

How can reactions be carried out?

A

at low temperatures, energy and pressures compared to conventional industrial methods

333
Q

Describe the yield received from reactions compared to conventional industrial methods

A

They give higher yield with higher specificity

334
Q

What can microbes obtain after being amendable to genetic manipulation?

A

desired yield and quality with high efficiency

335
Q

What are the basic principles of metabolic processes of microorganisms for product formations?

A
  1. microbial cells are used as the end products ex: single cell proteins
  2. Microbial metabolic products are used as end products - they may be either primary end products or secondary metabolites ex: primary end products - alcoholic beverages, secondary metabolites - antibiotics
  3. Microbial metabolic processes are used as end products ex: bioremediation (heavy metal remediation), metal extraction (Cu,Fe) retting (production of fibers)
  4. Genetically modified microorganisms are used to produce end products

ex: productions of commercial enzymes (amylase from Aspergillus niger) vaccines (hepatitis B), hormones (insulin)

336
Q

What is industrial microbiology?

A

It is the large scale production of economically important products using microorganisms and their metabolic processes

337
Q

What expanded the scope of industrial microbiology?

A

recent technological and biotechnological advances expanded the scope of industrial microbiology

338
Q

What is used in industrial microbiology?

A

Bacteria, fungi, algae and viruses

339
Q

What are microorganisms considered as in industrial microbiology?

A

Miniature chemical factories

340
Q

Why are microorganisms called miniature chemical factories?

A

Various energy releasing (catabolic) and energy acquiring (anabolic) chemical reactions take place here

341
Q

What occurs within these miniature chemical factories?

A

Raw materials (substrates) are concerted into end products, one or more byproducts, and wastes.

End products can be separated from by purification to obtain a purified industrial products

342
Q

How can end products be separated in industrial microbiology?

A

End products can be separated from by purification to obtain a purified industrial products

343
Q

What are single cell proteins?

A

Microbial cells are grown in large scale as food supplement and rich in proteins are called single cell proteins

344
Q

chemical reacto

A
345
Q

Give ex. for the alcoholic beverages microorganisms are involved in the production of?

A

Beer
Wine
Sake
Toddy
Ethanol

346
Q

What ferments sugars into ethanol and CO2?

A

Yeast, Saccharomyces cerevisiae

347
Q

How much ethanol is produced globally by fermentation?

A

More than 70%

348
Q

What is the most widely used fermentation substrate?

A

Sucrose derived from sugarcane

349
Q

In addition to sucrose derived from sugarcane, what else is used as a fermentation substrate?

A

Simple sugars derived from plants and dairy waste are also used

350
Q

Give ex. for alcoholic beverages and the way they are derived

A

Beer - by the fermentation of cereal grain salt

Wine - produced by the fermentation of grapes or other suitable fruits

Toddy - Produced by the fermentation of sap of palms such as Palmyra and coconut

Arrack - Produced by the fermentation of palm tree sap such as coconut and sugarcane

351
Q

What are the 2 steps in vinegar production?

A

Alcoholic fermentation: sugars in malted grain, sap of palms, sugarcane and fruit juices is fermented by S. cerevisiae. Ethanol is subjected to acetic acid fermentation.

Acetic Acid fermentation: Ethanol derived from alcoholic fermentation undergoes incomplete oxidation and is concerted to acetic acid. This process is highly aerobic and involves Acetobacter sp. and Gluconobacter sp

352
Q

Write the chemical equation for the production of vinegar.

A

C2H5OH ——————————–> CH3COOH + H20
Acetic acid bacteria

353
Q

How are dairy products made?

A

By the fermentation of milk

354
Q

How is sugar lactose in milk fermented?

A

Sugar lactose in milk is fermented by lactic acid producing bacteria into lactic acid. These bacteria are killed during pasteurization. So they are added externally when making dairy products.

355
Q

Why are bacteria added externally when fermenting sugar lactose in milk?

A

These bacteria are killed during pasteurization. So they are added externally when making dairy products.

356
Q

Give examples for dairy products produced by fermentation

A

Curd and yoghurt is produced by the fermentation of lactose sugar in milk by a mix population of Lactobacillus bulgarcius, Lactococcus lactis and S. thermophilus. L. bulgaricus adds flavor and Streptococcus spp. adds a creamy texture and flavor

Production of cheese - Streptococcus sp. Penicillium molds

Lactic acid is commercially produced by using waste products from cheese and butter industry. L bulgaricus ferments lactose into lactic acid.

357
Q

How is a majority of commercially produced organic acids obtained?

A

Through microbial fermentation

358
Q

What fermentation substrates have been used to produce organic acids?

A

Beat or Cane molasses

359
Q

What organisms have been used to produce organic acids?

A

Aspergillus niger

360
Q

Give ex. for organic acids

A

Citric acids - sucrose fermented by Aspergilus niger

361
Q

What is leaching?

A

Some metals from ores are extracted with the help of microorganisms. This process is called leaching.

362
Q

What is one of the best ex. for extraction?

A

Extracting copper from lower grades of copper ore which other extraction methods are unprofitable. Thiobacillus ferroxidans recover copper from the ore that contains iron and sulphur. 70% of copper in the ore can be recovered by this microbial process.

363
Q

What other metals aside from cu can be extracted using microbial processes?

A

Uranium, gold and cobalt ore

364
Q

What microorganism produces riboflavin vitamin?

A

Fermentation by fungi

365
Q

What microorganism produces vitamin B12?

A

Pseudomonas sp. and Propionibacterium sp

366
Q

What microorganism produces Vitamin C?

A

Acetobacter sp

367
Q

What is the commercial production of vaccines done by?

A

A variety of microbial antigens used in active immunization against various diseases. Some of them are genetically engineered vaccines

368
Q

Give an ex for genetically engineered vaccines used in active immunization

A

Hepatitis B vaccines

369
Q

Give ex. for the commercial production of various antibody preparation used for passive immunization?

A

anti toxins against tetanus

Botulism toxin

Immunoglobulin against rabies

370
Q

What are the enzymes commercially produced

A

Amylase: Aspergillus niger, A.oryaze, Bacillus subtilis

Protease: A. oryzae

Lipase: Rhizopus spp

Invertase: Sacchromyces cerevisiae

Cellulase: A.niger

371
Q

What are the most important secondary metabolites of microorganisms?

A

Antibiotics

372
Q

How are many antibiotics still produced by?

A

Microbial fermentation

373
Q

Give ex. for antibiotics

A

Tetracycline: S. aureofaciens

Penicillin: Penicillium chrysogenum

Streptomycin: Streptomyces griseus

374
Q

Conventionally, where is insulin extracted from?

A

animal pancreas

375
Q

Why cant insulin often meet the demand?

A

Because this is expensive

376
Q

How is insulin produced at the present cheaply?

A

By using genetically modified E.coli and S.cerevisiae

377
Q

What is the insuline produced with genetic modifications similar to?

A

Human insulin

378
Q

What are animal-derived hormones used as an alternative to earlier?

A

human growth hormones

379
Q

How are animal derived hormones different from human growth hormones?

A

they work with less efficiency

380
Q

How are human growth hormones produced successfully at present?

A

By genetically engineered E.coli in large scale

381
Q

What is retting?

A

It is the process of loosening fibers from woody stem or other plant material such as coir

382
Q

What is required for the plant materials in retting?

A

Plant materials must be immersed in water for varying periods of time depending on the plant material

383
Q

What bacteria participates in retting?

A

Heterogenous bacterial populations participate in the process under aerobic or anaerobic conditions

384
Q

How do bacteria participate in retting?

A

Bacteria secretes enzymes, mainly pectinases, to facilitate loosening

385
Q

What are the main enzymes secreted by bacteria in retting?

A

pectinases

386
Q

What is biogas?

A

Anerobic digestion of organic waste produces various gases called biogas

387
Q

What is biogas?

A

Anerobic digestion of organic waste produces various gases called biogas

388
Q

How does the type of biogas produced differ?

A

It depends on the substrate biodegraded

389
Q

What are the products of biogas production

A

The activity of acetogenic bacteria on organic waste products produce carbon dioxide and hydrogen, whereas, the activity of methanogenic bacteria produces methane

390
Q

Why is much attention given to renewable replacement fuels?

A

because petroleum-based fuel supply is expensive and sometimes uncertain.

391
Q

What are some renewable replacement fuels?

A

Ethanol, Butanol, Biodiesel and biogas

392
Q

In brazil, what is a large amount of ethanol produced by?

A

Microbial fermentation of sugarcane to be used as a source of fuel

393
Q

How have ethanol and butanol been produced?

A

Efforts have been made to produce ethanol and butanol from cellulosic materials such as wood, wastepaper and cornstalks by using genetically modified bacteria

394
Q

What have many researches go on to produce biodiesel from?

A

Microalgae

395
Q

What is sugars in bread dough fermented by?

A

S. cerevisiae (baker’s yeast)

396
Q

What is the primary function of fermentation in bread?

A

Generating carbon dioxide

397
Q

How is bread dough produced?

A

With grain flour such as wheat, rye and rice.

398
Q

What does dough do in the presence of CO2?

A

Dough traps CO2 and rises up due to the pressure during baking and forms an open crumb texture

399
Q

How are various chemical substances not readily degradable in nature released?

A

Industries and agriculture

400
Q

Give ex. for synthetic substances that are not biodegraded or very slowly degraded by microorganisms and retain in the soil for long periods and also contaminates groundwater?

A

Plastic
Residue of pesticides such as heavy metals
Insecticide DDT
Herbicide 2,4-D

401
Q

What is bioremediation?

A

It is the technology that applies of living organisms to remove, degrade or detoxify pollutants

402
Q

Where does bioremediation naturally occur?

A

In the soil

403
Q

In what occasions can microorganisms be used in bioremediation processes?

A

In most occasions

404
Q

What can the growth of microorganisms in polluted soils and water be stimulated to promote?

A

Biodegration/bio-removal of pollutants

405
Q

What microorganisms can be used to degrade/remove a specific pollutant from polluted sites?

A

Microorganisms with selected properties or genetically modified microorgaisms with selected properties

405
Q

What microorganisms can be used to degrade/remove a specific pollutant from polluted sites?

A

Microorganisms with selected properties or genetically modified microorgaisms with selected properties

406
Q

What is bioremediation currently used for?

A
  • remediate soil and water contaminated with oil spills, toxic metal waste, hazardous organic waste, etc
  • decompose waste water from good processing and chemical plants
407
Q

What does the accumulation of solid waste from house hold (garbage) possess?

A

Various environmental and health issues

408
Q

In waste management, how is waste degraded by?

A

By microorganisms either aerobically or anaerobically

409
Q

What does composting do?

A

It degrades waste anaeorbically

410
Q

What happens at the end of composting?

A

Waste is converted to a stable material like humus

411
Q

Where is most garbage placed?

A

As large compacted landfills or piles, where conditions are mostly anaerobic

412
Q

In landfills or piles, how is waste degraded?

A

Anaerobically by using methanogenic bacteria

413
Q

What is produced as a byproduct of the degradation process?

A

Methane gas

414
Q

What can methane gas be used for?

A

Generate electricity or as natural gas

415
Q

Why do microorganisms have various applications in agriculture?

A

For improving yield
Agronomic characteristics such as improved nitrogen and phosphorus absorption
Resistance to pest and diseases and tolerance to drought, etc.

416
Q

What are the most limiting nutrients in soil for plant growth and development?

A

Nitrogen and phosphorus

417
Q

Why are chemical fertilizers applied to the soil?

A

To improve bioavailability of nutrients such as nitrogen and phosphorus

418
Q

What is done to improve bioavailability of nutrients such as nitrogen and phosphorus?

A

chemical fertilizers are applied to the soil

419
Q

What can extensive use of synthetic fertilizer result in?

A

environmental problems such as deprivation of soil and water quality.

420
Q

Why has much attention been given for microorganisms that can be applied into cropping systems?

A

To improve bioavailability of N and P

421
Q

What are bio-fertilizers?

A

The microbial inoculants that may be applied into cropping systems to improve bioavailability of N and P

422
Q

What is the most limiting nutrient among all major plant nutrients?

A

Phosphorous

423
Q

Why can the bioavailability of phosphorous in any type of soil be neglected?

A

Because a very low amount of P applied to the soil remain available for plants

424
Q

What bacteria contributes to improve the solubility of phosphorous in the soil solution?

A

Mycorrhizae and Phosphate solubilizing bacteria

425
Q

How do Mycorrhizae and Phosphate solubilizing bacteria contribute to improve the solubility of phosphorous in the soil solution?

A

These bacteria and fungi secrete organic acids that dissolve minerals containing phosphorous and chelate cationic partners of phosphate ions, thereby release phosphorous into the soil solution

426
Q

At present, where are commercial formulations of microbial bio-fertilizers available?

A

In the market

427
Q

What is biological nitrogen fixation?

A

It is a process where microorganisms convert atmospheric molecular nitrogen into its soluble form

428
Q

What happens to the soluble forms of nitrogen produced by nitrogen fixation?

A

By some plants directly or converted into desired forms of nitrogen (ex: symbiotic nitrogen fixing, free living nitrogen fixing)

429
Q

Give ex. for symbiotic nitrogen fixing

A

Rhizobium sp. form intimate relationships with leguminous plants. The fixed nitrogen is released to the soil when plants die making nitrogen available for other plants. Various rhizobium inoculations are commercially available

Nitrogen-fixing cyanobacteria, Anabaena sp. form symbiotic associations with water fern Azolla. This system has been successfully used in rice cultivation in many countries

430
Q

Give ex. for free living nitrogen fixing

A

Free living nitrogen fixing bacteria such as Azotobacter are present in high concentrations at rhizosphere

431
Q

What are the plant growth-promoting substances produced by the many microorganisms in the plant rhizosphere?

A

Auxins (indole-3-acitic acid)
Cytokinins

432
Q

What are the bacteria that produce plant growth-promoting substances in the plant rhizosphere?

A

Pseudomonas putida, P.florescens: auxin
Azotobacter sp. Rhizobium sp., subtilis, P. fluorescens, cytokinins
Acetobacter sp, Azospirillum sp: Gibberellin

433
Q

What can the extensive use of chemical pesticides do?

A

It leads to hazardous side effects to people
These substances or their residues persist in food and the environment
The residual toxicity may affect non-target organisms
Overuse of pesticides develop resistance against pesticides among pests

434
Q

What has been done to replace synthetic chemicals as pesticides?

A

Environmentally friendly and less toxic alternative strategies are required to replace them.

435
Q

What are being explored to control pests and diseases?

A

Naturally occurring microorganisms

436
Q

What are the microbial formulations currently commercially available and widely used in many cropping systems?

A

Entomopathogenic fungi
bacteria
viruses

437
Q

What are entomopathogenic fungi?

A

These fungi infect a broad range of insects leading to insect death. They have been formulated into myco-insecticides

438
Q

What are entomopathogenic bacteria?

A

Bacillus thuringiensis: insecticidal and toxic for many insect larvae: protein crystals produced by this bacterium are toxic to larvae when ingested. This toxin is called Bt toxin. After ingestion toxin is dissolved and lyse tissues of the guts of larvae. most biopesticide formulations currently in use are Bt-based.

439
Q

How are most biopesticide formulations currently in use?

A

they are bt-based

440
Q

What is bt toxin?

A

insecticidal and toxic for many insect larvae: protein crystals produced by this bacterium are toxic to larvae when ingested. This toxin is called Bt toxin.

441
Q

What happens do bt toxin after ingestion?

A

After ingestion toxin is dissolved and lyse tissues of the guts of larvae.

442
Q

What is composting?

A

It is a process used to convert plant remains into the equivalent of natural humus by microbial degradation. Degradation of organic matter by a mix population of microbes under warm, moist and aerobic conditions

443
Q

How is degradation of organic matter done in composting?

A

Degradation of organic matter by a mix population of microbes under warm, moist and aerobic conditions

444
Q

How does the initial activity of thermophilic bacteria on plant remains increase temperature of the pile to?

A

To 55-60c

445
Q

What occurs as a result of the initial activity of thermophilic bacteria on plant remains increase temperature of the pile to 55-60c?

A

Thermophilic bacteria dominate in the degradation process for few days

446
Q

What occurs in composting when the temperature decreases over time?

A

Thermophilic microbial population is replaced by mesophilic microbial populations

447
Q

How can the process of thermophilic microbial population being replaced by mesophilic microbial population be enhanced?

A

By the addition of moisture and supply of oxygen through turning the pile.

448
Q

What microbes can be used to contribute to the breakdown of organic matter into compost, under than bacteria?

A

fungi
Actinomycetes
protozoa

449
Q

What does soil provide to the growth of microorganisms?

A

An adequate physical and chemical environment

450
Q

What space and nutrients does soil include?

A

minerals
decomposing organic materials
water
gases such as carbon dioxide
oxygen
nitrogen

451
Q

How does the soil environment change within a few cm dept of soil?

A

There are different amounts of oxygen, moisture, light and nutrition, increasing the diversity of soil microorganisms

452
Q

Where can the largest community of bacteria be found in soil?

A

The top few cm of soil

453
Q

What factor decreases along with increasing depth of soil?

A

Microbial number

454
Q

What represents majority of soil microflora?

A

Bacteria

455
Q

What can be found in the soil microflora, other than bacteria?

A

fungi
algae
protozoa
actinomycetes

456
Q

Why are actinomycetes mentioned separately despite being a member of domain bacteria?

A

Because of their significances

457
Q

What do microorganisms in soil play a major role in?

A

the decomposition of complex organic substances and participate in cycling of elements in biogeochemical cycles

Elements are oxidized and reduced by microorganisms for their metabolic requirements

458
Q

Why are elements are oxidized and reduced by microorganisms?

A

for their metabolic requirements

459
Q

What is mineralization?

A

It is the decomposition of plant and animal residue by using extracellular enzymes of bacteria and fungi.

460
Q

What is the action of enzymes on mineralization?

A

They break down complex organic materials into simple inorganic materials such as CO2 and H20.

461
Q

Why is mineralization a major process?

A

It is the way by which plant nutrients are made available and recycling

462
Q

How does mineralization help?

A
  • Helps remove plant and animal debris from the earth surface allowing other organisms to live
  • Recycle minerals which are found in limited quantities on earth
463
Q

Why do all organisms require nitrogen?

A

To synthesize proteins, nucleic acids and other nitrogen-containing compounds

464
Q

What % of molecular N is available in the atmosphere?

A

About 80%

465
Q

Why is it essential to convert atmospheric molecular N into bioavailable forms of N?

A

Because it is not biologically available for organisms

466
Q

What bioavailable forms of N do certain groups of microorganisms fix gaseous molecular N into ?

A

ammonia
nitrate
nitrite

467
Q

Why must nitrogen available on earth, organisms and atmosphere follow cyclic paths?

A

To fix gaseous molecular N into bioavilable forms of N

468
Q

What are the 4 key steps in the nitrogen cycle?

A

Ammonification
Nitrification
Denitrification
Nitrogen Fixation

469
Q

How does more than 90% of organic N in the soil exist?

A

As proteins

470
Q

How are proteins from dead plants and animals decomposed?

A

By extracellular proteolytic enzymes secreted by microorganisms into amino acids

471
Q

What is done to the resulting amino acids taken from the decomposed dead plants and animals?

A

They are take into microbial cells and are subjected to ammonification in which amino groups of amino acids are converted into ammonia (NH3)

472
Q

How is ammonium ions (NH4+) ions produced in moist soil?

A

Ammonia is solubilized in water to produce NH4+

473
Q

What is done by the ammonium ions produced by moist soil?

A

They are utilized by plants and soil microorganisms

474
Q

What occurs to the ammonia in dry soil?

A

It rapids disappears into the atmosphere

475
Q

What is nitrification?

A

It is the process of oxidation of nitrogen in the ammonium ion to produce nitrate

476
Q

What is nitrification performed by?

A

By nitrifying bacteria living in soil

477
Q

What are the 2 stages of nitrification?

A
  1. in the first stage, Microorganisms such as Nitrosomonas oxidizes ammonium ions into nitrites
  2. in the second stage, microorganisms such as Nitrobacter oxidizes nitrites into nitrates
478
Q

How do plants utilize nitrate?

A

As their source of nitrogen. therefore, microorganisms play essential roles in providing nitrogen in bioavailable forms for plants and animals

479
Q

What is denitrification?

A

In the absence of atmospheric oxygen, some microorganisms use nitrate and reduces it into n2. this process is called denitrification.

BIOLOGY STRUCTURED (13 decks)

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