Microbial world + classification + Growth + Metabolism Flashcards

Question

What is Light Microscopy: Dark field

Answer 1

⚫ A technique for improving the contrast of unstained, transparent specimens ⚫ Dark field can dramatically improve image contrast (especially of transparent objects) while requiring little equipment setup or sample preparation ⚫ The technique does suffer from low light intensity in final image of many biological samples and continues to be affected by low apparent resolution

Answer 2

⚫ Shows differences in refractive index as a difference in contrast ⚫ Circular annulus in the condenser produces a cone of light ⚫ Cone is superimposed on a similar sized ring within the phaseobjective ⚫ Every objective has a different size ring, so for every objective another condenser setting has to be chosen ✓ Staining not required x Halos can form which obscures detail

Answer 3

Key features: 1) Resolution 2) Magnification 3) Objectives 4) Illumination

Answer 4

⚫ Resolution = ability to distinguish two very small and closely-spaced objects as separate entities.

Answer 5

⚫ Resolution is best when the distance separating the two objects is short.

Answer 6

⚫ Resolution is determined by certain physical parameters that include the wavelength of light, and the light-gathering power of the objective and condenser lenses.

Answer 7

⚫ The human eye is best adapted for green light and our ability to see detail may be compromised with the use of blue or violet. ⚫ Most manufacturers of microscopes correct their simplest lenses for green light

Answer 8

⚫ Most microscopes are known as compound microscopes: ⚫ a magnified image of an object is produced by the objective lens. ⚫ this image is magnified by a second lens system (the ocular or eyepiece) for viewing.

Answer 9

⚫ Final magnification of the microscope is dependent on the magnifying power of the objective times the magnifying power of the ocular.

Answer 10

⚫ Objective magnification powers range from 4X to 100X ⚫ Ocular magnification ranges are typically 8X-12X with 10X being most common ⚫ As a result, a standard microscope will provide you with a final magnification range of ~40X up to ~1000X

Answer 11

⚫ Each objective lens consists of six or more pieces of glass that combine to produce a clear image of an object ⚫ These are needed to provide corrections that produce image clarity

Answer 12

⚫ Essential factor in producing a good image with the light microscope is obtaining adequate levels of light in the specimen or object plane ⚫ It is not only necessary to obtain bright light around the object, but for optimal imaging, the light should be uniform across the field of view

Answer 13

⚫ The best way to illuminate the specimen involves the use of yet another lens system, known as a condenser

Answer 14

In epifluorescence microscopy, a parallel beam of light is passed directly upwards through the sample, maximizing the amount of illumination using an excitation filter an emission filter and a dichroic mirror

Answer 15

⚫ Creates various images by focusing a high energy beam of electrons onto the surface of a sample ⚫ Detects signals from the interaction of the incident electrons with the sample surface

Answer 16

The type of signals gathered in an SEM vary and can include ⚫ secondary electrons ⚫ characteristic x-rays ⚫ back scattered electrons

Answer 17

Microbiology is a biology of microorganisms (tiny organisms visible only under a microscope).

Answer 18

CHECK SLIDES

Answer 19

Almost certainly, the term "bacterium" was introduced in 1828 by Christian Gottfried Ehrenberg, a famous German naturalist. The Greek βακτηριον means "small stick".

Answer 20

Studying bacteria played an enormous role in the development of modern biology, medicine and industry.

Answer 21

2 potential answers: - self-generation (from non-living matter) - generation from themselves

Answer 22

The argument of Pasteur against spontaneous generation 1) Sterilising the content of the flask 2) At upright position of the flask no microbial growth occurred. 3) If the liquid reached the flask’s neck with trapped microbes, the microbial growth occurred soon

Answer 23

Area-to-volume ratio is much higher in small cells. As a result, the exchange of substances is quicker. Advantages for the smaller cell: metabolism, reproduction and cell communications occur at higher rate that provides greater chances for survival and evolution.

Answer 24

Living cells contain 4 main classes of compounds which differ them from a non-living organic matter they are: Proteins - structural components of the cell, enzymes and regulators; encoded by genes; synthesised in ribosomes; Nucleic acids - genetic material (DNA and RNA, substances of heredity); Lipids - components of cellular membranes, cell wall and storage granules; Polysaccharides - components of cell walls and capsule.

Answer 25

Metabolic activities make cells chemically very complex and diverse.

Answer 26

1) Metabolism 2) Reproduction (Growth) 3) Differentiation 4) Communication 5) Movement 6) Evolution

Answer 27

1) Uptake of nutrients from the environment, their transformation within the cell, and elimination of wastes into the environment. The cell is thus an open system

Answer 28

Chemicals from the environment are turned into new cells under the direction of pre existing cells Reproduction is based on : a) Replication of DNA 2) Equal distribution of replicated DNA into 2 cells after division of the initial cell

Answer 29

Formation of a new cell structure such as a spore, usually as part of a cellular life cycle Differentiation is not a compulsory property of all microbial cells, but those species that form spores survive better unfavourable conditions.

Answer 30

Cells communicate or interact primarily by means of chemical that are released or taken up. One of the consequences of cell communications is the quorum sensing mechanism. It allows a population to sense critical amount of cells and stop divisions.

Answer 31

Living organisms are often capable of self propulsion Motility is not a compulsory property of all microbes

Answer 32

Cells contain gene and evolve to display new biological properties. Phylogenetic trees show the evolutionary relationship between cells.

Answer 33

Coding functions: genetic processes based on information encoded by DNA E.g. DNA replication, transcription, RNA, Translation

Answer 34

Machine functions: biochemical and physiological processes based on metabolism. E.g. 1. Energy: ADP + Pi = ATP 2) Metabolism 3) Enzymes

Answer 35

*increasing size of cells (enlargement of cells) *increasing number of cells (cell division=replication)

Answer 36

1) A parent cell prepares for division by enlarging cell wall, plasma membrane and overall volume. DNA replication then starts. 2) Septum begins to grow inwards as chromosomes move to opposite ends of the cell. Other cytoplasmic components are distributed to the 2 developing cells. 3) The septum is synthesized completely through the cell centre, creating two separate cell chambers 4) At this point, the daughter cells are divided some species separate completely whilst others remain attached forming chains doublets or other cellular arrangements.

Answer 37

Counting viability of cells using serial dilutions is a basic technique in microbiology.

Answer 38

10ml of broth culture + 1ml of culture (10+1): 1 = 11 times 20 ml of broth culture +5ml of culture (20+5): 5 = 5 times 10ml of broth + 10ml of culture (10+10):10 = 2 times

Answer 39

For diluting many simultaneous samples, saline or water could be used.

Answer 40

a square or rectangular shaped archaeon.

Answer 41

Henk Bolhuis and Francisco Rodriguez-Valera taking samples from a freshly harvested crystalliser pond in Alicante, Spain. From this sample, 'Haloquadratum walsbyi' was isolated and cultivated

Answer 42

Evaporation of sea water results in crystalliser ponds with: concentration and precipitation of calcium carbonate, calcium sulphate, sodium chloride and magnesium chloride.

Answer 43

At the last stage of halite formation (before the magnesium chloride is precipitated), the square bacteria dominate (80% of the total microbial biomass).

Answer 44

Growth medium for H. walsbyi contains up to 2 M of MgCl in addition to 3.3 M of NaCl.

Answer 45

Haloquadratum walsbyi (H. walsbyi), a square-shaped archaeon, is important because its unique morphology and ability to thrive in extremely salty environments provide insights into adaptation strategies in extreme environments, cell shape determination, and the potential for life in similar, harsh conditions on other planets.

Answer 46

Protein = 55 Lipid = 9.1 Polysaccharide = 5 Lipopolysaccharide = 3.4 DNA = 3.1 RNA = 20.5 Numbers = percent of dry weight

Answer 47

includes two general, mutually complementary processes – synthesis (= anabolism, energy-consuming process) and breakdown (=catabolism, energy-releasing process)

Answer 48

Anabolism & catabolism = metabolism

Answer 49

The main features of chemical reactions outside of living cells are: - they occur spontaneously; - without particular control; - wherever and whenever possible; - usually reactions in the nature are very rapid.

Answer 50

- they occur in certain order and in certain compartments of the cell or the organ; - they are under strict control –due to the presence of regulatory mechanisms; - they don’t occur at any time; - biochemical reactions are relatively slow – due to the biological catalysts (mostly enzymes).

Answer 51

Nutrients are substances required for metabolism and reproduction of cells Macronutrients are required in large amounts. Micronutrients are required in small amounts. The process of uptake and initial processing of nutrients is called nutrition

Answer 52

In contrast to higher organisms, prokaryotes don’t have specialised structures for nutrition. The whole prokaryotic cell is involved into nutrition all the time during active reproduction.

Answer 53

When nutrition is limited due to the lack of nutrients, the bacterial growth is inhibited, and many bacterial species could undergo sporulation, the temporary state of “conservation”.

Answer 54

Anabolism: the sum of biochemical processes towards the synthesis of cell constituents from simpler molecules. It requires energy.

Answer 55

the sum of biochemical processes leading to breakdown of complex compounds to simple substances. It releases energy.

Answer 56

Phototrophic organisms convert solar energy to chemical energy and production of ATP.

Answer 57

Chemotrophs oxidise a broad range of organic and inorganic compounds to produce ATP.

Answer 58

Autotrophs – can use inorganic CO2 as a single source of carbon (e.g. prototrophs and many chemolitotrophs).

Answer 59

Heterotrophs – require one or more organic compounds as a source of carbon (e.g. chemoorganotrophs).

Answer 60

oxygenic photosynthesis – oxygen (O2) is evolved (in cyanobacteria); anoxygenic photosynthesis – oxygen is not produced (purple and green bacteria).

Answer 61

Differences in metabolism form a basis for structural differences that are integrated in morphological diversity of organisms.

Answer 62

Differences in processes of obtaining energy make a basis for metabolic diversity of all microorganisms, not only bacteria or archaea.

Answer 63

includes fermentation and respiration - two ways of conservation of energy from organic sources of carbon. Both processes consist of series of catabolic reactions (breakdown reactions).

Answer 64

Fermentation is an anaerobic catabolism in which an organic substance serves as a donor and acceptor of electrons and ATP is produced by substrate-level phosphorylation (from energy-rich intermediates in the process of fermentable substrate breakdown).

Answer 65

Respiration is catabolism where organic substance is oxidized by oxygen (or substitute) as electron acceptor, and ATP is produced by oxidative phosphorylation.

Answer 66

Both fermentation and respiration occur after glycolysis.

Answer 67

catabolism of glucose to pyruvate. The pyruvate is broken to fermentation products (ethanol + CO2 or lactate).

Answer 68

Lactic acid fermentation is anaerobic respiration in Lactobacillus and other bacteria (the same in muscle cells during working hard and fast).

Answer 69

Ethanol fermentation occurs in yeasts

Answer 70

Citric acid cycle (CAC, also known as Krebs cycle): a way of generation of ATP (=energy) via respiration after glycolysis. CAC has bioenergetic and biosynthetic roles. CAC pruduces important compounds for anabolism (biosynthesis): a-ketoglutarate and oxalacetate (precursors of a few aminoacids); succinyl-CoA (precursor for cytochromes, chlorophyll and others).

Answer 71

Carbon (C) is a major macronutrient for all living cells (~50% of a dry weight). It is a component for all macromolecules. e.g. methane Nitrogen (N) is the second most abundant element of the cell (~12% of dry weight). It is included into proteins, nucleic acids and other cell components. Nitrogen is available from the nature in organic and, mostly, inorganic (ammonia NH3 , nitrate NO3- or N2) forms. Most bacteria use ammonia, some use nitrates, and rare bacteria (nitrogen fixing) could use N2 as a single nitrogen source.

Answer 72

These organisms inhabit soil and are capable of fixing N2 aerobically, non-symbiotically.

Answer 73

The other essential macronutrients are: Phosphorus (P) - needed for nucleic acids and phospholipids); Sulphur (S) - for amino acids cysteine and methionine; vitamins thiamine, biotin and lipoic acid; also for coenzyme A); Potassium (K) - required for many enzymes, e.g. for protein synthesis); Magnesium (Mg) - for stability of ribosomes, membranes and nucleic acids; for activity of many enzymes). Calcium (Ca) (not essential for many microorganisms) - stabilises cell walls and helps in thermo-resistance of endospores. Sodium (Na) is required by some microorganisms (e.g. murine microbes) but not all (fresh water microbes can grow without it).

Answer 74

plays a role in respiration (it is a component of cytochromes and iron-sulphur proteins involved in electron transport). It is needed in less amounts than other macronutrients

Answer 75

Cells obtain iron from different insoluble minerals by specialised components – siderophores.

Answer 76

Siderophores are different organic compounds (like phenol-derivatives, peptide-like- or lipid containing compounds) that bind iron and transport it into cells.

Answer 77

Enterobactins are siderophores of E. coli and Salmonella typhimurium.

Answer 78

Micronutrients are needed in trace amounts, as enzyme components Boron (B), Chromium (Cr), Cobalt (Co), Copper (Cu), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Selenium (Se), Tangsten (W), Vanadium (V), Zink (Zn) Not all of them are needed for all cells.

Answer 79

are organic compounds (vitamins, amino acids, purines and pyrimidines) needed by some cells in small amounts. Vitamins are most required growth factors.

Answer 80

are nutritional mixtures for cultivation of microorganisms in laboratory and industry. They can be chemically defined (defined medium) or undefined (complex medium).

Answer 81

Selective, differential, and enriched media are used for the isolation of particular species or for comparative studies of microorganisms.

Answer 82

Solid media (with a gelling agent, usually agar) are useful for isolation and maintenance of pure microbial cultures. They immobilise cells, allowing them to grow and form visible, isolated aggregates of cells (colonies)

Answer 83

Liquid media are used for a rapid and large scale cultivation of pure microbial cultures.

Answer 84

Rhizobial cells enter into the root hair via the root hair tip and cause nodule formation. The rhizobia multiply rapidly first in the plant cells and are transformed then into swollen, branched bacteroids (less motile but able to fix nitrogen). Symbiotic nitrogen fixation enhances production of many important crops.

Answer 85

Bacteria-plant symbioses are close, long-term interactions between bacteria and plants, where both organisms benefit, like nitrogen-fixing bacteria in legumes, or where one benefits at the expense of the other, as in some parasitic interactions

Answer 86

The O2 -binding protein leghemoglobin controls levels of the process in the nodule.

Microbial world + classification + Growth + Metabolism Flashcards

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