Chapter 6 Microbiology 29-56

31. Name other elements that are critical for the function of the cell.

Potassium, magnesium, and calcium

48. What are the advantages of biofilms?

Proper functions for sewage treatment systems

53. What is a culture?

The microbes that grow and multiply in or on a culture medium

52. What is culture media?

The nutrient material prepared for growth of microorganisms in a laboratory

54. What is a medium?

The nutrient material prepared for growth of microorganisms in a laboratory

37. Why is hydrogen peroxide toxic? What gets rid of it?

When produced, contains peroxide anion which is also toxic Catalase gets rid of it

46. How can biofilms cause disease?

Biofilms form on almost all indwelling medical devices, including mechanical heart valves. Biofilms also can include those formed by fungi such as candida, are encountered in many disease conditions, such as infections related to the use of contact lenses, dental caries and infections by pseudomonad bacteria

50. What is the process that leads to coordinated release of proteins in biofilms?

Biofilms reside in a matrix made up primarily of polysaccharides, but also containing DNA and proteins, that is often informally called slime.

39. What is the function of peroxidase? How does it differ from catalase?

Breaks down hydrogen peroxide as well. Its reaction does not produce oxygen

30. Why is phosphorus important?

Essential for the synthesis of nucleic acids and the phospholipids of cell membranes. Among other places, it is also found in the energy bonds of ATP

43. Why are lactic acid-producers important?

Many of the aerotolerant bacteria characteristically ferment carbohydrates to lactic acid. As lactic acid accumulates, it inhibits the growth of aerobic competitors and establishes a favorable ecological niche for lactic acid producers. Example: acidic fermented foods such as pickles and cheese

36. Why is superoxide dismutase important? What it do?

Neutralizes the toxic form of oxygen superoxide radicals Covert superoxide radicals into molecular oxygen and hydrogen peroxide.

34. What effect does oxygen have on each of these?

Obligate aerobes: are at a disadvantage because oxygen is poorly soluble in the water of their environment. Therefore, many aerobic bacteria have developed, or retained, the ability to continue growing in the absence of oxygen. Facultative anaerobes: can use oxygen when it is present but are able to continue growth by using fermentation or anaerobic respiration when oxygen is not available. Their efficiency in producing energy decreases in the absence of oxygen. Obligate anaerobes: these bacteria do use oxygen atoms present in cellular materials, the atoms are obtained from water. Aertolerant anaerobes: cannot use oxygen for growth, but they tolerate it fairly well. On the surface of a solid medium, they will grow without the use of special techniques required for obligate anaerobes. Many of the aerotolerant bacteria characteristically ferment carbohydrates to lactic acid. Microaerphiles: they are anaerobic, they do require oxygen. They grow only in oxygen concentrations lower than those in air.

32. How is oxygen used in cells? What are obligate aerobes, obligate anaerobes, facultative anaerobes, aerotolerant anaerobes and microaerophiles?

Obligate aerobes: organisms that require oxygen to live Obligate anaerobes: are bacteria that are unable to use molecular oxygen for energy-yielding reactions Facultative anaerobes: can use oxygen when it is present but are able to continue growth by using fermentation or anaerobic respiration when oxygen is not available. Ex. Yeasts Aertolerant anaerobes: cannot use oxygen for growth, but they tolerate it fairly well. On the surface of a solid medium, they will grow without the use of special techniques required for obligate anaerobes. Microaerphiles: they are anaerobic, they do require oxygen. They grow only in oxygen concentrations lower than those in air.

56. Define sterile.

Contain not living microoganisms so that the culture will contain only microbes we add to the medium.

38. What is the function of catalase?

Converts it into water and oxygen

40. Why is ozone important?

Important form of reactive oxygen

41. Why is the hydroxyl radical important? What can it do?

Is another form of oxygen and probably the most reactive. Ingested pathogens are killed by the exposure to hydroxyl radical, as well as superoxide radicals , and peroxide anions of hydrogen peroxide.

51. What are some possible methods of getting rid of biofilms?

Lactoferrin, which is abundant in many human secretions, can inhibit biofilm formation. Lactoferrin binds iron, among pseudomonas that are responsible for cystic fibrosis biofilms, the cause of the pathology of this hereditary disease. The lack of iron inhibits the surface motility essential for the aggregation of the bacteria into biofilms.

47. How can microbes that produce biofilms spread?

Microbes and clumps of slime occasionally leave the established biofilm and move to a new location where the biofilm becomes extended.

49. Why are biofilms important in causing disease?

Microbes in biofilms are probably 1000 times more resistant to microbicides. Experts at the center for disease control and prevention estimates 70% of human bacterial infections involves biofilms.

55. Define inoculum.

Microbes that are introduces into a culture medium to initiate growth

44. What are biofilms and why are they important?

Microorganisms seldom live in the isolated single-species colonies Biofilms are usually attached to a surface such as rock in a pond, a human tooth or a mucous membrane.

29. Why is sulfur important?

Sulfur is used to synthesize sulfur-containing amino acids and the phospholipids of cell membranes.

35. What are the toxic forms of oxygen, and what gets rid of them?

Superoxide radicals/ superoxide anions: superoxide dismutase neutralize them Hydrogen peroxide/ Peroxide anion: catalase converts it into water and oxygen Hydroxyl radical

42. What are some organic growth factors?

They must be directly obtained from the environment Vitamins for humans Vitamins function as enzymes in order to function

45. What is quorum sensing?

ell to cell chemical communication, allows bacteria to coordinate their activity and group together into communities that provide benefits not unlike those of multicellular organisms