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Medical Microbiology 1-15 > Lecture 11 > Flashcards

Lecture 11 Flashcards

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Biology 101 flashcards USMLE® Step 1 flashcards
1
Q

At what ideal temperature ranges microorganisms grow?

A

-14 degrees celsius - 113 degrees celsius.

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2
Q

Define (Tmin).

A

The lowest temperature at which growth occurs.

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3
Q

Define (Tmax).

A

The highest temperature at which growth can occur.

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4
Q

Define (Topt).

A

Growth is the most rapid and optimum.

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5
Q

True or false. Each microbes can only grow within a temperature range that is characteristic of their own species.

A

True.

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6
Q

What are the temperature ranges for the growth of Escherichia Coli.

A

8-47 degrees celsius.

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7
Q

What is a cardinal growth?

A

Three key temperatures Tmax, Tmin and Topt.

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8
Q

What are the cardinal temperatures for E.Coli

A

Tmax-47 degrees celsius
Tmin-8 degrees celsius
Topt-37 degrees celsius (body temperature).

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9
Q

True or false. Survival occurs at temperatures below Tmin but death occurs above Tmax.

A

True.

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10
Q

What three groups are microbes divided into considering temperature range for growth?

A

1-thermophiles
2-mesopholes
3-psychorophiles and psychrotrophs

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11
Q

True or false. Thermophiles grow at higher temperatures thanks mesophiles and mesophiles grow at a higher temp than psychrophiles and psychrotrophs.

A

True.

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12
Q

What is E.coli considered?

A

Mesophile

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13
Q

What can psychrophiles and psychrotrophs do that mesophiles and thermophiles can’t?

A

Grow at temperatures around 0 degrees celsius.

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14
Q

What is distinguishes psychrophile from psychrotrophs?

A

They have a lower max temp for growth- specifically 20 degrees celsius.

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15
Q

Define termoduric

A

Termoduric describes microbes that can survive exposure to temperatures above their Tmax.

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16
Q

Explain lambda, f and C for the following formula of electromagnetic radiation, (lambda)f=c

A

lambda=wavelenght
f-frequency
c=velocity

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17
Q

Define ionizing radiation

A

X-rays and gamma are of enough energy to ionize molecules (remove electron from an atom).

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18
Q

Define non-ionizing radiations

A

Certain ultra violet has less energy and excites molecules- increase atomic electron energy.

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19
Q

When speaking if ultraviolet rays- what wavelength have the greatest microbicidal efficiency?

A

260 nm

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20
Q

Name two places where germicide lamps utilized and what are there functions?

A

1-These lamps are utilized in hospital operating rooms.
2-on contaminated surfaces in the dairy industry.
These lamps are used to reduced the size of microbial populations.

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21
Q

True or false. Ultraviolet rights penetrate matter well. Elaborate.

A

False. They do not. As a consequence, the microbicidal action is mostly on the surfaces.

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22
Q

True or false. Ultraviolet rays can either kill microbes or cause mutation in them.

A

True

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23
Q

True or false. The DNA is not specifically affected when speaking of ultraviolet rays effects.

A

False. The DNA is specifically affected.

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24
Q

What wavelength do x-rays include?

A

1nm - 10nm

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25
Q

How are x-rays produces?

A

By the interaction from a fast moving electron with atomic electrons or atomic nuclei.

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26
Q

True or false. X-rays are lethal to microorganisms?

A

True

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27
Q

True or false. They do not penetrate matter well.

A

False, they do penetrate well.

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28
Q

True or false. X-rays cause mutations in microorganisms.

A

True

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29
Q

Give 2 points as to why it is impractical to use x-rays to reduce the size of microbial population.

A

1-expensive to produce in quantity

2-They are difficult to use efficiently as they are given off in all directions.

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30
Q

What sizes are gamma rays considered to be?

A

From 0.001 nm - 1 nm

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31
Q

True or false. Gamma rays are edited from certain radioactive isotopes?

A

True

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32
Q

True or false. Gamma rays are not lethal to microorganisms.

A

False. They are lethal.

33
Q

Gamma rays have shorter wavelengths and a higher energy compared to what other rays?

A

X-rays

34
Q

What are more penetrating? Gamma rays or x-rays?

A

Gamma rays

35
Q

Gamma rays are very penetrating and can sterilize materials of considerable thickness. What food industry most utilize these types of rays.

A

The food industry to sterilize meat, poultry and packaged foods.

36
Q

What type of medical things are gamma rays used to sterilize?

A

Antibiotics, hormones, sutures, plastic materials such as syringes.

37
Q

True or false. Is there concern that food industries utilize gamma rays as sterilization there could be potential in making the food carcinogenic?

A

True.

38
Q

When referring to acoustic radiation, what does cps stand for?

A

Cycles per second.

39
Q

How many cps are sonic waves? supersonic waves? and ultrasonic waves?

A

12,000-16,000 cps, larger than 16,000 cps and larger than 200,000 cps.

40
Q

Acoustic radiation is not used to reduced the size of microbial population, but rather…(finish the sentence).

A

in research laboratories to disrupt microbial cells so intracellular constituents can be extracted i.e intracellular enzymes.

41
Q

By what means is the disruption of the microbial cell?

A

Sonication

42
Q

What does sonication mean?

A

The use of acoustic radiation

43
Q

Explain the process of sonication.

A

The microbial cel is suspended in a fluid and subjected by acoustic radiation with specific energy for a specific time.

44
Q

What is considered to be of sufficient energy.

A

20,000 cps

45
Q

Name the three microbes that are most resistant to acoustic radiation.

A

1-Acid-fast bacteria and endospores
2-Cocci are more resistant to bacilli
3-Gram-positive bacilli are more resistant to Gram-negative bacilli.

46
Q

What is the min, optimum and max pH ranges for E.coli

A

Min. 4.4
Opt. 6-7
Max. 9

47
Q

What are the min, optimum and max pH ranges for S. pneumoniae

A

Min. 6.5
Opt. 7.8
Max. 8.3

48
Q

Explains the process of oxidation when speaking of electrons.

A

The substance will lose electrons.

49
Q

Explain the process of reduction when speaking of electrons.

A

The substance will gain electrons.

50
Q

What do we consider the pair of reactions when speaking or reduction and oxidation?

A

Redox reactions.

51
Q

What is the method of measurable value used to measure the potential tendency of a substance to undergo oxidation or reduction?

A

An O-R potential

52
Q

What do substances with negative O-R potentials tend to undergo?

A

Oxidation

53
Q

What do substances with positive O-R potentials tend to undergo?

A

Reduction

54
Q

True or false. In order for a microbe to grow in a medium, the medium must have an appropriate O-R potential.

A

True.

55
Q

Define osmosis

A

The diffusion of solvent molecule through a semipermeable membrane.

56
Q

True or false. The cytoplasmic membrane is semipermeable?

A

True.

57
Q

Define hypotonic medium.

A

Has a higher solute concentration that the cell.

58
Q

Define plasmolysis.

A

Waters moves from the area of lower solute concentration (the cell) to the area of higher solute concentration (the medium)

59
Q

Define what a osmotic lysis is.

A

When the cell sweets ans bursts.

60
Q

What concentration of NaCl is harmful to bacteria?

A

Greater than 1%

61
Q

Name 3 types of bacteria that are able to withstand larger NaCl concentrations and their percentage.

A

1-Indegenous to the sea: 3.5-4%
2- Bacteria of the Dead Sea and the Great Salt Lake of Utah: 29 %
3-Bacteria that grow in pickling brines: 20-30%

62
Q

Generally speaking, at what percentage are bacteria inhibited by NaCl and sugar?

A

NaCl: 10-15%
Sugar: 50-70%

63
Q

What is the termed used to define the mechanism of microbial inhibition?

A

Plasmolysis

64
Q

True or false, you can preserve foods by salting or sugaring?

A

True.

65
Q

True or false. The microbes are not killed by plasmolysis, it can be a reversible process.

A

True

66
Q

Define desiccation

A

Drying process which causes cessation of metabolic activity.

67
Q

What follows cessation in desiccation of cell.

A

Decrease in viable cells.

68
Q

The longevity of the cells post desiccation varies on what two factors?

A
  1. The microbe itself

2. The medium in which the microbe is desiccated.

69
Q

True of false. Desiccation is not a method of preserving foods. Elaborate

A

False. It is- as long as it’s kept dry.

70
Q

Define Lyophilization.

A

Also known as freeze drying where the material is first frozen then dried.

71
Q

True or false. Lyophilization microbe remain viable for years.

A

True

72
Q

Define a mutation.

A

It’s a change in nucleotide sequence of DNA.

73
Q

Define genetic recombination.

A

A formation of a new chromosome from DNA contributed by 2 other organisms.

74
Q

What is the new chromosome called after a generic recombination? Name the new formation in bacteria (there is the formation of a new chromosome and…)

A

Recombinant chromosome. In bacteria there is also the formation of a new plasmid.

75
Q

In bacteria, genetic recombination is brought about what three processes?

A

1: Transformation
2: Transduction
3: Conjugation

76
Q

When speaking of genetic recombination, define the transformation process.

A

The recipient takes a naked DNA from the environment and integrates it to the chromosome.

77
Q

When speaking of genetic recombination, define the transduction process.

A

A bacteriophage is the vector, it then carries the DNA form the donor bacterium, which gets replicated, to the recipient bacterium. The DNA is then integrated in the chromosome.

78
Q

When speaking of genetic recombination, define the conjugation process.

A

Cell-to-cell contact occurs by two cells by means of the F plus processed by the donor. The F plus then contracts is and brings it to two cells closer together.
DNA is transferred by a way of conjugation bridge. The DNA is finally integrated in the chromosome.

Medical Microbiology 1-15 (15 decks)

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