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SAC Microbiology > Lecture 3 > Flashcards

Lecture 3 Flashcards

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1
Q

All of the following are examples of light microscopy EXCEPT ______.

A) Electron
B) Fluorescent
C) Dark-field
D) Phase-contrast

A

Electron

Electron microscopy uses beams of electrons instead of rays of light. Electron microscopy can achieve far better resolution than light microscopy can.

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2
Q

All of the following are examples of differential stains EXCEPT______.

A) Spore stain
B) Gram stain
C) Acid-fast stain
D) Metheylene blue

A

Methylene blue

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3
Q

In microscopy, the ability to distinguish two objects separated by a small distance is _________.

A

Resolution

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4
Q

In microscopy, ______ is the smallest distance by which two objects can be separated and still be distinguished.

A

Resolution

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5
Q

The main reason we stain organisms while viewing them is ?

A

To increase contrast of organisms from the surrounding medium.

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6
Q

To increase resolution, all factors must be considered EXCEPT ______.

A) a detector (lens) with sufficient resolution for the given wavelength
B) the wavelength should be smaller than the object
C) the contrast between the object and its surroundings
D) the type of bacteria

A

the type of bacteria

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7
Q

To increase resolution, several factors are considered:

A

wavelength, light and contrast, and lens quality

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8
Q

What is the wavelength of visible light?

A

400–750 nm

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9
Q

When bacterial samples are made to adhere to the slide, this process is called ______.

A

fixation

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10
Q

Cells may be fixed with _____ or by _____ treatment.

A

methanol; heat

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11
Q

_____ is the bending of light as it enters a substance that slows its speed.

A

Refraction

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12
Q

While performing a gram stain on a mixed culture, your cell phone rings and you accidentally leave the decolorizing solution on too long. What color would you predict your gram-positive cells to be upon completion of the procedure?

A) Blue
B) Colorless
C) Pink
D) Purple

A

Pink

The decolorizing step is the most critical step while performing a gram stain. Leaving the decolorizing solution on too long will result in the over-decolorizing of the gram-positive cells, causing them to lose their purple stain. Upon the addition of the safranin stain, all cells will stain pink.

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13
Q

Gram positives have more ____ in their outer layer than negatives.

A

Peptidoglycan

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14
Q

5 examples of differential stains:

A
  1. Gram
  2. Acid-fast
  3. Endospore
  4. Flagella
  5. Capsule
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15
Q

Steps in gram staining:

A
  1. Add methanol/heat to fix cells to slide
  2. Add crystal violet
  3. Add iodine, which binds stain to cells
  4. Wash with ethanol to decolorize (dehydrates cell)
  5. Crystal violet stain is removed from gram negatives
  6. Add safranin counter stain
  7. Safranin stains gram negatives
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16
Q

Carbohydrates are made up of what elements in what ratio?

A

C:H:O in a 1:2:1 ratio

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17
Q

The simplest carbohydrates are called ?

A

Monosaccharides

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18
Q

Two bonded monosaccharides are called ?

A

Disaccharides

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19
Q

The reaction to bond two monosaccharides is called ?

A

Dehydration

20
Q

The reaction break apart a disaccharide is called ?

A

Hydrolysis

21
Q

Lipids are usually polar or non-polar?

A

Non-polar

22
Q

What type of bond between two amino acids?

A

Peptide bond

23
Q

What happens when a protein loses it’s shape due to temperature, pH, or salt?

A

Denaturation

24
Q

Name the nitrogenous bases in DNA.

A

Adenine, Thymine, Guanine, & Cytosine

25
Q

In RNA, what nitrogenous bases replaces what?

A

Uracil replaces Thymine

26
Q

The backbone of DNA is made up of ?

A

Sugars and phosphate groups

27
Q

The “rungs” of DNA are made up of ?

A

Nitrogenous bases

28
Q

Energy is removed from ATP by hydrolysing ?

A

Phosphate

29
Q

What is this called?

A

Phospholipid

30
Q

What is this called?

A

Nucleotide

31
Q

What is this called?

A

Protein

32
Q

What is this called?

A

Sterol

33
Q

Light absorption

A

The object blocks part of the light

34
Q

Light reflection

A

The wavefront bounces off the surface

35
Q

Light refraction

A

The light bends when it enters the surface that changes its speed

36
Q

Light scattering

A

A small fragment of the light is scattered in all direction

37
Q

Prokaryotic DNA is concentrated within the ____ region of the cell.

A

Nucleoid

38
Q

Prokaryotic ribosome size

A

70S

39
Q

Eukaryotic ribsome size

A

80S

40
Q

The major component of bacterial cell walls is ____; it is only found in bacteria.

A

Peptidoglycan

41
Q

____ is thought to stabilize peptidoglycan by increasing its rigidity

A

Teichoic acids

42
Q

Mycobacteriaceae have an external layer of waxy ____ in the cell wall.

A

Mycolic acid

43
Q

What staining method is used to penetrate mycolic acid?

A

Acid-fast stain

44
Q

Tumbling is the ____ rotation of flagella.

A

Clockwise

45
Q

Running is the ____ rotation of flagella

A

Counter-clockwise

46
Q

•What is the function of the cell wall in prokaryotes?

A

Protecting the cell from changes in osmotic pressure and maintaining its shape

SAC Microbiology (19 decks)

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