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Microbiology > Microbil Cell Structure And Function > Flashcards

Microbil Cell Structure And Function Flashcards

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Biology 101 flashcards
1
Q

Many different types of light microscopy:

A

• Bright-field
• Phase-contrast • Dark-field
• Fluorescence

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2
Q

the ability to make an object larger

A

Magnification

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3
Q

the ability to distinguish two adjacent objects as separate and distinct

A

Resolution

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4
Q

Specimens are visualized because of differences in contrast (density) between specimen and surroundings

A

Bright-field scope

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5
Q

_____ improves contrast

A

Staining

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6
Q

____ are organic compounds that bind to specific
cellular materials

A

Dyes

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7
Q

Examples of common stains

A

methylene blue, safranin, and crystal violet

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8
Q

_______ separate bacteria into groups

A

Differential stains

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9
Q

_____ is widely used in microbiology

A

Gram stain

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10
Q

Bacteria can be divided into two major groups:

A

gram-positive and gram-negative

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11
Q

Gram-positive bacteria appear _____ and gram-negative bacteria appear ______ after staining

A

Purple, red

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12
Q

• Invented in 1936 by Frits Zernike
• Phase ring amplifies differences in the refractive index of cell and surroundings
• Improves the contrast of a sample without the use of a stain
• Allows for the visualization of live samples
• Resulting image is dark cells on a light background

A

Phase-contrast microscopy

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13
Q

• Light reaches the specimen from the sides
• Light reaching the lens has been scattered by specimen
• Image appears light on a dark background
• Excellent for observing motility

A

• Dark-field microscopy

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14
Q

• Used to visualize specimens that fluoresce
• Emit light of one color when illuminated with another color of light

A

Fluorescence microscopy

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15
Q
  • Specific on staining DNA: A-T rich region
  • Can stain both live (less efficient) and fixed cells - Excited by an ultraviolet light (358nm) emit blue
    color (461nm).
A

DAPI

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16
Q

Two types of electron microscopes:

A

• Transmission electron microscopes (TEM)
• Scanning electron microscopes (SEM)

17
Q

• Electromagnets function as lenses
• System operates in a vacuum
• High magnification and resolution (0.2 nm)
• Enables visualization of structures at the molecular level
• Specimen must be very thin (20–60 nm) and be stained (osmic acid,permanganate, uranium lanthium or lead
salts)

A

Transmission electron microscopy (TEM)

18
Q

• Specimen is coated with a thin film of heavy metal (e.g., gold)
• An electron beam scans the object
• Scattered electrons are collected by a detector, and an image is produced
• Even very large specimens can be observed • Magnification range of 15✕–100,000✕

A

Scanning electron microscopy (SEM)

19
Q

cell shape

A

Morphology

20
Q

Major cell morphologies

A

Coccus (pl. cocci)

Rod

Spirillum

21
Q

spherical or ovoid

A

Coccus (pl. cocci)

22
Q

cylindrical shape

A

Rod

23
Q

spiral shape

A

Spirillum

24
Q

Cells with unusual shapes

A

Spirochetes, appendaged bacteria, and filamentous
bacteria

25
Q

Size range for prokaryotes:

A

0.2 μm to >700 μm in diameter

26
Q

Most cultured rod-shaped bacteria are between______ wide and_____ long

A

0.5 and 4.0 μm, < 15 μm

27
Q

• Examples of very large prokaryotes

A

• Epulopiscium fishelsoni
• Thiomargarita namibiensis

28
Q

Size range for eukaryotic cells:

A

10 to >200 μm in diameter

29
Q

Size of Epulopiscium fishelsoni

A

(600um long, 75um wide)

30
Q

Size of Thiomargarita namibiensis

A

(400 – 750um)

31
Q

• Thin structure that surrounds the cell
• Vital barrier that separates cytoplasm from environment
• Highly selective permeable barrier; enables concentration of specific metabolites and excretion of waste products

A

Cytoplasmic membrane

32
Q

Composition of membranes

A

Microbiology (3 decks)

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