2: Observing Microorganisms Through a Microscope

Question 1

diameter of most bacteria

Answer 1

0.2 to 2.0 micrometers

Question 2

diameter of typical human RBC

Answer 2

7 micrometers

Question 3

spiral-shaped bacterium that is the leading cause of stomach ulcers, chronic inflammation, and resulting stomach cancer

Answer 3

helicobacter pylori

Question 4

magnification of objectives lenses

Answer 4

low power=10X; high dry=40X; oil immersion=100X

Question 5

magnification of ocular lens

Answer 5

10X

Question 6

ability of the lenses of a microscope to distinguish between two separate points a specified distance apart

Answer 6

resolution

Question 7

Light microscopes cannot resolve structures smaller than____

Answer 7

0.2 micrometers

Question 8

a measure of the light-bending ability of a medium

Answer 8

refractive index

Question 9

how does staining bacteria help them be more easily seen?

Answer 9

changes their refractive index relative to the surrounding material

Question 10

helps reduce undesired refraction because it has the same refractive index as glass

Answer 10

immersion oil

Question 11

type of microscope used to diagnose syphilis, examine living microbes in liquid suspensions

Answer 11

darkfield microscope.

Question 12

syphilis

Answer 12

treponema pallidum, corkscrew microbes

Question 13

permits detailed examination of internal structures of living microbes

Answer 13

phase-contrast microscope

Question 14

uses two beams of light and prisms thereby adding contrasting colors to the view. similar to phase-contrast microscopy

Answer 14

Differential Interference contrast (DIC) microscopy

Question 15

employs a UV light source. requires specimen to be tagged with fluorchrome dyes that attach to specific antibodies. very rapid diagnostic test

Answer 15

fluorescent microscopes

Question 16

what bacterium is responsible for tuberculosis and what type of microscope is used to detect its presence?

Answer 16

Mycobacterium Tuberculosis. fluorescent microscope

Question 17

fluorescent dyes can be attached to specific antibodies which in turn can be used to label specific microbes

Answer 17

fluorescent antibody technique, or immunofluorescence

Question 18

specimens are stained with fluorchromes so they emit light, then scanned in fine cross-sectional slices with short-wavelength blue light. computer then contructs 3D complete image

Answer 18

confocal microscopy

Question 19

chancre

Answer 19

painless ulcer caused by syphilis

Question 20

can track the activity of living cells in real time

Answer 20

two-photon microscopy

Question 21

sends sound waves through specimen. can resolve as small as 1 micrometer

Answer 21

scanning acoustic microscopy (SAM)

Question 22

uses beam of electrons rather than light and uses magnets rather than lenses. resolves smaller than 0.2 micrometers. used to view viruses

Answer 22

electron microscopy

Question 23

electron microscope that provides only 2D and can magnify up to 100,000X

Answer 23

transmission electron microscope

Question 24

electron microscope that provides 3D and can magnify up to 10,000X

Answer 24

scanning electron microscope

Question 25

greater resolving power than electron microscopes and can be used to view molecules, such as DNA

Answer 25

scanning-probe microscopy

Question 26

simultaneously kills microorganisms and glues them to the slide

Answer 26

fixing

Question 27

stains the background, not the microbe. give example

Answer 27

negative stain. india ink prep

Question 28

what stain must be used to visualize cryptococcus neoformans or klebesiella pneumoniae

Answer 28

negative stain/ india ink

Question 29

often causes marked thickening of the subarachnoid space secondary to the hight mucopolysaccharide content of the organisms wall. at the same time, paucity of acute inflammation results in very little brain swelling. likes to prow in the brain of someone with AIDS. opportunistic.

Answer 29

cryptococcus meningitis

Question 30

space outside of brain where you find CSF

Answer 30

subarachnoid space

Question 31

used to visualize cell shape and arrangements only

Answer 31

simple stain

Question 32

differential stains

Answer 32

gram stain and acid-fast stain

Question 33

steps to gram stain

Answer 33

crystal violet>gram’s iodine (mordant)>alcohol or acetone alcohol (decolorizing agent)>safranin

Question 34

gram positive

Answer 34

blue bacteria

Question 35

how do all fungi (yeasts and molds) gram stain?

Answer 35

gram positive (blue)

Question 36

gram negative

Answer 36

red bacteria

Question 37

how do all human cells gram stain?

Answer 37

gram negative (red)

Question 38

how do mycobacterium gram stain?

Answer 38

gram positive, if at all

Question 39

“fixes” the gram stain so that it is harder to wash away

Answer 39

gram’s iodine, mordant

Question 40

used to stain members of the genus mycobacterium

Answer 40

acid-fast stain

Question 41

steps to acid-fast stain

Answer 41

carbolfuchsin (red dye)> heat> decolorize iwth acid alcohol > methylene blue

Question 42

acid fast bacteria

Answer 42

red bacteria

Question 43

non-acid fast bacteria

Answer 43

blue bacteria

Question 44

how do all human cells acid-fast stain?

Answer 44

non-acid fast (blue)

Question 45

microbe detected with acid-fast stain that affects the skin and nervous system. is temp sensitive (can’t survive in high temps)

Answer 45

mycobacterium leprae (leprosy)

Question 46

microbe detected with acid-fast stain that affects the lungs and spreads throughout the body

Answer 46

mycobacterium tuberculosis

Question 47

preparations for determination of motility

Answer 47

hanging drop or wet mount

Question 48

what must happen before microbes can be stained?

Answer 48

they must be “smeared” on a slide and “fixed” by gentle heating