Chapter 2-Microscopy

Question 1

What is the size of the smallest viruses?

Answer 1

they are measured in nanometers (nm)

Question 2

Microscopes produce _________ images

Answer 2

magnified

Question 3

microscopes vary in _____________, ____________, & _______________.

Answer 3

illumination source, focusing method, specimen preparation

Question 4

use visible light to illuminate specimens, can be simple or compound

Answer 4

light microscopy

Question 5

objective magnification X ocular magnification

Answer 5

total magnification

Question 6

the ability to distinguish two close adjacent objects as separate and distinct

Answer 6

resolution

Question 7

what determines resolution?

Answer 7

wavelength of light used and the lenses used

Question 8

specimens are visualized because of differences in contrast between specimen and surroundings, has a specific condenser lens, produces a dark image against a brighter background

Answer 8

bright-field microscope

Question 9

distance between the front surface of lens and surface of cover glass or specimen when it is in sharp focus

Answer 9

working distance

Question 10

uses a special condenser lens, image is formed by light reflected or refracted by specimen, bright image of the object against a dark background, observe a living, unstained preparation

Answer 10

dark-field microscope

Question 11

converts slight differences in refractive index and cell density into easily detected variations in light intensity, used to observe living cells

Answer 11

phase-contrast microscope

Question 12

used to visualize specimens that fluoresce after exposure of specimen to UV, violet, or blue light, some cells naturally fluoresce, shows a bright image of the object resulting from the fluorescent light emitted by the specimen, can locate specific proteins in cells

Answer 12

fluorescence microscope

Question 13

creates image by detecting differences in refractive indices and thickness of different parts of specimen, excellent way to observe living cells

Answer 13

differential interference contrast microscope (DIC)

Question 14

creates a sharp composite 3D image of specimens by using laser beam, aperture, to eliminate stray light, and computer interface

Answer 14

confocal microscopy

Question 15

what are 2 types of slide preparations?

Answer 15

(1) unstained preparations

(2) stained preparations

Question 16

why can is staining an effective mechanism for observing specimens?

Answer 16

stains improve contrast of the final image (specimen vs. surrounding)

Question 17

kills microorganisms, preserves internal and external structures and adheres them to the slide

Answer 17

fixation

Question 18

any distortion in the true morphology of the microorganism due to the technique itself

Answer 18

artifact (done through heat fixation or chemical fixation)

Question 19

coloring ion

Answer 19

chromophore

Question 20

chromophore cation, binds to cells and most dyes

Answer 20

basic dye

Question 21

chromophore anion, repelled by cells and stains background

Answer 21

acidic dye

Question 22

make internal and external structures of cell more visible by increasing contrast with background

Answer 22

dyes

Question 23

simple staining techniques involve using __ dye and has few steps. all slides are stained in the same way

Answer 23

1 dye

Question 24

differential staining techniques involve using ____ dyes and has several steps. Microorganisms are divided based on their staining properties (gram stain or acid-fast stain)

Answer 24

2 dyes

Question 25

most widely used differential staining procedure, divides bacteria into 2 groups of negative and positive

Answer 25

gram staining

Question 26

positive and negative classifications of a gram stain are based on _______________?

Answer 26

differences in cell wall structure

Question 27

acid fast staining structures have a high __________ content in cell walls

Answer 27

lipid

Question 28

endospore staining, capsule staining, and flagella staining are all examples of _________________

Answer 28

staining specific structures

Question 29

uses electrons instead of light as illuminating beam, uses magnets and metals, allows for microbial study in great detail

Answer 29

electron microscopy

Question 30

uses magnets to observe denser regions of a specimen, electrons scatter when passing through think sections

Answer 30

transmission electron microscope

Question 31

when using a transmission electron microscope, specimens are fixed _______________

Answer 31

chemically

Question 32

negative stain, shadowing, and freeze etching are examples of various preparation methods that allow for _______________

Answer 32

dark backgrounds and some 3d observation

Question 33

grow microorganisms, either liquid of solid substance

Answer 33

culture

Question 34

the nutrient material used to culture microorganisms (liquid or broth, solid medium contains solidifying agent)

Answer 34

medium

Question 35

contains 2 or more specimens

Answer 35

mixed culture

Question 36

contains only 1 specimen

Answer 36

pure culture

Question 37

free of all viable microorganisms

Answer 37

sterile

Question 38

adding microorganisms to culture media

Answer 38

inoculation

Question 39

any unwanted microorganism

Answer 39

contaminant

Question 40

anything done to minimize contamination

Answer 40

aseptic technique