Chp 4 -Microscopy, Staining & Classification

Question 1

1 mm (millimeter)= ___ um (micrometers)

Answer 1

1,000 um (micrometers)

Question 2

1 um (micrometer) = ____ nm (nanometers)

Answer 2

1,000 nm (nanometers)

Question 3

The size of a bacterium is 0.5 mm. What is its size in um?

Answer 3

500 um

Question 4

What are the different types of light microscopes?

Which one do we use in lab?

Answer 4

Bright-field= Used in lab
Dark-field
Phase-contrast
Differential Interference
Fluorescent

Question 5

What are the magnifications for LPO, HPO, OIO?

Answer 5

LPO= 10X
HPO= 40X
OIO= 100X

Question 6

What are the general principles off microscopy?

Answer 6

Wavelength of radiation
Magnification
Resolution
Contrast

Question 7

What is wavelength?

Answer 7

Distance between the waves

Question 8

What is the relationship of wavelengths to resolution?

Answer 8

Inversely related

• smaller/shorter wavelengths : higher resolution
• larger/wider wavelengths : lower resolution

Question 9

What is resolution?

Answer 9

Sharpness or clearness of an image

Question 10

What is the effect of immersion oil on resolution?

Answer 10

Increase the resolution= sharper image

Question 11

What caused light rays to bend when traveling from air to glass?

Answer 11

Air & glass have different optical densities causing light rays to bend

Question 12

What is contrast?

Answer 12

Staining; color the specimen, increases contrast

Question 13

When observing microbes under the microscope, how is contrast increased?

Answer 13

Staining

Question 14

What is the charge of the chromogen of acidic stains?

Answer 14

Acidic= - (negative)

Question 15

What are some examples of acidic stains?

Answer 15

Congo red
Nigrosin
India Ink

Question 16

What is the charge of the chromogen of basic stains?

Answer 16

Basic= + (positive)

Question 17

What are some examples of basic stains?

Answer 17

Crystal Violet
Safranin
Methylene Blue
Carbolafuchsia

Question 18

What is a bacterial smear?

How is it prepared?

Answer 18

Thin film of bacteria on a glass slide

1- Sterilize
2- Spread Culture (circular motion) size of penny
3- Air dry
4- Heat fixation

Question 19

Why are bacterial smears heat fixed?

Answer 19

• kill bacteria

- coagulate proteins= attach them to the slide

Question 20

In simple staining how many stains are used?

Answer 20

1 Dye

Question 21

What are the uses of simple staining?

Answer 21

Cell size
Cell shape
Cell arrangement (morphology)

Question 22

What is the purpose of gram-staining?

Answer 22

Divides the bacteria into 2 groups: Gram - or +

Question 23

How many stains are used in Gram- staining?

Answer 23

2

Question 24

In gram-staining what is the primary stain and what is the secondary stain?

Answer 24

Primary- Crystal Violet

Secondary- Safranin

Question 25

What is the function of the mordant? In gram staining what is the mordant?

Answer 25

Intensifies the stain Iodine

Question 26

At the end of gram staining process what is the color of the gram + bacteria and gram - bacteria?

Answer 26

Gram + = Purple | Gram - = Red/Pink

Question 27

What is the purpose of acid-fast staining?

Answer 27

Separate it into 2 groups: Acid-fast bacteria & Non-acid fast bacteria.

Question 28

Differentiate acid-fast bacteria from non-acid fast bacteria?

Answer 28

Acid fast has mycolic acid that adds protection Non-acid fast does not have mycolic acid

Question 29

In gram staining, account for the difference in color of the cells after application of ethanol

Answer 29

Gram - (negative) has outer-membrane and ethanol goes through phospholipid bilayer leaking out the color

Question 30

How many stains are used in acid-fast staining method? What is the purpose of using heat in this staining method?

Answer 30

2 Heat-fixation

Question 31

In acid-fast staining, what is the primary stain & the secondary stain?

Answer 31

Primary= Carbolfuchsin Secondary= Methylene Blue

Question 32

Account for the difference in color of the cells after application of acid-ethanol?

Answer 32

Acid-fast bacteria retain the color because of the structure of the cell wall in gram +

Question 33

At the end of the staining process, what is the color of the acid-fast bacteria and the non-acid-fast bacteria?

Answer 33

Acid-fast= Red Ex. AFB= acid-fast bacillus Mycobacterium tuberculosis Non-acid fast= Blue

Question 34

How many stains are used in endospore staining? What the the primary and secondary stain?

Answer 34

2 ``` Primary= Malachite Green Secondary= Safranin ```

Question 35

What is the purpose of using heat in endospore staining?

Answer 35

To drive the stain into the endospore

Question 36

At the end of the endospore staining process, what is the color of the endospores and vegetative cells?

Answer 36

Endospores= Green Vegetative Cells= Red

Question 37

What is microbial classification and what are its purposes?

Answer 37

Orderly arrangement of microorganisms into groups of larger units. Purpose: 1) Bring sense of order and organization 2) Enhance communication

Question 38

What are the three domains?

Answer 38

1) Bacteria - cell wall--- peptidoglycan 2) Archaea- doesn't have peptidoglycan 3) Eukarya

Question 39

Who proposed the division of the organisms into 3 domains?

Answer 39

Woese, Kandler, and Wheelis

Question 40

Out of the 3 domains which of the domains contain the prokaryotes?

Answer 40

Bacteria and Archaea

Question 41

What are the kingdoms under Domain Eukarya?

Answer 41

Protista, Fungi, Plantae, and Animals

Question 42

What are the taxonomic categories in order from the biggest group to the smallest group?

Answer 42

Domain, Kingdom, Phylum, Class, Order, Family, Genus and Species

Question 43

What is a bacterial species?

Answer 43

Group of strains that share many stable properties (basic properties).

Question 44

What is a bacterial strain?

Answer 44

Population of microbes descended from a single culture

Question 45

What is a biotype or biovar?

Answer 45

Strain with a characteristic biochemical pattern

Question 46

What is a serovar?

Answer 46

Strain that differs in antigenic structure

Question 47

What are sine genera of bacteria under Family Enterobacteriaceae? Why are they of medical importance?

Answer 47

All ferment glucose, all rod in shape, all gram-negative, and all oxidase negative. Ex. Escherichia, Proteus, Enterobacter, Salmonella, Klebsiella, serratia, shigella, and yersinia. Most of them cause disease common in hospitals and labs.

Question 48

Who introduced binomial system of nomenclature?

Answer 48

Carlous Linnaeus

Question 49

How are scientific name written?

Answer 49

Genus (first letter capitalized and underlined) and Specific (not capitalized and underlined) OR Italicize both but not underlined

Question 50

How are bacteria identified?

Answer 50

By determining their phenotype and genotype

Question 51

What are examples of phenotypes and genotypes of bacteria?

Answer 51

Phenotype (their physical appearance)= cell size, shape, and arrangement. Genotype (molecular and genetic characteristic) = DNA