week 2-Microscopes, Staining, Taxonomy

Question 1

Contrast

Answer 1

Differences in intensity between two objects, or an object and its background

Question 2

objective

Answer 2

magnification lenses

Question 3

What magnification does the blue objective lens provide?

Answer 3

40x
can see some protozoa/fungi

Question 4

What magnification does the white objective lens provide?

Answer 4

100x
needed for bacteria

Question 5

What magnification do the oculars provide?

Answer 5

10x

Question 6

What is the TOTAL magnification the blue objective lens and oculars can provide?

Answer 6

400x

Question 7

What is the TOTAL magnification the white objective lens and oculars can provide?

Answer 7

1000x

Question 8

What is the purpose of the oil used with the white objective lens?

Answer 8

Oil immersion lens increases resolution (detail)

Question 9

What is electron microscope used for

Answer 9

to see very small bacterial virus
inside bacterial cells (ultrastructures)

Question 10

what a Transmission Electron Microscope can show you

Answer 10

observe internal structures of cells and to see small bacteria and viruses

Question 11

what a Scanning Electron microscope can show you?

Answer 11

can observe surface details of microbes and outer cellular structures

Question 12

What can dark-field microscopy be used for?

Answer 12

-Live specimens(no staining)
-Specimen appears light against dark background
-also used for colorless microorganisms

Question 13

What is the importance/purpose of staining?

Answer 13

increases contrast and resolution

Question 14

Acidic dye
Basic dye

Answer 14

Acidic dyes stain alkaline structures
* Basic dyes stain acidic structures

Question 15

What is a simple stain and what can it show?

Answer 15

Composed of one single basic dye
-Used to determine size, shape, and arrangement of cells

Question 16

What is a differential stain and what can it show (beyond what a simple stain would show)?

Answer 16

Use more than one dye
Distinguishes between different cells,
chemicals, or structures

Question 17

Gram stain

Answer 17

Distinguishes between cell walls—
-Gram positive cell walls stain purple(crystal violet)
-Gram negative cell walls stain pink(safranin)

Question 18

Acid-Fast Stain

Answer 18

used to stain cells with waxy cell walls that would not be able to retain the stains in the Gram stain technique

Question 19

Endospore Stain

Answer 19

will show endospore

Question 20

What “special” stains can be used in microbiology?

Answer 20

-Simple stains used to identify specific microbial structures
-Negative stains
-Flagler stains
-Fluorescent stains

Question 21

Why is the Gram stain the most important stain for bacteria?

Answer 21

distinguishes between gram positive or gram negative wall

Question 22

List and describe the correct order of steps for a Gram stain (assume your slide is already prepared). Be able to describe results (color of cells) after each step

Answer 22

start with fixed smear
1 -cover with crystal violet dye
-(wait one minute, then rinse with water)
-all cells should be purple

2-cover with iodine- allows cv to stick to cells
(wait one minute, rinse with water)

3-hold slide at slant-
-rinse slide with alcohol drop by drop
15 seconds/rinse water-
-will decolorize and show difference in pos (purple) and neg(clear)

4-Put safranin on slide
-wait one minute-rinse with water
-Gram positive are purple, gram negative are pink
-blot with paper so water is gone

Question 23

What is the purpose of the iodine in a gram stain?

Answer 23

Helps crystal violet stick to cells

Question 24

What is the purpose of the alcohol in a gram stain?

Answer 24

Helps decolorize- will show different colors in gram negative walls and gram positive

Question 25

Define “taxonomy”—what is the purpose of classifying organisms?

Answer 25

consists of classification and organization of organisms

-Make predictions based on knowledge of similar organisms
* To understand evolutionary connections

Question 26

What is the general difference between “higher” level groups and “lower” level groups of classification?

Answer 26

-The higher levels are more general, cover more ground
-lower levels become very specific and general to properly identify what it is

-as you get lower, you share more characteristics with other people in group

Question 27

If 2 bacteria are in the same Genus—what information does that give you?

Answer 27

share many characteristics
like brothers

Question 28

Describe how a species is named using binomial nomenclature

Answer 28

-First name is genus
-second name is specific epithet

-together they indicate the specific species an organism belongs to

Question 29

(what is a specific epithet?
What does the specific epithet describe?

Answer 29

describes a specific unique characteristics (usually an adjective) of the organism

Question 30

What is the proper protocol when writing the name of a species? How can a species be abbreviated?

Answer 30

Genus is capitalized
specific epihpet is lower case

Question 31

How does a dichotomous key work?

Answer 31

Series of paired statements where only one of two “either/or” choices applies to any particular organism

Family tree looking thing

Question 32

What are some of the main types of criteria and lab techniques used for classifying and identifying microorganism

Answer 32

-Physical characteristics
-Staining
* Biochemical tests
* Serological tests
* Phage typing
* Analysis of nucleic acids

Question 33

How can carbohydrate fermentation tests (a type of biochemical test) help identify microorganisms?

Answer 33

Ability to ferment a specific carbohydrate

Ability to utilize certain molecules like amino acids, starch, citrate

use biochemical tests to identify pathogens

Question 34

What are some of the main ways bacteria are classified by taxonomy

Answer 34

domain
phylum
class
order
family
genus
species