Unit 3 Lab Exam

Question 1

Stain increase ______ needed for viewing cells

Answer 1

contrast

Question 2

Stains = solvent + ____________

Answer 2

chromogen

Question 3

What is the portion of the chromogen that gives the dry its color

Answer 3

chromophore

Question 4

What is the portion of the chromogens that have charged portions that allow them to interact with cellular components through ionic and covalent bonding

Answer 4

auxochrome

Question 5

Define simple stain

Answer 5

react uniformly with all microbes and only distinguish the organisms from their surroundings

Question 6

What are two examples of simple stains

Answer 6

methylene blue and CV

Question 7

Define differential stains

Answer 7

discriminate between various bacteria, depending upon the chemical or physical composition of the microbes

Question 8

What is an example of differential stain

Answer 8

gram stain and acid-fast stain

Question 9

Define specialized stains

Answer 9

designed to detect specific structures of cells such as flagella or endospores that may be present in some microbes but not others

Question 10

Why do we heat fix slides for stains

Answer 10

cells will wash off the slides that are not heat fixed; don’t overheat as cells will be ruptured or distorted

Question 11

bacilli or bacillus

Answer 11

rod shaped cells

Question 12

cocci or coccus

Answer 12

spherical cells

Question 13

elongated spheres

Answer 13

ovoid

Question 14

Gram positive stains

Answer 14

purple

Question 15

gram negative stains

Answer 15

pink

Question 16

What is the purpose of the immersion oil with the microscope

Answer 16

to prevent light scattering

Question 17

Size and shape of bacillus cereus; generally observed in

Answer 17

large and bacilli; chains

Question 18

size and shape of staphylococcus epidermidis

Answer 18

relatively small and coccus shaped

Question 19

size and shape of saccharomyces cerevisiae

Answer 19

larger than bacterial cells and are ovoid in shape

Question 20

3 things needed to clean the microscope

Answer 20

all oil wiped off
10x objective lens in place
stage centered

Question 21

What happens if for the gram stain you have too thick of a smear

Answer 21

slide is hard to destain, resulting in gram negative looking gram positive

Question 22

What happens if the destaining the slide is not long enough

Answer 22

gram negative cells will appear gram positive

Question 23

What gram bacteria are the following
S. epidermidis
P. fluorescens

Answer 23

gram positive
gram negative

Question 24

What is the order of a gram stain

Answer 24

CV
Iodine
Alcohol-acetone
Safranin

Question 25

What type of dyes are used for capsule stain

Answer 25

India ink
CV

Question 26

What stain does it require you don’t heat dry or blot dry

Answer 26

capsule stain

Question 27

What type of species doesn’t stain regularly and needs the acid-fast stain

Answer 27

mycobacterium

Question 28

What can dye the mycobacterium cells?

Answer 28

treatment with cold carbol fuchsin for several hours or at high temps for five minutes will dye the cells

Question 29

Define endospores

Answer 29

dormant cell structures produced by some species of bacteria, including those in the genera bacillus and clostridium

Question 30

Endospores are extremely _____ and resist inactivation by heat, chemicals, and radiation

Answer 30

resilient

Question 31

What dyes are used in the endospore stain

Answer 31

malachite green
safranin counter stain

Question 32

What is the CV in the gram stain

Answer 32

primary stain–initially stains all cells purple

Question 33

What is the iodine in the gram stain

Answer 33

it acts as a mordant (fixer) and forms a complex with the CV, fixing it to the cells

Question 34

What is the alcohol-acetone in the gram stain

Answer 34

this reagent dissolved the lipids in the gram negative cell outer membrane, allowing the removal of crystal violet-iodine complex from these cells

Question 35

What is the safranin in the gram stain

Answer 35

country stain for the decolorized cells