Bacteriology (17)

Question 1

Flame-sterilization

Answer 1

A technique that utilizes heat, in our case from a bunsen burner, to sterilize non-flammable materials (including inoculating loops)

Question 2

Working with bacterial cultures

Answer 2

Agar plates: remove lid only when performing the procedure, perform the procedure quickly

Bacterial broth tube: hold at 30º to 45º angle and flame the top

Question 3

Prokaryotes

Answer 3

1. Most are unicellular (some are colonial)
2. No nuclear envelope
3. DNA found in nuclear space in a naked circular molecule (sometimes a plasmid)
4. Reproduce asexually via binary fission
5. Cell wall is composed as peptidoglycan
6. Sometimes, the cell wall is covered by a capsule (a sticky layer of polysaccharides or proteins)

Question 4

Fimbriae

Answer 4

Hair-like projections that help the prokaryote stick to structures, substrates, or other members in a colony

Question 5

Pilli

Answer 5

Longer than fimbriae

Question 6

Punctiform (<1mm)

Answer 6

Classification of bacterial colony by shape

Question 7

Round

Answer 7

Classification of bacterial colony by shape
Circular

Question 8

Filamentous

Answer 8

Classification of bacterial colony by shape
Threadlike

Question 9

Irregular

Answer 9

Classification of bacterial colony by shape

Question 10

Smooth

Answer 10

Classification of bacterial colony by edge shape
Distinct colony edge

Question 11

Curled

Answer 11

Classification of bacterial colony by edge shape
Almost scalloped looking

Question 12

Wavy

Answer 12

Classification of bacterial colony by edge shape
Regular lobes

Question 13

Lobate

Answer 13

Classification of bacterial colony by edge shape
Irregular lobes

Question 14

Filamentous

Answer 14

Classification of bacterial colony by edge shape

Question 15

Smooth

Answer 15

Classification of bacterial colony by surface

Question 16

Concentric

Answer 16

Classification of bacterial colony by surface
ridges

Question 17

Wrinkled

Answer 17

Classification of bacterial colony by surface

Question 18

Contoured

Answer 18

Classification of bacterial colony by surface
ridges

Question 19

Other characteristics of classification

Answer 19

Pigmentation
Opacity
1. Opaque (no light passes through)
2. Translucent (permits light through, objects not visible)
3. Transparent (permits light through, objects visible)

Question 20

Example 1:

Answer 20

Name: Bacillus subtilis
Characteristics:
1. Irregular (shape)
2. Lobate (edges/margins)
3. Surface: unsure
4. Grey/Green color
5. Opaque

Question 21

Example 2:

Answer 21

Name: Escherichia coli (E. coli)
Characteristics:
1. Irregular (shape)
2. Lobate (edges/margins)
3. Wrinkled (surface)
4. White color
5. Transluscent

Question 22

Example 3:

Answer 22

Name: Micrococcus roseus
Characteristics:
1. Punctiform (shape)
2. Smooth (edges/margins)
3. Smooth (surface)
4. Yellow/beige in colro
5. Opaque

Question 23

Example 4:

Answer 23

Name: Rhodospirillum rubrum
Characteristics:
1. Irregular (shape)
2. Curled (? edges/margins)
3. Smooth, shiny
4. White
5. Opaque

Question 24

Example 5:

Answer 24

Name: Sarcina lutea
Characteristics:
1. Round/irregular (shape)
2. Smooth (edges/margins)
3. Smooth
4. Dark in color
5. Opaque

Question 25

Example 6:

Answer 25

Name: Serratia marcescens Characteristics: 1. Round (shape) 2. Round/slight curl? (margins) 3. Concentric 4. White/yellow 5. Opaque

Question 26

Classifying bacterial cells by morphology: Cocci

Answer 26

Round

Question 27

Classifying bacterial cells by morphology: bacilli

Answer 27

Rod like

Question 28

Classifying bacterial cells by morphology: spirilli

Answer 28

Spirals

Question 29

Classifying bacteria by cell wall structure: Gram +

Answer 29

1. Simple cell wall 2. Thick peptidoglycan cell wall layer 3. No outer lipopolysaccharide wall layer 4. Retain crystal violet/iodine 5. Appear blue/purple due to rxn between crystal violet and peptidoglycan cell wall

Question 30

Classifying bacteria by cell wall structure: Gram -

Answer 30

1. Complex cell wall 2. Thin peptidoglycan cell wall layer 3. Outer lipopolysaccharide wall layer 4. Retain safranin 5. Appear pink/red due to rxn between outer membrane and safranin

Question 31

Gram Staining Technique

Answer 31

Procedure to differentiate bacterial "species" based on cell wall properties 1. Can be Gram + or Gram - 2. Bacteria is fixed on slide using the following procedure: - Crystal violet, rinsed with water - Iodine, rinsed with acetone - Safranin, rinsed with water

Question 32

Streak Plate Technique

Answer 32

Serial dilution of bacteria across three areas of an agar plate so that bacterial colonies can be isolated, investigated, and identified Procedure: 1. Dip sterile cotton swab into bacterial culture and swab across 1/3 of agar plate 2. Flame inoculation loop and allow to cool 3. Touch loop to one end of swabbed area and zigzag to another side of the agar plate 4. Repeat step 2 5. Repeat step 3 for last remaining 1/3

Question 33

Disinfecting agents

Answer 33

Decontaminate nonliving objects (surfaces, doorknobs)

Question 34

Antiseptic agents

Answer 34

Slows/stops the growth of microorganisms on external surfaces of body (skin)

Question 35

Antibiotic agents

Answer 35

Used to inhibit bacterial growth inside of living organisms

Question 36

Testing the efficacy of agents used to control/stop bacterial growth

Answer 36

Measuring the zone of inhibition

Question 37

Zone of inhibition procedure

Answer 37

1. Take sterile cotton swab and dip into liquid culture and run back and forth across the plate 2. Rotate 90 degrees and repeat 3. Place antibiotic disks onto first plate and disinfecting agents (listerine, isopropyl, and bleach) onto second plate 4. Allow space in between disks 5. Make sure to label

Question 38

Comparing zones of inhibition

Answer 38

After incubation, we can compare the zone of inhibitions 1. Using a ruler, measure the diameter of the zone of inhibition (cleared areas around the disks) 2. More sensitive bacteria is to the agent, the wider the zone of inhibition (most antimicrobial efficacy)