Lab IIIA: Introduction to Culturing and Characterizing Bacteria

Question 1

Are Bacteria are prokaryotic or eukaryotic microorganisms?

Answer 1

PROKARYOTIC

Question 2

Through which process do bacteria divide?

Answer 2

Binary fission

Question 3

In optimal growing conditions, one bacterium can divide into 2 daughter cells in roughly how many minutes?

Answer 3

in 20 minutes!! (A LOT)
(4 x 10^21 replicas of itself in 24H)

Question 4

Culturing bacteria is necessary for WHAT?

Answer 4

for research applications and identification of bacteria.

Question 5

Bacteria can be cultured in WHAT? (name 2 mediums)

Answer 5

• liquid medium
• semi-solid medium

Question 6

What do we call a liquid medium?

Answer 6

a broth

Question 7

What is a semi-solid medium made of?

Answer 7

made of agar (red algae protists; polysaccharides)

Question 8

Name an advantage of liquid medium:

Answer 8

cells can reach very high cell concentrations

Question 9

On agar, each cell can produce what?

Answer 9

an isolated, macroscopic colony by cell division over night

Question 10

Bacteria can be cultured under different conditions such as WHAT? (3)

Answer 10

temperature, pH, and oxygen levels

Question 11

The metabolic diversity in bacteria explains why they occupy almost every imaginable environment and ecological role on the planet. HOW SO? Tell me more about their metabolism (2):

Answer 11

some are photosynthetic = primary producers

MOST are not photosynthetic = decomposers or mutualists

Question 12

What do we can species that infect plants and animals and cause diseases?

Answer 12

pathogenic bacteria (a minority of species)

Question 13

What are great ways to identify and differentiate bacteria (2)?

Answer 13

using certain stains (gram +/-) or antibiotics

Question 14

Why do we want to identify bacteria?

Answer 14

goes beyond the essential need of biological classification (taxonomy). It is essential to effectively treat infections. (important for clinical microbiologists)

Question 15

Bacteria can be characterized at what 3 levels?

Answer 15

• colony level
• cell level
• molecular level

Question 16

a colony from a particular bacterial species will have (3 things)?

Answer 16

• characteristic shape
• surface texture
• color

Question 17

What is the cell wall of bacteria made of?

Answer 17

structural polymer -> peptidoglycan

Question 18

What are the characteristics of a Gram-negative cell

Answer 18

• pink/red
• OUTER MEMBRANE
• THIN peptidoglycan
• plasma membrane

Question 19

What are the characteristics of a Gram-positive cell

Answer 19

• purple/blue
• THICK peptidoglycan
• plasma membrane
  (NO outer membrane)

Question 20

Name 3 basic cell shapes

Answer 20

• Coccus
• Bacillus
• Spirillum

Question 21

Name all 5 different cell arrangements:

Answer 21

• single
• Diplo
• spirilla
• strepto
• staphylo

Question 22

What is strepto?

Answer 22

in chains

Question 23

What is staphylo?

Answer 23

in clumps

Question 24

What are endospores?

Answer 24

resistant, dormant cell triggered by
adverse conditions

Question 25

Name 2 genera of bacteria that can produce endospores

Answer 25

Bacillus & Clostridium

Question 26

Name all 4 different modes of nutrition in Organisms

Answer 26

- Photoautotroph - Chemoautotroph - Photoheterotroph - Chemoheterotroph

Question 27

Most bacterial species are what?

Answer 27

Chemoheterotrophs (like animals, fungi and some protists)

Question 28

What do Chemoheterotrophs do?

Answer 28

they consume live/dead organic material to obtain organic compounds (breakdown organic comp. for energy)

Question 29

Some bacteria are also what?

Answer 29

Photoautotrophs (like plants and algal protists)

Question 30

What are photoautotrophs capable of doing?

Answer 30

use light as an energy source (produce organic comp. from inorganic comp. such as CO2)

Question 31

Which 2 modes of nutrition are unique to prokaryotes?

Answer 31

Chemoautotrophs & Photoheterotrophs

Question 32

Prokaryotic metabolism also varies with respect to WHAT?

Answer 32

oxygen

Question 33

What are the 3 different metabolisms concerning oxygen?

Answer 33

Obligate aerobes Facultative anaerobes Obligate anaerobes

Question 34

Which prokaryotic metabolism is Poisoned by O2?

Answer 34

Obligate anaerobes

Question 35

Which one will use O2 if present but can also grow by fermentation?

Answer 35

Facultative anaerobes

Question 36

Which one REQUIRES O2 for cellular respiration?

Answer 36

Obligate aerobes

Question 37

Where is E. coli commonly found?

Answer 37

in the lower intestine of vertebrates (such as humans)

Question 38

Where is B. subtilis commonly found

Answer 38

in the soil

Question 39

This diversity stems from different WHAT?

Answer 39

different ENZYMES

Question 40

What is the Aseptic technique?

Answer 40

a procedure to prevent infection from pathogens like bacteria and viruses. It involves applying strict rules during medical procedures to minimize the risk of contamination

Question 41

Name 2 ways to culture bacteria (the ways)

Answer 41

- the streak method - the lawn of bacteria

Question 42

What does the streak method consist of?

Answer 42

used for E. coli & B. subtilis used to ISOLATE individual bacterial colonies by diluting the sample across the plate, allowing for the growth of separate colonies originating from single bacterial cells.

Question 43

What does the lawn method consist of?

Answer 43

uniform bacterial lawn covering the entire plate, which is useful for certain applications such as antibiotic sensitivity testing or phage susceptibility assays

Question 44

There is another method (zig-zap streak/pattern), why use this strategy?

Answer 44

- decrease cell density gradually to isolate cells from one another

Question 45

Give info for E. coli 1) cell shape 2) cell arrangement 3) gram stain (+ or -) 4) flagella or no flagella 5) colony shape 6) colony pigmentation 7) colony texture 8) colony reflection 9) colony transparency

Answer 45

1) bacillus 2) single 3) gram - 4) no flagella 5) circular 6) tan 7) smooth 8) glossy 9) translucide

Question 46

Give info for B. subtilis 1) cell shape 2) cell arrangement 3) gram stain (+ or -) 4) flagella or no flagella 5) colony shape 6) colony pigmentation 7) colony texture 8) colony reflection 9) colony transparency

Answer 46

1) bacillus 2) strepto 3) gram + 4) no flagella 5) non-circular 6) white 7) rough 8) matte 9) opaque

Question 47

Give info for S. aureus 1) cell shape 2) cell arrangement 3) gram stain (+ or -) 4) flagella or no flagella

Answer 47

1) coccus 2) staphylo 3) gram + 4) no flagella

Question 48

Give info for S. volutans 1) cell shape 2) cell arrangement 3) gram stain (+ or -) 4) flagella or no flagella

Answer 48

1) Sprilillum 2) single 3) gram - 4) flagella

Question 49

Which antibiotic targets DNA replication?

Answer 49

Norfloxacin (NOR)

Question 50

Which antibiotic targets Protein synthesis?

Answer 50

Streptomycin (S)

Question 51

Which 2 antibiotics target cell wall synthesis?

Answer 51

Penicillin (P) & Cefotaxime (CFX)

Question 52

Where do you find E. coli?

Answer 52

in the gastrointestinal tract of humans/animals

Question 53

Where do you find B. subtilis?

Answer 53

in the soil

Question 54

Which one is sensitive to penicillin (E.coli or B.sub)?

Answer 54

B.subtilis sensitive E. coli resistant

Question 55

Do they have flagella (both)?

Answer 55

non-visible at 1000X

Question 56

Which one can break down starch using amylase?

Answer 56

B. subtilis CAN breakdown starch using amylase (E. coli can't)

Question 57

What is a bacterial colony?

Answer 57

mass of bacterial cells that have arisen from a single mother cell