lab 1-3

Question 1

studying bacteria requires…

Answer 1

isolating bacterial species from the environmental samples containing mixed cultures (obtaining pure culture)

Question 2

liquid media

Answer 2

growth studies or biochemical analysis

Question 3

solid media

Answer 3

liquid media containing solidifying agent (agar) used for pure culture

Question 4

factors that influence how bacteria grows and how growth might appear on solid media

Answer 4

• Physical factors - temp, pH, water, oxygen, pressure.
• incubation time
• plate vs agar
  
  • plate= separate mixtures and isolating colonies
  • slants= generate stocks of bacteria (less risk of contamination due to sealed cap)

Question 5

flocculent

Answer 5

suspended chunks of pieces

Question 6

sediment

Answer 6

growth on bottom

Question 7

ring

Answer 7

growth at top around edge

Question 8

pellicle

Answer 8

membrane at the top

Question 9

uniform fine turbidity

Answer 9

evenly clouded throughout

Question 10

colony morphology

Answer 10

look at pic

Question 11

Mycobacterium smegmatis

Answer 11

fried egg appearance due to waxy cell membrane (mycolic acids)

Question 12

Streptomyces griseus

Answer 12

dry texture, has mold‐like appearance

Question 13

Proteus mirabilis

Answer 13

colonies spread (highly motile microbes

Question 14

Serratia marscens

Answer 14

forms red colored pigment (when grown below 30°C)

Question 15

Bacillus subtilis

Answer 15

soil odor; endospore forming bacteria

Question 16

Pseudomonas aeruginosa

Answer 16

produce pigments; blue‐green
(pyocyanin) & yellow‐green (pyoverdine)

Question 17

Enterobacter aerogenes

Answer 17

motile, produce uniform fine
turbidity (UFT)

Question 18

Staphylococcus epidermidis (or aureus)

Answer 18

non‐motile, sediment

Question 19

– Mycobacterium smegmatis

Answer 19

non‐motile, waxy layer of bacteria leads to pellicle formation at surface

Question 20

parfocal

Answer 20

objective lens that can be changed with minimal or no refocusing (lens that stays in focus when magnification/focal length is changed)

Question 21

microscope information

Answer 21

• Magnification= an increase in the apparent size of the image
• Refraction of light by lenses results in magnification.
  – Condenser
  – Objective lens
  – Ocular lens (acts as a magnifier and produces an enlarged image of the image produced by the objective lens) (x10)
• The system of lenses ultimately forms a real image that is inverted (flipped & backwards).

Question 22

resolution

Answer 22

clarity/sharpness of the image

Question 23

total magnification =

Answer 23

`objective lens magnification x ocular lens magnification

Question 24

limit of resolution

Answer 24

the minimum distance two points can be to still be
viewed as separate points; also called resolving power.

Question 25

resolution =

Answer 25

wavelength / n.a. obj. lens x n.a. condenser

Question 26

Numerical aperture

Answer 26

refers to the light gathering ability of the objective lens and condenser.

Question 27

staining

Answer 27

Optimum amount of light; high contrast

Question 28

oil immersion lens (x100)

Answer 28

oil has same refractive index as glass,
less light refracted, more enters lens.

Question 29

types of objective lens magnification

Answer 29

• scanning: 4x
• low power: 10x
• high dry: 40x
• oil immersion: 100x
• condenser: none

Question 30

oil immersion used for what cell

Answer 30

bacterial cell

Question 31

microorganism growth requirements

Answer 31

• nutrients available
• oxygen/other gases available
• moisture
  appropriate pH
• contamination prevented

Question 32

complex v defined media

Answer 32

• defined: exact chemical composition known
• complex: contains complex nutrients of undefined composition (ex: yeast extract)