MICR 200B Lab Quiz #1 Flashcards Preview

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Flashcards in MICR 200B Lab Quiz #1 Deck (21):
1

What reagents are added to LB medium for bacteriophage lambda cultivation?

Magnesium and maltose.

2

What does LB stand for in LB medium?

Lysogeny broth.

3

What type of medium is LB?

Supportive (general purpose).

4

What is the advantage of selective media?

They can increase the relative numbers of a particular microorganism that would otherwise be present in very low numbers compared to the total number of bacteria.

5

Why is the ability to generate solid media important?

It is the most effective way to isolate different microorganisms from each other.

6

What concentration of agar is used to solidify liquid media?

1.5%.

7

Why is agar a good solidifying agent?

- Indigestible by most microorganisms
- After melting, remains molten until ~45 °C
- After solidifying, won't melt again until ~100 °C

8

What concentration of agar is used to make phage overlay media?

0.7%.

9

What concentration of agar is used to make semi-solid motility media ("sloppy")?

0.3%.

10

When is filtration typically used to sterilize culture medium?

For media supplements that would be destroyed by the high heat of an autoclave.

11

Which destroys endospores: sterilization, disinfection, or sanitization?

Sterilization only.

12

Define wild-type.

An organism or virus with the most common phenotype or genotype of its species (found in nature).

13

Define mutant strain.

A strain of an organism or virus that manifests new or different characteristics (compared to the wild-type of its species) as a result of changes to its DNA.

14

Define mutation.

Any change in the genetic information of a bacterium that makes it different from the most prevalent form, either in terms of a particular strain or a particular gene.

15

Define spontaneous mutation.

A mutation occurring in the absence of any outside stimulus.

16

Define induced mutation.

A mutation occurring as a result of a chemical or physical mutagen.

17

Define conditional mutation.

A mutation creating changes in proteins that are only observable as changes in phenotype under specific conditions (e.g. change in temperature or growth medium).

18

Define auxotroph.

A biochemical mutant with a mutation in an anabolic pathway such that it can no longer synthesize a certain nutrient.

19

Define prototroph.

A microorganism that can synthesize the same nutrients as most members of its species and can grow on minimal media.

20

Define substrate utilization mutant.

A mutant that has lost the ability to catabolize a particular substrate.

21

Define resistance mutant.

A mutant that has gained the ability to grow in the presence of an antimicrobial compound, toxin, or pathogen that would otherwise be harmful to wild-type cells.