Lab A-D

Question 1

Liquid Medium

Answer 1

Referred to as broth to grow large number of bacteria in short period of time

Question 2

Solid Medium

Answer 2

1-2% agar, its a polysaccharide extracted from seaweed and its utilize in two ways.
Slant: tubes with medium solidified in a test tube, angled for greater surface area and to store cultures for long period of time.
Plates: Petri dish contains agar used for isolating individual cells from culture. Uses inoculating loop to spread it across the agar surface.

Question 3

Semi-Solid Medium

Answer 3

Low agar concentration, does not solidify. Its used for motility studies

Question 4

Defined

Answer 4

All chemicals used are known, no yeast, animal, or plant tissue present.

Question 5

Complex

Answer 5

Media contains some ingredients of unknown chemical composition. Contains peptones, meat extract, and yeast extract.

Question 6

Selective Media

Answer 6

Designed to allow growth of certain organisms while preventing growth of others

Question 7

Differential Media

Answer 7

Allows you to tell organisms apart based on their differing appearances on that medium.

Question 8

Cell size

Answer 8

Measured in um

Question 9

Bacillus

Answer 9

Gram positive, rod-shaped

Question 10

Coccus

Answer 10

Spherical, ovoid, or round shape

Question 11

Coccobacilli

Answer 11

Intermediate shape between cocci and bacilli, very short rods

Question 12

Spirillum

Answer 12

Rigid spiral structure

Question 13

Pleomorphic

Answer 13

Group of cells different in shape, size or colour

Question 14

Ocular micrometer

Answer 14

Microscopes eye piece that has a rules scale to measure size of individual cells

Question 15

Stage micrometer

Answer 15

Special slide containing a scale marked off in 10 um

Question 16

Steps of gram staining

Answer 16

1) Make thin smear of bacteria in slide and air dry
2) Apply crystal violet (primary stain) rinse with water
3) Apply iodine and rinse with water
4) wash with ethanol for 5-10 sec
Apply safranin, rinse with water and blot dry

Question 17

What is the role of crystal violet in gram staining?

Answer 17

Its the primary stain which enters the cell and stain everything in a non-discriminating fashion.

Question 18

Role of Iodine in gram staining?

Answer 18

Its a mordant, enters cell and form a large crystal violet-iodine compound that get stuck in the pore of peptidoglycan

Question 19

Role of ethanol in gram staining?

Answer 19

Washes away the lipids of gram negative cell walls and appears to make peptidoglycan more porous so CVI complex is washed out.

Question 20

Role of Safranin in gram staining?

Answer 20

Pink counterstain which makes gram negative seen more

Question 21

Aerobic

Answer 21

Organism that requires oxygen to grow

Question 22

Obligate aerobes

Answer 22

Needs oxygen for growth dies without it

Question 23

Facultative anaerobes

Answer 23

Use oxygen when it’s available, if no oxygen Will switch to metabolism that doesn’t need oxygen

Question 24

Aerotolerant anaerobes

Answer 24

Doesn’t require oxygen to grow

Question 25

Microaerophile

Answer 25

Requires oxygen but in low concentration