microorganism cultures

Question 1

what is agar

Answer 1

a polysaccharide of galactose obtained from seaweed, which is used to thicken the medium into a gel

Question 2

what is aseptic technique

Answer 2

sterile techniques used in culturing and manipulating microorganisms

Question 3

what type of material will microorganisms grow on

Answer 3

any material which supplies carbon compounds for respiration and nitrogen for protein synthesis

Question 4

what are the two types of growth medium which microorganisms are grown in

Answer 4

broth kept in bottles

or agar which is melted and poured into petri dish

Question 5

what is held in a petri dish

Answer 5

agar

Question 6

what does agar contain

Answer 6

yeast,
salt
water
glucose

Question 7

what is the standard procedure to reduce likelihood of contaminating medium with unwanted microorganisms

Answer 7

-wash hands

2-disinfect working area

3- have bunsen burner on blue roaring flame- heat air and prevent airborne microorganisms to settle

4- heat bottle necks of vessel to prevent bacteria in air entering bottle

dont fully lift petri dish lid, as bacteria in air can enter dish

Question 8

what do you do with metal equipment or glassware before making contact with desired microorganisms

Answer 8

always pass it through a roaring flame to kill any bacteria on the equipment

Question 9

what are the three main steps used in microbiology

Answer 9

• sterilisation
• inoculation
• incubation

Question 10

what equipment is used to sterilise equipment to be used

Answer 10

autoclave

Question 11

what degrees is the autoclave set at for sterilisation

Answer 11

121 deg

Question 12

how long does the autoclave sterilise for

Answer 12

15 min

Question 13

how does the autoclave sterilise equipment

Answer 13

high temp of 121, kills all living organism.

Question 14

why is the petri dish lifted only slightly

Answer 14

to prevent any unwanted microorganisms in the air to enter the petri dish

Question 15

what is inoculation

Answer 15

introduction of microorganisms to a sterile medium

Question 16

what are the 2 main ways of inoculation

Answer 16

spreading
and
streaking

Question 17

what is spreaking

Answer 17

the inoculating loop is used to transfer liquid medium droplets onto the surface of agar. drop is dragged by loop across surface multiple times

Question 18

what is spreading

Answer 18

sterile glass spreader is used to spread a drop of liquid medium over the surface of agar. to create an even distribution

Question 19

what is the procedure of incoluating an agar plate

Answer 19

heat inoculating loop on blue flame, let cool,

remove broth culture cap and heat bottle neck on blue flame

dip cooled sterile inoculating loop in broth.

flame bottle again and recap

streak over surface of agar. then reheat the inoculating loop on flame.

use tape and partially tape agar place, flip upside down, label and incubate at 25 deg

Question 20

what is incubation

Answer 20

petri dish is placed in warm environment to allow growth of microorganism into visible colonies.

Question 21

why must u store petri dish upside down

Answer 21

prevent condensation droplets to fall onto surface of agar and disrupt colonies

Question 22

why must u only partially tape agar plates

Answer 22

as if u fully tape it removes oxygen and air flow, which allows anaerobic bacteria to develop which can be harmful

Question 23

how long are organisms usually incubated for

Answer 23

24-36 hr

Question 24

why is it important to only inoculate agar plate with a standard sized drop of broth culture

Answer 24

to much broth culture can cause the colonies to be impossible to count