Lab2

Question 2

Which two broad groups are fungi divided into?

Answer 2

Yeasts (essentially unicellular) and moulds (multicellular)

Question 3

Which two broad groups are fungi divided into?

Answer 3

Yeasts (essentially unicellular) and moulds (multicellular)

Question 4

What kind of pathogens are fungi?

Answer 4

opportunist pathogens

Question 5

What sort of conditions do fungal spores readily proliferate in?

Answer 5

Warm, moist conditions like Auckland

Question 6

In order to visualse moulds microscopically, they can be stained with what?

Answer 6

lactophenol blue or light green

Question 7

Yeasts take up gram stain reagents, but cannot be described as… what? why is this?

Answer 7

gram positive or gram negativethis is because they are not bacteria, and their cell wall is different from bacteria

Question 8

How can yeasts be easily distinguised from bacteria?

Answer 8

easily distinguished by sizeYeasts are eukaryotic and eukaryotic cells are generally bigger than prokaryotic cells (bacteria)

Question 9

What does candida albicans look like when grown on SDA?

Answer 9

spherical cells similar to cocci (except they are bigger)

Question 10

What happens after c. albicans growth in serum broth?

Answer 10

it undergoes a budding process and the buds eventually develop into long, thin extensions of the cell

Question 11

What are these long and thin extensions of thecell called?

Answer 11

pseudohyphae. This is to distinguish them from the real multicellular hyphae of moulds

Question 12

What are the main mode of vegetative growth for moulds?

Answer 12

The formation of long, branching filamentous structures (hyphae)

Question 13

What do moulds produce for reproduction?

Answer 13

they form conidiophores (fruiting bodies) which contain the small round conidia (spores)

Question 14

what is the diagnostic feature of candida albicans grown in serum broth?

Answer 14

long and thin extensions from the cell known as pseudohyphae this results from a budding process in the serum broth

Question 15

What is SDA?

Answer 15

Sabouraud Dextrose Agar

Question 16

give an example of a genus of bacteria which do not stain readily by gram stain

Answer 16

mycobacterium

Question 17

How are these bacteria stained?

Answer 17

Staining of these organisms is facilitated by the application of heatonce stained, they retain dyes and resist decolourisation with acid or acid alocholthus they are known as acid fast organims

Question 18

After staining, what do acid fast organisms look like?

Answer 18

they are NOT decolourised,they retain the carbol fuchsin primary stain and appear RED

Question 19

after staining, what do non-acid fast organisms look like?

Answer 19

These are DECOLOURISEDThey accept the counterstain methylene blue and appear BLUE

Question 20

What kind of pathogens are fungi?

Answer 20

opportunist pathogens

Question 21

What sort of conditions do fungal spores readily proliferate in?

Answer 21

Warm, moist conditions like Auckland

Question 22

In order to visualse moulds microscopically, they can be stained with what?

Answer 22

lactophenol blue or light green

Question 23

Yeasts take up gram stain reagents, but cannot be described as… what? why is this?

Answer 23

gram positive or gram negativethis is because they are not bacteria, and their cell wall is different from bacteria

Question 24

How can yeasts be easily distinguised from bacteria?

Answer 24

easily distinguished by sizeYeasts are eukaryotic and eukaryotic cells are generally bigger than prokaryotic cells (bacteria)

Question 25

What does candida albicans look like when grown on SDA?

Answer 25

spherical cells similar to cocci (except they are bigger)

Question 26

What happens after c. albicans growth in serum broth?

Answer 26

it undergoes a budding process and the buds eventually develop into long, thin extensions of the cell

Question 27

What are these long and thin extensions of thecell called?

Answer 27

pseudohyphae. This is to distinguish them from the real multicellular hyphae of moulds

Question 28

What are the main mode of vegetative growth for moulds?

Answer 28

The formation of long, branching filamentous structures (hyphae)

Question 29

What do moulds produce for reproduction?

Answer 29

they form conidiophores (fruiting bodies) which contain the small round conidia (spores)

Question 30

what is the diagnostic feature of candida albicans grown in serum broth?

Answer 30

long and thin extensions from the cell known as pseudohyphae this results from a budding process in the serum broth

Question 31

What is SDA?

Answer 31

Sabouraud Dextrose Agar

Question 32

give an example of a genus of bacteria which do not stain readily by gram stain

Answer 32

mycobacterium

Question 33

How are these bacteria stained?

Answer 33

Staining of these organisms is facilitated by the application of heatonce stained, they retain dyes and resist decolourisation with acid or acid alocholthus they are known as acid fast organims

Question 34

After staining, what do acid fast organisms look like?

Answer 34

they are NOT decolourised,they retain the carbol fuchsin primary stain and appear RED

Question 35

after staining, what do non-acid fast organisms look like?

Answer 35

These are DECOLOURISEDThey accept the counterstain methylene blue and appear BLUE

Question 36

describe the method of the zihl-neelsen staining procedure

Answer 36

1. Fixed slide is flooded with carbol fuchsin and heated to steaming for 5 mins. Stain must not dry out due to heatat this stage both types of cells will appear red2. Slide is washed with tap water, and cells are decolourised with acid-alcohol drop by drop until the deep red appearance of the slide is reduced to pink. this takes 10-30sec* acid fast cells retain the stain and will look pink, microscopically* non acid fast cells unable to withstand treatment with acid alcohol, this results in leeching of red carbol fuschin from cell wall. They will appear colourless at this stage3. Methylene blue - counter stain is applied (2 mins) this is not taken up by acid fast cells, but the blue counter stain is absorbed by non acid fast cells. 4. Slide is washed, then blotted dry.

Question 37

what accounts for the acid fast property of the mycobacterium species?

Answer 37

Mycobacterium have a thick cell wall, but no cell membrane so do not take up gram stain….. ?