Intro To Microbiology

Question 1

Describe Protozoa

Answer 1

-Unicellular eukaryotes
-2-100 μm
-Many are free-living- e.g. euglena (pond-water)
-Several are important human pathogens - Malaria
-Often affect the immunocompromised
-Mainly a threat in developing countries

Question 2

Protozoa examples

Answer 2

trypanosomiasis (chagas disease), malaria, cryptosporidium, Toxoplasma gondii

Question 3

Describe fungi

Answer 3

Eukaryotic organisms with a variety of forms and types
Saprophytes, parasites & commensals
Relatively large
Complex life cycles
Commercially important- baking, brewing
and pharmaceuticals (artemesinin)
External, rigid cell wall- containing chitin
and polysaccharides
Filamentous or yeast forms
Many are dimorphic
e.g. Candida

Question 4

Importance of fungi in the mouth

Answer 4

Acute pseudomembranous candidosis (thrush)
White patches - Candida cells fibrin & epithelial cells
- Detach if rubbed

Question 5

Who was Antonie Van Leeuwenhoek?

Answer 5

First modern microbiology

Question 6

What are the different types of bacteria?

Answer 6

-cocci
-diplococci (two)
-tetrads (four)
-sarcina (3D)
-streptococci (long chain)
-staphylococci (bunches)

Question 7

What are the different shapes of bacilli (w/examples)?

Answer 7

-extended irregular rods e.g. fusobacterium
-kidney bean e.g. vibrio spp
-corkscrew e.g. treponema spp
-helical e.g. campylobacter
-can form filaments too

Question 8

describe how you can know the cell wall structure using gram stain

Answer 8

-gram positive (if they stain) means there is one membrane with granular material outside made of peptidoglycan chain and no outer lipid layer, it retains the stain and looks purple
-gram negative (if no stain) means there is a thin peptidoglycan layer and have an outer lipid membrane, stain is not retained

Question 9

How do we grow bacteria in a lab?

Answer 9

-streak on agar
-grow at 37°C
-stain
-choice of growth media is crucial (bacteria need to like it otherwise don’t know if bacteria died or not present)

Question 10

What is haemolysis?

Answer 10

when bacteria releases something that kills the blood cells

Question 11

what are the three phases of bacteria growth?

Answer 11

-lag phase: organism grows v slowly as it adjusts to food source in the medium
-log phase: exponential growth bc it is used to the new environment and has the enzymes ti degrade the food
-stationary phase: ran out of food, number of cells level off bc some die

Question 12

Bacteria in the environment (including body) encounter a succession of feast and famine situations
what is a feast and famine situation?

Answer 12

-continued cycles of growth and starvation
-the competition among the bacteria make it able to adapt quickly to rough and changing situations

Question 13

Describe binary fission

Answer 13

-way in which bacteria reproduce
At critical mass, chromosome replicates
Cell septum forms
Cells divide

Question 14

Describe genetic transfer in bacteria