Microbiology 1

Question 1

What are t/he 5 different major groups of human pathogens?

Answer 1

Protozoa - eukaryotes
Fungi - eukaryotes
Bacteria - prokaryotes
Viruses - non living
Prion proteins

Question 2

What are the difference between a eukaryote and a prokaryote?

Answer 2

Eukaryotes - bigger
Eukaryotes - complex where as prokaryotes are simple
Eukaryotes - multi cellular (pro = single celled)
Eukaryotes - no/flexible cell wall
Prokaryotes - rigid walls

Question 3

What structures do a prokaryote have that Eukaryotes dont?

Answer 3

Plasma membrane
Cell wall (peptidoglycan)
Ribosomes
Capsule/flagellar/pili

Question 4

What is a nucleoid and where is it found?

Answer 4

Contains DNA and proteins
No nuclear membrane
Primitive DNA
Found in Prokaryotes

Question 5

How many layers of peptidoglycan do gram negative bacterias have?

Answer 5

Single layer

Question 6

Describe the gram negative cell wall?

Answer 6

Outer membrane
Layer of Peptidoglycan
Inner membrane

Question 7

What are flagella and fimbriae for?

Answer 7

Adherence and sex

Question 8

What do bacteria (prokaryotes) need for growth?

Answer 8

Food 
Moisture 
Correct temperature (37 degrees)
Correct pH (around 7.4)
(Oxygen)

Question 9

What are the different types of atmospheres?

Answer 9

Aerobic - growth in presence of O2 (some of these organisms can gown anaerobically but less well)
Microaerophillic - atmosphere with reduced conc of O2 and enriched with CO2
Anaerobic - no O2 present

Question 10

What are prion proteins?

Answer 10

Infections proteins that have no DNA or RNA

Question 11

Describe prion proteins

Answer 11

They cannot be removed by disinfection or sterilsation

Question 12

Describe Viruses?

Answer 12

They have either RNA or DNA (single or double stranded)

Have a protein coat +/- a lipid envelope

Question 13

Describe bacteria?

Answer 13

Contain DNA and RNA
One double stranded chromosome (sometime plasmids too)
Cell membrane and cell wall +/- capsule
Flagella/Pili

Question 14

What are plasmids?

Answer 14

Circular bits of DNA in the cytoplasm

Question 15

What is a pathogen?

Answer 15

A harmful organism

Question 16

What is a commensal?

Answer 16

An organism that is part of the normal flora

Question 17

What is an opportunistic pathogen?

Answer 17

An organisms that will probably only cause infection in an immunocompromised individual
(an organism that causes infection when opportunity/change in natural immunity arises)

Question 18

What is a contaminant?

Answer 18

An organism that has got into a culture by accident

Question 19

What is pathogenicity?

Answer 19

The ability of a microorganism to produce disease

Question 20

What is virulence?

Answer 20

The degree of pathogenicity of an organism (ie. how easily can the organism cause disease)

Question 21

What can bacterias produce?

Answer 21

They can produce toxins (enzymes) which can kill us

Question 22

What toxins do gram negative and positive bacteria produce?

Answer 22

Exotoxin - gram positive - produced inside the cell then exported from it
Endotoxin - gram negative - produced on the cell wall

Question 23

What can some of the toxins do?

Answer 23

They can interact with cells of the immune system causing the release of cytokines
They can also damage red/white blood cells making vessels leaking, causing decreased BP, affecting blood clotting, causing sepsis and septic shock.

Question 24

What can some gram positive bacilli do?

Answer 24

They can form spores

• C.Diff
• Bacillus (bacillus anthrax)

Question 25

What is a spore?

Answer 25

Its inactive, hardy form of bacteria that cannot replicate but can survive adverse conditions fort many years.

Question 26

What is anthrax linked to?

Answer 26

Heroin - drugs

spores form from animal skin survived in heroin powder

Question 27

Describe fungi?

Answer 27

Moulds - produce spores e.g. aspergillum, does not stain

Yeasts - reproduce by budding, e.g. candida, stain as large gram positive oval structures.

Question 28

What is sterilisation?

Answer 28

Destruction of 99.99% of micro-organisms and spores

- examples, steam under pressure, heat, irradiation etc

Question 29

What is disinfection?

Answer 29

Removal/destruction of PATHOGENIC micro-organism, enough to make an item safe
-example, hot water, chemicals.