S2) Introduction to Microbes

Question 1

Identify the 4 constituents of the ‘microbial world’

Answer 1

• Viruses
• Bacteria
• Parasites
• Fungi

Question 2

Identify 8 micro-organisms and list them in order of increasing size

Answer 2

→ Prions

→ Proteins

→ Viruses

→ Mycoplasma / Chlamydiae / Rickettsiae

→ Mitochondria

→ Bacteria

→ Eukaryotic cells (yeasts, protozoa, etc)

→ Worms

Question 3

List 4 components of a virus

Answer 3

• Envelope
• Protein coat
• Spikes
• Nucleic acid (DNA / RNA)

Question 4

What are the different bacterial shapes?

Answer 4

Question 5

What colour do Gram positive bacteria stain?

Answer 5

Stain purple

Question 6

What are the components of Gram positive gram stains?

Answer 6

• Plasma membrane
• Periplasmic space
• Peptidoglycan

Question 7

What colour do Gram negative bacteria stain?

Answer 7

Stain red

Question 8

What are the components of Gram negative gram stains?

Answer 8

• Plasma membrane
• Periplasmic space
• Peptidoglycan
• Outer membrane (lipopolysaccharide and protein)

Question 9

Identify and describe different bacteria in terms of their oxygen tolerance

Answer 9

• Aerobes – require oxygen in environment for survival
• Anaerobes – require oxygen-free environment for survival

Question 10

Identify 3 medically important Gram Positive cocci bacteria

Answer 10

• Staph aureus
• Streptococcus pneumoniae
• Strep pyogenes

Question 11

Identify 2 medically important Gram Positive bacilli bacteria

Answer 11

• Listeria monocytogenes
• Clostridium difficile

Question 12

Identify 2 medically important Gram Negative cocci bacteria

Answer 12

• Neisseria meningitidis
• Neisseria gonorrhoeae

Question 13

Identify 4 medically important Gram Negative bacilli bacteria

Answer 13

• E.coli
• Klebsiella pneumoniae
• Salmonella typhi
• Haemophilus influenzae

Question 14

Identify two mechanisms of bacterial pathogenesis

Answer 14

• Virulence factors
• Toxins

Question 15

Identify 4 virulence factors and provide an example for each

Answer 15

• Host entry e.g. polysaccharide capsule
• Adherence to host cells e.g. pili, fimbrae
• Invasiveness e.g. enzymes such as collagenase
• Iron sequestration e.g. siderophores

Question 16

Identify 2 types of toxins and provide and example for each

Answer 16

• Exotoxins e.g. diphtheria toxin
• Endotoxins e.g. lipopolysaccharide

Question 17

Identify 2 types of fungi and provide and example for each

Answer 17

• Yeasts (unicellular) e.g. Candida albicans
• Moulds (multicellular) e.g. Dermatophytes

Question 18

Identify 2 types of parasites and provide and example for each

Answer 18

• Protozoa (unicellular) e.g. Plasmodium falciparum
• Helminths (multicellular) e.g. Roundworms, tapeworms

Question 19

Describe the kinetics of bacterial growth in a liquid medium

Answer 19