Micro-organisms and Health (week 5)

Question 1

what is the role of bacterial pili / fimbriaea

Answer 1

hair like structures that aid adhesion to host cells

Question 2

what colour are gram positive bacteria and why?

Answer 2

purple - many layers of peptoglycen in cell wall: keeps purple stain in and drugs out

Question 3

what colour are gram negative bacteria and why?

Answer 3

pink - few layers of peptoglycen, stain washes out

Question 4

What type of bacteria is S. aureus?

Answer 4

Gram +ve coccus

Question 5

What type of bacteria are Helicobacter and Campylobacter?

Answer 5

Spiral

Question 6

What type of bacteria is E. Coli?

Answer 6

Gram negative bacillus

Question 7

Name a gram negative coccus bacteria

Answer 7

Neisseria meningiditis

Neisseria gonorrhoea

Question 8

What type of bacteria is C. diff?

Answer 8

Gram positive bacillus

Question 9

Name a gram negative coccobacilli

Answer 9

Haemophilus
Bordetlla
Brucellla
Pasteurella

Question 10

Describe how bacteria replicate by binary fission

Answer 10

cells divide to give 2 identical daughter cells, no exchange of genetic material

Question 11

Describe how bacteria replicate by conjugation

Answer 11

Conjugation tube forms between 2 bacteria and plasmid DNA is passed from one to another. Does not create new bacteria but genetic material is exchanged

Question 12

Describe how bacteria replicate by transformation

Answer 12

Plasmids picked up from environment surrounding bacteria

Question 13

Describe how bacteria replicate by transduction

Answer 13

Transfer of genetic material via a viral vector

Question 14

What is fungi cell wall made from?

Answer 14

Chitin

Question 15

Name the 2 classes of disease causing fungi

Answer 15

Yeats

Filamentous moulds

Question 16

What are helminths?

Answer 16

Parasitic worms

Question 17

How do parasites reproduce?

Answer 17

Asexually through fission

Question 18

What kind of nucleic acid does a virus contain?

Answer 18

DNA or RNA
Double or single stranded
Sense or antisense

Question 19

Briefly describe the stages of viral replication

Answer 19

1. Attachment / penetration of host
2. Release genome from protein coat
3. Produce early viral proteins
4. Genome replication in host nuclues
5. Produce late viral proteins - structural / capsid
6. Assembly of virion
7. Virion release

Question 20

how do retroviruses replicate?

Answer 20

reverse transcriptase enzyme converts RNA to DNA, which is then integrated into host DNA
host replication system then used

Question 21

How do prions cause disease?

Answer 21

Aggregate and cause misfolding of native proteins

Question 22

Name some diseases caused by prions

Answer 22

Creutzfeld-Jakob
Bovine spongiform
Encephalopathy
Scrapie

Question 23

What is the definition of microbiota?

Answer 23

All organisms in a given community

Question 24

What is commensalism?

Answer 24

one organism benefits, the other derives neither benefit or harm

Question 25

What is the types of bacteria are the most common bacteria found on the skin?

Answer 25

coagulase-negative staphylococci | staph aureus

Question 26

What type of bacteria is found in the mouth flora?

Answer 26

viridians / oral staphylococci

Question 27

How does vaginal flora differ pre and post puberty?

Answer 27

After puberty, circulating oestrogen causes glycogen production, meaning C. albicans can colonise

Question 28

True or false: the majority of bacteria found in the large intestine are aerobes

Answer 28

False - they are anaerobes

Question 29

How does normal microbiota aid metabolism?

Answer 29

synthesises secondary metabolites / vitamins e.g. vit K, vit B12 ferment unused energy substrates

Question 30

How does normal microbiota help resist colonisation of other species?

Answer 30

environmental manipulation e.g. lowering pH | produce anti-bacterial agents e.g. colicins, bacteriocins, fatty acids, metabolic waste products

Question 31

Which bacteria normally cause superficial abscesses

Answer 31

S. Pyogenes | S. auereus

Question 32

What is the host response to endotoxins?

Answer 32

Severe sepsis / septic shock Clinical features of infection Activation of clotting cascade can lead to DIC

Question 33

What is meant by 'incubation period' and 'period of inactivity'

Answer 33

1. period between infection with organism and manifestation of clinical features 2. period during which transmissible organisms may be transmitted to another person