Introduction To Microbes

Question 1

The size of micro-organisms

Answer 1

Viruses 
 I
V
Bacteria 
 I
V
Fungi
 I
V
Parasites

Question 2

Other types of micro-organisms

Answer 2

Prions - self replicating proteins - have some features of microbes but not microbes

MCR - bacteria but they are IC parasite need to hitch a ride on the hosts DNA

Mitochondria - not a microorganisms the result of bacteria eating one bacteria - synergistic relationship

Question 3

DNA viruses

Answer 3

Single-stranded non enveloped - e.g. Parovirus 19

Double - stranded, non enveloped - e.g. Adenovirus,

Human papilloma virus

Double stranded, enveloped e.g. HEP B, Herpes

Long term infection of HEP B can lead to other adverse affects such as liver cirrhosis and liver cancer and Inflammtion over body

Nucleic acid present in viruses
Protein coat is pretty tough - provides resilience to the microorganism

Some are covered in lipids - known as spikes - used for attaching to specific cell surfaces - need these for anchoring in order to initiate the process of virus entering the cell, without these virus would be ineffective (potential therapeutic target)

Question 4

RNA viruses

Answer 4

Single stranded, positive strand, icosahedral and non enveloped e.g. HEP A, E, Norovirus

Single stranded, positive strand , icosahedral/helical, enveloped e.g. HEP C, Rubella, Yellow fever

Single stranded, negative strand, helical, enveloped - e.g. Ebola, Measles, Mumps, Influenza

If Double stranded, icosahedral, non-enveloped

Question 5

Bacteriophages

Answer 5

Viruses that infect bacteria
Potentially could be used to treat bacteria - has been done historically - could be a good alternative to combat antibiotic resistance

Question 6

Typical bacteria

Answer 6

Circle of single stranded DNA present in the centre of this bacteria

These cells can also contain plasmids (free lying DNA) - often contain genes for virulence factors

Bacteria (using plasmids) can collect/carry “resistance genes” - which can confer resistance for a wide range of unrelated antibiotics, which can be spread from bacterial cell to bacterial cell - can also get cross special DNA crossing, so different species of bacterial can give antibiotic resistance to other species of bacteria
PDR - poor drug resistance
EDR - extensive drug resistant

Question 7

Bacterial shapes

Answer 7

Coccus (circular)
Spirillus (spiral)
Bacillus (rods)

Question 8

Gram positive and gram negative bacteria

Answer 8

Difference between the two is gram negative has an outer membrane made out of lipopolysaccaride and protein whereas the gram positive does not have this outer wall of lipopolysaccaride

Question 9

Oxygen tolerance

Answer 9

Aerobes

Question 10

Naming bacteria, fungi and parasites

Answer 10

Linnaean taxonomy

Gen

Question 11

Medically important bacteria

Answer 11

Gram positive cocci - Staph aureus, coagulase negative staph, alpha and ß haemolytic streptococci, strep pneumoniae

Gram positive bacilli - bacillus anthracis, bacillus cereus

Gram negative cocci - Neisseria meningitidis, neisseria gonorrhoeae

Gram negative bacilli - E. coli, salmonella, haemophilia influenzae

Question 12

Mech of bacterial pathogenesis

Answer 12

Virulence factors -
Host entry (e.g. polysaccharide capsule
Adherence to host cells (e.g. piliand fimbriae)
Invasiveness (e.g. enzymes such as collagenase)
Iron sequestration (siderophores)
Toxins - Exotoxins(e.g.diphtheriatoxin)
Endotoxins(lipopolysaccharide)

Question 13

Fungi

Answer 13

Yeasts (single-celled) -
– Candida albicans – Cryptococcus neoformans – Pneumocystisjiroveci

Molds(multicellular) -
– Aspergillusspecies – Dermatophytes

Question 14

Parasites:

Answer 14

Protozoa (single-celled) -
– Giardialamblia – Cryptosporidium parvum – Plasmodium falciparum – Trypanosomacruzi

Helminths(worms, multi-cellular) -
– Roundworms (e.gEnterobiusvermicularis) – Tapeworms (e.g. Taeniasaginata) – Flukes (e.g. Schistosoma mansoni)