L2: Introduction to Microbes

Question 1

What are the four main microbes?

Answer 1

Bacteria
Viruses
Fungi
Parasites

Question 2

What is the relative sizes of each one?

Answer 2

Viruses- smallest -10-8 - 10-7 –> electron microscope required
Bacteria- 10-6 - 10-5 –> some seen with eye
Fungi- 10-5 -10-4
Parasitic worms- 10-3 - 1 some very long

Unit metres

Question 3

What is the significance of mitochondria?

Answer 3

Micro-organism –> engulfed
Symbiotic relationship
Provide ATP, benefit from being inside cell

Question 4

What is the structure of a virus?

Answer 4

Nucleic acid (DNA or RNA)
Protein coat
Some lipid envelop
‘Spikes’ for attachment

Question 5

What is Baltimore classification?

Answer 5

Viruses grouped–> families

Depending on genome and replication method

Question 6

What are examples of three classification of DNA viruses?

Answer 6

SS, non enveloped (Parvovirus 19)
DS, non enveloped (Adenovirus)
DS, enveloped (Herpes, Hep B)

Question 7

How are RNA viruses classified? Give some examples?

Answer 7

RNA–> SS or DS

• -> Positive or negative strand (if SS)
• -> Icosahedral or helical
• -> Enveloped or non eveloped

SS, positive strand, icosahedral, non enveloped (Hepatitis A, E)
SS, positive strand, icosahedral or helical, enveloped (HIV)
SS, negative strand, helical, enveloped (Ebola)
DS, icosahedral, non enveloped (Rotavirus)

Question 8

Do viruses only infect one tissue in the body?

Answer 8

No some can infect more than one tissue

Question 9

What are bacteriophages?

Answer 9

Contain transferable DNA
Infect bacteria
Maybe used for treatment

Question 10

What is the structure of a bacteria?

Answer 10

Nucleoid (circular DNA)- main DNA
Plasmid
Plasma membrane 
Cell wall 
Capsule
Pili 
Flagellum

Question 11

What is a plasmid?

Answer 11

Plasmids- small circles of DNA, genes for virullent factors, antibiotic resistance –> transferred across species–> multi resistant bacteria

Question 12

What are the shapes of bacteria?

Answer 12

Coccus (cocci)
Bacillus (rods)
Spirillus -spiral- rare

Question 13

How can cocci be arranged?

Answer 13

Clusters –> Staphylococcus
Chains –> Streptococcus
Normally

Question 14

How does oxygen tolerance vary?

Answer 14

Aerobes –> survive in oxygen
Obligate aerobes–> need oxygen to survive
Anaerobes –> don’t need oxygen
Obligate anaerobes –> oxygen free for survival
Faculative anaerobes–> can make ATP in presence of oxygen and in absence of oxygen

Question 15

What does gram positive and gram negative mean?

Answer 15

Gram positive–> purple –> Peptidoglycan

Gram negative –> pink/red –> low peptidoglycan

Question 16

How are microbes named?

Answer 16

Genus, species

Additional info–> resistance, growth, typing

Question 17

Compare and contrast prokaryotes and eurkaryotes?

Answer 17

Chromosome
- P --> single, circular
- E --> multiple
Nucleus 
- P --> no nuclear envelop or nucleolus
- E --> NE and Nucleolus
Membrane bound organelle
- P --> No 
- E --> Yes
Cell Wall 
- P --> peptidoglycan 
- E --> No peptidoglycan, CW only plant cells 
Plasma Membrane 
- P --> No carbs or sterols 
- E --> Carbs and Sterols
Ribosome
- P --> 70s
- E --> 80s (70s in organelle)
Size
- P --> 0.2-2mm in diameter
- E --> 10-100mm in diameter

Question 18

What are the two types of fungi?

Answer 18

Yeast –> single cells

Moulds –> Multicellular

Question 19

What are the two types of parasites?

Answer 19

Protozoa –> single celled

Helminths (worms) –> multicellular