Major discoveries, microbial diversity and acellular microbes

Question 1

what are the three domains of life?

Answer 1

• bacteria
• archaea
• eukarya

Question 2

what is the most abundant type of virus on earth?

Answer 2

phages

Question 3

what are the four acellular entiities?

Answer 3

• Viruses: composed of protein and nucleic acid, lack
  metabolism and replicate only in host cells
• Satellites: subviral infectious agents composed of nucleic
  acid and protein that require a helper virus to replicate
• Viroids: non-translated ssRNAs, lack protein (Infect plants)
• Prions: infectious proteins, cause spongiform
  encephalopathies (BSE, scrapie, CJD)

Question 4

what is the size range of a virion?

Answer 4

~10-400nm

Question 5

what is a caspid?

Answer 5

Large macromolecular structure which serve as protein coat
of viruses

Question 6

what are the three types of caspids?

Answer 6

• helical
• icosahedral
• complex

Question 7

what are the steps of viral replication cycle?

Answer 7

1. Attachment (via binding specific
   host receptor)
2. Penetration / uncoating of
   nucleocapsid
3. Transcription & translation of viral
   proteins
4. Replication of viral genome
5. Assembly of viral progeny
6. Release