U1: C2: Microbiology

Question 1

Viruses basic structure

Answer 1

nucleic acid, capsid (protein), some have envelopes, and bacteriophage have tail & tail fibers nucleic acid can be ssRNA, ds RNA, ds DNA

Question 2

How do viruses infect hosts?

Answer 2

1. bacteriophage: contain enzymes that degrade the bacteria membrane and inject its genetic information (transduction in bacterium) 2. euk: glycoprotein on virus capsid or envelope bind to host receptors, and host endocytosis

Question 3

Viral 1. lysogenic 2. lytic

Answer 3

1. long period, viral genetics incorporated into the hosts DNA, remains latent until stressed (virus will have reverse transcriptase RNA-> DNA) 2. short period: reproduces till it bursts the host cell, and released all at one time. Burst = virulent

Question 4

1. • stranded RNA (unenveloped) 2. + stranded RNA (enveloped) 3. - stranded RNA

Answer 4

1. translation directly from RNA 2. carries reverse transcriptase, and integrase (lysogenic= AIDS) 3. complement to mRNA must be transcribed to + RNA before translation can occur (flu, rabies)

Question 5

categorize organisms by carbon source

Answer 5

1. autotrophs: use CO2 2. hetertrophs: use organic matter

Question 6

categorize organisms by energy source

Answer 6

1. phototroph: use light 2. chemotroph: use organic or inorganic matter

Question 7

Amphipathic

Answer 7

nonpolar and polar (such as phospholipid)

Question 8

gram positive vs gram negative

Answer 8

gram +: purple, due to staining of the thick peptidoglycan gram -: pink, due to the leakage of the stain on the thin peptidoglycan

Question 9

bacterial reproduction

Answer 9

binary fission (asexual) (2 DNA polymerase begin at the same pt of origin and replicate in opposite directions)

Question 10

bacterial genetic recombination

Answer 10

1. conjugation: transfer plasmid bw one another through the sex pilus, and some chromosomal DNA 2. transformation: take in plasmid and DNA fragments from external environments and integrate them into the genome (lysed bacterium or hosts) 3. transduction: bacteriophages undergoing lysogenic life cylce incorporate the viral DNA into the bacterial genome

Question 11

plasmids

Answer 11

independent from bacterial chromosome. one strand is cut, and one strand separates and both are replaced with cDNA.

Question 12

Retrovirus life cycle

Answer 12

1. retrovirus endocytosis by hosts 2. viral reverse transcriptase converts viral RNA genome into ds DNA 3. virally encoded enzyme called integrase adds to the viral DNA into the host’s genome at random places

Question 13

Transduction

Answer 13

transfer of genetic material by viruses 1. virus infected cell: host DNA degraded into fragments, viral DNA takes over control 2. hosts DNA fragment get packaged into virus progeny by accident 3. virus progeny infect another cell, injects previous hosts’s DNA fragment 4. fragment enters cell, find its homologous counterpart, and cross over

Question 14

Gram + vs -

Answer 14

1. Gram +
   
   1. purple, bc stain is stuck
   2. thick peptidoglycan
   3. also has a periplasmic space and plasma membrane
2. Gram -
   
   1. pink, bc stain is washed out
   2. thin peptidoglycan
      
      1. lipopolysac, periplasmic space, peptidoglycan, periplasmic space, plasma membrane