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MICR 3220 Lecture Notes - Lecture 21: Orf Eins, Orf 2, Rna-Dependent Rna Polymerase

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School
University of Guelph
Department
Microbiology
Course
MICR 3220
Professor
Paul Goodwin

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Document Summary

Read through strategy make orf 1 (126kd) and 2 (1+2=183kd) Orf 3 (30kd) and 4 (17) subgenomic strategy. Orf 3 = movement protein, orf 4 = coat protein. Orf 1 and 2, the two proteins now are produced in d(handout) associate with plant proteins (host proteins) result: formation of enzyme complex which is called the replicase (enzyme that replicated virus) This is not our virus this is the minus strand rather the virus is the plus strand. Replicated form acts as template to make more +strands, result: progeny genomes (nascent +rna) In addition to progeny genomes (full length genomes) we now produce sub genomic genomes. J: different five prime ends, start producing coat protein. We get viral replication complex this is a membrane associated process in the plant cell: in the endoplasmic reticulum with lots of membranes in it, you get vesicles that form in it (little vesicles blobbing off of er)

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Related Questions

1. Unlike Ebola virus, SARS virus
a. has large spikes that look like a “crown”.
b. is enveloped.
c. is helical.
d. is in the family Togaviridae.
e. is a ssRNA virus.

2. Which virus or virus family is described in the followingpassage?
Electron micrographs of the hemagglutinin subunits (in the presenceof SDS) showed
rods approximately 40 Ã wide and 140 Ã long. The neuraminidasesubunits had a quite
different appearance. In the presence of SDS, these were seen asoblong structures about 85 Ã long and 50 Ã wide with a centrallyattached fibre 100 Ã long possessing what appeared to be a diffusetail or small knob about 40 Ã in diameter at its end.1
a. Togaviridae
b. Epstein-Barr virus
c. Smallpox virus
d. Orthomyxoviridae
e. Filoviridae
f. Rabies virus

3-Following is a passage from the New England Journal ofMedicine:
______________________ is an exclusively human herpesvirus that ...becomes latent in
cranial-nerve and dorsal-root ganglia, and frequently reactivatesdecades later to produce shingles and postherpetic neuralgia. Inimmunocompetent elderly persons or
immunocompromised patients, ____________________ may producedisease of the central nervous system.
This passage refers to which virus?
a. West Nile virus
b. Smallpox virus
c. Epstein-Barr virus
d. Ebola virus
e. Varicella-zoster virus

4. Pneumoviruses can cause colds and pneumonia in humans. They aresingle-stranded,
negative-sense, nonsegmented RNA viruses. These enveloped virusesare surrounded by an envelope that is characterized by fusionglycoproteins and host-derived proteins. With this knowledge, it islikely that pneumoviruses
a. enter host cells via endocytosis.
b. leave host cells by budding.
c. enter host cells via membrane fusion.
d. A and B
e. B and C

5. Recall that poliovirus is a positive-sense (+) ssRNA virus. The5’ à ? 3’ strand of RNA,
once uncoating has taken place, can serve as an mRNA and encode forviral proteins.
However, in order for the virus to create more +ssRNA to package indaughter viruses, it must
a. generate a dsRNA molecule that can encode for the synthesis ofmore +RNA.
b. integrate into the host cell DNA.
c. utilize an RNA-dependent DNA polymerase to make aheteroduplex.
d. undergo reassortment
e. All of the above

6. Some influenza hosts, such as humans and pigs, cansimultaneously contract human,
avian and swine influenza viruses at the same time. What can occurduring the maturation phase of virus replication in such ahost?
a. Reassortment
b. RNA of all three sources: human, swine and avian, can bepackaged into a single
virion.
c. Genetic shift
d. All of the above

7. The HIV virion contains enzymes/proteins that do all of thefollowing EXCEPT
a. An enzyme that creates –DNA using +RNA as template.
b. A protein that serves as a chemokine receptor.
c. A DNA-dependent DNA polymerase.
d. An enzyme that allows +/- viral DNA to be spliced into the hostcell’s DNA.
e. A protein that mediates membrane fusion.

8. After a long series of biochemical tests, Kyle and Matt werefinally able to identify their Gram-negative unknowns asPseudomonas aeruginosa and Shigella dysenteriae,
respectively. As they compare notes, they realize that theirunknowns are in the
___________ Pseudomonadaceae and Enterobacteriaceae, respectively.However, they also note that both of their unknowns are in the______________ ? proteobacteria.
a. genera, species
b. phyla, family
c. families, class
d. order, phyla
e. classes, order

9-Hydrogenobaculum acidophilum is a resident of Yellowstone’sNorris Geyser basin. This thermoacidophilic microbe grows instringy, white mats and is a member of the phylum Aquificae.Hydrogenobaculum acidophilum
a. could be further researched in Volume 2 of Bergey’s Manual ofSystematic
Bacteriology.
b. is in the domain Archaea.
c. is a deeply branching bacterium.
d. is a proteobacterium.
e. All of the above

10-After talking about the Group A Streptococci (GAS) and theircapability to sometimes cause a flesh-eating disease callednecrotizing fasciitis, Derek decides to research this group a bitmore. As he reads, he quickly learns that
a. they are microaerophilic Gram-negative rods.
b. they are in the phylum ?-proteobacteria.
c. they are found Volume 4 of Bergey’s Manual of SystematicBacteriology.
d. they have less than 50 mol % GC content.
e. none of the above

1. In addition to identifying the genetic material, the experiments of Avery, MacLeod, and McCarty with different strains of Streptococcus pneumoniae demonstrated that
DNA is a double helix.
DNA may be taken up by bacterial cells and be active.
DNA is present in bacteriophage T2.
eukaryotic cells may be genetically transformed.
DNA binds to the cell wall of the bacterium.
2. In order to show that DNA in cell extracts is responsible for genetic transformation in Streptococcus pneumoniae, important corroborating evidence should indicate that _______ also destroy transforming activity.
temperatures high enough to kill cells
enzymes that hydrolyze proteins
enzymes that hydrolyze DNA
enzymes that hydrolyze polysaccharides
enzymes that hydrolyze RNA
3. Based on what you have learned about the experiments conducted by Griffith and Avery and colleagues with bacteria, which of the following would result in transformation of living R cells?
Pure RNA from S cells
Cell-membrane extracts from S cells
A mixture of pure RNA and protein from S cells
Cell-free extracts from S cells
Pure protein from S cells
4. A-T base pairs in a DNA double helix
form three hydrogen bonds with each other.
are more heat-stable than G-C base pairs.
are of a substantially different length than G-C base pairs.
are not accessible to DNA binding proteins.
are chemically distinct from G-C base pairs.
5. If 23 percent of the bases in a sample of double-stranded DNA are adenine, what percentage of the bases are uracil?
27
50
0
73
23
6. The uniform diameter of the DNA structure provides evidence for
antiparallel DNA strands.
a right-handed helix.
a double-stranded helix.
3′ end phosphorylation.
purine–pyrimidine pairing.
7. If a sequence of one strand of DNA is 5′-TGACTATC-3′, what is the complementary strand?
5′-ACTGATAG-3′
3′-TGACTATC-5′
3′-ACTGATAG-5′
3′-ACTGATAG-3′
5′-TGACTATC-3′
8. What structural aspect of the DNA facilitates dissociation of the two DNA strands for replication?
3′ end phosphorylation
Purine–pyrimidine pairing
Antiparallel DNA strands
Covalent bonds between sugars and phosphate groups
Hydrogen bonding between paired bases
9. If the Meselson–Stahl density gradient experiment had resulted in two bands of DNA molecules after only one round of replication, one containing only 15N and the second only 14N, this result would have indicated that replication was
unidirectional.
dispersive.
conservative.
bidirectional.

semiconservative.
10. The nucleoside analogue acyclovir, which is used to treat herpes simplex virus (HSV) infections, lacks a 3′ hydroxyl group (–OH). Predict what will happen if the host cell DNA polymerase incorporates a molecule of acyclovir into an elongating strand of HSV DNA.
The replication complex will no longer bind to origins of replication.
The DNA polymerase will only incorporate acyclovir molecules.
Acyclovir will bind single-strand binding proteins.
DNA polymerase will not be able to link a successive nucleotide.
Acyclovir will block the activity of the DNA helicase.
11. Which of the following does not demonstrate the stability of the DNA double helix?
Single-strand binding proteins are required to keep the strands apart.
Paired bases form hydrogen bonds.
High temperatures are required to denature it.
DNA synthesis requires energy.
DNA helicases require ATP.
12. What effect would a primase inhibitor have on DNA replication?
DNA polymerase would not be able to add bases to the DNA.
Primase would be blocked from joining the DNA replication complex.
Primase would not be able to provide primers for DNA polymerases.
DNA polymerase would not be able to use DNA as a template.
There would be no effect on DNA replication.
13. To replicate their DNA in a timely manner, most eukaryotic chromosomes
normally have uncoiled DNA.
have multiple origins of replication.
contain linear molecules of single-stranded DNA.
have two replication forks that move in the same direction.
are composed entirely of DNA.
14. Which statement about DNA replication is false?
Okazaki fragments are synthesized as parts of the leading strand.
Error rates for DNA replication are reduced by proofreading of the DNA polymerase.
The sliding clamp increases the rate of DNA synthesis.
Replication forks represent areas of active DNA synthesis on the chromosomes.
Ligases and polymerases function in the vicinity of replication forks.
15. In many eukaryotes, there are repetitive sequences called telomeres at the ends of chromosomes. After successive rounds of DNA replication, the _______ strand becomes shorter. In some cells, an enzyme called _______ repairs the shortened strand.
leading; telomerase
lagging; telomerase
lagging; DNA polymerase I
leading; DNA polymerase I
leading; replicase
16. A researcher studies normal human fibroblast cells. They can be maintained in culture but die off after about 30 cell generations. Unexpectedly, a colony of cells continues to survive and divide past 30 generations. Which scenario is most likely true for these cells?
DNA polymerase is constantly active.
Primase is able to extend the telomeres.
The mismatch repair system is extra efficient.
The telomerase gene is being expressed.
The cells do not need the ends of their chromosomes.
17. If DNA polymerase III introduces an incorrect nucleotide, what is the first corrective action made by the DNA repair system?
The replication complex excises the incorrect nucleotide.
The excision repair proteins remove the incorrect nucleotide.
The mismatch repair system scans for base-pairing mismatches.
There is no correction, because nucleotide errors by DNA polymerases are not repaired.
DNA ligase connects the correct nucleotide.
18. Choose the correct order of the following four events in the excision repair of DNA:
(1) Base-paired DNA is made complementary to the template.
(2) Damaged bases are recognized.
(3) DNA ligase seals the new strand to existing DNA.
(4) Part of a single strand is excised.
1, 2, 3, 4
2, 1, 3, 4
3, 4, 2, 1
2, 4, 1, 3
4, 2, 3, 1
19. Six complete cycles of PCR should result in a _______-fold increase in the amount of DNA.
64
32
12
128
6
20. When double-stranded DNA is heated to temperatures above 90°C, it denatures. Denaturation is a process that
breaks covalent bonds.
hydrolyzes DNA.
separates double-stranded DNA into two single strands.
causes new hydrogen bonds to form.
irreversibly destroys the double helical structure.