BACKGROUND:Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is an enveloped, (+)-sense, single-strandRNA virus thatcauses coronavirus disease 2019(COVID-19). The coronavirus familyis named for the crown-like spikes on the outer surface of thevirus and includes viruses that infect many species of animals,including camels, cattle, bats, and cats. The SARS-CoV-2 virusappears to have “spilled”out ofbats,its primaryanimal host,and intohumansin December of 2019 in Wuhan, China. COVID-19 symptoms appear2-14 days after exposure and include fever, dry cough, shortness ofbreath, chills, muscle pain, headache, diarrhea, and loss of tasteor smell.The virus spreads from person-to-person, primarily throughdroplets that are released when a person coughs or sneezes, butalso through indirect contact with secretions. It is highlycontagious and spread primarily by symptomatic individuals but alsoby individuals who are asymptomatic. Researchers are working at afrantic pace to design an effective vaccine and determine whetherpeople who recover from COVID-19 can be re-infected. Coronaviruseshave remarkably low mutation rates for RNA viruses. Theirreplicative enzyme has low fidelity (accuracy) but they haveacquired the gene for a 3’-to-5’ exonuclease (ExoN) that removesmismatches during and after RNA synthesis

QUESTIONS TO ANSWER:

1.(5pts) Fill in the missing terms in the replication cycleofSARS-CoV,a virus that is very similar toSARS-CoV-2with respect toits replication.

A.During attachment, the SARS-CoV___________________[namespecific viral ligand] binds receptor molecules on the___________________[name specific structure] of the host cell.

B.During penetration and uncoating, the virion enters the cellby___________________ and then releases its genome into thecytoplasm of the cell through ___________________[nameprocess].

C.During biosynthesis, the___________________[positive-and/ornegative] –sense genome isreplicated using the viral ______________________[name specificenzyme]to produce ___________________[positive-and/or negative]–sense strands. This activity will also produce___________________[name specific macromolecule] that will betranslated to produce viral structural proteins.

D.As a precursor to assembly, viral surface proteins aretranslatedin the ___________________[name host cell compartment].These surface proteins will then assemblewith other viral proteinsand a copy of the genome.

E.During release, infectiousvirions leave the host cell by theprocess of ___________________[name cell process].