BIL 150 Chapter 19: Viruses || WELL-ENLIGHTENED
How does a virus make more viruses generally? correct answers 1. First a virus enters a host
cell and releases its genome (either DNA or RNA)
2. Then viral genome is *replicated* by host enzymes
3. The viral genome is also *transcribed into viral mRNA which is then translated into viral
proteins* through the machinery of the host cell
3. The virus is then spontaneously *self-assembled* with the replicated viral genome and
viral proteins made from the viral mRNA
4. After a bunch of new viruses are made, then either the *host cell lyses and releases all the
viruses* OR *the host cell remains alive after some of the produced viruses leave and others
remain* (*lytic or lysogenic cycle*)
Virus correct answers An infectious particle consisting of genes packaged in a protein capsid
or membrane envelope (or both)
Viral genome correct answers -Can be either DNA or RNA, they can either be single or
double stranded
-Either single linear or circular molecule of nucleic acids, or multiple nucleic acid fragments
-Between 3 - 2,000 genes
4 Groups of Viruses (with independent origin form transposons and plasmids) correct
answers 1. RNA viruses
2. Reverse-transcribing viruses
3. Single-stranded DNA viruses
4. Double-stranded DNA viruses
Capsid correct answers The protein shell that encloses the viral genome; are built from
protein subunits called *capsomeres*
Different shape of capsids correct answers Can have a variety of structures; can be helical or
icosahedral viruses
Viral envelopes correct answers A membrane made from both viral and host cell molecules
that cloaks the capsid that in turn encloses a viral genome; they are derived from the
membranes of host cells
Viruses are _____________ ______________ __________________, which means they can
replicate only within a host cell. correct answers obligate intracellular parasites
How does a virus make more viruses generally? correct answers 1. First a virus enters a host
cell and releases its genome (either DNA or RNA)
2. Then viral genome is *replicated* by host enzymes
3. The viral genome is also *transcribed into viral mRNA which is then translated into viral
proteins* through the machinery of the host cell
3. The virus is then spontaneously *self-assembled* with the replicated viral genome and
viral proteins made from the viral mRNA
4. After a bunch of new viruses are made, then either the *host cell lyses and releases all the
viruses* OR *the host cell remains alive after some of the produced viruses leave and others
remain* (*lytic or lysogenic cycle*)
Virus correct answers An infectious particle consisting of genes packaged in a protein capsid
or membrane envelope (or both)
Viral genome correct answers -Can be either DNA or RNA, they can either be single or
double stranded
-Either single linear or circular molecule of nucleic acids, or multiple nucleic acid fragments
-Between 3 - 2,000 genes
4 Groups of Viruses (with independent origin form transposons and plasmids) correct
answers 1. RNA viruses
2. Reverse-transcribing viruses
3. Single-stranded DNA viruses
4. Double-stranded DNA viruses
Capsid correct answers The protein shell that encloses the viral genome; are built from
protein subunits called *capsomeres*
Different shape of capsids correct answers Can have a variety of structures; can be helical or
icosahedral viruses
Viral envelopes correct answers A membrane made from both viral and host cell molecules
that cloaks the capsid that in turn encloses a viral genome; they are derived from the
membranes of host cells
Viruses are _____________ ______________ __________________, which means they can
replicate only within a host cell. correct answers obligate intracellular parasites
