GE 21 Virus Deck 1 Flashcards
What is the function of a capsid in a virus?
(what is it made of, types?)
Protein coat, protects genome, shapes (helical, icosahedral, complex).
What types of genome can a virus have?
DNA or RNA, single-stranded (ss) or double-stranded (ds).
What is the role of an envelope in some viruses?
(made of)
Lipid membrane, aids entry, immune evasion.
What are glycoproteins in viruses responsible for?
Attach to host receptors, essential for infection.
How do glycoproteins facilitate viral infection?
Recognize and bind host cell receptors, mediate viral entry.
What are the key differences between DNA and RNA viruses?
DNA Viruses: More stable, replicate in nucleus. RNA Viruses: Higher mutation rate, replicate in cytoplasm.
What is the Regressive Hypothesis in viral evolution?
Viruses evolved from free-living cells, lost genes, became parasites.
(aka reduction hypothesis, most widely accepted)
What does the Progressive Hypothesis suggest about viral evolution?
Mobile genetic elements became self-replicating viruses.
(aka genetic escape hypothesis)
What is the Virus-First Hypothesis?
Viruses predate cells, evolved from self-replicating RNA molecules.
How many groups are in the Baltimore Classification?
7 groups based on genome type and replication.
Group I of the Baltimore Classification includes which type of virus?
dsDNA (e.g., Herpes, HPV).
What is the first step in viral replication?
Attachment – Virus binds host cell receptor.
What occurs during the entry step of viral replication?
Endocytosis (naked viruses) or membrane fusion (enveloped viruses).
What happens during the uncoating step of viral replication?
Genome released inside host cell.
How do DNA and RNA viruses differ in replication?
DNA viruses use host polymerase, RNA viruses use viral polymerase.
What is the lytic cycle in viral replication?
Virus hijacks host machinery, rapid replication, cell lysis, virion release.
What is the lysogenic cycle?
Viral DNA integrates into host genome, host cell replicates with viral DNA.
What can trigger the transition from the lysogenic to the lytic cycle?
(specifics)
Stress (UV light, chemicals, immune suppression).
What is the function of reverse transcriptase in retroviruses?
Converts RNA to DNA, integrates into host genome.
What is the difference between horizontal and vertical viral transmission?
Horizontal: Spread between individuals. Vertical: Passed from parent to offspring.
How do vaccines protect against viral infections?
Expose immune system to viral antigens, memory cell formation.
What are live-attenuated vaccines?
Weakened virus, strong immune response (e.g., MMR, polio).
What characterizes inactivated vaccines?
Killed virus, safer but weaker response (e.g., flu shot, rabies).
What are subunit vaccines?
Only viral proteins (e.g., HPV, Hepatitis B).
