A2.3 Viruses HL Flashcards
Viruses
Small infectious particles, ranging from 20 nm to 500 nm in size
Capsid
Protein sheath surrounding and protecting a virus’s genetic material.
Genetic Material of Viruses
Either DNA or RNA, can be single- or double-stranded.
Single-stranded RNA Viruses
Examples include HIV, influenza, coronaviruses.
Double-stranded DNA Viruses
Include bacteriophage lambda, variola virus, herpesviruses.
Enveloped Viruses
Viruses surrounded by a lipid and protein membrane, like HIV and influenza.
Non-enveloped Viruses
Viruses without an envelope, more stable, e.g., adenovirus.
Viral Genome Size
Ranges from as few as four genes to thousands of genes
Lytic Cycle
Viral replication process causing host cell destruction
Lysogenic Cycle
Dormant viral state, integrating its genome into the host cell genome
Obligate Intracellular Parasites
Viruses rely on host cells for replication and survival
Convergent Evolution in Viruses
Unrelated viruses develop similar traits independently
Retroviruses
RNA viruses with high mutation rates, e.g., HIV.
Viral Evolution
Fast adaptation and change over time, especially in RNA viruses
Recombination in Viruses
Exchange of genetic material between viruses
Host Cell Dependency
Viruses depend on host cells for energy, nutrients, and replication machinery
Viral Structure Diversity
Wide variety in shapes and genome types
Viral Origins
Possible origins include ancient genetic material, viroids, and transposons
Viral Reproduction
Cannot occur independently; relies on host cell machinery
Viral Mutation Rates
RNA viruses mutate faster due to error-prone replication enzymes
