Chapter 13

• Virus have specificity
• Generalists: Virus that can infect a wide range of hosts.
• Capsid: The protein coat of a virus that surrounds the genetic material.
• Nucleocapsid: The combination of capsid and nucleic acid within a virus particle.
• Envelope: A lipoprotein layer surrounding some viruses, derived from host cell membranes.
• Capsomere: A protein complex that is a vesicle that is surrounded by a lipid bilayer
• Helical: Long tube structure
• Polyhedral: Virus that looks like a 20 sided dice
• Complex: Doesn’t fit under helical or polyhedral
• bacteriophages: viruses that infect bacteria
• Viral spikes: Proteins on the surface of viruses that allow them to attach to cells
• Lytic Cycle: A type of virus infection in which the virus replicates inside the host cell and then bursts out of the cell
• Virus attach by recognizing surface glycoproteins on a host
• Steps of Lytic Cycle: Attachment, Entry/Penetration, Bio(synthesis), Assembly, and Release.
• Attachment: Virus attaches to specific sites on the bacterial cell wall using its tail fibers.
• Entry/penetration: The virus injects its DNA into the cytoplasm of the bacterium through an opening created by the contraction of the tail sheath.
• Biosynthesis: Inside the bacterium, the virus uses the host's machinery to produce more copies of itself.
• Assembly: New virions assemble from their component parts (protein subunits and nucleic acid) within the infected cell.
• Release: Finally, the newly formed viruses are released from the infected bacteria when it ruptures or lyses.
• Lysogenic Cycle: Temperate phages and same has lytic cycle but a couple more steps
• Lysogenic Steps: Attachment, Entry, Prophage insertion, Replication, Induction, Biosynthesis, Assembly and Release.
• Prophage Insertion: After entry, the phage genome is inserted into the chromosomal DNA of the host cell
• Induction: If the host cell encounters stressful conditions such as UV light, chemicals, or other environmental factors, the prophage can be induced to enter the lytic cycle.
• Lysogenic conversion: a process in which a bacterium becomes infected with a virus and is able to replicate the virus
• Burst time: How long it takes when a virus attaches until new ones are released.
• Burst Size: How many are created
• Replication of Animal Virus: Attachment, Entry, Replication, Release
• Entry for animal virus: Direct Penetration, Membrane Fusion, and Endocytosis.
• Direct penetration: Sinks into the cytoplasmic membrane and virus genome enters the cell.
• Membrane fusion: The viral envelope fuses with the host-cell plasma membrane, releasing the nucleocapsid into the cytosol.
• Endocytosis: The process of engulfing material from the extracellular environment into the cell.
• Enveloped Virus are released by Budding
• Naked Virus are released by Exocytosis or Bursting of the cell
• Virus Latency: A virus can remain in a host cell for long periods of time without causing any harm. (Proviruses)
• Culturing viruses: Media consisting of mature organisms, embryonated eggs, and cell cultures.
• Neoplasia: abnormal growth of cells that can lead to cancer
• Metastasis: Occurs when tumors spread
• Malignant: cancerous, malignant tumours are cancerous and can spread to other parts of the body
• Benign: A tumour that does not spread to other parts of the body.
• Carcinogenic: Factors that can cause cancer