Viruses & Immune System

Viruses & Immune System

1. Cycles of Phages

   • Lytic Cycle
     • phages infect a healthy cell, phage DNA is injected as host DNA degrades,viral genomes and proteins synthesize, then 3 sets of proteins self-assemble to form heads, tails, and tail fibers. The cell then lyses and releases the bacteria. This kills the cell.
   • Lysogenic cycle
     • phages infect a healthy cell, phage DNA is injected, phage DNA circularizes, phage DNA integrates into bacterial chromosome (prophage), bacterium reproduces and copies the prophage to its daughter cells, daughter cell obtains prophage. The cell is not killed.
   • temperate phage
     • also known as lambda phage, these phages can replicate in both cycles

2. medication used against viruses

   • antibiotics
     • do not work against viruses since they are nonliving, and antibiotics work only against living things
     • FDA
       • also known as the Food and Drug Administration, they check medicines and products to make sure they are safe for consumption.
   • treating viral infections
     • infections can be treated by getting vaccinated.

3. Types of Cells

   • retrovirus
     • an RNA animal virus where the enzyme reverse transcriptase, which transcribes RNA into DNA
   • B cells
     • lymphocytes that remain and mature in the bone marrow
   • T cells
     • lymphocytes that migrate to the thymus and mature there

4. Defenses against viruses

   • nonspecific defense
     • they include skin, mucous membranes, and secretions
   • innate immunity
     • molecular recognition relies on a small set of receptor proteins that bind to molecules or structures that are common to a group of viruses, bacteria, or other microbes. Present at birth with broad defenses
   • acquired immunity
     • molecular recognition relies on a vast arsenal of receptors which recognize a feature typically found in a pathogen
   • defense against foreign pathogens
     • defenses include skin, mucous membranes, secretions, antibodies, inflammatory response, antimicrobial proteins, natural killer cells, and phagocytic cells
   • autoimmune disorder
     • a disease where the immune system is active against particular molecules in the body
   • fevers
     • response by the immune system in an attempt to destroy pathogens by raising the body temperature