Learning Target: Virus Anatomy and Physiology I Can… Explain how viruses infect host cells and manipulate the host cell into manufacturing more viruses. I Will… Identify the fundamental structural components of a virus List Characteristics of viruses Describe two common ways viruses infect host cells Describe the two types of viral infection pathways

Learning Target: Virus Anatomy and Physiology Virus – Infectious particle made only of a nucleic acid strand (either DNA or RNA) surrounded by a protein coat Nucleic acid Single strand, double strand Linear, circular or segmented Protein coat – Capsid Individual protein components Different shapes Some viruses have a lipid layer Spikey surface protein and sugar structures Used to attach to host cell Can be used to identify the virus

Learning Target: Virus Anatomy and Physiology

Viruses Do not have ribosomes Cannot make enzymes Cannot make proteins Do not carry on metabolism Inactive outside of the host cell Unable to reproduce without host cell Cannot copy DNA Viruses are NOT alive

Learning Target: Virus Anatomy and Physiology Virus shapes act lock-and-key Can only infect certain cells Spikes bind to cell membrane proteins Usually species specific e.g. Tobacco Mosaic Virus Some viruses can cross between different species e.g. H1N1 (Swine flu) Some viruses start in birds Mutate and pass to another species such as pigs Mutate again and infect humans Rabies virus infects all mammals

Learning Target: Virus Anatomy and Physiology Two common ways viruses infect host cells 1)Simple Injection Virus attaches to cell surface Injects nucleic acid into cell’s cytoplasm Like a syringe e.g. T-Bacteriophage 2)Endocytosis Eukaryotic cells infected Virus fuses with the cell membrane receptors Releases capsid into cytoplasm in vesicle e.g. HIV Continue

Learning Target: Virus Anatomy and Physiology T-Bacteriophage infects E. coli bacteria Simple injection method Return

Learning Target: Virus Anatomy and Physiology Viral RNA uses Reverse Transcriptase enzyme to make Viral DNA genes Return

Learning Target: Virus Anatomy and Physiology Once virus nucleic acid is inside host cell, 2 basic types of infection occurs Lytic Cycle: Virus nucleic acid takes control of host DNA Turns on host genes to copy virus genes Viral genes direct transcription and translation of proteins Capsids Enzymes Enzymes help copy viral DNA Host cell energy assembles viral parts Viral enzymes dissolves host cell membrane Destroys host cell and releases new viruses Lytic Cycle

Learning Target: Virus Anatomy and Physiology Lysogenic Cycle: Virus combines its DNA into DNA of the host cell (Recombinant DNA) Viral DNA genes inserted into host DNA New set of genes Prophage in bacteria Provirus in other organisms New genes may change cell traits e.g. HPV link to cervical cancer Cell goes through mitosis Daughter cells get identical copies of new genes Two Paths: Dormant and continued passing through mitosis Activated by stress trigger Enters Lytic Cycle and destroys cell e.g. Herpes viral cold sore

Learning Target: Virus Anatomy and Physiology Lytic Cycle or Lysogenic Cycle Return

Learning Target: Virus Anatomy and Physiology Lytic Cycle Virus is a “Bad house guest” Moves in Trashes the place Blows up the house Leaves for new house Lysogenic Cycle Virus moves in Stays and does not leave If stressed Trashes the place Blows up house and leaves for new house

Learning Check √: Virus Anatomy and Physiology 1.Name the two ways in which a virus (or virus’ DNA) can enter a cell: a)__________________________ b)__________________________ 2.What are the two viral infection cycle pathways? a)_________________________ b)_________________________ 3. Why can’t you catch most viruses that infect plants or other animals.

Learning Target: Communicable Disease Chain of Infection I Can… Describe how communicable diseases are transmitted and how the chain of infection can be broken. I Will… Define the terms; Pathogen, Infectious, Disease, and Communicable List different types of disease categories Diagram the chain of infection in communicable diseases Provide examples of ways to break the chain of infection at each link

Learning Target: Communicable Disease Chain of Infection Pathogen – Any living organism or particle that can cause an infectious disease. Infectious – capable of causing an infection Disease damaging change in structure or function of cells, tissues, etc… Communicable – able to be passed from host to host “Contagious” Host cell – cell infected by pathogen Contagion – another name for a pathogen

Learning Target: Communicable Disease Chain of Infection Communicable Diseases Differs from other diseases Types of disease categories Genetic – inherited through the DNA e.g. Cystic Fibrosis, Color blindness Congenital – born with condition, but not genetically based Environmental/Chemical – brought on by exposure to environmental factors such as U.V. light (skin cancer) or chemical such as Tar/nicotine (lung cancer) Communicable – caused by a pathogen and can be passed from host to host

Learning Target: Communicable Disease Chain of Infection Chain of Infection Infectious agent Reservoir Host Portal of Exit Transmission Portal of Entry Susceptible Host Infectious agent Bacteria Virus You Blood/body fluids Secretions Wound Direct/Indirect Contact Droplets Airborne Respiratory Digestive Wound Low resistance individual

Learning Target: Communicable Disease Chain of Infection Breaking Chain of Infection Infectious agent Reservoir Host Portal of Exit Transmission Portal of Entry Susceptible Host Isolation Prompt treatment Cover mouth/ Nose Wound Bandage Hand washing, Sanitation, Disinfection Gloves Mask Bandage Vaccination Rest Nutrition