VIRUSES - Small non-cellular particles - Seen only with an electron microscope - Classified according to their shape - Classified according to their molecular structure

COMMON VIRAL NAMES: HerpesChicken pox InfluenzaMono HIVCancer (HPV) SmallpoxMono CowpoxShingles Polio Hepatitis Rabies

IN ORDER TO STUDY VIRUSES…. WE MUST: Isolate it from its host Hosts could be: animals plants bacteria cells

Inside the host it produces new viruses All viruses have one type of nucleic acid: DNA or RNA Most viruses are haploid Viral nucleic acid is covered by a protein coat (called a CAPSID)

SHAPES OF VIRUSES Two shapes: cubic symmetry & helical symmetry CUBIC HELICAL

CHEMISTRY OF VIRUSES Most viruses have no enzymes Cannot make protein on its own Require the protein synthesis machinery of its host cell Cannot make their own ATP Act as intracellular parasites Replicate themselves by making copies if their parts which are assembled using host building block materials

Viruses do not grow bigger then divide They dissemble, make new parts, they assemble parts identical to the parent virus All of this takes place in the host cell Are viruses living ?

DIFFERENCES BETWEEN VIRUSES & CELLS VIRUS CELLS DNA or RNA, in various forms as the genetic info. Few proteins, mainly as a cover for nucleic acid Few or no enzymes Cannot make ATP Intracellular synthesis then assembly Always both DNA & RNA as genetic info. Hundreds of proteins in various structures All have sugars & lipids Hundreds of enzymes Makes ATP Division by mitosis or fission

VIRAL REPLICATION ATTACHMENT & entrance: virus chemically recognized its host & attach to it. Whole virus or only its DNA or RNA enters its host cell

SYNTHESIS of protein and nucleic acid Molecular info. Inside the virus directs the host cell to replicate viral proteins

ASSEMBLY of the units: The viral nucleic acids, enzymes, and proteins are brought together and assembled into new viruses RELEASE of new virus particles: Newly formed viruses released from infected cell and the host cell dies

LYTIC & LYSOGENIC CYCLES OF VIRUSES LYTIC CYCLE can be completed in as little as minutes 300 new viruses can be produced Lysis = destruction or bursting open of host cell releasing new viruses BACTERIOPHAGES (viruses that infect bacteria) cause cell lysis (cell death)

LYSOGENIC CYCLE = replicated viruses can lay dormant inside their host Dormant virus can be activated by stress, temperature increases above 37 degrees, lack of certain food nutrients.

VACCINES VACCINES are solutions that are prepared from viral components or inactivated viruses Body reacts to vaccine as if it were a real virus and produces antibodies

I HAVE LIKELY BEEN VACCINATED AGAINST: Chicken pox Polio Measles Mumps Rubella Influenza HPV hepatitis

Your Dog & Cat Against….RABIES