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Virus

Virus. Virus. A life form that can only replicate inside of cells. Can be RNA (single or double stranded) or DNA viruses. That describes the type of genetic information that they release. Reproduction/Replication (Different than animals and plants)

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Virus

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  1. Virus

  2. Virus • A life form that can only replicate inside of cells. • Can be RNA (single or double stranded) or DNA viruses. That describes the type of genetic information that they release. • Reproduction/Replication (Different than animals and plants) • Causes Horizontal Gene Transfer, the transfer of genetic information (which causes resistance to antibiotics)

  3. Lytic Cycle • Attachment: The capsid of the virsus attaches to the receptors of the cell. • Penetration: The DNA of the virus enters the cell. This can occur by endocytosis, membrane fusion, or go in a break in the cell wall. • Biosynthesis: The virus is synthesized, once it puts out of commission all the functions that it does not need. • Maturation: Capsids and Virus DNA combine to make viruses. • Release: Lysozyme is made and the viruses are let out; the cell dies.

  4. Lysogenic Cycle • Attachment: Caspid attaches to the receptor of the cell. • Penetration: The virus DNA enters the cell but the virus DNA becomes latent, or inactive in replication. • Integration: Virus DNA meshes with the host DNA, the cell does not die. Virus DNA is called prophage and it is replicated with the cell’s DNA. A copy of the prophage will be in every future cell. • Maturation and Release only occur if something triggers it to occur.

  5. Integration • At this stage, the virus DNA will join with the cell DNA, creating new genomes and new viruses. So the virus becomes part of the cell DNA. • The combined cell and virus DNA will be replicated by translation and transcription.

  6. HIV • Step 1: It attaches to cell. • Step 2: It goes inside the cell. • Step 3: The RNA becomes DNA and integrates into the cell DNA. • Step 4: Be latent. Meanwhile, virus RNA is turned into virus protein. • Step 5: Virus RNA and proteins leave cell. New virus is formed. • Step 6: Virus leaves and matures. • (HIV goes through many mutations and replicates many times)

  7. Effects on Hosts (Latent Cells) • When the virus is latent and has prophage in the cell, the cell will have new traits. Ex. A bacteria that causes strep throat will causescarlet fever because of the toxin made in the bacteria.

  8. Mutations • RNA have high mutation rates because their polymerases do not have DNA polymerase, which can help prevent mutations.

  9. Viruses • Antigenic Shift: Two or more strains of viruses join together to make a new strand. • Reassortment: The viruses mix their components together to make a new virus. (Similar viruses) • Antigenic Drift: many mutations inside of genes that control antibody building. Basically, it helps the virus be immune to the antibodies. • Transduction: DNA is moved from one bacteria cell to another through viruses. (This helps with viruses becoming resistant to antibiotics)

  10. Transposons • Transposons: parts of DNA that can move from one part of DNA to another part of the DNA of the cell. This causes mutations. • They are not viruses but are similar in activities. • Retrotransposons are a class of transposons.

  11. Works Cited • Biology. McGraw-Hill. Pgs: 364-371, G-2. • http://en.wikipedia.org • http://images.google.com/ • http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Transposons.html • http://www.niaid.nih.gov/topics/HIVAIDS/Understanding/Biology/pages/hivreplicationcycle.aspx • http://medical-dictionary.thefreedictionary.com/antigenic+drift

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