Today in class, we went through the notes about viruses and watched a video about the flu. Here's a basic overview of the notes.
Viruses: Living or non-living?
- viruses are between life and non-life
- Living characteristics: contain genes (RNA or DNA), are highly organized (complex protein structure
- Non-living characteristics: not made of cells, cannot reproduce on thier own: viruses don't have the necessary structures to reproduce so they must use the structures of living cells
Structure
- nucleic acid, the genetic material, is inside a protein coat
- often include: head (where genes are held), tail, tail fibers
The virus in the animation on the left is called a T4 Bacteriophage. It is easy to see the structure of this virus.
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookdiversity_1.html
Reproduction: Lytic and Lysogenic Cycles
Lytic Cycle
- virus injects genes into a host cell
- "hijacks" cell structures and uses them to make copies of itself
- viruses eventually causes the cell to lyse (burst)
- viruses are released to find a new host cell
Lysogenic Cycle
- virus injects genes into host cell
- viral genes are incorporated into normal cell genes
- genes are passed on without the cell making copies of the virus
- while in lysogenic cycle, cell does not lyse
- environmental changes will trigger the viral genes to switch to the lytic cycle
Plant Viruses
- affect plants: interfere with growth and damages crops
- most plant viruses have RNA not DNA
- viruses are designed to get past plant epidermis and cell walls
- no cure for the majority of plant viruses
- humans have created plants that are resistant to certain viruses
Examples: Tobacco mosiac virus (TMV) and tomatoes, PRSV and papaya
Animal Viruses
- many have a phosolipid outer layer, just like a cell's plasma membrane: allows viruses to slip in and out of the cell through endocytosis and exocytosis
- reproduce in cell's cytoplasm: needs ribosomes to make viral proteins
- RNA and DNA viruses
- RNA viruses: HIV, mumps, common cold, polio
- DNA viruses: chicken pox, herpes, hepatitis
http://www.sciencegateway.org/resources/biologytext/cb/virus/virus.html
HIV: the cause of AIDs
- Retrovirus: reproduces by the use of viral DNA molecules
- normally, cells use DNA to produce RNA (transcription)
- HIV has cells use RNA to produce DNA (reverse transcription)
- RNA then makes proteins
- viral genes now in cell's genes, cell is producing viral proteins
- Drugs for HIV: inhibit reverse transcription or inhibit production of the viral proteins
The full notes are on Moodle. The video we watched featured influenza, the flu, and was basically a review of the notes.
Homework: review viruses, moodle notes, work on group project script, work on textbook notes sheet
NEXT SCRIBE: Yvette
No comments:
Post a Comment