LEQ: How does microbial DNA impact our lives?

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LEQ: How does microbial DNA impact our lives?. 10.17 to 10.23. Viral life cycles. Viral Life Cycle. Lytic viral replication cycle resulting in the release of new viruses by breaking open the host cell. Viral DNA directs host cell to make new viruses. - PowerPoint PPT Presentation


LEQ: How does RNA help to make a protein?

LEQ: How does microbial DNA impact our lives?10.17 to 10.23Viral life cycles

Viral Life CycleLytic viral replication cycle resulting in the release of new viruses by breaking open the host cell. Viral DNA directs host cell to make new viruses.

Lysogenic viral replication cycle in which the viral genome is incorporated into the host chromosome as a prophage new phages are not produced and host is not destroyed

RNA Virus Reproductive Cycle1. Envelope of virus fuses with cell membrane2. Enzymes remove protein coat3. Viral enzyme uses the viral RNA genome as a template for making complementary RNA which can do 2 things4. produce viral protein5. produce more viral RNA6. New protein coats surround new RNA7. Virus leaves the cell by coating themselves with cell membrane

Herpes virusEnveloped DNA virus that reproduces in the host cell nucleusCan remain dormant in certain nerve cells for long periods of timeStress activates herpes virus flare ups

Polio VirusThis virus attacks nerve cells which do not divide damage is permanent Treated with vaccine

Plant VirusesStunt plant growth & diminish crop yieldsCommon plant virus tobacco mosaicViruses enter through damaged tissue Viruses transmitted to plants viainsects, gardeners and farmers using contaminated tools, infected plant to offspringHow would a virus spread through an individual plant?plasmodesmatta

Emerging VirusesAIDS Acquired Immune Deficiency Syndrome

Caused by HIV a RETROVIRUS (uses reverse transcriptase)

early 80s 1st cases in US in San Francisco

Infects and kills several kinds of white blood cellsRetrovirusRNA virus that reproduces by means of a DNA molecule; it reverse transcribes its RNA into DNA; its DNA is inserted into the chromosome; its DNA then transcribes the production of more viral RNA and viral proteinAIDS is a retrovirus because it has2 copies of RNAReverse Transcriptase

Acquired Immune Deficiency Syndrome and Human Immunodeficiency Virus - are named for what they do - wipe out the immune system.RNA Retro Virus1. Viral envelope fuses with cell membrane2. Enzymes remove protein coat3. Reverse transcriptase converts viral RNA into DNA

4. DNA is integrated into host DNA5. Viral genes are transcribed to produce more viral RNA and protein6. New viruses are assembled7. New viruses exit the cell taking host cell membrane with them *Retroviruses can be dormant for years before being expressed

Emerging VirusesEbola

Recognized in 1976 in Central Africa

Causes hemorrhagic fever, vomiting, massive bleeding and circulatory failure often fatal

Emerging Viruses West Nile

First seen 1990 in North America

Causes encephalitis (swelling of the brain)

Spread by mosquitoes

Emerging VirusesSARS Severe Acute Respiratory Syndrome

February 2002 in China

Within 3 months 8,450 were infected 10% died

Caused by corona virus

Emerging VirusesH1N1 / Swine Flu

2009 outbreak in Veracruz, Mexico

Typical flu symptoms

Virus killed more than 18,000

Emerging VirusesMutations of existing viruses can produce new viral diseases; diseases evolve into a new species that can infect individuals who were immune to the original strainPeople come in contact with other species in the process we are exposed to the viruses that infect the other speciesSpread of viral diseases is rapid due to globalization (worldwide travel), promiscuity, blood transfusions, intravenous drugs, etcBacterial DNA Transfer (1 of 3)Transformation the incorporation of new genes into a cell from DNA that cell takes up from the surrounding environment (Griffith)

Bacterial DNA Transfer (2 of 3)Transduction the transfer of bacterial genes from one bacterial cell to another by a phage

Bacterial DNA Transfer (3 of 3)Conjugation the union (mating) of 2 bacterial cells resulting in the transfer of DNA between the 2 cells

Bacterial DNA Transfers

New DNA integration occurs by crossing over between the 2 DNA molecules incorporating new DNA into existing DNABacterial PlasmidsPlasmid small circular DNA found in bacteria (and yeast) that is separate fro the chromosomeF Factor a piece of DNA that can exist as a plasmid; it carries the genes needed to make sex pili & other structures needed for conjugation; F = Fertility; allow for the spread of DNA to other cells

Bacterial PlasmidsR Plasmid bacterial plasmid that carries genes for enzymes that destroy particular antibiotics result in antibiotic resistant bacteria.


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