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Virus Structure, Classification, and Cycles of Infection
Lila Tefft, Joe Greger, and Melanie Huot
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Overview Viruses Different Viruses Viral Reproduction Definition
Structures Identification as living or nonliving Different Viruses Bacteriophage Adenovirus Retrovirus Viral Reproduction Lytic Cycle Lysogenic Cycle Compare and Contrast
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What is a virus? Made of proteins and nucleic acids
Only reproduces by infecting living cells Can infect all life forms Differ widely in structure and size Virus attacking cell LT
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Visuals of Viruses T4 Bacteriophage Tobacco Mosaic Virus
Influenza Virus LT
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Structure of Viruses Either has RNA or DNA- information to transmit to host cell Surrounded by CAPSID- Protein coat surrounding genetic material Allows virus to bind to cell LT
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Are Viruses Alive? ABILITY TO REPRODUCE GENETIC INFORMATION
YES, THEY ARE ALIVE NO, THEY ARE NOT ALIVE ABILITY TO REPRODUCE GENETIC INFORMATION ADAPTS TO ENVIRONMENTS HAS NO CELLS/MADE UP OF MOLECULES CANNOT CREATE ENERGY CANNOT LIVE WITHOUT HOST LT
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Bacteriophage Virus infecting Bacteria
Composed of a DNA and RNA core with a protein coat Attaches itself to the surface of a cell and injects its Genetic Information throughout Largely distributed across the globe within the Biosphere Makes up most of all living organisms of Earth JG
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Adenovirus Most common Respiratory Illness causing:
sore throat Pneumonia Conjunctivitis (pink eye) Cold-like symptoms such as: headache, coughing, and/or diarrhea Infants most susceptible to adenovirus due to weak immune system People with a compromised Immune system are susceptible JG
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Retrovirus Single-stranded positive-sense RNA Virus
Considered an Obligate Parasite: targets a host cell to exploit it for resources Uses different coding sequence: RNA → DNA → RNA → Polypeptide Now considered Provirus: New DNA is then incorporated into the host cell genome JG
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Retrovirus (cont.) - Reverse Transcriptase
DNA polymerase enzyme that catalyzes the process of Reverse Transcription Enzyme used to generate Complementary DNA HIV uses reverse transcriptase to generate new viruses Generates a long-term infection Non-retroviruses widely used as Antiretroviral Drugs JG
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The Lytic Cycle Virus will attach to the bacterium, or HOST cell
Inject GENETIC material Reproduce itself Particles assemble selves into NEW viruses Overrun the host cell and break off, LYSING, and killing cell MH
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The Lysogenic Cycle Phage attaches to BACTERIUM Inject DNA
DNA CIRCULIZES – Incorporates self into GENOME MH
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The Lysogenic Cycle cont.
Becomes DORMANT Host cell divides – PROPHAGE passed to daughter cells Phage DNA can SEPARATE from chromosome – enters LYTIC cycle MH
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Lytic Cycle versus Lysogenic Cycle
Cell and DNA destroyed Virus replicates SEPARATELY Symptoms of viral infection Both Methods of viral reproduction Attach to cell and insert DNA Replicates using HOST Lysogenic PROPHAGE, cell not destroyed No viral symptoms Phage DNA in daughters Can enter LYTIC Cycle MH
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WHAT ARE VIRUSES MADE OF?
ABC's WHAT ARE VIRUSES MADE OF? Carbohydrates and proteins B. Proteins and lipids C. Phospholipids D. Proteins and nucleotides LT
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WHAT ARE THE TWO MAIN STRUCTURES FOUND IN VIRUSES?
ABC's WHAT ARE THE TWO MAIN STRUCTURES FOUND IN VIRUSES? Mitochondria and nucleus DNA and cell membrane Protein coat and genetic material Chloroplasts and mitochondria LT
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A BACTERIOPHAGE VIRUS INFECTS:
ABC's A BACTERIOPHAGE VIRUS INFECTS: Nucleus Bacteria Blood cells Nerve cells JG
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A RETROVIRUS, AKA OBLIGATE PARASITE, IS CONSIDERED A:
ABC's A RETROVIRUS, AKA OBLIGATE PARASITE, IS CONSIDERED A: Antiretroviral Virus Provirus RNA Virus DNA Virus JG
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WHEN CAN A VIRUS INSIDE OF A CELL BE DORMANT?
ABC's WHEN CAN A VIRUS INSIDE OF A CELL BE DORMANT? Lytic Cycle Before determining which cycle to go through After it has been reproduced Lysogenic Cycle MH
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WHAT IS AN OUTCOME OF THE LYTIC CYCLE?
ABC's WHAT IS AN OUTCOME OF THE LYTIC CYCLE? Cell reproduces passing virus to daughter cells Phages overrun and destroy the cell Prophage may leave chromosome Phage DNA is integrated in cell DNA MH
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Summary Viruses Different Viruses Viral Reproduction Definition
Structures Identification as living or nonliving Different Viruses Bacteriophage Adenovirus Retrovirus Viral Reproduction Lytic Cycle Lysogenic Cycle Compare and Contrast
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