Virus Structure, Classification, and Cycles of Infection Tommy Merlo, Ashley Christiansen, Megan Rathke and Dakota Hurwitz

Overview What is a virus and its structure Different types of viruses and real-life example The Lytic Cycle The Lysogenic Cycle

What is a virus? Contains a nucleic acid in proteins Protein capsid Microorganism Humans have healthy viruses

Part 2 Differences Single or double stranded RNA or DNA genomes Different shapes Small or big bases

Structures Viruses Contain All viruses contain DNA and RNA Funtion of DNA: stores an organism's genetic material in the nuclei Function of RNA: transcribe and translate genes and proteins

All viruses contain protein capsids Part 2 All viruses contain protein capsids Function of protein capsids: shell of the virus and encloses genetic material

Bacteriophage “Bacteria eater”- infects bacteria Injects DNA into the bacterium Infects and kills host cell through replication Made up of DNA or RNA and a protein coat

Adenovirus Group of viruses that can infect membranes AC Adenovirus Group of viruses that can infect membranes All ages but mostly babies and children Highly contagious Lasts a few days to a week

Retrovirus Contain RNA as their genetic information AC Retrovirus Contain RNA as their genetic information Uses the enzyme Reverse Transcriptase Insert their DNA into the DNA of the host cell May remain dormant Responsible for some types of cancer and AIDS

Real Life Examples Bacteriophage Adenovirus Phage Therapy Pinkeye Phage therapy is the therapeutic use of bacteriophages to treat pathogenic bacterial infections, such as E.coli Adenovirus Pinkeye Infects the the mucous membrane that lines the eyelid and eye surface. Symptoms: Swelling/ itching of eyelids, redness in white of eye, tearing, clear/thickish drainage Treatments: antibiotic eyedrops/ointment, warm or cold compresses

Real Life Example Retrovirus AIDS AC Treatments: antiretroviral therapy- a combination of medicines to fight HIV infection Non-nucleoside reverse transcriptase inhibitor: bind to and block HIV reverse transcriptase to prevent HIV from replicating Retrovirus AIDS attacks and destroys the CD4 helper lymphocyte, which are crucial to the immune system and immune response. Symptoms: rapid weight loss, frequent fevers, swelling of the lymph glands, diarrhea, Memory loss, depression, and other neurologic disorders

Lytic Cycle Usually considered as the main method of viral reproduction Its job is to destroy all infected cells in the body Also destroys the cell membrane Viruses that only use the lytic cycle are Virulent Viruses

Lytic Cycle Steps 1-3 Virus attaches itself to the bacteria Virus puts DNA in the bacteria DNA uses cellular machinery to reproduce itself 1 2 3

Lytic Cycle Steps 4. Proteins are produced from the genes in the DNA 5. The particles assemble into new viruses 6. Viruses overrun the cell and burst free and kill the cell 4 5 6

Lysogenic Cycle A virus integrates its DNA of the host cell The host cell’s viral genetic information replicates Prophage- DNA that’s embedded in the host’s DNA It isn’t always active; may take years DH

Lysogenic cycle of Infection The first two steps are both parts of the Lyctic cycle Bacteriophage injects DNA into bacterium(cell walls that lack organelles and an organized nucleus, including some that can cause disease) Bacteriophage DNA forms a circle DH

Lysogenic cycle of infection (pt 2) Bacteriophage inserts itself into host cell Prophage may replicate for generations(mitosis) Prophage can exit the bacterial chromosome, then enter the Lyctic DH

Differences between Lytic and Lysogenic Lysogenic viruses don’t lyse the host cell right away Remains inactive for a period of time Replicates Host DNA Lytic takes over immediately Lytic makes copies of itself DH

Similarities Between Lytic and Lysogenic Both methods of viral replication Steps one and two are the exact same Both occur after there is a virus in a cell

Single or double stranded DNA or RNA is an example of how viruses can be different. True False True

What are 2 structures viruses contain? RNA and Protein capsids DNA and RNA DNA and protein capsids DNA or RNA and Protein capsids D

Which 2 steps of the Lysogenic cycle are the same as the Lyctic? Last two First two No steps are the same The middle two B

What enzyme is the Retrovirus named after? AC What enzyme is the Retrovirus named after? Helicase Reversicase Reverse Transcriptase Ligase Transcription Reverse Transcriptase

The Lytic cycle doesn’t lyse the host cell right away. True False B

AC True or False A bacteriophage infects your respiratory tract, eyes, intestines, urinary tract, and nervous system. False!!!

True or False? The lytic cycle begins before the virus enters the cell. FALSE

What is considered the main method of viral reproduction? A: Glycolysis B: Lytic Cycle C: Lysogenic Cycle D: Virus Cycle B

Now you know…. What a virus is and its structure The different viruses and examples The Lytic cycle The Lysogenic cycle