Viruses vs. Cells

By: Carson Yarbrough 11-17-15 P.2

HIV Virus

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Influenza Virus

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Bacteriophage virus

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Plant Cell

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Animal Cell

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The Lytic Cycle

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The Bacteriophage virus is a virus that reproduces using the Lytic cycle, above is an image of the Lytic cycle of the Bacteriophage virus. In general the Lytic cycle is very fast compared to the lysogenic cycle. First the virus attaches and enters the cell. Next the host cell makes thousands of copies of the virus. Then new viruses burst out of the cell destroying it. Lastly, new viruses are released and seek out other cells to infect.

The Lysogenic Cycle

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Some viruses such as herpes and HIV reproduce through the lysogenic cycle. The lysogenic cycle is a more longer infection. First the virus attaches and enters the cell. Next the virus DNA incorporates into the host cells DNA. Then the cell divides and each new daughter cell has the viral DNA. Eventually the virus becomes active and enters the Lytic cycle.

Characteristics of Life

The 8 characteristics of life are:

1. Living things grow and develop

2. All living things reproduce

3. All living things maintain homeostasis

4. Living things respond (adapt) to the environment

5. Living things have cellular organization

6. Living things obtain and use material and energy

7. Living things are based on a universal genetic code

8. Living things as a group evolve


Viruses have a very small amount of the characteristics of life. Viruses do not obtain and use material and energy. They do not maintain homeostasis or matabolize. Viruses cannot reproduce ON THEIR OWN, viruses reproduce by hijacking the reproductive structures of other cells. Viruses do not move and they do not go through respiration processes. Most importantly they have no cellular structure.


Although viruses are non-living they do show some characteristics of living things. They are made of proteins and glycoproteins like cells are. They contain genetic information needed to produce more viruses in the form of DNA and RNA. Lastly, they evolve to adapt to their hosts.

Questions

1. Describe the typical structure of a virus. What is a virus made of? What biomolecules would you find in a virus?

Viruses have a very small structure they are much smaller than the cells they infect. A virus either contains DNA or RNA surrounded by a protein coat called a capsid. Some have a lipid membrane surrounding the capsid called a envelope. Some viruses also have enzymes. The biomolecules that you would find in a virus are nuclei can acids and proteins.

2. Discuss the different ways viruses gain entry into a cell.

One way a virus enters a cell is when the virus attaches to the host cell. The Virus injects it’s DNA or RNA into the host cell. Viruses genetic material takes over the cell.


Enveloped viruses are enclosed in a membrane similar to the one of the host cell. The virus and the envelope fuse and the virus enters the cell through endocytosis.

3.Explain why the Ebola virus would not infect a tobacco plant?

Viruses are very specific about what cells they infect. The Ebola virus infects animal cells (humans) but are not able to infect plant cells therefore Ebola would not be able to effect a tobacco plant.

4. Name five viruses and the type of cell that they attack.

Bacteriophage is a virus that attacks only bacteria cells. The HIV virus attacks and kills T-helper cells. The influenza virus mainly attacks animal cells. The West Nile virus attacks animal cells. Lastly, rabies infect animal cells also.

5. You have been diagnosed with the flu. Explain why a doctor will not provide you with a prescription for antibiotics in order to cure your infection?

The doctor will not provide antibiotics to improve my infection because antibiotics do not kill viruses. Antibiotics are medicines used to treat infections or diseases caused by bacteria. Viruses are organisms that are not living and antibiotics are used to kill off living organisms.

6. How is it that a person can be infected with a virus such as HIV and not exhibit symptoms?

A person can be infected by HIV and not experience symptoms because when your body gets HIV it takes several years for the virus to attack and kill enough T-cells in your body to start experiencing symptoms. The virus can infect 10 billion cells a day, yet only 1.8 billion can be replaced daily. After many years of a constant battle, the body does not have enough numbers of T-Cells to have an immune response against infections. At the point when the body is unable to fight off infections, a person is said to have the disease AIDS.


It is not the virus or the disease that ultimately kills a person; it is the inability to fight off something like a cold.