Viruses VS. Cells

By Caitlin Kresta

Types of viruses:

Plant and Animal Cell:

Big image

Characteristics of Life

There are 8 characteristics every living thing shares:

  • they grow and develop
  • have a genetic code
  • they respond to the environment
  • made of cells
  • able to reproduce
  • maintain homeostasis
  • obtain and use material energy
  • evolve

Of these eight characteristics, viruses only share two. Viruses contain genetic material such as DNA or RNA, and they pass the material onto their offspring. As a result of having genetic material, small mutations can occur over time, allowing the virus to evolve.

Lytic Cycle

The Lytic cycle happens rapidly. After the virus attaches itself to the host cell, it penetrates the cell membrane to inject its' DNA/RNA. The host cell then makes 100's of copies of the virus DNA/RNA, not realizing that it is harmful. When enough DNA/RNA is produced, the new viruses assemble. Finally, when enough viruses form, they burst out of the host and seek other cells to infect, while leaving the dead host behind. An example of a virus that reproduces by the Lytic Cycle would be Influenza.

Lysogenic Cycle

The Lysogenic Cycle is more of a slow moving process. The virus attaches, penetrates, and embeds DNA into the host cell. This embedded DNA is called a prophage. The virus then becomes dormant, allowing the cell to replicate and produce daughter cells. Eventually, the virus is activated and enters the Lytic Cycle. An example of a virus that uses the Lysogenic Cycle to reproduce would be HIV.


1. Describe the typical structure of a virus. What is a virus made of? What biomolecules

would you find in a virus?

The basic virus structure consists of a strand of DNA or RNA, Enzymes, and a protein coat (capsid). Some more complex viruses have an outer lipid membrane called the envelope. This simple structure has only the biomolecules nucleic acids, proteins, and sometimes lipids.

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

There are two ways a virus may gain entry to a cell. One way is by the virus having specific protein spikes on the envelope that match the protein on the outside of the host cell. The envelope then fuses together with the host's cell membrane and allows the DNA to enter the cell. The second way is by absorption. The host cell recognizes the viruses proteins, creates a vesicle around the virus, and absorbs it.

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

Viruses are specific when it comes to the cells they attack. For example, a virus with a capsid or envelope that was structured to imitate an animal's' cell membrane, would not try to enter a plant cell.

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

HIV: attacks Helper-T cells

Influenza: attacks Respiratory Cells

Ebola: attacks Fibroblasts of any type

Type 1 Herpes: cells of the mouth and lips

Type 2 Herpes: cells of the genitalia

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.

Antibodies fight viruses, and by taking antibiotics, which kill antibodies you would actually be helping the virus spread. Viral infections and Bacterial infections are extremely different, which is why you should not take medication that isn't prescribed for your specific infection.

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


HIV is a virus that goes through the Lysogenic Cycle. This means that the host call can go months, even years without the virus entering the Lytic Cycle. Once it enters the Lytic Cycle though, then you experience symptoms (AIDS)