Biology Questions about viruses I need help with

Question

1.Each virus only infects specific types of cells or organisms. For most viruses, how do they determine what cells they can infect? In other words where does the specificity?

2.There have been recent outbreaks of dog flu in the Us. Why doesnt this virus infect human?

3.Reverse transcriptase is required by what kind of viruses?

4.What cellular process forms the foundation of the Baltimore Classification Scheme?

5.The enzymes that are used to replicate a virus are synthesized by what?

Answer 1

For I virus to 'stick to' its target (a necessary step in gaining entry, whether it is a bacterial virus or one that attacks eukaryotes such as you and me), there must be a 'lock and key' relationship between proteins on the surface of the virus and proteins on the surface of its target. Since different cells have different proteins on their surfaces, a virus can only stick to cells that match the 'key' that the virus uses to stick to targets.

Answer 2

1) Viruses will have an attachment protein in the capsid or glycoprotein in the envelop that will bind to specific receptor sites on the host cell/organism.

3) Retroviruses require reverse transcriptase to convert RNA to DNA. HIV is an example of this.