Lecture 7

Question 1

What are pathogens

Answer 1

Bacteria and Viruses

Agents that cause disease symptoms in thier hosts

Question 2

What are the 4 general properties of viruses

Answer 2

1. A virus is a small nonliving particle with a nucleic acid genome
2. Viruses are non-living; must be taken up by a living cell to replicate
3. Tobacco mosaic virus (TMV) first virus discovered - can be spread by spraying the sap from an infeated plant onto another plant
4. In 1900 the first human virus was identified - virus that causes yellow fever

Question 3

What are viruses

Answer 3

Small infectious particle that consists of nucleic acid enclosed in a protein coat

Over 4000 different types

Vary greatly in their characteristics, including their host range, structure, and genome composition

Question 4

What is a host cell

Answer 4

Cell that is infected by a virus

Question 5

What is the host range

Answer 5

The number of species and cell types that can be infected

Can be narrow (few species) or broad (many species)

Question 6

What are some of the notable structural differences

Answer 6

They range in size from 20 to 400 nm in diameter

All viruses have a capside (protein coat) but it varies in shape and complexity

Some have a viral envelop derived from host cell plasma membrane

Many virsus have protein fibers with a knob or spike glycoproteins that help them bind a host cell

Question 7

What is bacteriophages

Answer 7

Viruses that infect bacteria; may have more complex protein coats

Question 8

What are the 5 differences in genomes

Answer 8

1. DNA or RNA
2. Single stranded (ss) versus double stranded (ds)
3. Linear versus circular
4. Some viruses have more than one copy of the genome
5. Vary considerably in size from a few thousand to more than 100 thousand nucleotides in length