VirusesViruses

Indiana Science Text Pg 52-55Indiana Science Text Pg 52-55

Ebola Virus1918 influenza virus

VirusVirus

Virus – Virus – Strand of DNA (hereditary Strand of DNA (hereditary material) surrounded by a protein material) surrounded by a protein coat.coat.

VirusVirus

Viruses – Living or Nonliving?Viruses – Living or Nonliving? Made up of cells? Made up of cells? Grow and develop?Grow and develop? Use Energy?Use Energy? Respond to surroundings?Respond to surroundings? Reproduce?Reproduce?

NONO

NONO

NONO

NONO

YESYES

NONLIVINGNONLIVING

VirusVirus HostHost – Living thing that provides a source – Living thing that provides a source

of energy for a virus or organism.of energy for a virus or organism. ParasiteParasite – Organism that lives in or on a – Organism that lives in or on a

host and causes harm.host and causes harm. Almost all viruses act like parasites Almost all viruses act like parasites

because they must be inside a living cell because they must be inside a living cell to reproduce AND they to reproduce AND they destroy the cells in destroy the cells in which they multiply. which they multiply.

Viruses vary in size, but all areViruses vary in size, but all are much much smaller than cells. smaller than cells.

VirusVirus

Active VirusActive Virus Examples – Examples – cold, influenza (flu)cold, influenza (flu) After entering the cell, IMMEDIATELY After entering the cell, IMMEDIATELY

goes into actiongoes into action Virus’s genetic material takes over cell’s Virus’s genetic material takes over cell’s

functionfunction

Active VirusActive Virus

1.1. Virus attaches to cellVirus attaches to cell2.2. Injects genetic Injects genetic

material into the cellmaterial into the cell3.3. Cell produces virus’s Cell produces virus’s

proteins and genetic proteins and genetic materialmaterial

4.4. Parts assemble to Parts assemble to form new virusesform new viruses

5.5. Cell bursts when too Cell bursts when too full and release new full and release new virusesviruses

Hidden VirusHidden Virus

Hidden (latent) Virus Example – cold sore Doesn’t take action immediately

Hidden VirusHidden Virus1.1. Virus attaches to a cellVirus attaches to a cell

2.2. Injects genetic materialInjects genetic material

3.3. Virus’s genetic material Virus’s genetic material becomes part of cell’s becomes part of cell’s genetic material.genetic material.

4.4. Virus becomes active.Virus becomes active.

5.5. Cells produce virus’s proteins Cells produce virus’s proteins and genetic materialand genetic material

6.6. Parts assemble to make new Parts assemble to make new virusesviruses

7.7. Cell bursts – releases virusCell bursts – releases virus

Effects on other OrganismsEffects on other Organisms

Most viruses attach to Most viruses attach to oneone kind of kind of host cellhost cell

Viruses are transferred byViruses are transferred by AirAir ObjectsObjects

A virus that enters bacteria is called A virus that enters bacteria is called a a bacteriophage.bacteriophage.

Fighting VirusesFighting Viruses

A vaccine is A vaccine is weakened virus particles weakened virus particles that helps you not to be infected by that that helps you not to be infected by that virus.virus.

The first vaccine was made in 1796 by The first vaccine was made in 1796 by Edward JennerEdward Jenner. It was created to fight . It was created to fight smallpoxsmallpox..

Ways to treat a virus include:Ways to treat a virus include: RestRest Some medications – Antiviral medicationsSome medications – Antiviral medications

Research with virusesResearch with viruses

Viruses can be good. They are being Viruses can be good. They are being used in used in gene therapygene therapy..

Some day, they may cure people Some day, they may cure people with with genetic disorders genetic disorders or or cancercancer using virus to change DNA.using virus to change DNA.