All Three Are Caused By Viruses

Herpes Simplex - Is the virus responsible for cold sores

Ebola Virus- a fatal virus that infects humans through handling of infected chimpanzees gorillas and forest antelopes

HPV- (Human Papillomavirus)- over 130 types identified, some cause warts and others can cause cancer

Other Viral Diseases……….

SHINGLES

RUBELLA

HERPES

AIDS patient with lesions

HAND, FOOT, & MOUTH DISEASE

EBOLA

Dead or Alive?

To be Alive you need to: 1. Have cells (or be a cell!) 2. Ingest nutrients and energy 3. Be homeostatic 4. Respond to stimuli 5. Reproduce 6. Grow and develop 7. Have adaptations to the environment

Are Viruses Cells or Made of Cells?

NO, a virus is little more then a protein coating and a strand of DNA or RNA

Do Viruses Reproduce?

Living Non living

Yes viruses carry DNA and are able to reproduce

Viruses rely on host cells to reproduce, they can not reproduce on their own

Do Viruses Obtain Energy?

Living Non Living

Viruses control host cells therefore using the host cells processes to obtain the energy needed to reproduce

Viruses have no cell activity and therefore require no food.

Do Viruses Grow?

Living Non-Living

Some scientists argue that virus growth occurs inside a host cell where parts of viruses are being built during reproduction

A virus does nothing inside it’s protein coat therefore it does not grow.

Do Viruses React to stimuli?

Living Non Living

Viruses are able to evolve and hence react to its environment .

Some argue that viruses react to stimuli based on the host cell

Viruses cannot move themselves therefore cannot react to stimuli

Are Viruses Homeostatic?

Living Non Living

Some argue that a viruses ability to change its protein coat is a method of controlling homeostasis.

Homeostasis refers to regulating internal environment such as electrolyte concentration or sweating for temperature control. Viruses have no such functions.

Do Viruses have adaptations to the

environment? Living Non Living

Viruses have DNA or RNA that can evolve over time therefore increasing their chance for survival. They adapt through genetic mutation and rapid reproduction.

This is one of the stronger arguments for viruses being alive.

Your Turn

Write an argument stating your position if you believe viruses are living or non living. Back up your argument with your current knowledge about viruses and any ideas you learned from the presentation. You may also use chapter 17 of your text for further information. You must address all 7 requirements to be considered alive.

Viruses

Technically viruses are not alive! They are Obligate Parasites Viruses rely on host cells for:

transportation, cellular machinery, and reproduction