Symbiosis

Symbiosis

• A close, and often long term relationship between different species– Mutualism (+,+) – both benefit– Commensalism (+, o) – one benefits, other unharmed– Parasitism (+, -) – one benefits, other harmed

With your shoulder partner, think of examples of each.

In a symbiotic mutualism, the clownfish feeds on small

invertebrates that otherwise have potential to harm the sea

anemone, and the fecal matter from the clownfish provides

nutrients to the sea anemone. The clownfish is additionally protected from predators by the anemone's

stinging cells, to which the clownfish is immune.

From Wikipedia

Viruses

Virus = Poison (latin)Obligate, intracellular parasites

Viruses and Human Health?

• Which human diseases and conditions are caused by viruses?

• Take two minutes with your neighbor to discuss which diseases and conditions are a result of viral infections.

What are viruses?

• Viruses are non-living, and therefore do not fit in the 6 kingdom classification system

• Viruses are tiny chemicals that can invade cells and use the cells organelles to reproduce

Viral Composition

Protein Capsid

May or may not have a membrane

Nucleic Acid CoreCan be DNA or RNA

Viral Composition

• Protein capsid coat• Nucleic acid core:– DNA – either double (dsDNA) or single stranded (ssDNA)• Eg. Smallpox, adeno-associated viruses

– RNA – antisense RNA, sense RNA, dsRNA, retroviruses• Eg. Ebola, poliovirus, reovirus, HIV

• Membrane:– Some viruses will be surrounded in a phospholipid

membrane

Virus Replication

• Do not contain cells, therefore no cell division• Replicate in a host cell• Types of cells/organisms they can replicate in

are called the host range• Use host cell to make copies of itself

Viral Life Cylces

Retroviruses

• Contain the enzyme reverse transcriptase• Copies viral RNA into DNA• DNA enters chromosomes of host• Then called a provirus

Retr

oviru

s: H

IV

Vaccines

• A preparation of dead, or weakened pathogens, that when introduced into the body cause the production of antibodies or T cells, without causing the disease

• Pathogen: An infectious, or biological agent that causes disease

• Antibody: protein produced by B Cells used to help fight off infections