There are 8 categories of life.

”Genus” and “species” produce the scientific names of animals.

Rules to scientific names: Genus and species are always italicized. First letter of Genus is capitalized while species is left in lower case.

Aristotle was the first to attempt to classify animals.

Karl von Linnaeus used a Latin system of classification of animals ( Based on resemblance to other life forms.)

Charles Darwin demonstrated that all organisms are related by common systems.

Similarity of DNA helps to clarify not classify organisms.

Before 1970 all forms of

Chapter 19

Diversity of Viruses:

Host specific, reproduce in the host’s cells (not cellular), nucleic acids wrapped in a protein coat of its own DNA or rNA, extremely small, cannot grow, cannot reproduce, spreads to other organisms, multitude of shapes.

Bacteriophage- virus that attacks bacteria

Viruses will attack specific types of cells and can also mutate. (AZT limits the replication of HIV viral agents)

Viroids- do not have a protein coat, they are unique to plants (citrus)

Prions- neural wasting disease, loss of bodily function, smallest known infectious agents. Only protein based. Only found in neural tissues.

Gram-Stain Sample Test- differentiates possible domain of viral agents based on cell wall structure.

Prokaryotes can be rod, corkscrew, or spherical shaped. They have flagella. Form bio-films to adhere to surfaces which protects against antibiotics.

Prokaryotes can endure extremes of climate change and varying atmospheric pressures. (Extremophiles)

Many prokaryotes can go dormant for years. They go into a non-functioning state. Diverse metabolism, anaerobic or aerobic. (Causes tetanus).

A few bacteria are photosynthetic (cyanobacteria) like plants.

Endospores- resistant structures that help bacteria to survive. Helps in dormancy (Anthrax)