{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Test 1- Outline+1b

Test 1- Outline+1b - NOTES FOR BIOLOGY 1002 SECTIONS 001...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
NOTES FOR BIOLOGY 1002 SECTIONS 001 and 002 Outline 1B CHAPTER 19 The Diversity of Viruses, Prokaryotes, and Protists Microbes consist of organisms that are too small to be seen clearly without a microscope (a.k.a. microorganisms). These microorganisms include: - prokaryotes , which range in size from 0.2-10 micrometers in diameter. and - unicellular eukaryotic organisms of the kingdom Protista that are in the 10-100 micrometer range. (See fig 19-1) How big (or small) is a micrometer? 1/1,000,000 of a meter. But just how small is that? The period at the end of this sentence is about 1/2 millimeter (500 micrometers) in diameter. There are groups of biological entities that are even smaller than bacteria. These groups are, VIRUSES, VIROIDS, AND PRIONS -some are things that can make organisms sick. -these are not organisms, because they don’t have all the requirements for being alive. They are however derived from organisms. > Viruses A virus particle is small (0.05 - 0.2 micrometers) and comes in many different shapes (see fig. 19 -3). These particles all have two parts: genome - the genetic information can be either DNA or RNA (ds or ss) capsid - a protein coat that surrounds and protects the genome Some viruses also have an envelope , a membrane (phospholipid bilayer) that surrounds the capsid The entire function of a virus is to take control of a host cell to produce more virus particles. A biological hijacking.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The genetic material of the virus “reprograms” the host cell to make more viruses (See A closer look page 362-363). Because viruses require a host for their reproduction, can’t make their own proteins and have no energy conversion mechanisms, they aren’t alive. The cell type that a virus will infect, or host, is usually very specific and the host species, which the virus can infect, are often a narrow range. Even bacteria are susceptible to viral infection from bacteriophage . (See fig. 19-4) > Viroids are even simpler/smaller biological entities. - viroids are small fragments of ssRNA (either linear or circular) with no protein coat. Like a virus, a viroid takes over the cell it infects. Viroids are plant pathogens that can infect citrus, potatoes, and other crop species. > Prions are unusual infectious particles - prions are protein particles with NO GENETIC MATERIAL. Most prions have been linked to degenerative diseases of nervous tissue especially the brain. Include in these prion diseases are kuru or scrapie and more recently “mad cow disease” The prion is an improperly folded version of a natural protein (see fig. 19-5). The wrongly folded protein seems to cause other copies of the protein to covert from the correct folding pattern into the incorrect form. As the bad copies accumulate, they result in physical changes in the tissue. THE PROKARYOTIC DOMAINS The organisms that make up the two prokaryotic domains ( Bacteria and Archaea ) were the first organisms to arise on earth (about 3.5 billion years ago).
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}