by Miller & Levine
[complete Table of Contents]
the pull-down menu to jump to any of the Book's 40 Chapters:
A page of information from various sources about this bacterium and
how it infects human cells
An Issues Feature for Chapter 19 describes the pros and cons of mass vaccinations
against this virus.
The Center for Infectious Disease Research & Policy at the University
Bacteria & Viruses
Updated Information on Mad Cow Disease,
two brand-new "Virtual
Textbook" pages for teaching about mad cow disease (BSE) and
its human equivalent (CJD). Also a new essay by Joe Levine: "The
Bird Flu? Flu Vaccine? How does the flu keep us guessing every year?
"What's up with the Flu?"
( a new teaching and learning resource)
lack peptidoglycan, a carbohydrate found in the cell walls of eubacteria,
and their membrane lipids are quite different. Also, the DNA sequences
of key archaebacterial genes are more like those of eukaryotes than eubacteria.
Prokaryotes are identified by their shapes,
the chemical natures of their cell walls, the ways they move, and the
ways they obtain energy.
19-2: Bacteria in Nature
Bacteria are vital to maintaining the
living world. Some are producers that capture energy by photosynthesis.
Others help to break down the nutrients in dead matter and the atmosphere,
allowing other organisms to use the nutrients.
Bacteria cause disease in one of two
general ways. Some damage the tissues of the infected organism directly
by breaking them down for food. Other bacteria release toxins (poisons)
that harm the body.
A typical virus is composed of a core
of either DNA or RNA surrounded by a protein coat.
In a lytic infection, a virus enters
a cell, makes copies of itself, and causes the cell to burst.
In a lysogenic infection, a virus embeds
its genome into the DNA of the host cell and is replicated along with
the host cell's DNA.