Download Chapter 18: Viruses and Prokaryotes

Section One: Studying Viruses and
Prokaryotes
 Bacteria
 Pathogen: any living organism or particle that can cause
an infectious disease
 Living
 Virus
 An infectious particle made only of a strand of DNA or
RNA surrounded by a protein coat
 Non living
 Cannot be targeted by antibiotics
 Cannot reproduce by themselves
 Rely on living cells to reproduce and make proteins
Section Two: Viral Structure and
Reproduction
 Viral Structure
 Capsid: a protein shell
that holds the genetic
material of the virus
(sometimes surrounded
by a lipid envelope)
 Bacteriophage: virus
that infects bacteria
Section Two: Viral Structure and
Reproduction
 Virus Reproduction
 Happens through host cell infection


Lytic
 an infection pathway in which the host cell bursts, releasing
the viral offspring into the host’s system, where each then
infects a new cell
Lysogenic
 A phage combines its DNA into the host cell’s DNA, then
divides the host cell so that its DNA is passed on
 Can enter the lytic cycle or continue dividing
Section Two: Viral Structure and
Reproduction
Section Three: Viral Diseases
 Vaccines
 A substance that
stimulates the body’s
own immune response
against the invasion of
microbes (bacteria or
viruses)
 Made from weakened or
dead bacteria and
viruses
Section Four: Bacteria and Archae
 Bacteria and Archae
 Have plasmids
 Move by flagella: long, whip
like tail used for movement
 Have cell wall
 Bacteria: have peptidoglycan
in their cell wall
 Archae: have lipids in their
cell wall
 Both can reproduce through
conjugation: exchange of
parts of chromosomes
through a bridge of pill
formed by contact of two or
more cells
Section Six: Antibiotic Resistance
 Antibiotic Resistance
 Bacteria can evolve resistance to antibiotics
 Caused by inappropriate or incomplete use of antibiotics
 Resistance occurs through natural selection
 Those that survive being partially treated by antibiotics
or are have genes that make them resistant pass on their
genes and resistance