16.1 Prokaryotic life began on a
young earth
I. The Oldest Fossils
A. Stromatolites- are thin layers of rock
that contain ancient fossils
B.Prokaryotes are simple organisms that
lack true nuclei and many of the organelles
found in eukaryotes
II. How Did Life Begin?
A. The early Earth was able to produce
organic molecules that are essential to life
and this was duplicated by Stanley Miller
B. Miller’s experiment was able to produce
simple molecules but experiments show
that even more complex molecules could
be created by duplicating the early Earth
Miller-Urey
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II. How Did Life Begin?
C. RNA is thought to be the molecule that
started to store genetic information and
direct protein synthesis
D. Experiments have shown that
polypeptides can come together and form
microscopic, fluid-filled spheres
E. All of the experiments support a
hypothetical four-stage sequence for how
life could have developed
RNA
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III. Where Did Life Begin?
A. It used to be thought that life began in
shallow water
B. Deep Sea vents are populated with
prokaryotes that resemble some of the
earliest cells
Concept 16.2
Diverse prokaryotes populate
the biosphere
I. Diversity of Prokaryotes
A. Most bacteria do not cause disease and many
can be helpful to humans or other organisms
B. Prokaryotes help cycle nutrients between
organisms, the soil and the atmosphere
C. The are two Types of Prokaryotes
1. Archaea- which means “ancient” live in some
of the most extreme environments on Earth
2. Bacteria- differ from archaea in their nucleic
acids, enzymes and cell wall
II. Structure and Function of
Bacteria
A.
Cell Shape
1. Cocci- Spheres
2. Bacilli- Rods
3. Spirochetes- Spirals
B. Cell Wall Structure- Gram
positive (purple) or Gram negative (red)
C. Motility- About half are motile
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III. Reproduction
A. Rapid Reproduction-Some bacteria can divide
every 20 minutes
B. Genetic Reproduction
1. Transformation- Bacteria take up DNA from the
environment and incorporate it
2. Conjugation- Two bacterial cells join together
and transfer genetic material
3. Binary fission- makes a duplicate copy
C. Endospore Formation- Some bacteria form spores
when environmental conditions become severe
Binary Fission
Nutrition
D. Modes of Nutrition
1. Photo- gets energy from
photosynthesis
2. Chemo- gets energy from chemical
sources
3. Autotrophs- obtain carbon atoms
from CO2
4. Heterotrophs- obtain carbon from
existing organic molecules
IV. Cyanobacteria and the
“Oxygen Revolution”
A. Earth’s early atmosphere very little
or no free oxygen
B. Cyanobacteria release oxygen as a
byproduct of photosynthesis
C. Nearly all eukaryotes are aerobic and
owe their evolution to cyanobacteria
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Concept 16.3
Prokaryotes perform essential
functions in the biosphere
I. Chemical Recycling
A.Many prokaryotes perform an essential
function by breaking down organic waste
products and dead organisms in the
environment
B.Carbon is returned into the atmosphere as
carbon dioxide, nitrogen is taken from the
atmosphere and “fixed” in nitrogen
compounds in soil and water
II. Human uses of Prokaryotes
A. Humans use bacteria to remove pollutants from
water, air and soil in a process called
bioremediation
B. Pseudomonas bacteria has been shown to be
able to help clean up oil spills
C. Bacteria are also used to clean up arsenic,
copper, zinc, lead and mercury. They can also be
used to make vitamins and antibiotics
D. Genetic engineering is finding more and more
uses for bacteria
Concept 16.4 Some prokaryotes
cause disease
I. How Bacteria Cause Illness
A. Bacteria and other microorganisms
that cause disease are called pathogens
B. Most pathogenic bacteria cause
disease by producing one of two types
of bacterial poisons. One type is
secreted by the bacterium and the other
is a component of the bacteria’s cell
wall
II. Defense Against Bacterial
Diseases
A. The major reason for the decline in bacterial
diseases is better hygiene and public health
measures
B. The human body has built in defenses against
disease
C. The other way to defend against bacterial
diseases is through the use of antibiotics
Concept 16.5 Viruses Infect Cells
by Inserting Genes
I. Virus Structure and
Reproduction
A. A virus is composed of a short piece of DNA
or RNA surrounded by a protein coat
B. There are two ways that viruses reproduce
1. Lytic Cycle- the virus attaches itself to
the host and injects its DNA
2. Lysogenic Cycle- the virus injects its
DNA into the host and it is incorporated
into the host cell’s DNA
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II. Viruses and Disease
A. A virus that causes disease
must use the host cell to
reproduce
B. Antibiotics do not work on
viral illness so the body’s
immune system must destroy
the virus
III. HIV: A Retrovirus
A. AIDS is the disease which is caused by the
HIV virus
B. HIV is a retrovirus which means their
genetic information is carried in RNA
C. The RNA is transcribed into DNA with the
help of the enzyme reverse transcriptase
IV. Defense Against Viral
Disease
A. Vaccines are deactivated varieties or
small pieces of pathogen that stimulate the
immune system to respond to a particular
pathogen
B. The first vaccine was for smallpox; it was
invented in the 1700’s by Edward Jenner
C. Some viruses mutate rapidly and are not
recognized by the body, such as the flu and
HIV