Chapter 25, pages 498-504
Chapter 25, pages 509-517
Basic Botany-1 0:00-4:22
Five Kindgoms-2 0:00-17:00
I. Characteristics of Kingdom Monera
A. Cells very small
1. About 1/1000 (0.001) the volume of the smallest eukaryotic cells
2. About 1/10 (0.1) the length of the smallest eukaryotic cell
B. Morphology
1. Most unicellular
2. Some colonies contain specialized cells
3. Some filaments contain specialized cells
C. Anatomy
1. Contains ribosomes
2. Lacks membrane-bound organelles typical of eukaryotes
a. Thus none of the following:
(1) Mitochondria
(3) Golgi complex
(4) Lysosomes
b. Genetic material
(1) Single circular DNA molecule loose in cytoplasm
(2) No nuclear membrane
(3) DNA replicates before cell division by simply splitting
which avoids the
complexity of
mitosis
3. Most have a
cell
wall surrounding the
cell
membrane which differs in composition
and
structure from
eukaryotes
4. Some have flagella but flagella differ in composition and structure from eukaryotes
a.
Eukaryote flagella - two central hollow
microtubules
surrounded by 9 pairs of
similar microtubules
b. Prokaryote flagella - solid structure made of long filaments of protein
5. No prokaryotes have cells
II. Archaebacteria
A. Bacteria appear similar under the microscope but differ biochemically
B. Characteristics of archaebacteria
1. No peptidoglycan in the cell wall
2. Inhabit extreme environments
C. Three groups
a. Occur only in extremely salty environments
b. Found in salt brines used to cure fish (red patches on fish)
c. Osmotic potential of cell usually within range of most bacteria
d. Some are photosynthetic, using the purple pigment bacteriorhodopopsin
2. Methanogens
a. Anaerobes
b. Produce methane from carbon dioxide and hydrogen
c. Inhabit sewage and swamps and are common in digestive tracts
d. Most common of the archaebacteria
a. Grow in hot, acidic environments
b. Common in hot sulfur springs
III. Cyanobacteria (Cyanophyta)
A. Occurrence
1. Ponds, lakes, swimming pools
2. Moist soils, dead logs, and the bark of trees
3. Oceans
4. Some in hot springs and on snow
B. Morphological forms
1. Few are unicellular
2. All are microscopic
3. Most are large
globular
colonies
or long
filaments
held together by
extracellular
materials
4. Some cells that are in a colony show specializations for division of labor
b. Reproduction
c. Attachment of colony to substrate
C. Most are photosynthetic autotrophs
1. Chlorophyll a - green pigment found in eukaryotes also
2. Carotenoids - orange pigment also found in eukaryotes
3. Phycocyanin - blue pigment found only in cyanobacteria and red algae
4. Phycoerythrin - red pigment found only in cyanobacteria and red algae
5. None of these pigments
are in
plastids.
The pigments are
dispersed
along
membranes
in the
periphery
of the cell or stacked in the cytoplasm.
D. Reproduction
a. The circular chromosome replicates to two chromosomes
b. Cell pinches in two with each new cell getting a chromosome
2. Colonies or filaments may fragment
3. Fragments are called hormogonia
4. Endospores
a. Thick-walled cells
b. Highly resistant to adverse conditions
c. Can remain dormant for many years and still be viable
d.
Form when the colony/filament/individual cell begins to experience adverse
conditions
E. Structure
a. Internal membranes within the cell near the margins of the cell
b. Other prokaryotes do not contain lamellae
c. Contain chlorophyll and enzymes needed for photosynthesis
2. Cell wall
b.
Polysaccharides,
that are not cellulose, are linked with
polypeptides
to form the
microfibrils
of the cell wall
c. May secrete a thin gelatinous sheath or a thick matrix around the cell wall
(1) Often contains pigments
(2) Often contains toxins that prevent other organisms from feeding on them
3. Color of various species
a. About half of the species are blue-green in color, the rest are different colors
b.
The various colors of the
cyanobacteria
are due to the different relative amounts
of each of the pigments are included
c.
Various colors of the different species: brown, black, purple,
yellow, blue,
green, and red
d.
Red
Sea - gets its name form a cyanobacterium that produces a red
algal
bloom
there occasionally
4. Locomotion
a. None contain flagella or organs of mobility
b. Some are able to sway back and forth slowly
c. Some have a slow gliding motion
F. Significance of Cyanobacteria
1. Producer of oxygen and organic material
2. Fix nitrogen
a. Produce nitrates and ammonia
b.
Because of cyanobacteria in rice paddies in
Southeast
Asia,
rice
is grown for
many years on the same land without nitrogen fertilizer
c. Added to soil to increase crop yield in some areas
3. Spirulina is used directly as human food
4. Symbiotic relationships with other organisms
a. Protists, fungi and some plants
b. With fungi they form some kinds of lichens
c. Endosymbosis
(1) Within the cells of other organisms
(2) Usually the
cyanobacterium
lacks a
cell
wall and functions like a
chloroplast
within the
host
cell
(a) Prochloron - lives in the cloaca of a tunicate
(b) Possesses both chlorophyll a and b
5. Tolerates extreme environmental conditions
a. Tolerates extreme:
(1) Salinity
(2) Temperature
(3) pH
b. Can thrive in polluted lakes and ponds
c. Often become the dominant species in polluted lakes and ponds
d. These cyanobacteria are usually inedible for fish
e. Cyanobacteria produce blooms in the water
(1) Many individuals of algae will die because of overcrowding and shading
(2) Their decomposition by
heterotrophic
bacteria
consumes large amounts of
oxygen
from the water
(3) Fish die from lack of oxygen
(4) During the day, the cyanobacteria produce enough oxygen for
both the fish
and the cyanobacteria, however at night when the
fish and algae must
breathe oxygen, there isn't enough because no
photosynthesis
is
occurring and the fish die
f. Produce toxic metabolic products that will also kill fish and other animals
IV. Eubacteria
A. Introduction
1. Most bacteria belong to this group (classic bacteria)
2. Almost universally present
3. What happens when there is adverse conditions for bacteria?
a. Most can form naturally dehydrated endospores
b. Remain viable for years
c.
Ice and rock from
glaciers
in
antarctica
contain viable bacteria that have been
dormant
for 10,000 years
B. Structure
1. Morphology
a. Most are single-celled
b. Some species are colonies
c. Some are filaments
d.
Cell membrane present with
electron transport system attached to the
cell
membrane
e. Cell Wall
(1) Contains peptidoglycan
(2) Peptidoglycan is found only in
prokaryotes
and is one of the major
components of the bacterial
cell wall
(3) Peptidoglycan is two types of sugar linked with a short peptide
(4) The short peptide is two amino acid molecules long
(5) The cell wall keeps the cell membrane from bursting
when the cell is in a
hypotonic
solution
(6) The bacterial cell can live without a cell wall but
to do so it must be in an
isotonic
solution
(7) Most bacterial cells cannot live in a hypertonic solution
2. Staining Properties
(1) Absorb and retain crystal violet stain
(2) Cell walls are very thick and consist primarily of peptidoglycan
(3) Examples: Streptococcus and Staphylococcus
(1) Do not absorb and retain crystal violet stain
(2) Cell wall is composed of three layers:
(a) Inner cell membrane
(b) Thin peptidoglycan layer
(c) Thick outer layer of lipoprotein and lipopolysaccharide
(3) Examples: Escherichia coli and Salmonella
3. Significance of gram-positive and gram-negative bacteria
a. Cell strength
(1) Gram-positive
(a) Thick peptidoglycan layer
makes cell wall less likely to break under
stress
(b) More susceptible to attack by lysozymes (present in human tears)
(2) Gram-negative
(a) Breaks easier under stress
(b) Semipermeable outer membrane protects from lysozyme penetration
b.
Penicillin
is effective against gram-positive bacteria because it
interferes
with
peptidoglycan synthesis, resulting in a
fragile
cell
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