INTRODUCTION TO THE LIVING WORLD
KINGDOM MONERA
KINGDOM PROTISTA
LECT # 1
Introduce the organization of the living world
• The algae (singular, alga) are generally considered
simple plant-like organisms, both morphologically and
anatomically. This is a reflection of the stable, aquatic
environment, which they inhabit. Algae are found in
waters of varying salinity, including both fresh water
and marine environments. Although quite simple in
form, the algae are an extremely diverse group. They
vary in size from the minute (1-5 um) to the very large
species such as kelp, known to grow to 50 m or more in
length. Taxonomists suggest there are probably over
100,000 different algal species. This diversity has
occurred over 2 to 3 billion years.
Introduce the organization of the living world
• These differences are mainly morphological, rather than
anatomical, and are a result of changes in cell
differentiation and variations in planes of cell division.
Expressed in a different way, differences in algae are due
to differences in shapes of cells in single celled algae;
number of cells in multicellular forms and differences in
the planes of cell division. The Algal classification systems
can vary. Algal divisions have been established using
several criteria including pigmentation differences, type
of energy storage products, cell wall composition and the
presence or absence of flagella (as well as the number
and placement of these flagella, when present).
INTRODUCTION TO CLASSIFICATION
OF ORGANISMS
• In order to systematically study the diverse organisms on earth, scientists
had to organize the vast amount of different species of organisms.
Taxonomy (Greek, "organizing rules") is the science of naming, describing
and classifying the organisms into similar groups. The formal classification
scheme in use today consists of a series of 7 major categories or taxa
(singular, taxon). We place organisms in these taxa based on their
similarities, then group similar taxa into larger and larger groupings. The
basic structure of classification currently used is as follows:
• KINGDOM PHYLUM (DIVISION)
• CLASS
• ORDER
• FAMILY
• GENUS
• SPECIES
• (A good acronym for remembering the above order of classification is:
"King Phillip Came Over For Good Spaghetti")
INTRODUCTION TO CLASSIFICATION
OF ORGANISMS
• Once plants and animals are classified and assigned to
major taxa, each kind of organism needs to be identified by
a name. We use a binomial system of nomenclature based
upon the scheme originally introduced by Carolus Linnaeus,
in the 18th century. In this system, each organism is
identified by a universally understood two-part Latin or
Latinized name consisting of the name of the genus and the
species to which the organism belongs, so that the rat is
always Rattus rattus and the earthworm is always
Lumbricus terrestris whether it is being studied in Japan,
Egypt, or Canada. The genus name is always capitalized
while the species name is not. Both are underlined or
italicized. The two words together are called the species
name or scientific name of an organism.
INTRODUCTION TO CLASSIFICATION
OF ORGANISMS
• In this course, you will also note that the spelling of
certain biology words changes depending on whether
they are used in a singular or plural form, for example:
bacterium (singular) and bacteria (plural). Some other
examples are: spirillum (spirilla), ovum (ova)
• Most biologists divide the living world into five
"Kingdoms". These Kingdoms are:
• 1. Kingdom Monera
• 2. Kingdom Protista
• 3. Kingdom Fungi
• 4. Kingdom Plantae
• 5. Kingdom Animalia
Unicellular Algae
• These are the simplest algae. Except for a few that live in damp
terrestrial habitats, these organisms are mainly confined to aquatic
environments which provide an adequate supply of nutrients,
water, a means of dispersal and a degree of support. Thus, these
simple organisms can survive and even thrive in this environment.
Although they consist of a single cell, botanists are able to place
them in literally thousands of different genera and species. The
range of cellular morphology is, at least in part, an adaptation for
floatation or for predation avoidance. These organisms must have
some ability to float at least through a portion of their life cycle
because they must remain near enough to the surface to obtain
sufficient light for photosynthesis. Large irregular shaped cells have
the advantage of being avoided by herbivores in the water. Most of
the animals, which eat algae, are very tiny and these cells would be
difficult for them to ingest.
Unicellular Algae
Chlorella
genus of green algae found either
singly or clustered in fresh or salt
water and in soil. The alga cell is
spherical and has a cup-shaped
chloroplast. Chlorella’s reproduction
is asexual by nonmotile reproductive
cells (autospores). It has been
extensively used in photosynthetic
studies, in mass cultivation
experiments. Because Chlorella
multiplies rapidly and is rich in
proteins and B-complex vitamins, it
has also been studied as a potential
food product for humans both on
Earth and in outer space.
Non-motile unicell
•
Unicellular Algae
Chlamydomonas
•
Genus of green biflagellated singlecelled organisms of disputed
classification, placed botanically in the
green algal order, Volvocales,
Chlamydomonas is considered a
primitive life-form of evolutionary
significance. The more or less oval cells
have a cellulose membrane (theca),
pigment-containing chloroplast.
Although photosynthesis occurs,
nutrients also may be absorbed through
the cell surface. Asexual reproduction is
by zoospores; sexual reproduction is by
formation of gametes. The
development of motility, sexual
differentiation,. There are some 500
species of Chlamydomonas
Motile unicell
COLONIAL ALGAE
• These organisms are also found primarily in the aquatic
environment. Morphological variation is due to differences in
number and plane of cell division only. These algae have only one
basic vegetative cell type. Division in definite and consistent planes
results in formation of a regular colony while division in random
planes results in the formation of irregular colonies. Some colonial
algae possess flagella for motility. Again, the major environmental
pressure is the need to remain in the photosynthetic zone. Because
of the potential increase in sinking rates due to the increase in
mass, these algae tend to inhabit shallow waters where the
effective light penetration is to the bottom. In addition, many
colonial forms have small cells, which secrete mucilage. The
mucilage is less dense than water and aids in buoyancy
COLONIAL ALGAE
Pandorina
• Pandorina is a green alga
composed of 8, 16, or sometimes
32 cells held together at their
bases to form a globular colony
surrounded by mucilage. The cells
are ovoid or slightly narrowed at
one end to appear keystone- or
pear-shaped. Each cell has two
flagella with two contractile
vacuoles at their base, an
eyespot, and a large cup-shaped
chloroplast with at least one
pyrenoid.with at least one
pyrenoid
COLONIAL ALGAE
Pandorina
•
•
The colonies coordinate their flagellar
movement to create a rolling, swimming
motion. Pandorina shows the beginnings
of the colony polarity and differentiation
seen in Volvox since the anterior cells have
larger eyespots. Molecular sequencing has
shown that pandorina is monophyletic
Asexual reproduction is by simultaneous
division of all cells of the colony to form
autocolonies that are liberated by a
gelatinization of the colonial envelope.
Sexual reproduction occurs by division of
each cell of the colony into 16-32
zoogametes. Zoogametes show
indications of heterogamy, a slight
difference in the size and motility of the
pairs that fuse to form the smooth walled
zygote
COLONIAL ALGAE
Volvox
• genus of chlorophytes, a
type of green algae. It forms
spherical colonies of up to
50,000 cells. They live in a
variety of freshwater
habitats, in 1700. Volvox
developed its colonial
lifestyle 200 million years
ago.
COLONIAL ALGAE
Volvox
• is the most developed in a
series of genera that form
spherical colonies.Each mature
Volvox colon is composed of
numerous flagellate cells
similar to Chlamydomonas, up
to 50,000 in total and
embedded in the surface of a
hollow sphere or coenobium
containing an extracellular
matrix made of a gelatinous
glycoprotein
COLONIAL ALGAE
Scenedesmus
•
is a small, nonmotile colonial green alga
consisting of cells aligned in a flat plate.
The colonies most often have two or
four cells, but may have 8, 16, or rarely
32 and are occasionally unicellular. The
cells are usually cylindrical but may be
more lunate, ovoid, or fusiform.
Typically the end cells each have two
long spines up to 200 µm in length
protruding from their outer corners,
and other cells may have additional
spines or chitonous bristles. Each cell
contains a single parietal, plate-like
chloroplast with a single pyrenoid. The
cell walls may be covered in bumps or
reticulations that are best viewed with
scanning electron microscopy.
COLONIAL ALGAE
Pediastrum
•
Pediastrum is a common, nonmotile
green alga with flattened colonies of
cells in an elaborate starlike pattern.
Pediastrum colonies are coenobial - the
number and arrangement of cells is
genetically determined for each
species. The colonies are made up of at
least four cells. The cells are often
notched or lobed, and sometimes bear
short horns or bristles that both
improve buoyancy in the water column
and help to prevent predation. The cell
walls may be smooth or ornamented.
The parietal chloroplasts have a single
pyrenoid.
COLONIAL ALGAE
Merismopedia
•
has cells arranged in perpendicular
rows one cell thick to form
rectangular colonies. The colonies
may be flat or slightly wavy and are
held together by colorless,
indistinct mucilage. Except for a
few species, the colonies are
usually microcopic, and may have
subcolonies. The cells are usually
blue-green or occasionally reddish
in color, 1-7 µm in diameter, and
are spherical or oval-shaped before
dividing and hemispherical after
dividing. Some planktonic species
have gas vesicles for bouyancy
COLONIAL ALGAE
Microcystis
•
A unicellular, planktonic
freshwater cyanobacterium.
The existence of intracellular
structures, the gas vesicles,
provides cells with buoyancy.
These hollow, gas-filled
structures can keep
Microcystis cells close to the
surface of water body, where
there is optimal light and
oxygen for growth. the
colonies can accumulate at the
water surface and form
surface water blooms
COLONIAL ALGAE
Gloeocapsa
•
may be unicellular or made up of small
groups of cells grouped within
concentric mucilage envelopes. The
individual colonies are usually spherical,
microscopic, and enclosed within larger
masses of mucilage. The cells are ovalshaped or ellipsoidal, and hemispherical
after dividing. Each cell has a rounded,
firm, inner mucilaginous sheath
surrounded by older sheath material
from the parent cell, revealing the
pattern of cell division. The sheaths are
colorless or vivid shades of yellow,
brown, red, orange, blue, or violet, and
may be affected by changes in pH. The
cells are usually bright blue-green or
olive green and do not have distinct gas
vesicles