kingdom protista

2. • You must have seen ponds covered with green plants.
• You always thought that those are mosses. Didn’t you? Well no!
• We will see what those are.
• It is time to peek deeper into another kingdom in this chapter:
Protista.
• We will also take a look at their characteristics and examples.
• We place all single-celled eukaryotes under Protista.

3. • A protist is a group of eukaryotic organisms which
are not classified as either an animal, plant or
fungus.
• They possibly share certain morphological and
physiological characteristics with animals or
plants or both.
• The term protist typically is used in reference to a
eukaryote that is not a true animal, plant, or
fungus the cells of protists have highly organized
nucleus and specialized cellular organelles.
• Some protists have flagella or cilia for locomotion.
• They inhabit an environment that contains water.

4. Characteristics of Kingdom Protista
• Protists are simple eukaryotic organisms.
• Most of them are unicellular, some are colonial
and some are multicellular like algae but they do
not have specialized tissue organization.
• Most of the protists live in water.
• Some live-in moist soil and even in the body of
humans and plants.
• Like all eukaryotic cells, the protists also possess a
characteristic central compartment called
the nucleus, where the genetic material is
present.

5. • They also have specialized cellular organelles that
perform definite functions within the cell.
• Their nucleus is membrane bound.
• Nuclei of protists contain multiple DNA strands.
• Photosynthetic protists like various types of algae
contain these organelles that are the site of
photosynthesis (the process of harvesting sunlight
to produce nutrients in the form of
carbohydrates).
• The plastids of some protists are similar to those
of plants.

6. • Some protists that live in anoxic conditions
(environments that lack oxygen) use an organelle
called the hydrogenosome (a modified version of
mitochondria) for some of their energy
production; for example, in Trichomonas
vaginalis.)
• In protists that have mitochondria, aerobic
respiration takes place, the protists, that live in
the mud below ponds or in digestive tracts of
animals are strict facultative anaerobes, the
respiration occurs with the help of
hydrogenosome.

7. • They form cysts in adverse conditions.
• When the protozoan parasites, are exposed to very
harsh conditions during various stages in their life
cycle, they form cysts around them.
• An encysted form allows them to survive in extreme
conditions.
• Some protists are pathogens for both animals and
plants. Example: Plasmodium falciparum causes
malaria in humans.
• They show movement by flagella or cilia.
• Most protists have mitochondria (organelle which
generates energy for cells to use).

8. Mode of Nutrition

11. Locomotion in Protists

12. Pseudopodia
• They are projections of the cytoplasm of unicellular protists
or eukaryotic cell membrane.

13. Lobopodia
• Lobopodia refer to the finger-shaped pseudopod and is the
most common type observed in nature.
• They are characterized as short, blunt, and bulbous
projections that contain both endoplasm and ectoplasm of
the organism.
• An example is the lobose amoebae, which is considered the
largest of all pseudopodia.

14. Filopodia
• Characterized by having thin and thread-like pseudopod,
filopodia has the ability to branch out or anastomose.
• They are filiform and slender with pointed ends that are
mostly made of ectoplasm.
• The projections are supported by microfilaments. Examples
include Lecithium and Euglypha.

15. Reticulopodia
• Imagine pseudopodia being used as a means to communicate
with other cells.
• Reticulopodia is a specialized pseudopod that communicates
with another pseudopodium, thus creating a network called
reticulum.
• Also called reticulosepseudopodia, they create complex
projections wherein the individual
pseudopodium fuses with one another
to create what looks like irregular nets.
• This type of pseudopodium also
functions in both ingestion of food
and locomotion.
• Examples - Foramineferans.

16. Axopodia
• Axopodia are pseudopods supported by arrays of
microtubules.
• The pseudopodia are enveloped by cytoplasm; thus, it is used
most for phagocytosis or ingestion of food particles.
• Protists from the genus Radiolaria and Heliozoa are examples
of this type of pseudopodium.