Download Biology II Chapter 19 – Protists

Biology II
Chapter 19 – Protists
Members of Kingdom Protista are animal-like, plantlike, and fungus-like. Protists may
be unicellular or multi cellular, microscopic or very large, and heterotrophic or
autotrophic.
REVIEW - A heterotroph is like a human or other animal; they cannot produce their own
food and must eat other organisms to live. A heterotroph is an organism that cannot fix
carbon and uses organic carbon for growth.
An autotroph is an organism that creates its own food through photosynthesis or
chemosynthesis. This is like a plant or protist. An autotroph or "producer" is an
organism that produces complex organic compounds from simple substances present in
its surroundings, generally using energy from light or inorganic chemical reactions.
An autotroph is self-feeding.
Protist may be unicellular or multicellular. The characteristic that all protists share is
that unlike bacteria, they are ALL eukaryotes (a eukaryote is
any organism whose cells contain a nucleus and other structures ((organelles)) enclosed
within membranes; all multicellular organisms are eukaryotes,
including animals, plants and fungi).
Eukaryote
Mitochondria are unusual organelles. They act as the power plants of the cell, are
surrounded by two membranes, and have their own genome.
Nucleus is a dense organelle present in most eukaryotic cells, typically a single rounded
structure bounded by a double membrane, containing the genetic material. Acts as the
cell brain.
Ribosomes are the protein builders or the protein synthesizers of the cell. They are like
construction guys who connect one amino acid at a time and build long chains.
Golgi body gathers simple molecules and combines them to make molecules (a molecule
is a group of two or more atoms that stick together) that are more complex. It then
takes those big molecules, packages them in vesicles (a vesicle is a
small organelle within a cell, consisting of fluid enclosed by membranes), and either
stores them for later use or sends them out of the cell.
Endoplasmic reticulum- While the function of the nucleus is to act as the cell brain, the
ER functions as a manufacturing and packaging system.
Nucleolus - Ribosomes make proteins; therefore, the nucleolus plays a vital role in
making proteins in the cell.
MTOC (microtubule-organizing center) - MTOCs have two main functions: the
organization of eukaryotic flagella and cilia and the organization of the spindle
apparatus, which separate the chromosomes during cell division.
Protozoa (animal-like protists). The animal-like protists are called protozoa. Unlike
animals, though, all protozoans are unicellular. Other protists are plantlike autotrophs
using photosynthesis to make their food.
Algae - Plantlike protists. Algae do not have organs such as roots, stems and leaves.
Unicellular algae produce much of the oxygen in Earth’s atmosphere and are the basis
of aquatic food chains.
Members of the Kingdom Protista are animal like protists that are unicellular
heterotrophs; plantlike protists are photosynthetic autotrophs and may be unicellular or
multicellular. All protozoans are unicellular heterotrophs that feed on other organisms
or dead organic matter. They usually reproduce asexually (some reproduce sexually).
MOVEMENT OF PROTOZOANS
Some protozoans use cilia or flagella to move. Protists called flagellates have one or
more flagella. Flagellated protists move by whipping their flagella from side to side.
This is single flagella.
Ciliates: Protozoans with cilia; use the cilia to cover their bodies to move. Ciliates are a
group of protozoans characterized by the presence of hair-like organelles called cilia.
Paramecium: Paramecia are unicellular organisms but their cells are quite complex with
many organelles and structures that are each adapted to carry out a distinct function.
Cilia
Oral groove (mouth spore)
Gullet
Micronucleus and macronucleus
Anal pore
Contractile vacuole
Hypotonic
The cell is encased by an outer covering
called a pellicle through which thousands
of tiny, hair-like cilia emerge. The
paramecium can move by beating its cilia.
Paramecia feed primarily on bacteria that
are swept into the gullet by cilia that line
the oral groove.
Food moves into the gullet becoming
enclosed at the end in a food vacuole.
The micronucleus plays a major role in
sexual reproduction. The large
macronucleus controls the everyday
functions of the cell.
Waste material leaves the cell through the
anal pore.
Because a paramecium lives in a
freshwater, hypotonic environment, water
constantly enters its cell by osmosis. A
pair of contractile vacuoles pumps out the
excess water.
A hypotonic solution is a solution with
a lower salt concentration than in
normal cells of the body and the blood.
A paramecium usually reproduces asexually by dividing crosswise and separating into
two daughter cells. Whenever their food supplies dwindle or change, paramecia usually
undergo a form of conjugation. In this complex process, two paramecia join and
exchange genetic material. Then they separate and each divides asexually passing on
its new genetic composition.
Sporozoans: Parasitic protozoans. Most sporozoans produce spores. A spore is a
reproductive cell that forms without fertilization and produces a new organism. All
sporozoans are parasites. Most are found in a host that has a ready food supply such as
an animal’s blood or intestines. Plasmodium members of the sporozoan genus are
organisms that cause the disease malaria in humans and other mammals and in birds.
Sporozoans are any of a large group of parasitic one-celled animals (as the parasites
that cause malaria) that have a complicated life cycle usually involving both asexual and
sexual generations often in different hosts.
Sporozoans are parasites that complete part of their life
cycle inside of cells of a host organism. During much of
their life cycle they are unable to move by themselves.
On the right is Pneumocystis carinii. It often causes
pneumonia in AIDS patients.
Plasmodium that mosquitoes transmit to people cause human malaria. Plasmodium,
commonly known as the malaria parasite, is a large genus of parasitic protozoa.
Infection with these protozoans is known as malaria, a deadly disease widespread in the
tropics.
ASSIGNMENT
Use the diagram on page 507 and describe the location and function of each organelle.
Make a table with the headings “Function” and “Organelle”. Beneath the Function head
list: Digestion, Locomotion, Protection, Excretion, Homeostasis and Reproduction.
Complete the Section Assessment on page 509 (1-4).
Others move and feed by sending out cytoplasm-containing extensions of their plasma
membranes called PSEUDOPODIA. Temporary projections of eukaryotic cell
membranes or unicellular protists. Cells that possess this faculty are generally referred
to as amoeboids.
Amoebas are composed of just one cell. They are protozoans with no fixed shape. Most have no hard
parts and look like blobs of jelly; however, some amoebas do build shells. Amoebas move by making
part of its body move in the direction it wants to travel then slowly the rest of the cell follows. In order
to eat, an amoeba splits itself into two cells.
Amoebas: Shapeless protists have no cell walls and form pseudopodia to move and feed.
As a pseudopod forms, the shape of the cell changes and the amoeba moves.
Amoeba feeds on small organisms such as bacteria. The amoeba approaches food,
pseudopodia form and eventually surrounds the food. The food becomes enclosed in a
food vacuole, and digestive enzymes break down the food.
Overview of cycle between autotrophs and heterotrophs. Photosynthesis is the
main means by which plants, algae and many bacteria produce organic
compounds and oxygen from carbon dioxide and water.