Protists and Fungi

Protists and Fungi Chapter 11 P. Lobosco

Monday November 8, 2010 • There will be no grades given out until this Friday. Please do not ask! • HW-Read 11-1 and do the section review on page 273, questions 1-10 due Wed. Use spiral notebook.

Section 1 - ProtistsObjectives Describe the characteristics of protists. Describe four ways that protists get food. Describe three ways that protists reproduce. s

Protists share some traits. • A protist is a member of the Kingdom Protista. • All protists are eukaryotes, which means that their cells have a nucleus. They are less complex than other eukaryotic organisms. • Protista are related more by how they differ than how they are similar. • Some scientists think that Kingdom Protista should be divided into several kingdoms

Protists are diverse. • Protists are very diverse and have few traits in common. • Some protists control their own movement, others cannot

Protists and Food • Some protists produce their own food. They are producers. • Some eat other organisms. • Some eat decaying matter.

Heterotrophs • The protists that must get their food from their environment are heterotrophs. • Many heterotrophs eat small living organisms, such as bacteria, yeast or other protists. • Some are decomposers and eat decaying matter.

Slime Molds • Some protists get energy in more than one way. • Slime molds get energy by engulfing both small organisms and particles of organic matter.

Parasites • Some heterotrophs are parasites. • An organism that a parasite invades is called a host. • Parasites cause harm to their host. • They may invade fungi, plants or animals.

Potato Famine • During the mid 1800’s, a parasitic protist wiped out most of the potatoes in Ireland. • Many people died of starvation.

Protist Reproduction • Like all living things, Protist reproduce. • Some reproduce sexually. • Most reproduce asexually, by binary fission, like Euglena.

Binary Fission • Binary fission is reproduction in which one single-celled organism splits into two single-celled organisms. • Some single-celled protists use multiple fission to make more than two offspring from one parent. • Each new cell is a single-celled protist.

Protist Sexual Reproduction • Sexual reproduction requires two parents. • Member of the genus Paramecium sometimes reproduce sexually by a process called conjugation.

Paramecium Conjugation

Conjugation • During conjugation two individuals join together and exchange genetic material by using a small second nucleus. • Then they divide to produce four protists that have new combinations of genetic material.

Protists Producers • Many protists can reproduce sexually and asexually. • In some protist producers, the kind of reproduction alternates by generation. • A parent will reproduce asexually, and its offspring will reproduce sexually. • Other protists reproduce asexually until environmental conditions become stresssful, lack of water or food, and then they will use sexual reproduction.

Reproductive Cycles • Some protists have complex reproductive cycles. • These protists may change forms many times, such as the Plasmodium Vivax, which causes malaria.

The Life Cycle of P. Vivax

Section 2 - Kinds of Protists Objectives Describe how protists can be organized into three groups based on their shared traits. List an example for each group of protists.

Journal Entry • Do you know what algae is? Have you ever seen it? What does it look like? Algae needs a lot of water in order to live. Where do you suppose most algae live? • Record and illustrate your answers in your science journal.

Kinds of Protists • Protists are organized into three groups • Producers • Heterotrophs that can move • Heterotrophs that cannot move

Examples of Producers • Red algae • Green algae • Brown algae • Diatoms • Dinoflagellates • Euglenoids

Producers • Many protists are producers which use the sun’s energy to make food through photosynthesis. • These protist producers are known as algae.

Algae • All algae have the green pigment chlorophyll, which is used for making food. • Most algae have other pigments that give them a color. • Most algae live in water.

Many-Celled Algae • Some algae are made of many cells. • Many-celled algae generally live in shallow water along the shore. You know these algae as seaweeds.

Single-Celled Algae • Free floating single-celled algae are called phytoplankton. • These algae cannot be seen without a microscope. • They float near the water’s surface.

Phytoplankton • Phytoplankton provide food for most other organisms in the water. • They also produce much of the world’s oxygen.

Red Algae • Most of the world’s seaweeds are red algae. • Red algae live in tropical oceans, attached to rocks or other algae. • Red algae are usually less than 1 m in length.

Green Algae • The green algae are the most diverse group of protist producers. • They are green because chlorophyll is the main pigment in their cells. Most live in water or moist soil. • Others live in snow, tree trunks and inside other organisms.

Single-celled Green Algae • Many green algae are single celled. • Individual cells of green algae, like Volvox, live in groups called colonies.

Brown Algae • Most of the seaweeds found in cool climates are brown algae. • They attach to rocks or form large floating beds in ocean waters with only the top part exposed to sunlight. • They have chlorophyll and a yellow-brown pigment.

Diatoms • Diatoms are single-celled, found in both salt water and fresh water. • They make up a large part of the phytoplankton. • The cell walls contain a glasslike substance called silica. • The cells are enclosed in a two part shell.

Dinoflagellates • Dinoflagellates are single celled. • Most live in salt water, but a few live in fresh water and even snow. • They have two whip like strands called flagella. • The beating of the flagella causes the cells to spin through the water.

Euglenoids • They are single celled protists that live in fresh water • They use their flagella to move through the water. • Many are producers but some become heterotrophs when there is not enough light to make food. • Others do not have chlorophyll and must always get food.

Euglenoids • Digestion occurs in a food vacuole. • Oxygen passes through the cell membrane. • The food vacuole joins with the cell membrane to release waste. • They have an eyespot and respond to light.

Structure of a Euglenoid • Photosynthesis takes place in chloroplasts, which contain chlorophyll. • Most euglenoids have two flagella, short and long. • They can’t see but they have eyespots sense light. • A contractile vacuole holds excess water and removes it from the cell.

Heterotrophs that can Move • Some heterotrophic protists have special traits that allow them to move and are known as protozoans. • Those that can move are usually single-celled consumers or parasites. • Some examples are: • Amoebas • Shelled amoeba-like protists • Zooflagellates • Ciliates

Amoebas • Amoebas are jellylike protozoans, found in both salt and fresh water, in soil and as parasites in animals. • They look shapeless but are highly structured. • They have vacuoles to get rid of excess water.

Amoebas • Many amoebas eat bacteria and small protists, but some are parasites that get food by invading other organisms. • Certain amoebas live in human intestines and cause dysentery which causes internal bleeding.

Amoebic Movement • Amoebas and amoeba-like protists move with pseudopodia, which means “false feet”. • To move the amoeba stretches a pseudopod out from the cell and then the cells flows into the pseudopod.

Amoebas Catching Food • Pseudopodias are also used to catch food. • When it sense a food source, it moves toward the food and surrounds it, forming a food vacuole. • Enzymes move into the vacuole to digest the food and the digested food passes into the amoeba.

Amoebas and waste • Amoebas reverse the process to get rid of wastes. • A waste-filled vacuole is moved to the edge of the cell and released.

Amoeba • Amoeba proteus can sense light and tends to move away from it. • Just before it reproduces, it rounds up into a ball with tiny pseudopodia extensions. Over the next 15 minutes or so, it splits and becomes two. Image below shows one amoeba in the final stages of splitting. Look carefully and you can see the clear channel between the two new amoebas.

Shelled Amoeba-like Protists • Not all amoeba-like protists look shapeless, some have an outer shell. • Radiolarian shells look like glass ornaments. • Foraminiferans have snail-like shells. They move by poking pseudopods out the pores in the shell.

Zooflagellates • Zooflagellates are protists that wave flagella back and forth to move. • Some live in water. Others live in the bodies of other organisms.

Zooflagellates and Parasites • Some zooflagellates are parasites that cause disease. • Giardia lambliacan live in the digestive tract of many vertebrates., causing severe stomach cramps.

Zooflagellates and Mutualism • Some zooflagellates live in mutualism with other organisms, each helping the other live. • The zooflagellate that lives in the gut of termites digests the cell walls of the wood that termites eat and in return the termite gives the protist food and a place to live.

Ciliates • Ciliates are complex protists. They have hundreds of tiny hair-like structures known as cilia which they use for both moving and feeding. • The best known ciliate is Paramecium.

Structure of a Paramecium • The cell of a paramecium has two kinds of nuclei. • A large nucleus called a macronucleus controls the function of the cell. • A smaller nucleus, the micronucleus, passes genes to another paramecium during sexual reproduction.

Stentor • The stentor moves using cilia. • It creates a whirlpools to suck in food and is sometimes called the trumpet cell. • It is large enough that it can sometimes be seen without the microscope. It forms a ball in order to look larger. • Digestion occurs in a food vacuole. • Oxygen is diffused or released through the cell membrane. Food vacuoles join with the cell membrane to release waste.

Protists and Fungi