Chapter 20 Protists Pages: 496-520. 20-1 The Kingdom of Protista Kingdom of Protista is a diverse group that may include more than 200,000 species Is

Chapter 20 Protists

Pages: 496-520

20-1 The Kingdom of Protista

Kingdom of Protista is a diverse group that may include more than 200,000 species• Is an organism that is not a plant, animal or fungus

• Multicellular protists are grouped with unicellular protists because multicellular protists are very similar to unicellular protists

• Were the first eukaryotes on earth and are thought to have evolved from a symbiosis of several cells according to Lynn Margulis

20-1 The Kingdom of Protista

Classification of Protists:• Are very diverse organisms

• Some biologists argue that they should be broken up into several kingdoms

• Currently we classify them based on the way they obtain nutrition:• Heterotrophs= called animal like protists

• Autotrophs using Photosynthesis= called plant like protists

• External digestion= fungus like protists

20-2 Animal Like Protosits: Protozoans

Animal like protists are sometimes calledProtozoans

• Are heterotrophs

• Are distinguished from one another by the way they move

• There are 4 Phylums

1. Zooflagellates: Protists that swim using flagella• Live in lakes and streams

• Absorb food through their cell membrane

• Most reproduce asexually through mitosis and cytokenesis


2. Sarcodines: Protists that use pseudopods for feeding and movement• Contain ameobas, foraminiferans, and heliozoans

• Ameobas use amoeboid movement and food vacuoles to digest food

• Foraminiferans are found in warmer ocean regions and secrete shells of calcium carbonate

• Heliozonas look like the sun’s rays because of spikes of cytoplasm that project from silica shells


3. Ciliates: Use cilia (short hair like structures similar to flagella) for feeding and movement• Are Found in both fresh and salt water

• Some of the best know are in the genus Paramecium

• Paramecium use Trochocysts (small bottle shaped structures) for defense if confronted by danger

• Paramecium have 2 types of nucleui:

• Macronucleus= “working library” of genetic information

• Micronucleus= “reserve copy” of genetic information


Ciliates continued…..• Gullet: an indentation used by cilia to collect food

• Contractile vacuoles: cavities in cilia's’ cytoplasm used to collect water

• Contracts to remove water to help cells maintain homeostasis

• Cilia reproduce asexually by mitosis or cytokinesis or sometimes by conjugation


4. Sporozoans: Phylum of protists that do not move on their own and are parasitic• Act as parasites on a large variety of

organisms including: birds, worms, fish and humans

• Reproduce by means of sporozites

• Sporozites can attach to host cell, penetrate it, and then live within it as a parasite


Animal Like Protists & Disease:• Animal like protists are some of the most

common organisms in the world

• Some also cause serious disease• EX: Sporozoan Plasmodium causes the disease

known as malaria- spread by female mosquito

• EX: Zooflagellates Trypnssoma cause the disease African Sleeping Sickness spread by the tsetse fly

• EX: Entamoeba ameobas cause amebic dysentery causing intestinal bleeding


Animal like Protists and Ecology• Some animal like protists are beneficial and

live symbiotically with other organisms• EX: Trichnomypha is a Zooflagellate that lives

within the digestive tract of termites and digests the cellulose in the wood that the termites eat, breaking it down for them.

20-3 Plantlike Protists: Unicellular Algae

Plant like protists are able to carry out photosynthesis

We commonly call plant like protists “algae”

We consider all forms of algae to be protists

20-3 Plantlike Protists: Unicellular Algae Chlorophyll and accessory pigments allow

algae to harvest and use the energy from the sunlight

Different forms of algae have adapted with different forms of chlorophyll: Chlorophyll a, Chlorophyll b, and Chlorophyll c• Each form of chlorophyll allows for algae to capture

different wavelengths of the sun’s light• Allows for an increase in the range of depths in

which algae can live• Allows for algae to use more than just the sun’s red

and violet wavelengths


There are 4 main groups of unicellular algae:• Euglenophytes

• Chrysophytes

• Diatoms

• Dinoglagellates


Euglenas are plantlike protists with:• Members of phylum Euglenophyta

• Two flagella making them excellent swimmers

• No cell wall

• Can act as heterotrophs if no sunlight is available

• Have an intricate folded cell membrane called a pellicle allowing them to crawl through mud if there is no water to swim


Chrysophytes are plantlike protsists with:• Members of phylum Chrysophyta

• Include the yellow green and brown algae

• Have gold colored chloroplasts

• Name means “golden plants”

• Cell walls sometimes contain pectin

• Generally store food in the form of oil instead of starch

• Reproduce asexually and sexually


Diatoms are plantlike protists with:• Belong to the phylum of Bacillariophyta

• Produce thin delicate cell walls rich in silicon– the main component of glass

• Are among the most abundant and beautiful organisms on earth


Dinoglagellates are plantlike protists with:• Members of phylum Pyrrophyta

• ½ are photosynthetic and other ½ are heterotrophs

• Generally have 2 flagella

• Can reproduce asexually or by binary fission

• Like Chrysophyta, members of Pyrrophyta have cell walls that contain cellulose


Ecology of Unicellular Algae:• Found in both fresh and salt water

• Are important organisms that act as the base of the food chain for other aquatic organisms

• Make up the majority of photoplankton- photosynthetic organisms found near the surface of the ocean

• Can grow in algal blooms– an enormous mass of algae- that deplete the water of nutrients like oxygen that can other organisms like fish

20-4 Plantlike Protists: Red, Brown and Green Algae

Red, Brown and Green Algae have the following characteristics:• Look similar to aquatic plants

• Are mostly multicellular

• Possess highly specialized tissues

• Many have cell walls

• The three phylums differ by the photosynthetic pigments they use


Red Algae is a plant like protist with:• Members of phylum Rhodophyta

• Able to live at great depths

• Contain chlorophyll a and accessory pigments called phycobilins

• Lack flagella and centrioles

• Can be red, green or purple

• Are eaten by coral in coral reefs


Brown Algae is a plantlike protists with:• Members of the phylum Phaeophyta

• Contain Chlorophyll a & c and a brown accessory pigment

• Largest & most complex form of algae

• Are yellow-brown in color

• All are multicellular

• Commonly found in cool, shallow coastal water

• EX: Giant Kelp


Green Algae are plant-like protists with:• Members of the phylum Chlorophyta which means

“green plants”

• Share many characteristics with plants like cell wall composition, multicellularity, and photosynthetic pigments

• Contain chlorophyll a & b

• Found in fresh and salt water

• There are three types of green algae: unicellular, colonial, or multicellular


Reproduction in Green Algae• Life cycle of many algae include both a haploid and

diploid generation

• Some switch back and forth between haploid and diploid their entire lives• EX: In life cycle of algae Ulva, one of the phases

produces male & female gametes known as gametophytes

• Some switch back and forth between sexual and asexual reproduction• Ex: Chlamydomanas (single-celled green algae)

reproduces asexually by producing zoospores


Human Uses of Algae:• Are major food source for ocean life

• They produce much of Earth’s oxygen through photosynthesis

• Chemicals in algae are used to treat stomach ulcers, high blood pressure, and other health problems

• Used in food products such as ice cream,

• Used in chemicals such as plastics

20-5 Funguslike Protists

Funguslike Protists: • Look similar to fungi

• Are heterotrophs that absorb nutrients through dead or decaying organic matter

• Have centrioles

• Lack chitin cell walls that true fungus have

• Include the groups: Cellular Slime Molds, Acellular Slime Molds, and Water Molds


Slime Molds are funguslike protists with:• Play roles in recycling organic material

• Form mold-like clumps that form spores

• There are two major groups:• Cellular Slime Molds

• Acellular Slime Molds

• Found in damp and rich organic matter such as the forest floor or backyard compost


Water Molds are funguslike Protists with:• Are also called Oomycetes

• Are members of the Phylum Oomycota

• Thrive on dead or decaying matter in the water & some are plant parasites on land

• Produce thin filaments known as hyphae

• Display both sexual and asexual reproduction during their lifetime

• In oomycetes, sexual reproduction takes place in specialized structures formed by the hyphae called the antheridium and oogonium

Kingdom Fungi

Chapter 21

Fungi

Eukaryotic Heterotrophs Have cell walls made of chitin (only

similarity to plants) Digest food outside their body & absorb

it through cell wall. Multicellular Grow on their own food source.

Fungi Structure

The body is multicellular & composed of many hyphae tangled together into a thick mass called a mycelium.

Hyphae – filament that can develop cross walls with 2 nuclei.

Fungi Reproduction

Most reproduce both asexually & sexually. Asexual-takes place when hyphae break off &

begin to grow on their own.• Can produce spores that scatter & grow.

• Spores are produced in a sporangia. Sexual-takes place when hyphae of

opposite mating types meet and fuse together.

Fungi are diploid during a small part of their life cycles.

Common Molds

Ex. Bread Mold Zygospores-resting spore that contains

zygotes formed during sexual phase. Rhizoids-anchor fungus to the bread. Stolons-stem-like hyphae that run along

the surface of the bread. Gametangia-produce haploid gamestes

when hyphae fuse.

Yeast

Unicellular fungi Yeast form asci (ascus-plural) with

ascospores which become active in a moist environment.

Budding-process of asexual reproduction. When baking bread, yeast causes the bread

to rise because the fermentation (no oxygen present) of the yeast produces carbon dioxide.

Club Fungi

Ex. Mushrooms Basidium-spor-bearing structure that

looks like a club. Gills-hold the basidia on the underside of

mushroom caps. Stalk-stem.

Imperfect Fungi

Deuteromycetes-fungi that do not appear to have sexual reproduction.

Penicillum-Penicillium notatum is a mold that grows on fruit & is the source of the antibiotic penicillin.

Ecology of Fungi Since fungi are heterotrophs, the cannot

make their own food. They cannot move or capture food, but their

mycelia can grow very rapidly into tissues & cells of plants & other organisms.

Saprobes-obtain food from decaying organic matter.

Parasites-harm other organisms while living directly on or within them.

Symbionts-live in close & mutually beneficial association with other species.

Ecology of Fungi

Fungi that are Decomposers play an essential role in balancing ecosystems by breaking down dead organisms.

The breakdown is sped up by fungal production of digestive enzymes.

They return important trace elements & nutrients to the soil.

Ecology of Fungi Fungi that are Parasites feed on living

organisms and cause serious disease to plants and animals.

Some cause disease in humans. The growth of yeasts in moist regions of

the body is kept in check by competition from bacteria.

Infections can be treated by antibiotics. Ex. Wheat rust, athletes foot, yeast

infections in female reproductive tracts.

Ecology of Fungi

Lichens are an example of fungi that are Symbiotic.

They are composed of an alga or a cyanobacterium & a fungus living together.

Ecology of Fungi

Some fungi are Mutualistic. Almost half of the tissue of trees is

beneath the ground as roots. These roots are tangled in a partnership

with a web of fungal mycelia. This mix is called mycorrhizae.

Documents

Chapter 20 Protists Pages: 496-520. 20-1 The Kingdom of Protista Kingdom of Protista is a diverse group that may include more than 200,000 species Is