B I O L O G Y 1 1

Kingdom Protista

2 million people a year…because of a protist!

3000 Kids a day!

Introduction to Protists

Protists (from the Greek first) are the first kingdom of unicellular, eukaryotic organisms (cells contain a nucleus and membrane bound organelles).

They are approximately 1.5 billion years old indicating that the evolution of the first protist took approximately 2 billion years (the oldest fossil of a moneran is 3.5 billion years).

How did Protists come to be???

There is a strong resemblance between several of the organelles (mitochondria and chloroplasts) and cyanobacteria and bacteria.

The cilia and flagellum found in eukaryotic cells are similar to a group of bacteria referred to as spirochetes.

One hypothesis is that the previous prokaryotes lived with another moneran in a symbiotic relationship.

This hypothesis is called the Endosymbiont Hypothesis

The Endosymbiont Hypothesis

How Kingdom Protista is broken down…

KINGDOM PROTISTA

Animal Like

Protists

Plant Like

Protists

Fungus Like

Protists Phylum Ciliophora

Phylum

Zoomastigina

Phylum Sporozoa

Phylum Sarcodina

Phylum

Euglenophyta

Phylum Pyrrophyta

Phylum

Chrysophyta

Phylum

Acrasiomycota

Phylum

Myxomycota

Animal like Protists- Phylum Ciliophora

#1-Phylum Ciliophora-Cilia bearing protists

Cilia – hair like projections, composed of microtubules, that are able to move and propel the organism through water.

Ciliophora – approximately 7000

members are either solitary or live in

colonies and are known as ciliates

Animal like Protists- Phylum Ciliophora

Paramecium (Example of Phylum Ciliophora) Large single celled organism that contains two different

kinds of nuclei – a macronucleus and a micronucleus Obtains food by using its cilia to force water into an

indentation in one side of the cell called a gullet. The food is forced into cavities called food vacuoles that break off into the cytoplasm and fuse with lysosomes that contain digestive enzymes

Waste materials are emptied into the environment when

the food vacuole fuses with the anal pore.

Animal like Protists- Phylum Ciliophora

Paramecium cont’d

Because water is constantly entering the paramecium due to osmosis there are contractile vacuoles that once filled with water, contract and pump water back out.

Reproduce asexually through binary fission Single paramecium elongates, splits its gullet in two, and the cell

divides crosswise giving two identical cells.

Under stressful conditions (starvation and changes in temperature) paramecia will undergo sexual reproduction in a process called conjugation

Paramecium Life Cycle

Paramecium Conjugation

Macronuceli disintegrate and their diploid micronuclei undergo meiosis so that by the end each paramecia have 4 haploid micronuclei

3 of the 4 micronuclei disintegrate and the 1 remaining one divides to form 2 identical haploid micronuclei

The paramecia exchange one micronucleus so that each cell has one micronuclei obtained from the other paramecium

Paramecia separate and the 2 haploid micronuclei in each paramecium fuse to form a new diploid micronucleus. From the micronucleus a new macronucleus is formed.

Phylum Zoomastigina

#2 Phylum Zoomastigina – Animal like Protista with Flagella Move through the water by means of 1 – 4 flagella Generally able to absorb food through cell walls and live

in environments that have enough food for them to absorb. Some live in other organisms to utilize the nutrients that the other organism consumes.

They reproduce mainly through asexual reproduction but

are able to produce gamete cells through meiosis which fuse together forming an organism with a new set of genetic information.

Phylum Zoomastigina

With the lack of a cell wall, nutrients are able to be passively absorbed into the protist. They live in environments in which there is plenty of nutrients – lakes, ponds or as parasites of other organisms

Typically when organisms are stressed – through change in temperature, oxygen levels, or nutrient levels, they need to find ways to ensure that they can survive – as a result they produce gamete cells through meiosis which fuse to “create a new combination of genetic information.

Phylum Sporozoa

#3 Phylum Sporozoa – spore producing parasitic protists.

Non motile parasites that infect worms, insects, fish, birds, and humans

Complex life cycles that involve more than one host.

Reproduce by means of cells that are enclosed in a protective membrane (spore)

Spores attach to a host cell, penetrate it, and then live within it as a parasite.

Eg.- Plasmodium – causes malaria

How does Malaria work?

Phylum Sarcodina

#4 Phylum Sarcodina – Protists with false feet

Amoebas – flexible active cells without cell walls, flagella, cilia, and even a definite shape. They move by extending the pseudopod and then the cytoplasm stream into it. It eats in a similar manner in which it extends its cytoplasm over its food and then ingesting it to form a food vacuole.

Phylum Sarcodina

Reproduce through binary fission – one large ameba divides by mitosis to produce two smaller but genetically identical amoebas.

Also contain three groups known as heliozoans, radiolarians, and foraminifers

These organisms create delicate

shells in a variety of ways.

Plant Like Protists

#1 Phylum Euglenophyta – Flagellates with Chloroplasts

Closely related to Zoomastiginans

Most common member is Euglena

Long cell which has two flagella that it uses to propel it forward through water

Able to move by changing its shape so that it can “crawl” along a surface. This movement is very animal like in appearance

Phylum Euglenophyta

Has an eyespot at the end with the flagella that it uses to find bright light as it is filled with between 10 to 20 chloroplasts

If there is no sunlight available it can also absorb nutrients that are in the water around it (these organisms that can absorb decayed organic nutrients are referred to as saprophytes)

Phylum Euglenophyta

The pellicle (cell membrane and associated structures) is unusual because it consists of a series of ribbon like ridges that spiral around the surface of the organism. Underneath each ridge is a small sac and microtubules that are thought to be responsible for maintaining the cells shape and its euglenoid movement.

Reproduces asexually by binary fission. Just before division the cell doubles the number of ridges by placing them between existing ones. It starts division at the ends with the flagella.

Phylum Pyrrophyta

#2 Phylum Pyrrophyta – Fire Protists

Group of organisms known as dinoflagellates most of which are photosynthetic (though some have lost their chloroplasts and are heterotrophs

Usually swim using two flagella one of which wraps around the organism like a belt and the other trails behind like a tail

Many are covered in thick plates that give them an armored appearance

Phylum Pyrrophyta

Reproduce asexually through binary fission

Luminescent and will give off light with sudden movement

Unlike all other eukaryotes, dinoflagellates do not have their DNA bound with special proteins called histones.

Phylym Chrysophyta

#3 Phylum Chrysophyta: Golden Protists Three organism in this phylum –

yellow-green algae, golden-brown algae, and diatoms.

Contain one or two gold-green

chloroplasts Cell walls contain the

carbohydrate pectin instead of cellulose and store food as oil instead of starch.

Phylym Chrysophyta

Some have flagella

Reproduce both sexually and asexually and although usually solitary, they can live in threadlike colonies

All but about 2000 of the

species in this phylum

belong to the diatoms

Phylym Chrysophyta

Diatoms

Cells that produce cell walls rich in silicon which is the main ingredient in glass.

Cell walls are like the two sides of a petri dish so that one side fits snuggly into the one beside it

Photosynthetic and most abundant species in the ocean.

Fungus like Protists- Phylum Arasiomycota

#1 Phylum Acrasiomycota

These slime molds are cellular

They begin their life cycle as individual cells and they look amoeba like

When they need food the free living cells gather to form a reproductive fruiting body

Examples of different slime molds

Phylum Myxomycota

#2 Phylum Myxomycota

These slime molds are acellular

They begin their life cycle like Acrasiomycota, but these slime molds produce a structure called plasmodia

Unlike Arasoimycota, Myxomycota is a single multinucleate cell