What Are Protists?

Name: ______________________________ Date: ____________

In this exercise we will explore the Internet to learn about Protists, but first we need to understand where the Protists fit in the classification system.

Easier said than done!

We have a problem in taxonomy today; the classification of biological organisms is anything but cut-and-dried (or carved in stone)! A certain amount of chaos now reigns and will continue to reign until the next great synthesis occurs among biologists. This means that you can expect a certain amount of disagreement between what textbooks and the various sites on the web will tell you about classification.

Right now you are familiar with two current models of classification:

• A living thing is either a Prokaryote or Eukaryote.
• A living thing is in one of the following kingdoms: Monera, Protista, Fungi, Plantae or Animalia.

We tend to overlay the two as follows:

Prokaryote = Monera

Eukaryote = Protista, Fungi, Animalia and Plantae.

But biologists have many other schemes in the works. One new classification scheme classifies all living things into three “Domains”.

1. What are the names of the three domains?

A.

1. Why are the prokaryotes divided into two different domains in this classification model?

A.

1. How are the Archaea different from the Bacteria?

A.

1. Which domain are the Protista in?

Some biologists have married the three domain system and the five kingdom system and come up with a six kingdom system (shown below). Note: Archaeabacteria is the old name for Archaea.

Image from W.H. Freeman and Sinauer Associates, used by permission

Within this system, the Protists are the most difficult kingdom to classify!

It is certain that Protists belong in the domain Eukarya, but what characterizes Protists? The Kingdom Protista has become a “dumping ground” for organisms that don’t fit into the other three kingdoms. They are always eukaryotes, but after that just about anything goes. Protist classification is still in such flux that many of the group names are just not worth learning. In fact, some biologists predict that it is likely the Protista will be divided into 10-12 kingdoms in the coming years!

1. What are the general characteristics of Protista?

A.

Even though opinions vary widely, the kingdom Protista is understood to consist of three general groups. Use your textbook (pg. 401–409) and the web sites below to create a concept map overview of the Protist kingdom. The following terms should be included in your concept map:

Concept Map of Protista

Now that you have done the overview, let’s learn a little more about a few interesting Protists. First, a well-known representative of the Plant-like Protists:

Euglenoids

Euglena have flagella and a gullet like an animal cell. (heterotrophic injestion)

Euglena have chloroplasts like a plant cell (autotrophic photosynthesis)

And Euglena have been known to lose their chloroplasts, forcing them to absorb nutrients from their envronment (Heterotrophic absorbtion)

Consequently, Euglenoids arguably can be classified as animal, plant and fungus!

1. Two reasons the Eugleonoids are considered to be animal-like are:

A.

1. What are three ways Euglenoids can eat?

A.

1. How do Euglenoids move? Does their flagella indicate the front end or the back end of a euglena?

A.

Euglena wants to move towards the light for photosynthesis! Q. How does Euglena orient itself so it can move towards the light? Explain in your own words.

A.

Euglenoids keep their shape because of a pellicle. Q. Define pellicle.

A.

Now let’s move on to some animal-like protists; the Protozoa

Ciliates

Ciliates are an example of animal-like Protists. They are covered with up to 17,000 cilia beating from 40 to 60 times a second in a coordinated fashion!

Cilia are used for locomotion. A movie of a moving paramecium!

The following link is a rather large site on Protista.

Scroll down until you find ciliates and answer the following questions:

1. What is the difference between a macro- and a micro- nucleus?

A.

1. How do ciliates deal with osmosis and the influx of excess water?

A.

1. How do ciliates eat and excrete wastes?

A.

1. What are trichocysts?

A.

Rhizopods

Another Protozoan group we shall examine is called Rhizopoda or Sarcodina.

A typical rhizopod is the ferocious predator Amoeba proteus. The interesting thing about Amoeba is that their cytoplasm can exist in two states: the liquid “sol” endoplasm and the semi-solid “gel” ectoplasm. The two consistencies work together to help the Amoeba move and feed.

So how do they move?

A quick link explaining how they move.

1. What is a pseudopod?

A.

1. How does an Amoeba survive harsh environmental conditions?

A.

The Amoeba seems like a harmless little guy, but some species are downright nasty!

1. What are the symptoms of amoebic dysentery?

A.

Just for fun, check out the Amoeba Dance site.

Sporozoans

Finally, let’s take a look at a not-so-nice group of Protozoans – the Sporozoans. These parasitic organisms cannot move on their own because they do not need to! They are passed from host to host in a constant disease cycle.

1. Scroll down to the section on Sporozoans. Name two human diseases caused by Sporozoans:

A.

1. A Sporozoan has a different life cycle from the disease-causing Amoeba you saw earlier. What is the major difference in life cycles?

Protist:          A new bunch of organisms…

Some questions to ponder:

1. How do these animal eat?
2. How do they regulate water balance?
3. How do they reproduce?
4. What are some characteristics that can be used for classification?
5. How are different types of protists both unique and different?
6. What is the advantages and disadvantages of living in fresh water?
7. What is the difference between a zooplankton and a phytoplankton?
8. What phylums and kingdom do all these creatures belong to?

What is new! ( Comparing Protists to Bacteria and Virus)

1. Protists are eukaryotes and so have

• distinct nucleus
• membrane bound cell organelles
• unique flagella
• are single celled
• have cytoplasmic streaming

1. Protist can live in a variety of environments, but are now larger so they need to regulate water balance and store and/or make food.

2. Protist are more diverse in how they move, using flagellums, pseudopods and cilia and intermediate hosts.

3. Some protists can change their body shape or cell membrane during their life cycle.

4. Some protists can reproduce using sexual reproduction.

5. Some protist, are parasitic they are called protozoans and cause diseases.

6. Some protist have a silicone membranes and can glow in the dark!

7. Tiny protists are the major food choice of some of the worlds largest animals.

General Protist Notes:

Where are they may found….

• Usually single cell creatures found in pond water
• Over 50,000 living species
• other locations and points of interest include:

used as a means to clean sewage

found in intestines of termites for digestion of cellulose

may be an infectious diseases such as

plasmodium…          which is malaria

trympanosoma….    which is called sleeping sickness

• protist move in response to several stimuli. This movement is called Protist can respond both to light and chemical stimuli, positive phototropism allows organisms to be attracted to light. Negative tropism allows organisms to avoid harmful stimuli such as predators, low oxygen, lower temperatures and other possible harmful chemical or physical stimuli. This response ( to move away from a stimuli) is called an avoidance response.

On a historic note:

By jove! Forminifera ( type of diatom) has hard shell which are used for    dating early   forms of life. Protozoans also show shell like deposits, an             example is the White Cliffs of Dover in England.

Form and Function:

protists are Eukaryotes so…

• usually unicellular, so no tissues yet….
• have a nucleus with a membrane
• can be motile
• can be (animal like) heterotrophic or ( plant like) autotrophic
• have complex arrary cell organelles

Classification:

Note:  All protist belong to Kingdom Protista, which has four phylums.

• Mostly Autotrophs called Phytoplankton

1. Phylum Euglenophyta                         example        Euglena

• autotrophic, chlorphyll
• no cell wall
• move about with flagella
• found in fresh water and soil
• attracted to light ( positive phototropic)

1. Phylum Chrysophyta: example        Diatoms

• autotrophic, chlorophyll and yellow pigment ( golden algae)
• silica shell in cell wall form symetric shapes
• found in oceans
• positive phototropism
• silicas used in commercial product such as pool filters, silver polish and            toothpaste

1. Phylum Pyrrophyta: example        Dinoflagellates

• autotrophic, chlorophyll, have red pigment which makes “red tide”
• heavy rigid cell wall
• two (dino) flagella
• found in oceans
• some species glow in dark ( bioluminescence: phenomenon of living      things giving off light, have protein which converts chemical energy to         ight energy.

• Mostly Heterotrophs called Zooplankton:

1. Phylum Protozoa ( classified by how they move)

• usually heterotrophic
• no cell walls, usually moveable cell membrane
• can move about or live as parasite

Protozoan classification

class Sarcodinia    Amoeba

class Flagellata       trympanosoma and in termites

class Ciliophora      Paramecium

class Sporozoa       parasitic

Types of Locomotion:

flagella                                   found in Euglena

pseudo pod                          found in Amoeba

(cytoplasmic streaming)

            cilia                                         found in Paramecium

A quick comparison of three protist: ( note highlighted vocabulary)

Euglena:

1. for movement it uses a flagellum, which makes the Euglena                                                                         very fast.

2. for storing genetic material it has a nucleus and a nucleolus

which regulates protein sythesis and cell                                                                      control, it is asexual in reproductive behaviour

3. for energy Euglena are autotrophs and have a chlorplast,                                                                        with chlorophyll which allows for                                                                          photosythesis

4. for storing energy pyrenoids and parmylum store starch which                                                               is a product of photosythesis

5. for protection and water it has a pellicle which maintains shape and

balance                                            allows for diffusion across cell membrane.

6. Response to stimuli Euglena are attracted to light, this is call                                                                        phototropism

Amoeba

• for locomotions it has extensions of cytoplasm which are                                                                      called pseudopod ( false foot), so an                                                                                   amoeba will move very slow. Ectoplasm ( layer                                                      closest to cell membrane) is water like next to                                                                        internal gel like endoplasm

• for genetic material it has only one nucleus and is asexual

• for energy it has food vacuoles which digest food                                                                          with enzymes and move nutrients to

• to balance water it has contractile vacuoles, in a variety                                                              of positions within cytoplasm

.

• to maintain shape it has an inner membrane, endoplasm

and an outer membrane, ectoplasm,                                                                             these two layers are needed since it is                                                                          constantly changing shape.

• stimuli amoebas are attracted to food and                                                                                 some chemicals but move away from                                                                          harmful chemicals and light. (negative                                                                     tropism)

Paramecium

• for locomotion it has cilia surrounding whole body so it                                                                        moves very fast.

• for genetic information there is a micronucleus to controls                                                                                sexual reproduction, ( it divides during                                                                              conjugation)and a macronucleus to                                                                         control cell functions.

• for feeding it has a “mouth” called an oral groove                                                                           and a mouth pore

• for digestion it has a gullet which is like a stomach,                                                                           which forms food vacuoles

• for removal of food waste there is an anal pore

• for water balance there is a contractile vacuole

• for shape there is a distinct cell membrane, a                                                                                rigid pellicle which holds cells shape.

• for stimuli there are small “spears” call trichocyst                                                                                    which serve as a form of protection or                                                                               hunting for food.

1. Ways to compare Zooplankton:

The Amoeba

has

a nucleus

granular cytoplasm

vacuoles

semi-permeable membrane

engulfs food by using pseudopod

Other species

Forminifera

Radiolaria

Bacillaria

The Paramecium

member of class called the ciliates

has

cilia for locomotion

feeds through funnel like gullet

has 2 nuclei, reproduction through binary fission

for every single cell, 8 new ones are created

contractile vacuole controls water balance

sexual reproduction by conjugation

Protist are:

single cell

complex

can be in colonies ( example: Volvox..has up to 5000 cells in it)

The Acme “Us and them: Immuno Review”

It is a few days till the exam…you have studied hard. The quiz results are both good and bad…so..it is now the final minutes of the game…you have these options: give up, hope for divine intervention, waste time trying to write answers on a micro chip or apply your wit and will to answer these questions…

Part One:

• Components of us

How does our body recognize something, which is foreign?

The primary factor is recognizing some “thing”…be it alive or not..which does not fit the patterns we normally sense. For example..what is some thing new? It is some thing that comes along that we have not seen before. More often than not, the first responses is to go “pleech” or “ I don’t want to learn this” or “ that is gross”. So the human body has both a means to reject or accept all thing foreign. The foreign feature is known as an antigen.

So to review..

What is an antigen and where could they be found?

How is it recognized?

What cells are responsible for

1. identifying a foreign particle
2. responding to a foreign particle
3. labeling a foreign particle
4. removing a foreign particle
5. remembering a foreign particle

How would you compare:

An antigen to an antibody

A cell mediated response to a antibody or humoral response

• What is the similar and unique cells of both responses?
• What does one response make that the other does not?
• What cell types would increase with either response?
• What are some true and false comparisons regarding T and B cells?

A passive immunity to an active immunity

• Which one last for a longer time
• What type of immunity do you get when you are born?
• Why do antibiotics only provide a temporary solution?

Enter…them

Virus:

A virus is said to be both alive and not alive. They are so small that they cannot be filtered but they do form crystals. They have proteins, which means they must have DNA. This DNA can mutate. Because virus can change what proteins they can make with their DNA, this explains why we have so many types of flus. Yet is a virus alive? Does it produce any metabolic products or grow? What is it that signals the body that something foreign is there?

So…

• What surrounds virus genetic material?
• Can this structure change and how?
• When are virus active and not active and what words are used to describe that?
• How are virus classified?
• What is the big deal about “interferon”?
• How do viruses enter the body?
• What is the scoop with retroviruses?

Bacteria

Now bacteria are alive. Put simply they (bacteria) are soup in a bag in a box. Yet we all know there are lots of types of soups. Likewise, though bacteria are a simple life form labeled as “prokaryotes” there are a lot of forms of diversity. From simple pathogens to photosynthetic nitrogen fixers, the Monera are a diverse bunch of critters.

With this in mind..

• How many groups can bacteria be classified into?
• What are the features…that is structures folks..that all prokaryotes share?
• What are structures       you would or would not find in Monera?
• How do bacteria reproduce…asexually?
• What is a form of reproduction that is almost like sexual reproduction?
• What is the deal with strept, staph, cocci, baccilli and sphirrilium?
• What is the difference between gram positive and gram negative?
• How can bacteria survive harsh climates?
• Can you thoroughly compare anaerobic to aerobic respiration?
• What are the differences between photosynthesis and chemosythesis?
• What are the differences between photosynthesis and respiration?
• What are plant like features in bacteria?
• What are the interactions implied by the words parasitic, saprophytic, symbiotic, pathogenic, and mutalism?
• What type of bacteria seeks out light and what is this response called?

Putting it all together….

So a virus or a bacteria enters a body…no it is not a joke..

• What cells recognize the intruder?
• What cells turn on and off an immune response?
• If an intruder start using host fuel, what type of intruder would it be?
• What is the big deal about monoclonal antibodies ( source, function..and usage’s)
• What are four specific steps of an antibody or humoral response?
• What are four specific steps of a cell mediated response and how could you evaluate or see these steps occurring with cell populations or biochemicals
• What is the difference between a primary and secondary response

So you have a fatal virus…

What would be some examples?

Why would one virus be more virulent than another? For example small pox to HIV?

Possible cures…

What are problems with over using antibiotics?

What is the difference between a vaccine and an antibody?

Comparing types of immunity, which would provide the best or worst immunity

Getting sick

Getting a vaccine with dead pathogen

Getting a vaccine with weak pathogen

Getting an antibody that marks a specific pathogen

What is an allergy?

Finally..you have spent all this time studying this stuff…

Some one then states on the news..

“It is important to learn about the immune response”…could you now debate the pro and cons of this statement?