3. single celled organisms

3. Single Celled Organisms

Describe the structure of a

variety of single celled organisms and the functions

of their organelles

Note: This lesson is assessed in the

Microscope Internal but not the

External Exam

Unicellular Organisms

-Unicellular (one celled) organismsare good models for membrane transport, because they need to perform many functions with one cell,rather than many types of cells.

Unicellular organisms possess a highdegree of complexity for one cell.

Note: multicellular organisms have many cells, but each type performs one basic function. The interaction of the cells allows a multi-celled organism to live.

Euglena Paramecium Amoeba

You will be given diagrams of these three organisms.

Use the slides following to label and take notes about the functions of their organelles.

There are 3 main types of unicellular organisms

Some Common Unicellular Organisms1)Euglena: a genus of microscopicorganisms in the Protista Kingdom.

-lives in fresh water, and are especially common in warm seasons,when they populate drainage ditchesand ponds.

-Euglena has a spindle-shaped body, and range in size from 1/1000 to 1/100 of an inch (0.025 to 0.254 mm)long.

-Most species are green, because theycontain chloroplasts, which allows them to produce their own food. Theyserve as primary producers in many aquatic ecosystems.

-Some species also eat small particles of food.

-some Euglena also have a specialized“eye spot”, which serves as a light sensor,directing them toward available light.

-moves via a flagellum, which is a whip-like appendage that sticks out of the body.

Flagellum

Chloroplasts

Euglena Hibernation/ReproductionHibernation: when conditions are bad (dry or too hot/cold) Euglena forms into a sphere, called the palmelloid stage.

Each euglena then discards itsflagellum, and forms a mucusouter covering.

Euglena undergo reproduction called “binary fission” Each euglena first creates two of everything,then splits evenly into two halves.

2) Paramecium: another genus of Protists, often called “slipper protists”because of their shape like a bedroomslipper.

-usually less than 0.01 inches (.25mm)in length, and covered with very smallhair like projections called cilia.

Cilia are used in movement, and during feeding.

The most common paramecium is Paramecium caudata, which is used for research

-It eats small particles of food or bacteria from fresh water where it lives.

-Paramecium does NOT have chloroplastsso therefore is a strict consumer.

Paramecium ReproductionParamecium have twoways to reproduce.

1)They can reproduceAsexually, and splitinto two (binary fission)This type of reproduction does NOT involve the swap of genetic material, andmakes a clone of the parent.

2) The second form of reproduction is called conjugation, and involves the paramecium swapping genetic material.This type of reproductiondoes not result in a clone,but an individual with anew set of genetic instructions. This will lead to genetic variation within the population of paramecium.

3) Amoeba:one of the simplest of theprotists.

-moves by “pouring” cytoplasm into extensions of the cell membrane, called pseudopodia.

-Amoeba possess a very flexible cellmembrane, and constantly moving cytoplasm.

-the shape of the amoeba continually changes as new pseudopodia are created, and others disappear.

Eats by surrounding its prey with pseudopods, and slowly engulfing it.This is called phagocytosis.http://www.youtube.com/watch?v=pvOz4V699gk

Amoeba Anatomy

Pseudopods

Amoeba feeding sequence

1 2

3

4

New organelles Contractile vacuoles – used to pump excess

water out of the cells – they collect the water from the cytoplasm and excrete it through pores.

http://www.youtube.com/watch?v=mTXRcbjuYGU

Cilia – Hair like extensions of the cell membrane that contain microtubules. They are used to propel the organism throguh water in unicellular organisms.

Recap Quiz1. Which organism is a producer?2. Which organism moves by pouring

cytoplasm into extensions of its body?3. What is phagocytosis?4. What does a paramecium feed on?5. How do paramecium reproduce?