EuglenaEuglena

Plant or animal ?Plant or animal ?

(document prepared by S. Kaelin, S. Moretti & A. Pylypenko(document prepared by S. Kaelin, S. Moretti & A. Pylypenko

under the direction of N. Muller Mirza - original source of the case IDEAS-IoE) under the direction of N. Muller Mirza - original source of the case IDEAS-IoE)

(Université de Neuch(Université de Neuchâtel)âtel)

The cell’s structureThe cell’s structure

The cell is the basic unit of the living. Any The cell is the basic unit of the living. Any organism, from the simplest to the most organism, from the simplest to the most sophisticated, consists of cells, sophisticated, consists of cells, sometimes only one, sometimes several, sometimes only one, sometimes several, even several billions of different types, in even several billions of different types, in a very coordinated unit.a very coordinated unit.

The cells’ structureThe cells’ structure

The existence of a nucleus makes it The existence of a nucleus makes it possible to gather cells in a unit, the possible to gather cells in a unit, the EUCARYOTES, by opposition with the EUCARYOTES, by opposition with the PROCARYOTES which do not have a PROCARYOTES which do not have a nucleusnucleus

How to differentiate animal from plant?How to differentiate animal from plant?

The animal cellThe animal cell

The animal cells (50 micrometers) have a The animal cells (50 micrometers) have a nucleus (genetic information), mitochondries nucleus (genetic information), mitochondries (energy production), an endoplasmic reticulum (energy production), an endoplasmic reticulum (fabrication of proteins), apparatuses of Golgi (fabrication of proteins), apparatuses of Golgi (transformation of proteins) and lysosomes (transformation of proteins) and lysosomes (bag of enzymes). Contrary to the vegetable (bag of enzymes). Contrary to the vegetable cells, they do not have chloroplasts, cellular cells, they do not have chloroplasts, cellular wall or vacuole. The animal cells are wall or vacuole. The animal cells are surrounded only by one membrane, making it surrounded only by one membrane, making it possible the cell to be flexible and to yield to a possible the cell to be flexible and to yield to a pressure exerted on it.pressure exerted on it.

The animal cellThe animal cell

The vegetal cellThe vegetal cell Like the animal cells, the vegetable cells (200 micrometers) have Like the animal cells, the vegetable cells (200 micrometers) have

a nucleus (genetic information), mitochondries (energy a nucleus (genetic information), mitochondries (energy production), an endoplasmic reticulum (fabrication of proteins), production), an endoplasmic reticulum (fabrication of proteins), ribosomes (synthesis of proteins), apparatuses of Golgi ribosomes (synthesis of proteins), apparatuses of Golgi (transformation of proteins) and lysosomes (bag of enzymes). (transformation of proteins) and lysosomes (bag of enzymes). However, a vegetable cell is surrounded by a cellular wall made of However, a vegetable cell is surrounded by a cellular wall made of cellulose, which makes it more rigid. cellulose, which makes it more rigid.

Moreover, the vegetable cells contain vacuoles, which contain the Moreover, the vegetable cells contain vacuoles, which contain the vacuolar liquid, and the chloroplasts, which contain chlorophyl, a vacuolar liquid, and the chloroplasts, which contain chlorophyl, a green pigment. It is inside the chloroplasts that the process of green pigment. It is inside the chloroplasts that the process of photosynthesis takes place by which the plant produces its own photosynthesis takes place by which the plant produces its own food.food.

The vegetal cellThe vegetal cell

EuglenaEuglena

One can find euglena in the ponds rich in organic One can find euglena in the ponds rich in organic mattermatter

They are unicellular, free organisms (swimming in They are unicellular, free organisms (swimming in water thanks to one whip)water thanks to one whip)

The length of the cells varies from 20 to 300 µm; The length of the cells varies from 20 to 300 µm; they are cylindrical, or ovalthey are cylindrical, or oval

There are in general many chloroplasts of color There are in general many chloroplasts of color green-clearly, although certain species are green-clearly, although certain species are colourlesscolourless

The border animal-plant is not as distinct as for The border animal-plant is not as distinct as for more complex organismsmore complex organisms

Euglena structureEuglena structure

Euglena structureEuglena structure Protozoon whipped in fresh watersProtozoon whipped in fresh waters It is composed of chlorophyl and a rudimentary eye It is composed of chlorophyl and a rudimentary eye Tank: part of euglena being used to storeTank: part of euglena being used to store Nucleus: contains the genetic information of the cell Nucleus: contains the genetic information of the cell Contractile vacuole: cavity of euglena able to contractContractile vacuole: cavity of euglena able to contract Cellular membrane: membrane wrapping euglenaCellular membrane: membrane wrapping euglena Chloroplast: organelle of euglena, sits of photosynthesisChloroplast: organelle of euglena, sits of photosynthesis Nucleole: has the shape of a sphere which is in the euglena’s Nucleole: has the shape of a sphere which is in the euglena’s

nucleus nucleus Stigma: part of euglena sensitive to the lightStigma: part of euglena sensitive to the light Whip: mobile filament and length being used for the locomotion of Whip: mobile filament and length being used for the locomotion of

euglenaeuglena

EuglenaEuglena

Euglena can be nourished in two ways: Euglena can be nourished in two ways: organic production of matter from CO2 by organic production of matter from CO2 by

photosynthesis, thanks to their chloroplasts: photosynthesis, thanks to their chloroplasts: AUTOTROPHISM (property of the AUTOTROPHISM (property of the photosynthetic plants);photosynthetic plants);

absorption of dissolved organic matter in the absorption of dissolved organic matter in the water, which is digested: water, which is digested: HETEROTROPHISM.HETEROTROPHISM.

EuglenaEuglena

The following experiment is carried out: euglenes The following experiment is carried out: euglenes are put in the darkness during several days; they are put in the darkness during several days; they are nourished thanks to the dissolved organic are nourished thanks to the dissolved organic matter in water matter in water

What does it occur when one replaces them in What does it occur when one replaces them in the light? Some become again green and start the light? Some become again green and start again photosynthesis: their chloroplasts become again photosynthesis: their chloroplasts become again functional. In other cases, rarer, the again functional. In other cases, rarer, the euglenes lose their chloroplasts and remain euglenes lose their chloroplasts and remain heterotrophic, even in the darkness. heterotrophic, even in the darkness.

Did they become animals?Did they become animals?

Euglena : darkness/lightEuglena : darkness/light

Darkness Light

Question of debateQuestion of debate

Euglena: plant or animal? Euglena: plant or animal? Has euglena an animal or vegetal Has euglena an animal or vegetal

structure? structure? Does euglena behave like an animal or a Does euglena behave like an animal or a

plant? plant? What does reveal its mode of food? What does reveal its mode of food?

ProtestsProtests

To hold account of the difficulty for To hold account of the difficulty for distinguishing animal-plant, one gathered distinguishing animal-plant, one gathered the unicellular animals and the unicellular the unicellular animals and the unicellular plants in a common unit: PROTESTS.plants in a common unit: PROTESTS.

ProtestsProtests

The protest term (from The protest term (from protosprotos in Greek = first) in Greek = first) indicates one of the kingdom of living gathering indicates one of the kingdom of living gathering all the mobile and unicellular living beings. all the mobile and unicellular living beings.

Some of them, like the amoeba, resemble Some of them, like the amoeba, resemble typical animal cells.typical animal cells.

Others, like euglenes, borrow characteristics at Others, like euglenes, borrow characteristics at the same time from animal and vegetable cells.the same time from animal and vegetable cells.