Comparison of common characteristics

of living beings
Goal: describe living beings based on their
general characteristics

Experiment 1
Characteristics of the cells
Purpose of the experiment
You’ll identify the fundamental characteristics of cells, using
a chicken egg as a similar model.
Material
 Glass or deep recipient with 250ml capacity. (Somewhere a
chicken egg fits).
 Metal or plastic spoon
 Plate
 Magnifier
 Single-edge razor
 Napkins
 An egg
Substances
 Water
 Vinegar

Procedure
You probably remember that cells are the basic unit of living beings
and generally can be studied through microscopic observations. In this
activity you’ll identify the fundamental characteristics of the cell.
Not all cells are microscopic, some of them are presented in
extraordinary sizes just as bird and reptiles eggs in which new beings of the
species are developed. Of course that in almost any other animal, the eggs
are not big-sized, such as insects, some amphibians such as frogs or toads,
fishes and most of the superior order animals, the development of the new
being is not made out of the mother’s body.
After seeing that, check the egg that we requested and take note of the most
notorious characteristics:
The egg started to lose color and it went pale. Inside the vessel little bubbles
started rising because of the reaction of the vinegar and the egg.

With the other team members, relate what your team wrote with the information
that you have about the characteristics of cells and answer the following. Do you
find some similarities? Yes Which?
All similarities should be the same because the process was the same. The
color, the texture.

Probably in your answers highlight the existence of a membrane, because in the

eggs the membrane is not as evident. For observing it, do the following:

 Put a little bit of vinegar in the recipient. Introduce the egg and then add
more vinegar until is all covered.
 Using a spoon, move the egg inside the recipient so that its always touching
the vinegar. What happen?

The egg started to lose color and the shell lose strength and bubbles began
to emerge.

 Remove the foam that was created to help the action of vinegar-
 If it’s necessary, take out the egg from the liquid and substitute with new
vinegar. Put back the egg in the process.
Take notes of your observations:
The egg now stays on the vinegar but also the little membrane or “skin” of
the egg started to fall when we scratch it.
Comment with your team members. What cause the phenomenon you witnessed?
The vinegar began to make weak the egg thanks to a reaction and this
reaction also cause the foam.
Discuss your comments with the work teams, with
the help of the teacher reach one or more general
conclusions and write them down

Prepare a cardboard or flipchart sheet with the

results of the observations and expose when the
teacher says so
when the vinegar has dissolved all the shell,
remove the egg from the rinse liquid and dry it with
the pape

Carefully, each of the team members take the egg and turn it in all directions. What
do you feel?

Comment each other and take note of your observations

Then holding index and thumb fingers observe the egg

against the light and take note of the observations and
note the similarities and differences
Now put the egg without the shell over the plate. Take the pocket knife and make a
cut on the surface of the egg, from the upper point to the lower point of the egg.
Observe ¿What is happening?

The outer part of the egg became more elastic, but the interior remained
practically the same.

Separate the cover of the egg, rinse it, and put it over the napkin. What are it’s
characteristics?

Some characteristics of the egg when we put it on the napkin were that it was
transparent, softer and a little bouncy.

Separate the yolk from the egg-white and observe each of them. How does the
yolk keeps separated from the egg-white?

Because when we separate the egg-white and the yolk we could observe that
the yolk has like a little membrane that covers all the yolk and the egg-white
is only the liquid.

What do you have to do so that the yolk spills out? What are it’s implications?

If we want to spills out we have to touch a little hard and in that way we can
see how the little membrane breaks and that’s how the yolks spills out.

Comment your observations with the rest of your team, discuss the coincidences
and differences. Write your answers.

When we leave the egg for a long time in vinegar the shell dissolves, and
only one fabric remains around the egg. The egg became soft and could
bounce a little. The egg-white was a little thicker and the yolk still had the
same texture and appearance.

The cells are composed principally by a membrane, cytoplasm and a nucleus.

Knowing that in this experiment we have used an egg as a similar model to know
the parts of the cell, relate what you have seen in the previous activity with the
fundamental parts of a cell.

The membrane is:

The eggshell represents the membrane that protects the egg. The membrane
protects to the cell.

The cytoplasm correspond to:

To the egg white that contains proteins. The cytoplasm is formed by organic
and inorganic substances mixed in water and of viscous consistency

The nucleus correspond to :

To the yolk, which is surrounded by a membrane. The nucleus is inside the

cytoplasm and stores inside it the chromosomal material or DNA, called
Chromatin. It also contains the Nucleolus, which is formed by ribonucleic
acid (RNA) and proteins, which is the one that performs the function of
ribosome formation.

Besides the cellular membrane, is there another membrane in the cell? Which one
and where is it?

The nuclear envelope is a double membrane that delimits the nucleus of the
cell. It serves to separate the chromosomes from the rest of the cellular
content. The nuclear envelope appears to be crossed regularly by small
perforations or pores that allow the passage of certain materials, such as
ribonucleic acids and proteins, between the nucleus and the cytoplasm.