Name: ___________________________________________________  Period: __________

General Biology

Lab: Prokaryotic Cells VS Eukaryotic Cells

Introduction:

In the 17th century, Robert Hooke built a microscope powerful enough to see objects at greater magnification than had previously been possible.  Hooke used his microscope to examine a thin piece of cork.  While viewing this section of cork, he observed many individual units making up the cork.  He published a report in 1655 in which he called these units “cells” because they reminded him of the small cubicles in which monks lived.  Other scientists began to use microscopes to examine many different plants and animals and these scientists often saw structures that reminded them of the cork cells Hooke described.  Over the next 150 years, scientists realized that all living things are composed of cells.  With better microscopes, scientists observed that although cells vary in organization, size, and function.  All cells have the following structures:

·         A plasma membrane defining the boundary of the living material.

·         A region of genetic material (DNA or RNA)

·         A cytoplasm (the watery environment inside the plasma membrane that is not part of the genetic region where all chemical reactions occur.)

·         Ribosomes which are structures where proteins are made.

There are two basic types of cells: eukaryotic and prokaryotic cells.  Eukaryotic cells are those with a clearly defined nucleus and membrane-bound organelles.  Examples include single celled organisms called protists, plants, and animals.  Prokaryotic cells are those without a nucleus and membrane-bound organelles.   Examples are bacteria.

Purpose: To compare and contrast prokaryotic and eukaryotic cells and to practice using a microscope.

Procedure:

1.       Obtain a prepared slide of the common bacteria called bacillus.  Bacillus is a rod shaped bacterium and belongs to the kingdom Eubacteria.  Use the microscope techniques discussed in class earlier to focus on the bacteria under high power (400X).

2.      Call your teacher over to check your work.  ______________ Teacher’s initials.

 

3.      Make a sketch using pencil of the bacteria at 400X magnification in the data section.

4.      Label the parts of the prokaryotic cell in the data section using your textbook and handouts.

5.      Obtain a prepared slide of a euglena.  A euglena is a single celled photosynthetic eukaryote and belongs to the kingdom Protista.

6.      Use the microscope techniques discussed in class earlier to focus on the euglena under high power (400X).

7.      Locate the nucleus and put the pointer on the nucleus of the euglena. 

8.      Call your teacher over to check your work.  ______________ Teacher’s initials.

9.      Sketch a picture using pencil of the euglena at 400X magnification in the data section.

10.  Label the nucleus of the euglena by drawing a line to the nucleus and writing the word nucleus.

11.  Label the parts of the eukaryotic cell in the data section.

12.  Answer the analysis questions.

 

 

  

 

 

Examine the diagram of the bacterium below and label the parts using the following terms:  cell wall, plasma membrane, cytoplasm, ribosomes, nucleoid (DNA), flagella.

 

 

 

Examine the diagram of the euglena which is a photosynthetic single celled protist.  Label the following parts:  plasma membrane, cytoplasm, ribosomes, chloroplast, nucleus, vacuole, mitochondria, flagella.

 

 

 

Analysis:

1.       Compare and contrast the eukaryotic cells with the prokaryotic cell.  Fill in the table below.

Characteristics

Prokaryotic Cells

Eukaryotic Cells

Location of Genetic Material

(Cytoplasm or nucleus)

 

 

Membrane bound organelles

(Present or Absent)

 

 

Ribosomes

(Present or Absent)

 

 

Cell wall

(Present or Absent)

 

 

Plasma membrane

(Present or Absent)

 

 

Single Cellular, Multicellular, or both

 

 

 

2.       How does the size of the bacteria cell observed compare with the size of the protist cell?

 

3.       Is the cell below prokaryotic or eukaryotic?  Explain how you know.

____________________________

 

http://www.biology-resources.com/images/paramecium-big.jpg