USING THE MICROSCOPE TO OBSERVE CELLS
*****IMPORTANT!!!!!
BEFORE VISITING YOUR LEARNING
CENTER TO CARRY OUT THIS LAB
ACTIVITY PLEASE READ BELOW
Before you visit your Learning Center
to use the microscope, it is important that
know what you need to carry out the lab
activity. Please read the lab description
carefully before attempting the lab activity.
Also bring the following items with you
to your Learning Center when you go to do
the lab activity: (1) your dissecting tools
from your fetal pig dissection kit (you will
need your forceps, scissors, and teasing
needle); (2) a piece of paper with small text
printed on it (e.g., a page from a
newspaper, book, or brochure - paper must
be thin, not thick); and (3) something tiny
(e.g,, pollen grains from a flower, flea,
mosquito, tiny spider, hair shaft, etc. - it
must be small and thin enough for viewing
under the microscope) to look at under the
microscope.
Introduction
Of all the tools that scientists use,
perhaps the microscope is the distinctive
tool of the biologist. Since Anton van
Leeuwenhoek (1632-1723) first peered at
tiny "animalcules" in a drop of pond water
and Robert Hooke (1635-1703) first
observed the tiny compartments of cork he
called "cells", the microscope has revealed a
universe too small to be seen with the
unaided eye.
This microscopic universe is incredibly
diverse, consisting of bizarre forms of life
that challenge the imagination of science
fiction novelists. This is the universe of
bacteria, protozoa, and fungi. It also
includes very small plants and animals that,
while obscure to our eyes, have a
tremendous impact upon human health and
the ecosystem. Finally, even large plants
and animals have life history components
that can only be seen through the aid of a
microscope.
Through the eyepiece of the
microscope, we can examine and begin to
understand the fundamental units of living
things: cells. An individual cell is perhaps
the smallest component of a living thing
that we can easily identify as being alive.
While cells vary greatly in size, structure
and function, all cells share some major
characteristics: (1) cells are separated
from the external environment by a cell
membrane that maintains the internal
integrity of the cell by regulating what
enters and what leaves the cell; (2) cells
possess a genetic instruction set in the
form of DNA; (3) to stay alive, cells process
energy and materials in such a way as to
yield energy less capable of doing work; and
(4) cells grow and reproduce.
In this laboratory activity you will
become familiar with the use and care of
both the standard compound microscope.
In addition, you will learn how to prepare
materials for observations under the
microscope. Finally, you will also be
introduced to the basic types of cells and
their components.
The Parts of the Compound Microscope
BASE AND ARM
These components, the horizontal
base and the vertical arm, form the
supporting mechanism for the optical
portion of the instrument. Some
microscopes are hinged at the point of
attachment of the base and arm to permit
tilting of the instrument. Other models are
constructed in a fixed position and cannot
be inclined.
