(Do Beetroot exp using Vernier Equipment if it is available)

PART I:  INTRODUCTION
The biology of living organisms is studied at many levels including: the whole organism, an organ system (cardiovascular), organ (heart), tissue (cardiac muscle =  ventricle wall), or cell.   We have been studying whole organisms in their environment.  It is time to move on.  All organisms are either a single cell = unicellular: prokaryotes and most protisits, or multicellular: a few protists, fungi, plants and animals.  Today we mostly study cells from multicellular organisms, both plants and animals, to better understand their similarities and differences.  This lab is not intended to introduce you to the many (~200) kinds of cells in your body, we save that until Biology 206!, rather, the purpose is to show what cells have in common, and to make interesting comparisons between animal and plant cells.

OBJECTIVES:
By the end of this lab, you should be able to:
Describe the differences between Prokaryotes and Eukaryotes
Describe the basic similarities and differences in structure and function between plant-like and animal-like cells;
Identify the major components of each type of cell and describe the function of each;
Identify unknown cells as either plant or animal cells and justify your answer based on the characteristics of each cell type.
Begin to appreciate the tremendous diversity of cell structures and corresponding functions found in plants and animals.

MATERIALS:
Raw onion, Elodea leaf,  cardiac muscle slides, cover slips, methylene blue stain, toothpicks, water paper towels

PROCEDURES:
A. Plant cells - Onion bulb cells:
With forceps or fingernail, remove the inner transparent membrane (thinner the better) of a piece of raw onion.  Flatten it in a drop of water on a slide and coverslip it (no air bubbles!).  Under low/medium/high power, examine the long rectangular cells.  Note: it is difficult to distinguish any components.  Stain the cells with methylene blue (BE CAREFULL - IT IS DIFFICULT TO REMOVE FROM CLOTHING & BOOKS): add a drop of the stain to one side of the coverslip, apply a bit of paper towel to the other side to draw out water; and the stain flows in.  Examine the cells under low/med/high power, and sketch your observations:

Observations for A.
Plant cells - Onion bulb cells:
What is the length & width
of an onion cell?
(use the diameter of the field
of view under High Power
Magnification)

B. Plant cells - Elodea:
Carefully remove a single leaf from the tip of an Elodea plant (the aquatic plants in your ecosystem: also called Anacharis).  Prepare a wet mount of the leaf and observe under low and high power.  The cells of Elodea leaves are only a few cell layers thick: focus on the upper level to see chloroplasts scattered throughout.  A shift in focus down to the middle of the cell shows chloroplasts forming a ring around the inner edge of cells.

Observations for B:
Plant cells - Elodea:
Measure the size
of the Elodea cells
and sketch your
observations here.
 

C. Animal cells - Epithelial tissue:
Gently scrape the inside of your cheek with the flat end of a toothpick, and transfer this to a small drop of dilute methylene blue on a slide.  Stir, so the cells do not clump.  Coverslip and examine.  Note the nucleus & granules in the cytoplasm stain blue.  Center some cells and observe under high power.  Sketch a few cell & measure - what is the average size of the cells?  How does this compare with the sizes of the plants cells?  How big is the nucleus of the epithelial cell?

Observations for C.
Animal cells -
Epithelial tissue:
 

Cell Size =
Nucleus size =

D:  Prokaryotic vs. Eukaryotic cells
Cells range from simple prokaryotic to specialized eukaryotic.  We now focus on some of the similarities and differences in the structures and functions of cells.  In addition to prepared slides, use textbook & internet to complete diagrams and answer questions.  Always note the total magnification, next to every diagram.  Label as many parts as you can.
Sketch examples of prokaryotic & eukaryotic cells.

Prokaryotic                                                             Eukaryotic

Name                                                                       Name

Cell size                                                                    Cell Size

Prokaryotic and Eukaryotic cells compared:

.	Prokaryote	Eukaryote
DNA	.	.
Ribosomes/function?	.	.
Mitochondria?/Chloroplast?	?/?	?/?
Capsule	.	.
.	.	.

E:  Single cells in multicellular organisms:
Some cells in multicellular organisms are not part of a fixed network as seen in tissues.  Some cells are mobile and move to different locations in order to carry out their function(s).  Here are a few of the incredible diversity of such cells.

SLIDE 1:  These are starfish eggs (each egg is one cell).
Diagram a few
and label the
cell membrane,
the nucleus and
the cytoplasm
that you see.

What size are these cells in mm?

in micrometers?

SLIDE 2:  These are human sperm cells.
Diagram a few
of these cells
(use high power).

How are these cells specialized,
in terms of their structure,
to perform their specific function?
 

SLIDE 3:  These are the blood cells of a frog.
 

Diagram a few
frog blood cells, and
label the organelles.

SLIDE 4:  These are normal human red blood cells.

Diagram a few of
these human blood cells
and label the organelles.

What organelle(s) are
human red blood cells lacking?

How are human blood cells different from frog blood cells?
 

What is the special function of red blood cells?
 

SLIDE 5:  These are blood cells from a person suffering from sickle cell anemia.

Diagram a few
of these cells.
(make sure you
draw abnormal cells).

Why would the shape of these cells inhibit the special function of red blood cells?  (There are 2 reasons).