Upon completion of this lab, you should be able to
identify various types of cells from plants, protozoans, algae, and animals
distinguish between cilia and flagella
recognize the process of cyclosis
distinguish between white blood cells, red blood cells, and platelets
distinguish the differences between human blood cells and those from lower
animal groups
Introduction
In this laboratory investigation, you will have the opportunity to visualize
several different types of plant, animal, and protistan cells and organisms.
As you view them, try to keep in mind that, whether they are unicellular or
multicellular, organisms all have the same basic problems to solve. They also
have many of the same cellular structures to carry out their life functions.
As you view the slides, try to think about the various cell structures that
these cells have in common
Elodea leaves and cells: Use the embedded links to show
both
low and high powers (100X, 400X) and find individual cells. The circular
green structures around the edge of the cell are chloroplasts, which contain
chlorophyll for the process of photosynthesis. As
this animation shows, as the molecules move, the cytoplasm will begin
to flow around the edge of the cell, and the chloroplasts will move with it.
It will look like little green circular cars moving around the edge of the
cell. This process of cytoplasmic movement is known as CYCLOSIS. Note any
structures other than the chloroplasts that are part of the individual cells.
Here are some additional links that show cyclosis and cellular structure.
Spirogyra (green algae): This common
algae is found in ponds and carries on photosynthesis. It is also a source
of food for animal organisms in the pond or stream. Look at the cell arrangement:
a long string of cells attached end to end. This arrangement is known as a
FILAMENT.
Note the shape of the chloroplast and any other cellular details.
Zygnema:
This filamentous alga is often found with Spirogyra,
floating at the top of still or stagnant bodies of water. Zygnema
have two
distinctive star-shaped chloroplasts per cell, which make them easy to
identify under the microscope. Like Spirogyra, Zygnema serve as food sources
for water organisms and often exist as tangled
green or yellow-brown mats.
Euglena: These protists have features
of both plant and animal organisms. They are very small and can direct
their own movement by means of a whiplike appendage called a FLAGELLUM,
which is located at the front end of the cell. The flagellum will probably
be difficult to see. You may be able to see a small
orange or red spot near the base of the flagellum. This mass of pigment
materials senses light and helps the organism remain near sunlight so it can
carry
on photosynthesis See if you can find the chloroplasts. You should be
able to see the nucleus.
Paramecium caudatum: This animal-like protist has a slipper-like
body structure. It moves by mean of CILIA,
which are a short version of the flagellum. You may see the effect of their
movement as the organism moves through the water. Food is taken in through
a channel called the
oral groove, which may show up as a roundish, dented area in the cell.
This organism has two
nuclei, a large macronucleus and a smaller micronucleus. Paramecium gets
rid of excess water through a structure called the CONTRACTILE VACUOLE.
This
link has a number of Quick Time movies of different protozoans.
Allium (onion): This
link will provide you with a number of pictures of the onion skin taken
at both low and high power. Also visit the website of Steve Durr, who is mentioned
at the bottom of the onion site, and note many of the organisms previously
seen.
Trypanosoma: These slides are of blood, so most of what
you will see are blood cells. Scattered throughout the slide will be squiggly-looking
cells. These organisms are parasitic protozans that are spread by tsetse flies and various beetles and cause African Sleeping sickness and other neurological
disorders. Note the cell structure. The flagellum runs along the long
side of the cell and is connected
on the surface to the membrane that acts like a fin. The nucleus will be near the center of the cell, and there may be a dark structure near the front of the cell where the flagellum is attached.
Blood slides: Human and other animal blood slides are available
for viewing. The red blood cells are small and may have a light orange-red
to brown color. There are several larger and more colorful cells scattered
among the red blood cells. These are the white blood cells. In humans, there
are five different types of white blood cells. See how many different types
you can find in both human and other animal blood cell slides.
1000X magnification of fish
blood - white blood cell is a lymphocyte
1000X magnification of fish
blood - white blood cell is a basophil that contains lysosomal granules
and is thus called a granulocyte
Part I
Fungi are eukaryotic organisms that lack the ability to carry on photosynthesis. Their nutritional modes reflect this fact. Their main role in nature is to act, along with the bacteria, as decomposers. Their external digestion of substrate materials allows them to breakdown or degrade organic materials. These materials can then be absorbed back into the fungi or into other plants. It is thought that most (over 80%) of plants have fungi that live in or around their roots. These fungi are known as MYCORRHIZAE.
Dependent on growth conditions, fungi exist as single cells known as YEAST or as threadlike tubular strands of cells called hyphae. Some of these hyphae ascend and support the spore producing structure. Fungi are classified into groups on the basis of their sexual reproductive structure, or lack of one. Other hyphae descend into the substrate and anchor and absorb materials for the fungi, acting in some ways like roots. The total mass of the hyphae make up the body of the moldlike fungus known as the MYCELIUM.
Four groups are currently recognized:
Zygomycota - contains the bread mold; most common is Rhizopus
Ascomycota - sexual structure is called the ascus and usually contains 8 spores; contains single-celled yeasts such as Saccharomyces and multicelled morels and truffles; there are some important parasitic members as well
Basidiomycota - sexual structure is the basidium which hangs down from the cap of the familiar mushrooms; also important parasites in this group
Deuteromycota - sometimes known as the Imperfect Fungi because we have not identified a sexual reproductive structure yet; ringworm causing organisms as well as Penicillium and Aspergillus are in this group
A fifth group, the Lichens, are usually studied with the fungi. Lichens represent an organism created as the result of an apparent mutualistic relationship between a fungus and a photosynthetic partner. The photosynthetic partner may be an alga or a cyanobacterium. The body plan of the lichen resembles that of a leaf with the fungi in the place of the upper and lower epidermis and the photosynthetic partner in the area of the palisade cells.
Part II
Follow these links for a fun way to grow your own fungi at home.
There are a number of factors, both physical and chemical that can easily be tested at home. Try two or three of these.
the effects of temperature on fungi - put bread and a moist paper towel in a boilable plastic bag and microwave for two minutes. Be sure paper is still moist. Prepare a second slice and moist towel but omit the microwave step. Incubate at room temperature and record time of first growth and which type of bread.
the effects of salt - use moist towel, bread and salt the surface of one piece of bread but not the control. Incubate at room temperature and compare results.
dry bread versus moist bread
bread made with preservative and without
the effects of sugar or sugar substitutes on fungal growth