Download Lab - Science with Ms. Wang

Introduction to Cells Lab – This sheet stays in class
Objectives:
1. Examine the diversity of life that exists in pond water and cultures (grown in a lab).
2. Determine the type of organisms that are seen, whether they are autotrophs or
heterotrophs.
3. Observe similar and different cell structures of microbial organisms.
Introduction:
You will be examining pond water, aquatic plants and multiple cultured specimens. These samples include “plant like”
and “animal like” protists (single celled life forms with a nucleus). If these are “plant like” protists they are autotrophs
which means they make their own food through photosynthesis. If the protists are “animal like” they typically move and
are heterotrophs which means they have to eat to obtain nutrients and energy to survive. As you look at these amazing
life forms think about how they obtain and use energy as well as some of their basic structures you will be introduced to.
We will be learning more about these cell structures and have already talked about some of them in reference to
photosynthesis and respiration.
Pre-Lab Questions:
1. What is the difference between an autotroph and a heterotroph?
2. What organisms do think go through cellular respiration – autotrophs or heterotrophs? Why do you think so?
3. What substances would have to get into the organism for cellular respiration to happen? How do you think those
substances get into single-celled organisms?
Materials Needed:
Pond Water Samples and Protist Samples
Eyedroppers
Compound Light Microscope
1 Clean Slide
1 Clean Cover slip
Toothpick
Methylene Blue Dye
Procedure for Pond Water and Protist Observations:
1) You will observe each of the cultured protist specimens (the critters in the vials and jars at your stations) by
preparing a wet-mount slide. Follow these instructions:
a. Use the eyedroppers in the sample to place a drop of water on slide.
b. Place a cover-slip on top of the drop of water.
c. Look at the sample beginning on low power (4x). Focus the microscope.
d. Look at the sample on high power (10x). Focus the microscope and record observations for the
organism.
e. Clean the slide thoroughly between samples.
f. Prepare another sample and examine using the steps above.
2) Draw three different organisms in your journal and label them. Include as many as the cell parts as possible.
Not all of the organelle and cell structures will be able to be seen with our microscopes.
a. Label as many cell parts as possible.
b. Explain evidence you see that the organism is an autotroph or a heterotroph.
These are the main cell structures to look for:
1. Cell membrane – The boundary between the cell and its
environment; like the “skin” of a cell
2. Cytoplasm – What fills most of the body of the cell; the stuff that
holds organelles
3. Chloroplast (only present in plant-like cells) – Green structures
4. Vacuole (all cells, but plant cells have larger ones) – bubblelooking structures, for holding food, water, etc.
5. Nucleus (all eukaryotic cells, non-bacterial) – Usually shows up as
round, dark spot inside the cell
6. Flagella or cilia (used for movement but difficult to see) – hair-like projections on the outside of the cell
membrane
Try to determine if the organisms is a “plant like” or “animal like” organisms based on its characteristics.
Procedure for preparing a cheek cell slide:
1. Prepare your cheek cell slide as follows:
a. Put a single drop of water on the middle of your slide.
b. Take a toothpick and use it to gently scrape the inside of your cheek about 10 times. You do not need to
scrape very hard.
c. Swirl the tip of the toothpick in the drop of water.
d. Add 1 drop of methylene blue. This will stain the cheek cells so you can see them more easily.
e. Cover the liquid with a cover slip.
2. Look at the slide under scanning, low, and high power. Be sure to start on lowest magnification. ONLY use the
fine adjustment (small knob) to focus when you are looking under high power.
3. Sketch the cells you see and label them in your journal.
4. Rinse the slide and cover slip off and dry them off. Throw the toothpick away in the garbage.
Analysis Questions
1. Which of these organisms/cells were “plant like”/autotrophic? What organelles did they have in common?
2. Which of these organisms/cells were “animal like”/heterotrophic? What organelles did they have in common?
3. What do all the heterotrophic organisms need for their energy source?
4. Both protists and cheek cells need glucose and oxygen for cellular respiration. What is the difference between a
protist and a cheek cell in terms of how those molecules can get into the cytoplasm?
Introduction to Cells Lab
Introduction to Cells Lab
Make your drawings with simple, clear lines and LABEL the organelles you see.
Drawing of the Organism/Cell
Drawing of the Organism/Cell
Make your drawings with simple, clear lines and LABEL the organelles you see.
Drawing of the Organism/Cell
Drawing of the Organism/Cell
Autotroph or Heterotroph? What is the
evidence for this?
Autotroph or Heterotroph? What is the
evidence for this?
Autotroph or Heterotroph? What is the
evidence for this?
Autotroph or Heterotroph? What is the
evidence for this?
Drawing of the Organism/Cell
Drawing of a Cheek Cell
Drawing of the Organism/Cell
Drawing of a Cheek Cell
Autotroph or Heterotroph? What is the
evidence for this?
Similarities to Protists?
Autotroph or Heterotroph? What is the
evidence for this?
Similarities to Protists?