Prokaryotic and Eukaryotic Cells Lab Activity

Transcription

1 Prokaryotic and Eukaryotic Cells Lab Activity Name: Blk: INTRODUCTION Prokaryotic Cells Cells (the smallest individual units of life) are divided into two basic categories: prokaryotic cells, and eukaryotic cells. The cells of every organism apart from the bacteria are eukaryotic. Only bacteria have prokaryotic cells. Prokaryotic cells differ from eukaryotic cells in that they lack a membrane-bound nucleus and membrane-bound organelles. Prokaryotic cells are simpler in structure and are thought to have evolved before eukaryotic cells. However, both prokaryotic and eukaryotic cells share many similarities. Both have a plasma membrane, cytoplasm, DNA, and ribosomes. And, like plants and fungi, many prokaryotes also have a cell wall. Prokaryotic cells are generally much smaller than eukaryotic cells, and thus require higher magnification to see (about 1000X). However, some of the prokaryotes you will examine today are larger and all can easily be seen with a total magnification of 400X. Bacteria can be classified by shape into several groups, three of which are: coccus (spherical bacteria); bacillus (rod-shaped bacteria); and spirillum (corkscrew-shaped bacteria). Eukaryotic Cells Eukaryotic cells have a membrane-bound nucleus and organelles. Today, we will look at three groups of eukaryotic cells with the microscope: Single Celled Protozoans, Animal cells, and Plant cells. However, first you should use the diagrams provided and the descriptions below to become familiar with cell structure prior to looking at cells with the microscope. PROKARYOTIC CELLS (a) Bacteria (Prepared Slide) 1. Obtain the prepared bacteria microscope slide from your teacher. It will contain ALL THREE bacteria shapes. 2. Performing the steps that we went through during our previous lab, examine the slide with the compound microscope, using the low power 10X objective and finally the high power 40X objective. 3. You should observe 3 different shapes of bacteria (coccus-round, bacillus-rod, spirillum-spiral) on the slide. Draw each bacteria cell under HIGH power in the space below and identify the shape as (coccus, bacillus, or spirillum). 1

2 EUKARYOTIC CELLS The preserved specimens we will examine today are all one-celled creatures. (a) Volvox Volvox is an spherical shaped colonial protist that moves by means of hundreds of flagella. Each parent colony can have one to many daughter cells inside. 1. Examine a prepared Volvox slide with the compound microscope using the scanning (4X), low power (10X), and high power (40X) objectives. Adjust the light intensity in order to make observations easier. Draw the Volvox below under low and high power. Label the daughter cells inside the parent cell. (b) Paramecium Paramecium move very quickly using little hairs called cilia. It has two nuclei, the macro- and the micronuclei. 1. Examine a prepared Paramecium slide with the compound microscope using the scanning (4X), low power (10X), and high power (40X) objectives. Draw the Paramecium below under low and high power. Label the nucleus, cell membrane, cytoplasm in high power. (c) Euglena Euglena is a photosynthetic one celled creature that can actually consume other protists if the environment lacks light. 1. Examine a prepared Euglena slide with the compound microscope using the scanning (4X), low power (10X), and high power (40X) objectives. Draw the Euglena below under low and high power. Label the nucleus, cell membrane, cytoplasm in high power. 2

3 (d) Onion Peel Now, use the onion provided and create a wet mount slide by following the procedure below. 1. Using the forceps provided, peel a VERY THIN slice of onion and place this on your glass slide. 2. Add one drop of Iodine to the onion peel sample and place a cover slip over the newly stained tissue. 3. Observe under LOW and HIGH power. Make a drawing of a single cell in the onion peel under HIGH power. Label the nucleus, cell membrane, cytoplasm and cell wall in high power. (e) Elodea You will now examine a typical plant cell, from the leaf of the aquatic plant Elodea (Canadian pond weed). 1. Gently remove one SMALL LEAF from near the tip of an Elodea stalk. 2. Place the leaf on a clean slide, and add a drop of water and a coverslip. 3. Examine the leaf under LOW and HIGH power. Once you have centered the leaf in the field of view under low power, switch to the HIGH power objective. Make a drawing of a single cell in the Elodea leaf under HIGH power. Label the cell membrane, cytoplasm, chloroplast and cell wall in high power. 3

4 Eukaryotic Cell (Animal & Plant): Name each structure Contains enzymes

5 FUNCTION: Identify the function for each labeled cell part on the previous page. (use your screencast notes/textbook for help) 1. : 2. : 3. : 4. : 5. : 6. : 7. : 8. : 9. : 10. : 11. : 12. : 13. : 14. : 15. : 16. : 17. : 5