Directions: Read and highlight answering each question as you go. Two Kinds of Cells I find it interesting that if we look at every cell on earth from trees to humans to bacteria (yes, bacteria are a cell), we can categorize them into just two types. Before we get to their official names though, we have to figure out what makes them different. Inside each cell are a variety of different small organs called organelles. These really small organs perform many of the same type of jobs that your organs perform. There are organs that are similar to your stomach; there are organs similar to your kidneys; and there are organs similar to your brain (there are more, but let’s keep it simple for now ☺). It’s this organ that is similar to your brain that determines the difference between the two types of cells. This brain like organ is called a nucleus (nuke lee us). The nucleus controls how fast a cell grows, how much it eats, and when it reproduces. Your brain has very similar functions (plus a whole lot more). Whether a cell has a nucleus or not is what determines the difference between the two types of cells. Cells that do not have a nucleus are called prokaryotic (sound it out, pro kary ot ic). This type of cell happens to be the most common cell on earth. There are more prokaryotic cells than any other cell. The most common prokaryotic cell is bacteria. Yep, that very same stuff that most anti‐bacterial soap kills. There is also a bunch of weirdo cells that live in really strange environments that we will discuss later. One last interesting point is that prokaryotic cells are single celled meaning they exist as 1 cell. The other type of cell is called eukaryotic (u kary ot ic). Eukaryotic cells have a nucleus. All plants and animals have eukaryotic cells making your cells eukaryotic. Many eukaryotic cells are multi‐cellular meaning they have more than 1 cell grouped together. Think of the human body. We are eukaryotic and have 50‐100 trillion cells (50,000,000,000,000 cells). 1. What are the two basic kinds of cells? _______________________ and ________________________ Prokaryotes So these cells without a nucleus outnumber all of the other cells on earth. There are 2 main types of prokaryotic cells: Eubacteria (u bak teer ee uh) and Archaebacteria (ark ee bak teer ee uh). The most common type of prokaryotic cell is the eubacteria. This is the fancy name for bacteria. These tiny organisms can live almost anywhere. By the way, when I say tiny, they are the smallest cell on earth. Bacteria live in the soil and water and even on other organisms. For example, you have bacteria living on your skin, in your intestines, and on your teeth. These tiny single cell organisms help you digest food. Plaque that attacks your teeth and causes cavities is also a bacteria. Fluoride in the toothpaste helps destroy the plaque. 2. What are prokaryotes? ________________________________________________________________ 3. What are the most common prokaryotes (and the smallest cells)? _____________________________ DelliGatti – Two Kinds of Cells.docx The other type of prokaryotic cell is called archeabacteria. I call these the 6th graders of the single cell world since they are the weirdoes of cell biology (;‐)). What makes them strange is that they live in some of the harshest environments on earth. There are 3 types of archeabacteria: heat‐loving; salt‐loving; methane‐
making. Heat‐loving and salt‐loving are called extremophiles because they live in extreme locations. For example, heat‐loving cells live in hot springs such as the old faithful geyser in Yellowstone National forest which boasts a 220oF temperature. Salt‐
loving cells obviously love lots of salt. Places like the Dead Sea located near Israel and Jordan has salt levels that are extremely high. This type of cell loves this extra salty environment kind of like the way you love salty French fries. The third type of archaebacteria cell is the methane‐making cell. Methane‐making cells live deep in the ocean near volcanic vents. The temperature near these vents is so high the water boils around it as lava and other gases pour out of it much like a volcano on land. 4. What are three types of archaebacteria? __________________________________________________ Eukaryotes Where prokaryotic cells are tiny and always single cell, eukaryotic cells are large and mostly multi‐cellular. Although still small and hard to see without a microscope, they are about 10 times bigger than most bacteria cells. As we said before, eukaryotic cells have a nucleus. Eukaryotes represent the living things that you are most familiar. Animals, including humans, are eukaryotic. Yeast used to make bread is also eukaryotic. Although eukaryotic cells can be single cells, they are mostly multi‐cellular which means they are “many cells” working together. 5. How do eukaryotes compare in size to prokaryotes? a. Eukaryotes have more cells. b. They are about the same size. c. Eukaryotes are about 10 times smaller. d. Eukaryotes are about 10 times larger. 6. What does a eukaryote have that a prokaryote does not? a. One or more cells b. Cells with a nucleus c. Cells with a DNA d. Cells with membranes 7. Which if these words describes humans? a. eukaryote b. prokaryote c. protist d. Fungus 8. What does “multi‐celluar” mean? ________________________________________________________