Download HW 9/14 Two Kinds of Cells

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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 organelles that are similar to your stomach; there are organelles
similar to your kidneys; and there are organelles similar to your brain (there are more, but let’s keep it simple for now
). It’s this organelle 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.
1. What job does a nucleus perform?
a. The nucleus controls how fast a cell grows.
b. The nucleus controls how much a cell eats.
c. The nucleus controls how a cell moves.
d. The nucleus controls when a cell reproduces.
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.
2. Which of the following is not a fact about prokaryotic cells?
a. Prokaryotic cells do not have a nucleus.
b. Prokaryotic cells are more abundant than any other cell on earth.
c. Prokaryotic cells grow as large as humans forming tissues and organs.
d. Bacteria is a type of Prokaryotic 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
3. What do eukaryotic cells have that prokaryotic cells are missing?
a. Eukaryotic cells have skin while prokaryotic cells do not.
b. Eukaryotic cells have a nucleus while prokaryotic cells do not.
c. Eukaryotic cells have eyes while prokaryotic cells do not.
d. Eukaryotic cells can swim while prokaryotic cells do not.
The 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.
4. Which of the following is not an extreme environment where bacteria live?
a. Inside your stomach.
b. On your teeth.
c. Inside your toothpaste.
d. On your skin.
5. What is the most common prokaryotic cell (and the smallest cells)?
a. Human cells
b. Insect cells
c. Bacteria cells
d. Stomach cells
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.
6. Which of the following is not a type of archaebacteria?
a. Heat loving
b. Eubacteria
c. Salt-loving
d. Methane-making
Where prokaryotic cells are tiny and always single cell, eukaryotic cells are large and mostly multicellular. 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.
7. 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.
8. 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
9. Which if these words describes humans?
a. eukaryote
b. prokaryote
c. protist
d. Fungus
10. What does “multi-celluar” mean?
a. Less than one cell
b. One cell
c. More than one cell
d. Unknown number of cells