Download ws: Cell Membrane, The Gatekeeper

Biology
Jones
Name:
Period:
Date:
Cell Membrane…”The Gate Keeper”

Color the diagram of the cell membrane.
A. Protein channel (color all proteins the same)
B. Carbohydrate chains
C. Phospholipid head
D. Phospholipid tails
E. Cholesterol
C.
D.
B.
E.
A.
A.

Use your macromolecule notes and your cell membrane notes to answer the following questions.
1.
What molecule makes up the majority of the cell membrane? ______________________________
2. What are the monomers to the molecule in answer #1? ___________________________________
3. Draw a phospholipid and label the polar and non-polar regions.
4. What does it mean to be a polar molecule?
5. Other than the hydrophilic component of the phospholipid, what is another example of a polar
molecule that we have discussed in class? _____________________
6. What does hydrophilic mean?
7. What does hydrophobic mean?
8. How do phospholipids interact with water to form the phospholipid bilayer?
9. What types of molecules can slide across the phospholipids? What characteristics allow them the
move in and out the cell this way?
10. How do molecules get into the cell if they cannot slide across the phospholipids? What types of
molecules get in this way? What characteristics force these molecules to get into the cell this way?
11. How do the proteins stay anchored in the cell membrane?
12. What is the role of cholesterol in the cell membrane?
13. What is the fluid mosaic model? In your answer include what component contributes to the “fluid”
part and what component contributes to the “mosaic” part.
14. Structure and function: fill in the blank:
The __________________________controls the internal environment of the cell by only allowing
certain molecules to enter and exit the cell, so it is said to be _____________________________.
Because it has two layers of lipids and proteins it is called a ________________________. The
membrane can function as a gate keeper due to its structure. Cell membranes are mostly made of
_____________________ each one with a head that is _____________________ and two tails that
are _________________________. The head is water loving or _______________________ so they
face the polar water inside and outside the cell. The tails are water fearing or ___________________
so they face away from the water and form the center of the bilayer. Because the tails of the
phospholipids are non-polar, only small and _______________________ molecules can slide across them.
The two primary molecules that get into the cell this way are _____________ and ________________.
Even though it is polar, ____________ can very slowly slide across the phospholipids because it is so
small. Molecules that are large and have a ______________ have to enter the cell through
_____________________________.