Label the components of this diagram of the fluid mosaic model of membrane structure. Indicate the regions that are hydrophobic and hydrophilic.
Where in this transmembrane protein would you expect to find mainly hydrophilic amino acids?
A. a only D. a and c
B. b only E. a, b, and c
C. c only
If this protein was a glycoprotein, where would you expect to find an oligosaccharide attached?
a only C. c only E. a, b, and c
b only D. a and c
In this experiment, the time it takes for the “hole” to disappear is a measure of membrane fluidity. In a normal cell, the hole disappears in about 65 seconds. You alter the membrane to contain more saturated fatty acids. Which of the following is a reasonable expectation?
The hole will fill in faster
The hole will fill in slower
The hole will fill in 60 seconds
The hole will not fill in at all
None of the above
Imagine a phospholipid bilayer that is found in the hooves of reindeer migrating across the Arctic tundra. A. What changes to the membrane would make the
membrane stay more fluid at lower temperatures?
B. How do you think the membrane structure would differ in cells of the hooves compared to cells in the stomach?
i
What types of molecules can easily move across a phospholipid bilayer? What types of molecules have difficulty crossing the bilayer? Why?
Arctic willow
8. Fill in the table below:
Simple Diffusion
Proteins needed? Energy (ATP) needed? Direction of movement (up/down concentration gradient)?
Example of substance moved?
Facilitated Diffusion
Osmosis
Active Transport
s food for caribou, musk oxen, and arctic hares. How could
desaturases help the plant maintain membrane fluidity in cold temperatures?
Glucose moves in and out of liver cells and potassium (K+) moves into nerve cells down their concentration gradients through transport proteins. Glucose transport proteins bind a glucose molecule, change shape and deposit a glucose molecule on the opposite side of the cell membrane. The proteins that transport K+ are gated, they are activated by an electrical signal and open, allowing many K+ to rush into the cell. Which of the following statements is accurate? Select all correct choices.
A. glucose and K+ move across membranes by passive transport
B. glucose and K+ move across membranes by active transport
C. glucose and K+ move across membranes by facilitated diffusion
D. glucose moves through a channel protein and K+ moves through a carrier protein E. glucose moves through a carrier protein and K+ moves through a channel protein F. glucose moves through a channel protein and K+ moves through a pump
G. both glucose and K+ move through pumps
A. A solution of 1M glucose is separated by a selectively permeable membrane from a solution of 0.2 M fructose and 0.7 M sucrose. The membrane is not permeable to the sugar molecules.
Indicate which side initially is hypotonic, and which is hypertonic. Show the direction of water movement.
B. If the U-tube shown above had 2M glucose on the left-hand side instead of 1M glucose, how would that impact the rate of osmosis? Explain.
Salmon are amazing fish! They spend their early life in rivers, and then swim out to the ocean where they live most of their adult lives. When they are mature, they return to their natal river to spawn. It is believed that they use magnetoreception to locate the general position of their natal river and then use smell once they are close to find their natal spawning ground.
When salmon are in the ocean, their cells are __________ to their saltwater environment. When salmon are in the river, their cells are ___________ to their freshwater environment.
You are a doctor. You give a patient an IV of pure water. What would happen?
a. Their blood cells would shrink.
b. Their blood cells would burst.
c. The patient would slowly become rehydrated.
d. You would be promoted for your outstanding level of medical care.
A small number of people have been identified with nonfunctional aquaporin-1. Aquaporin-1 is a type of aquaporin found in kidney cells. Individuals without aquaporin-1would have a deficiency in which cellular process? Explain.
If you placed a plant cell in a hypertonic solution, what would happen? a. water would leave the cell, it would shrivel and die
b. water would enter the cell, it would explode
c. water would leave the cell, but it would not be harmed
d. water would enter the cell, but it would not be harmed e. None of the above
What is the molecule shown below? Explain how it is used to move substances across a membrane against their concentration gradient.
List and describe the three types of endocytosis discussed in lecture. Rank them in order of most to least selective. 1.
2. 3.
Explain how the cholesterol, carried in LDL complexes, enters your cells. Draw and label a lipoprotein complex.
