SI Worksheet 7
1. What does amphipathic mean? How does that apply to biological membranes?
Amphipathic means dual in nature. Phosphate groups are hydrophillic and the 2 fatty acid
chains are hydrophobic.
2. Water soluble materials cross the plasma membrane more readily than lipid soluble. T or F
3. Which direction of movement is most prevalent in the plasma membrane?
Lateral movement…. Vertical movement or flip-flopping is rare
4. What 2 things do the saturation level of fatty acid chains affect in a biological membrane?
Fluidity- a membrane with a lot of unsaturated fats would be more fluid and one with saturated
would be more viscous
Permeability
5. What other type of lipid molecule affects the fluid nature of the plasma membrane?
Cholesterol
6. What are the functions of the carbohydrate chains found on the outside of the cell?
Cell-cell recognition
Adhesion between cells
Immune system responses
7. Where would a trans-membrane protein be synthesized in the cell?
Rough ER, remember the orientation in which these membrane proteins are attached to the
vesicles during trafficking is the same orientation that they will be placed on the cell surface.
8. What kind of permeability describes biological membranes?
Selectively permeable
9. What is the biological importance function of microvilli on a cell surface?
Microvilli increase surface area, which leads to increased diffusion.
10. Diffusion uses ATP and is classified as passive? T or F
11. Describe a counter current exchange system? How is it important biologically, where can it be
found?
It can be found in the gills of a fish.. Fully oxygenated water moves in the opposite direction as the
blood… using this system fish can maximize diffusion all along the stream….
12. If fish didn’t use counter current exchange system what would happen to the its oxygen levels?
Its O2 percentage would be would max at 50 percent. Because it would reach equilibrium without a
gradient
13. Diffusion of water is ______.
Osmosis
14. Define
a. osmotic concentration- total solute concentration of a solution
b. osmotic pressure – measure of the tendency for a solution to take up water when separated
from pure water by a selectively permeable membrane, solute concentration goes up as osmotic
pressure goes up
15. 3 Problems
16. Specific linkage between mono and polysaccharides is a ________.
Glycosidic linkage
17. The measure of attraction for electrons an atom posseses in a covalent bond is its _________.
Electronegativity
18. Ribosomal RNA is made in the ___________.
Nucleolus
19. Proteins are broken down into amino acids by __________.
Hydrolysis reactions
20. The bond within a water molecule is a __________.
Polar covalent bond