Detailed study guide for the 2nd bio test. Includes all material needed for the 2nd test and tophat questions as well as diagrams needed.
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Diffusion and Osmosis
● Explain the process of diffusion and identify factors that affect the rate of diffusion
○ Random motion of substances resulting in net movement from areas of high
concentration to areas of low concentration.
○ Not energy requiring
○ FACTORS:
■ Temperature
■ Mass of the molecule
■ Gradient size
■ Pressure differential
■ Surface area
■ Type of membrane
● Describe the process of osmosis and use your knowledge to make predictions
○ Net diffusion of water across a selectively permeable membrane (from HIGHER to
LOWER concentration).
○ Has to have a difference in concentration.
TOP HAT QUESTIONS
Which of the following factors influence the diffusion rate of a molecule?
(A) - temperature
(B) - pressure differential
(C)- mass of the molecule
(D)- gradient size
A red blood cell is placed in a solution that has a higher concentration of impermeable
solutes than the inside of the cell. What will happen?
A
Cell will increase in size
B
Cell will decrease in size.
C
Cell will swell and burst.
D
Nothing happens to cell.
Cell Membranes
● Explain why the structure of cell membranes is referred to as a fluid mosaic
-describes cell membranes as a combo of phospholipids and proteins that move.
-describes how parts of the membrane can move around freely.
, TEST 2
● Describe how cholesterol and other variables affect membrane permeability in animals
-At high temperatures, cholesterol decreases fluidity and at low temperatures cholesterol
increases fluidity. ... In this way, the cholesterol makes the lipid bilayer more rigid and
decreases the lipid bilayer's permeability to small, water-soluble molecules.
● Identify various types of proteins that enable passive and active membrane transport.
(1) Carrier proteins=reversibly change their shapes to enable the passive diffusion of
certain substances. Highly selective, has to bind to the substance(protein), change
the shape, and then release it. SLOWER than channel proteins.
(2) Channel proteins= form openings in the cell membrane that allow passive diffusion of
certain substances. Highly selective, very quick, and can also be gated.
(3) Pumps= reversibly change the shape to actively transport substances, usually
against their concentration gradient (from low to high). Highly selective, require
energy(Active transport).
● Compare passive, active, and bulk transport.
Passive transport: does not require input of energy
Bulk transport: used to engulf or expel substances. Requires energy
Active transport: requires input of energy
TOP HAT QUESTION
How would the fluidity and permeability of cell membranes in animals change if the amount
of cholesterol in the membranes increased?
A- increase
B- decrease
C- no change
Explanation: will restrict movement through hydrophobic reactions, also will take up space causing it
to be more difficult to move through.
Which of the following will increase the fluidity and permeability of cell membranes in
animals?
A- reduce length of fatty acids in phospholipids
B- reduce cholesterol amount in the membranes
C- reduce fatty acid saturation in phospholipids
D- add double bonds to phospholipid fatty acids.
Explanation: unsaturated phospholipids increases fluidity
Energy Processes
● Describe the structure of ATP and explain its function of energy coupling in cells
○ a molecule that is used by all cells to temporarily store and transfer energy
○ Three phosphate groups, adenine ring, and a ribose sugar.
○ Energy is released from ATP by removing phosphate groups to form ADP and AMP.
○ Unstable, bulky, and not good for long term energy storage
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