Question

membrane transport
learning objective 11.1: define passive and active transport and explain the role of channels, carriers, and pumps in transport. the cell membrane
learning objective 10.5: given several models of membranes, predict how differences in phospholipid composition and cholesterol and permeability, and explain your reasoning.
0/1 point earned
to synthesize what youve learned about the molecules and processes involved in cell membranes, work with your study group to think of an example (or two, or three) that illustrates each of the following general statements. in each case, explain your logic.

• the structure of molecules and molecular machines makes their functions possible.
• in cells, important things often happen when one molecule binds to another.
• many or most events that occur at the cell membrane are highly regulated.
• cells and cell membranes are dynamic - their structure and their activity change over time.
• cells can do the work needed to sustain life using sources of energy like atp.
• many or most of the events and processes at the cell membrane are extremely specific in terms of the ions and molecules involved and the outcomes.

for example, you might discuss how membrane pumps do or do not relate to each statement. try doing the same with membrane channels or the composition of the lipid bilayer.
b i u t^ t_ i_x : = i=
0 / 10000 word limit

Explanation:

1. The structure of molecules and molecular machines makes their functions possible: Ion - channel proteins have a specific structure with a pore. This structure allows them to selectively allow certain ions to pass through the cell membrane, which is their function.
2. In cells, important things often happen when one molecule binds to another: When a neurotransmitter molecule binds to a receptor molecule on the postsynaptic cell membrane, it can trigger an electrical signal in the cell, which is crucial for nerve - impulse transmission.
3. Many or most events that occur at the cell membrane are highly regulated: The opening and closing of voltage - gated ion channels in neurons are regulated by changes in the membrane potential. This regulation ensures proper nerve - impulse generation and propagation.
4. Cells and cell membranes are dynamic - their structure and their activity change over time: During cell division, the cell membrane undergoes changes in shape and composition. Also, in response to environmental stimuli, the number and distribution of membrane proteins can change.
5. Cells can do the work needed to sustain life using sources of energy like ATP: Sodium - potassium pumps use ATP to actively transport sodium ions out of the cell and potassium ions into the cell. This helps maintain the ion gradients necessary for many cellular functions such as nerve - impulse transmission and muscle contraction.
6. Many or most of the events and processes at the cell membrane are extremely specific in terms of the ions and molecules involved and the outcomes: Glucose transporters are specific membrane proteins that only transport glucose molecules into the cell. This specificity ensures that only the required molecule is taken up for energy production and other metabolic processes.

Answer:

1. Ion - channel proteins' structure enables ion passage.
2. Neurotransmitter - receptor binding triggers nerve signals.
3. Voltage - gated ion channel opening/closing is regulated.
4. Cell membrane changes during cell division and in response to stimuli.
5. Sodium - potassium pumps use ATP for ion transport.
6. Glucose transporters specifically transport glucose.