BIO130H1 Lecture 15: lecture 15

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tanelephant390

29 Mar 2017

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Document Summary

The proteins that are involved in membrane transport: multipass transmembrane proteins, create a protein lined path across cell membrane, transport polar and charged molecules b. i. Ions, sugars, amino acids, nucleotides, and cell metabolites. Charged molecules don"t pass well because they don"t interact with the hydrophilic tails well. The transport proteins are selective they transport specific classes. The different cell membranes (plasma membrane vs cell membrane) have different compliments = gives organelles different functions a glucose taken upstream, broken down in cytosol, the transporters are the cell surface of the plasma membrane, not in the organelles. Passive: diffusion = diffusing from high concentration to low concentration this is used when a molecule is able to pass through the hydrophobic component of the membrane. Specialized proteins: channel proteins: create a channel and only move molecules by passive transport, transporter mediated: move molecules by passive or active transport.

Related Questions

During active transport in the neuron, the outside of the cell is _________________ and the inside is _______________.

positive, negative

more positive, less positive

more negative, less negative

negative, positive

In active transport, _____________ provides the energy to move molecules against their concentration gradient.

nucleus

potassium

sodium

adenosine triphosphate

________________ proteins can change shape when moving substances across the membrane.

Proteins that can be open or closed, based on different conditions, are called ___________.

bypass proteins

channel proteins

selective proteins

gated

Tunnels that allow charged ions to move easily across the plasma membrane without the use of energy are called ____________________.

channel proteins

glycolypipd proteins

phospholipid proteins

carbohydrate chains

____________ and ____________ make it easier for molecules to move across the plasma membrane.

small, negatively charged

small, positively charged

small, no charge

large, negatively charged

large, positively charged

1. The plasma membrane of liver cells contains a glucose uniportthat transports glucose by facilitated diffusion. When the[glucose] is higher inside the liver cell than the [glucose]outside the liver cell, the glucose uniport will

A. couple the transport of glucose out of the cell to thehydrolysis of ATP

B. couple the transport of glucose into the cell to thehydrolysis of ATP

C. switch to a closed conformation, allowing no transport ofglucose

D. transport glucose out of the cell by passive transport

E. transport glucose in of the cell by passive transport

2. Unlike the positive charged ion shown in the middle diagramof figure 11-4B, K+ is higher in concentration inside the cell. Howwill the membrane potential of a cell at rest (shown in both themiddle and right-hand diagrams of Figure 11-4B) affect theelectrochemical gradient for K+?

A. The membrane potential will increase the electrochemicalgradient

B. The membrane potential will decrease the electrochemicalgradient

C. The membrane potential will have no effect on theelectrochemical gradient

3. Which of the following proteins carries out activetransport?

A. gluclose symport

B. Bacteriorhodopsin

C. ABC transporter

D. NA K pump

E. All of the above

4. Aquaporin will not transport Na+ ions because

A. Two asparagine residues in the channel prevent the passage ofNa+ ions by binding the oxygen of each water molecule as it passesby

B. Na+ ions are repelled by the positive charges at the entranceto the channel

C. Na+ ions cannot make contact with the carbonyl (C=O) groupson all four sides of the channel

D. The passage of Na+ ions is energetically unfavorable becauseone side of the channel is hydrophobic in nature

5. The acetylcholine receptor is different from other channelproteins we have discussed, such as the K+ leak channel,because

A. The acetylcholine channel is composed of a single polypeptiderather than multiple subunits

B. The acetylcholine channel transports Na+ ions against theconcentration gradient for sodium

C. The acetylcholine channel has a much smaller diameter thanother channel proteins

D. The acetylcholine channel transports ions with theirassociated shell of water molecules

E. The acetylcholine channel is always open, and never switchesto a closed conformation

6. After opening briefly along the axon of a neuron,voltage-gated ion channels switch to an inactivated conformationthat slowly returns to the original closed conformation of theprotein. This slow change in conformation, requiring about amillisecond, is important because

A. all of the ions that were transported across the membranewhen the ion channels were open must be actively transported backto the other side of the membrane, restoring the originalconcentration gradient, before the ion channels can open again

B. ATP hydrolysis is necessary to drive this energeticallyunfavorable change in conformation

C. it prevents the action potential from reversing direction andtraveling back toward the cell body of the neuron

D. the channel protein must be dephosphorylated in order tocomplete the transport process and return to the originalnonphosphorylated conformation

limeelephant476

1. Which of the following pairings are/is correct?

Cholesterol: has a hydrophilic and hydrophobic end
Cholesterol: does not have a hydrophilic end since it is a lipid
Cholesterol: is often times wedged in between the phospholipids
1st and 2nd choices only
1st and 3rd choices only
2nd and 3rd choices only
All of the above
None of the above

2. Which of the following pairing/s is/are correct?

Cholesterol: helps maintain the integrity of the cell membrane
Cholesterol: the rigid four carbon rings prevent lipid tails from packing too closely
Cholesterol: the rigid four carbon rings also prevent the membrane from being too fluid
1st and 2nd choices only
1st and 3rd choices only
2nd and 3rd choices only
All of the above
None of the above

3. Which of the following pairing/s is/are correct?

Membrane proteins: help maintain concentration gradients
Concentration gradient: the difference of amounts of solutes on two sides of a solution
Solutes: are the substances dissolved in a solution
1st and 2nd choices only
1st and 3rd choices only
2nd and 3rd choices only
All of the above
None of the above

4. Which of the following pairing/s is/are correct?

Molecules: move around randomly on their own
Molecules: when concentrated create an unstable environment due to increased collisions of molecules
Diffusion: is the movement of molecules from a region of low concentration to a region of high concentration
1st and 2nd choices only
1st and 3rd choices only
2nd and 3rd choices only
All of the above
None of the above

5. Which of the following pairing/s is/are correct?

Passive movement: movement of molecules that is energetically favorable b/c free energy is released in the process
Passive movement: requires energy from outside of the system
Passive movement: occurs as molecules move up their concentration gradients
1st and 2nd choices only
1st and 3rd choices only
2nd and 3rd choices only
All of the above
None of the above

6. Which of the following pairings/s is/are correct?

Active movement: is a passive process
Active movement: is an energetically unfavorable process
Active movement: releases free energy
1st and 2nd choices only
1st and 3rd choices only
2nd and 3rd choices only
All of the above
None of the above

7. Which of the following pairing/s is/are correct?

Transport channels: allow movement of all ions through
Transport carriers: allow movement of all ions through
Channels : passive movement
Carriers: active movement
1st and 2nd choices only
1st and 3rd choices only
1st, 2nd, and 3rd choices only
2nd and 3rd choices only
All of the above
None of the above

8. Which of the following paring/s is/are correct?

Active transporters: movement of molecules up their concentration gradients
Active transporters: require energy
Active transporters: ATP dependent pumps, antiporters, symporters
1st and 2nd choices only
1st and 3rd choices only
2nd and 3rd choices only
All of the above
None of the above