BIOL 3324 Lecture Notes - Lecture 3: G Protein–Coupled Receptor, Juxtacrine Signalling, Tight Junction

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magentafly481

21 Sep 2016

School

University of Houston

Department

Biology

Course

BIOL 3324

Professor

Wayne Chad

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Document Summary

Osmosis= diffusion of water from high to low concentration: aquaporin= pore thru which water moves. Maintains osmotic equilibrium so that there is an equal amount of + and ions. Without the pump, passive leakage disrupts equilibrium. Thus water comes in the cell until equilibrium is established: response to cell swellage: water moves into the cell b/c the outside is hypotonic to the inside thus pumps move ions and solutes out of the cell. Water moves out of the cell and equilibrium is established. Tonicity= comparison of osmolality of one compartment to another: hypotonic= less concentrated, hypertonic= more concentrated, isotonic= equally concentrated. Epithelia= separate outside and inside of the body: tight junction= between cells, nothing can pass thru. Leaky tight junction= cells tightly together but some stuff can get thru: transcellular transport= stuff is transported thru cells. Solute pass across apical and basolateral membrane: paracellular transport= stuff is transported around cells. Solutes move thru the intracellular space between cells.

Related Questions

1. In lecture, we described a simple osmotic pressure gradient when discussing osmosis. For question #1, describe the simple osmotic pressure gradient, in terms of osmotic pressure, that exists across the red blood cell plasma membrane when red blood cells are suspended in a severely hypotonic solution, such as a 0.2% NaCl solution. Use scientific terminology.

2. We mentioned in class that biological systems are always in a state of osmotic equilibrium due to a combination of solute diffusion in some cases and osmosis in others. In this experiment, when you add the red blood cells to a severely hypotonic solution, what substances are moving across the red blood cell plasma membrane to achieve osmotic equilibrium, Na+ and Cl- or water? Explain why based on your understanding of the permeability characteristics of biological membrane. Always use scientific language.

CAN QUESTIONS 1 AND 2 BE ANSWERED DIRECTLY AND ADEQUATLEY PLEASE.

HERE IS AN INTRO TO THE LAB EXPERIMENT

Intro:

We have known for a very long time that the mammalian red blood cell plasma membrane is very permeable to water. Even the introductory biology student understands that if you put mammalian red blood cells in water, they will rapidly swell and break open (hemolyze) due to the rapid osmosis of water into the cell. The experimental question we are asking in today's lab experiment is "Is the high water permability of mammalian red blood cell plasma membrane due solely to the lipid bilayer, or are there water channels present in the membrane?"

Experimental Design:

It has been shown by several investigators that water movement through water channels can be blocked by the known K+ channel blocker, tetraethylammonium chloride (TEAC). Brooks, Regan and Yool (2000) showed that TEAC reduces the water permeability of human water channels expressed in the plasma membranes of frog ocytes. After preincubation of the oocytes for 15 min with 100 microM TEAC, the water permeability of frog oocyte plasma membrane containing human water channels was reduced 20 to 40%. The investigators concluded that treatment of cells with TEAC can be useful in determining the presence of aquaporins in membranes.The specific objective of today's experiment is to uncover the presence of water channels in mammalian red blood cell plasma membrane by determining the effect of tetraethylammonium chloride on the water permeability of mammalian RBC plasma membrane.

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

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________30. If you are investigating the inner structure of a new cell and see that it has a significantly larger amount of RER than other cells. You would conclude the cell does a great deal of____?
A. ATP synthesis

B. protein synthesis
C. DNA synthesis
D. active transport
E. polysaccharide hydrolysis

________31. If a cell comes in contact with a toxic substance such as H2O2, it could survive as long as it has a ___ to digest it.
A. DNA
B. peroxisome

C. mitochondria
D. phospholipids
E. intermediate filaments

________32. Some cells have structures to help them withstand osmotic pressure. For example,
A. Plant cells due to their walls
B. Animal cells due to the sodium/potassium pumps

C. Bacterial cell due to their swimming

D. Viruses due to their protein coats

________33. Evolution occurs only as a cell ____.

A. They undergo mitosis
B. Change in their gene pool
C. They move from one habitat to another

D. They begin to eat different foods

________34. Ribosomes are produced in the

A. nucleoli.
B. chromatin.
C. nuclear envelopes.

D. Golgi complex. E. cisternae.

________35. Algae are often green, but there are red and brown species also. What accounts for this difference in color?
A. The chlorophyll of chloroplasts
B. The pigments in other plastids

C. The presence of a mitochondria
D. The accumulation of cellular wastes

________36. The chloroplast and other like prokaryotes have which of the following that helps with photosynthesis?
A. They live in water based environments
B. They have chloroplasts in their cytoplasm

C. Change color in the dark vs. the sun
D. They have photoreceptor proteins in their membranes or mesosomes.

________37. Located in the membrane, we see a set of proteins called receptors that only connect with or bind to specific substances. This is called __.
A. ligand specificity.
B. hormone selectivity.

C. cell tonicity.
D. water saturation. E. signal resolution.

________38. Of the following statements, we could say that ___ is false.
A. All organisms are composed of cells and cell products.
B. An organism's structure and all of its functions are due to the activities of cells.
C. The cellular organelles are the simplest structural and functional unit of life.
D. Cells come from preexisting cells.
E. Cells are made from nonliving components including the nucleus, cell membrane and cytoplasm.

________39. If it is really true that our cells are the smallest anatomical unit that meets all of the properties of life, then which of the following could imply otherwise?
A. vacuoles
B. centrioles

C. Golgi apparatus
D. mitochondria
E. endoplasmic reticulum

________40. Oxygen is an absolute need for animal and plant cells alike due to the ___.

A. RER
B. Mitochondria
C. Lysosomes

D. DNA

________41. In a plasma membrane, we expect to see the carb/protein structures to extend into the ___, but the secondary messengers to move within the __.
A. extracellular fluid; cytosol
B. cytosol; extracellular fluid

C. intracellular fluid; cytosol

D. cytosol; intracellular fluid

E. extracellular fluid; plasma

________42. Bacteria are found in all of the following habitats:

A. Caves
B. Oceans
C. Animals

D. Everywhere on Earth

________43. Two solutions are separated by a selectively permeable membrane. Solution A has a higher concentration of an impermeable solute compared to solution B. Which of the following do you expect would happen?
A. solute will move from solution A to solution B

B. solute will move from solution B to solution A

C. water will more from solution A to solution B

D. water will move from solution B to solution A E. no movement of solute or water will occur

________44. In the kidney, we notice that almost all of the cells involved in the production of urine have high concentrations of the Na+/K+ pump. Which typically works to push Na+ ___ its concentration gradient by using ___.
A. up; active transport

B. up; facilitated transport
C. up; cotransport
D. down; active transport
E. down; facilitated transport

________45. In the charts of a patient recently admitted to the hospital noted that he was taking a medication called lithium and high doses of calcium supplements. Given this, we would expect the patientâs liver to have a higher than normal amount of __ to purify out the lithium and calcium.

A. lysosomes.
B. centrosomes.
C. mitochondria.
D. peroxisomes.
E. rough endoplasmic reticulum.

________46. We have long observed that our neural cells in the brain cannot replicate or replace themselves due to the lack of ____.
A. produce ATP.
B. divide.

C. produce enzymes.
D. secrete material across their plasma membrane E. conduct electrical signals.

________47. An organismâs structure and function is ultimately due to the structure and function of itâs __.
A. Organs
B. Tissues

C. Cells

D. Nuclei

BIOL 3324 Lecture Notes - Lecture 3: G Protein–Coupled Receptor, Juxtacrine Signalling, Tight Junction

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