8. Phosphate buffered saline (PBS) is often used as an isotonic solution to keep cells happy and alive. Though recipes vary, PBStypically contains 157 mM Na* and 4.5 mM K+, yet inside of the cell that ratio is switched (there is approximately 150 mM K*and only about 10 mM Nat). Why is PBS still considered isotonic? That is, why does putting cells into PBS not create a lot ofosmotic pressure?

Osmosis is the movement of water across the semipermeable membrane driven by the difference in…

Answered: 8. Phosphate buffered saline (PBS) is…

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter5: Membranes And Transport

Section: Chapter Questions

Problem 8TYK

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A8.
6. A carrot, when dried out, becomes soft. There is a way to make it firm and crisp. Explain how and why, using the following guidelines. a) Draw and label a representative cell of the carrot, in its dried state. Be precise in your drawing. b)Describe the type of extracellular solution that is appropriate to add to make the desired change (name and define what type of solution, the net movements of solvent and solutes, etc.). c)Draw a representative cell of the carrot, in its possible state after the change. Represent the movement of water using an arrow to indicate what has happened.
17. Muscle. Contractions which move the body depend heavily on diffusion. Why do we have difficulty moving our fingers etc. when they are cold ?
7. The diffusion constant for the membrane protein fibronectin is approximately 0.7 x 10-12 cm²/sec, whereas that for rhodopsin is about 3 x 10-9 cm2/sec. Calculate the distance traversed (in nanometers) by each of these proteins in 50 msec.
6. Which diagram shows the appearance of a cell with an original Y of -1.2 kPa, after being placed in a solution as shown? A B C D water potential (Y) of external solution / kPa -06 -1-2 -00 -1-5 7. Which pair of factors is inversely proportional to the rate of diffusion? A. Concentration gradient and surface area over which diffusion occurs. B. Distance over which diffusion occurs and size of diffusion molecule. C. Size of diffusion molecule and concentration gradient. D. Surface area over which diffusion occurs and distance over which diffusion occurs. 8. The diagram shows two molecules of glucose. Four possible bonding positions are labelled p, q, r and s; and t, u, v and w. CH,OH CH,OH ОН OH Но ОН Но OH S w u OH OH V When these two molecules condense to form glycogen, where could bonds form? A. p-u or p – v B. p- u or q - w C. p – v or q – w D. p – w or v - w
1. Qualitative thinking: For diffusion, it is important to understand the differences between diffusion rate and diffusive flux. a. Define diffusive flux and diffusion rate and write their equations based on Fick's first law. b. Write an equation that relates the two and show how the units balance on each side. c. Fill in the what happens to diffusive flux and diffusion rate (increases, decreases or stays the same) when the variables in the left column changes as noted: Variable Concentration difference, AC Diffusion distance, Ax Diffusion area, A Diffusion coefficient, D Change Increases Increases Increases Increases Diffusive flux Diffusion rate
5
Some antibiotics act as carriers that bind an ion on one side of a membrane, diffuse through the membrane, and release the ion on the other side. The graph shows the conductance of a lipid-bilayer membrane with a carrier antibiotic as a function of temperature. Conductance 40 39 38 Temperature (°C) 37 36 What can you conclude about the effect of a carrier antibiotic on the conductance of the lipid-bilayer membrane? A carrier antibiotic decreases the conductance of a lipid bilayer, regardless of temperature. A carrier antibiotic can shuttle ions across a membrane only when the lipid bilayer is quite rigid. A carrier antibiotic increases the conductance of a lipid bilayer, regardless of temperature. O A carrier antibiotic can shuttle ions across a membrane only when the lipid bilayer is highly fluid.
5. The diagram on the right illustrates experimental results taken from a publication by Peter Mitchell. Intact rat liver mitochondria were sus- pended in an anaerobic, isotonic KCI solution buffered to pH 7.2 with dilute glycylglycine. The pH of the suspension was monitored with a special, fast acting pH electrode, as illustrated on the right. An aliquot of 3-hydroxy-butyrate solution was added to a final concentration of 2 mM together with a pulse of O2. No other reagents were added prior to addition of the uncoupler FCCP indicated by the red arrow. (a) Under these experimental conditions in which mitochon- drial compartment is the proton concentration being monitored. Ex- plain. (b) When 3-hydroxybutyrate has been supplemented to the mitochondrial suspension, is the rate of respiration supported by substrate oxidation maximal or resting prior to addition of the un- coupler? Explain. (c) Does the pH of the medium increase or decrease upon addition of the uncoupler? Explain.…
2. Best description of a semi-permeable membrane in the context of osmosis. A. A membrane that allows neither solute nor solvent particles to pass through it. B. A membrane that allows solute particles, but not solvent particles, to pass through it. 1. A membrane that aliows solvent particles, but not solute particles, to pass through it. 2. A membrane that allows both solute and solvent particles to pass through it.
1) Draw a model of the plasma membrane to form a cell. Include a tube embedded in the membrane. Show 2 water molecules inside the cell and 12 water molecules outside the cell. Indicate which way the water will move through the aquaporin with an arrow. a) Using your knowledge of membrane transport, which direction will the water molecules move through the aquaporin? Why? b) Why would water have a difficult time crossing the cell membrane? Keep in mind the structure of water in your answer. 2) Develop an explanation for the necessity of having kinks in the hydrophobic tail of the phospholipids that make up cell membranes. a) Develop an explanation for the necessity of having kinks in the hydrophobic tail of the phospholipids that make up cell membranes.
uring dialysis, a semi-permeable membrane with a molecular weight cutoff of 10,000 is used. Select the true statements from the list below (more than one answer could apply) Group of answer choices A monoclonal antibody with a 150 kDa MW is retained and does not diffuse across the membrane A small enzyme with 20 kDa MW diffuses readily across the membrane Buffer salts with molecular weights ranging between 100 and 500 Da diffuse across the membrane until equilibrium (equal concentration) is reached on both sides of the membrane None of the above statements are correct Please answer asap

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