Study Guide 6 Membrane Structure and Transport Study Guide Readings: Biology in Focus 5.1-5.5 PDF

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chapter 6 study guide for weekly quizzes...

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Name ___ Group_______________ Membrane Structure and Transport Study Guide Readings: Biology in Focus 5.1-5.5

Biological Membrane: Cell membranes are selectively permeable barriers. •

Correlate the structure of different cell membrane components (e.g. phospholipids, cholesterol, oligosaccharides, integral and peripheral membrane proteins) with their functions, and predict how changes in membrane composition can affect membrane structure and fluidity.

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Compare different modes of transport of molecules across cell membranes with respect to pathway and energy source and predict how transport across membranes is influenced by physical, electrical, and chemical factors.

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Describe how active transport of ions by protein pumps generates an electrochemical gradient that can drive the passive transport of ions through protein channels.

•

Given an example of differences in solute concentration across a selectively permeable membrane, predict the directionality of net movement of water and the result in plant and animal cells.

•

Compare different ways in which large molecules are transported in bulk across membranes and elaborate the role of cell structures like receptors in this transport.

Compare and contrast the permeability of the lipid bilayer to non-polar molecules, ions, and polar molecules.

List 5 molecules that freely diffuse across the bilayer.

Describe how the hydrophobic interactions in the membrane contribute to the fluidity of membrane.

Why is cholesterol considered a ‘fluidity buffer’?

Lipid rafts are small denser regions of the plasma membrane that contain a high number of transmembrane proteins, saturated phospholipids and cholesterol molecules relative to the surrounding membrane. Label the phospholipid bilayer, integral, peripheral and transmembrane proteins, cholesterol, extracellular side, cytoplasmic side, glycoproteins, glycolipids, oligosaccharides, lipid raft region

Explain the pathway of the synthesis of all 4 membrane components and their orientation in the membrane. How does the interior lumen side of the organelles become the exterior facing side of the plasma membrane in this process?

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Describe six functions of the plasma membrane proteins.

Compare and contrast these broad types of membrane proteins: Transmembrane: Peripheral proteins: Glycoproteins: Transport proteins: Aquaporins: Carrier proteins:

Membrane Transport Distinguish between solute, solvent and solution.

List three factors that affect the rate of diffusion.

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Outline the conditions required for the following methods of membrane transport:

Simple diffusion

Concentration gradient

Membrane proteins required

ATP (source of energy)

yes

no

no

Osmosis Facilitated diffusion Active transport

Five dialysis bags, constructed from a semi-permeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed) and the percent change in mass of each bag was graphed. What is the independent and dependent variable in this investigation?

Explain which line represents the bag that contained a solution isotonic to the 0.6 molar solution at the beginning of the experiment.

Explain which line represents the bag with the highest initial concentration of sucrose.

Explain which line or lines represent(s) bags that contain a solution that is hypertonic to the surrounding solution at the end of 60 minutes.

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Transport in plants: Roots were cut off from barley plants and were used to investigate phosphate absorption. Roots were placed in phosphate solutions and air was bubbled through. The phosphate concentration surrounding the roots was the same in each case, but the percentage of oxygen in the air was varied.

Create a graph and analyze the following data on the rate of phosphate absorption in barley roots. Data point Oxygen (%)

Phosphate absorption (mmol/gh)

P

0.1

0.07

Q

0.3

0.15

R

0.9

0.27

S

2.1

0.32

T

21.0

0.33

Label the X and Y axes with the correct variable.

Plot the data points P, Q, R, S, and T from the data set onto the graph.

Provide a hypothesis as to why the rate of phosphate uptake reaches a maximum even in the presence of increased phosphate concentrations.

Explain the researcher’s hypothesis: Increased oxygen levels around the plant cells will increase the rate of glucose uptake.

Provide a hypothesis as to why the rate of phosphate uptake reached a maximum even in the presence of increased oxygen concentrations.

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An mRNA coding for a protein was isolated from the membranes of cells in which water diffuses rapidly across the membranes. When the mRNA was inserted into oocytes, which do not normally synthesize the protein, the water permeability of the oocytes was greatly increased. State the name of the protein coded for by the mRNA.

Where does the mRNA come from in this experiment?

Why is it important that the oocytes used in this investigation do not normally synthesize aquaporins?

Provide a mechanism to explain how the mRNA from one species can be used to make proteins in a different species.

Which of the following organelles are involved in the synthesis of a secreted protein? A: Nucleus, DNA, and RNA B: Nucleus, RER, Mitochondria C: RER, Golgi, Plasma Membrane D: Ribosomes, RER and Golgi E: Nucleus, RER, Golgi, Vesicles, Plasma Membrane

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State the independent and dependent variables.

Why did the cells with the aquaporin mRNA increase in volume?

What happened at point X?

What would the data look like if the two cells had been placed in a hypertonic solution? A: Both cells would lose water, shrivel and die B: Both cells would gain water, expand and burst C: Only the cell with the mRNA would lose water, the other would remain unchanged. D: Only the cell without the mRNA would lose water, the other would remain unchanged. E: Neither cell would change volume. What would the data look like if the two cells had been placed in an isotonic solution? A: Both cells would lose water, shrivel and die B: Both cells would gain water, expand and burst C: Only the cell with the mRNA would lose water, the other would remain unchanged. D: Only the cell without the mRNA would lose water, the other would remain unchanged. E: Neither cell would change volume.

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Label the diagram with the sequence of how the Na+/K+ works with ATP to pump ions across the membrane.

Explain why the sodium-potassium pump results in a net positive charge across the cell membrane.

Distinguish between phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Propose a hypothesis about how the processes of endocytosis and exocytosis help maintain a constant cell size.

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