PCB 3703C Lecture Notes - Lecture 4: Active Transport, Glut4, Extracellular Fluid

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31 Aug 2017

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Includes: simple diffusion, osmosis and facilitated diffusion: passive transport the net movement of molecules and ions across a membrane. Factors that affect simple diffusion are size of solute, the conc. of. Simple diffusion: when solute or molecule moves from concentrated area to solute, permeability of membrane to that solute and type of structure of solute or substance a low conc. area. Hydrophilic: solutes must cross cell membrane through water filled channels or pores. Facilitated diffusion: when 1st molecule/substance helps 2nd molecule transport to target cell (2nd molecule cannot enter target cell without help from 1st molecule) 1 (1) insulin binds to its receptor on cell membrane (2) because of binding it activates intracellular molecules such as. Means that we have two different ions and by consuming atp then we have pumping of these ions such as na+ and k+ pump. Examples are : when axon receives stimulus from the outside, leads to opening of.

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.

BIOL 110 Principles of Biology

1.Describe the structure of a plasma membrane.

2.Define an amphipathic molecule and give an example.

3.Explain the difference between integral and peripheral proteins.

4.Describe the fluid-mosaic model of a membrane.

5.Identify and discuss the function of proteins located in the plasma membrane.

6.Explain the difference between glycoproteins and glycolipids.

7.Why can carbon form chemical bonds with so many elements?

8.Explain the meaning of concentration gradient as it pertains to movement of substances into and out of cells.

9.Explain diffusion and osmosis.

10.What molecule is thought to facilitate the movement of water molecules through a plasma membrane?

11.Explain the difference between active and passive transport across the plasma membrane. Provide examples that occur in the human body.

12.Explain the impact to a cell if placed in a hypertonic solution; include a definition of hypertonic solution and why the change occurs.

13.Identify a similarity and difference between facilitated transport and active transport. Do not state that both move substances across the membrane.

14.Explain the sodium-potassium pump and identify the type of membrane protein involved.

15.Identify and explain the process used by cells to secrete substances.

16.Explain the composition of a plant cell wall and how it differs from the cell wall of a prokaryotic cell.

17.Explain the plasmodesmata and identify the kingdom in which they are found.

18.Define energy and identify the two basic forms of energy.

19.Define entropy.

20.Define metabolism.

21.Explain the difference between exergonic and endergonic reactions.

22.What are coupled reactions and what roles can ATP serve in these reactions?

23.Explain the difference between oxidation and reduction reactions.

24.What is energy of activation?

25.What factors affect the speed of enzymatic reactions?

26.What is an electron transport chain?

27.What occurs at the active site of an enzyme?

28.Define enzymatic inhibition.

29.Define chemiosmosis.

30.Define vitamins and identify their function.

Question 1

Plasma membranes are selectively permeable. This means that

	A.	glucose cannot enter the cell.
	B.	the plasma membrane allows some substances to enter or leave a cell more easily than others.
	C.	plasma membranes must be very thick.

Question 2

Oxygen molecules O₂ crosse a plasma membrane by

	A.	passive transport
	B.	osmosis
	C.	active transport

Question 3

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient.

		A. energy and channel proteins; against (up)
		B. transport proteins that make channels ; down
		C. energy ; down

Question 4

When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place, the water will

		A. move to the side with lower water concentration
	B.	move to the side with higher water concentration
	C.	move to the side with lower solute concentration

Question 5

Kinetic energy differs from chemical energy in that

	A.	chemical energy is a particular form of kinetic energy.
	B.	kinetic energy is the energy of a moving object, whereas chemical energy is the potential energy of molecules.
	C.	kinetic energy is stored energy that has the potential to do work, and chemical energy is the energy of movement.

Question 6

When a cell uses chemical energy to perform work, it uses the energy released from a(n) ________ reaction to drive a(n) ________ reaction.

	A.	exergonic; endergonic
	B.	endergonic; exergonic
	C.	spontaneous; exergonic

Question 7

When an enzyme catalyzes a reaction

		A. it raises the activation energy of the reaction.
		B. it lowers the activation energy of the reaction.
		C. it is used once and discarded.

Question 8

Which of the following statements regarding enzyme function is false?

		A. An enzyme's function depends on its three-dimensional shape.
		B. Enzymes are very specific for their substrates.
		C. Enzymes are used up when they catalyze a chemical reaction so must be synthesized for each new chemical reaction

PCB 3703C Lecture Notes - Lecture 4: Active Transport, Glut4, Extracellular Fluid

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