MODULE 7: Membrane transport, Lecture 15
Quadrant-2
Animations:
Concepts in Biochemistry - Interactive Animations - Wiley
www.wiley.com/.../animations/membrane_transport/membrane_transport...
Cellular. Transport. Active. Overview. Membranes. Diffusion/. Osmosis. Passive.
rewind. continue. Question: The same model is presented below, but glucose ...
Essential Biochemistry - Membrane Transport - Wiley
www.wiley.com/college/.../animations/membrane_transport/index.html
Molecules and Membranes. Membrane ... Gain an understanding of the importance of
membrane transport. to living cells. ... processes are animated. in the Main ...
3D Animation - Membrane Transport - McGraw-Hill Higher Education
highered.mcgraw-hill.com/.../3d_animation_-_membrane_transport.html
3D Animation - Membrane Transport (See related pages). (47.0K). MEMBRANE
TRANSPORT 3D ANIMATION Click here to play the animation.
Passive Transport
programs.northlandcollege.edu/biology/.../animations/passive1.swf
transport. In this animation, we will be focusing on three. specific types of passive
transport: simple diffusion ... (beginning with a quick tour of the cell membrane).
Active transport
programs.northlandcollege.edu/biology/.../animations/transport1.html
Transport. Membrane. Menu. passive. transport. active. Main. Back. Next. active
transport ... In this animation, we will be focusing on three. specific types of ...
Molecules Move across the Cell Membrane - Animation
www.sumanasinc.com/webcontent/animations/content/diffusion.html
Loading. 1 of. 4. Molecules Move across the Cell Membrane. Go to… Scene. Sumanas,
Inc. X. 1 Simple Diffusion. 2 Facilitated Diffusion. 3 Active Transport.
Membrane Transport - Johnwiley.net.au
www.johnwiley.net.au/highered/interactions/media/.../cell2a/screen0.swf
Primary active transport - support for electrochemical gradient. 6.2. ... Animation.
Create a Transport Condition -. Exercise. Membrane Transport Match-Up -.
Membrane Channels - PhET
phet.colorado.edu/en/simulation/membrane-channels
Insert channels in a membrane and see what happens. See how different types of
channels allow particles to move through the membrane.
Transport Across Cell Membranes - SlideShare
www.slideshare.net/wcadigpub2009zs/transport-across-cell-membranes
Nov 3, 2009 - Animation http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/ce/m3/s6/index.htm.
Transport review; Membrane Transport. III.
Page 1 of 16
Membrane Transport
mrphome.net/mrp/Membrane_Transport.html
Observe the animation below to see DIFFUSION. DIFFUSION is defined as "the
movement of particles FROM an area of HIGH concentration TO an area of LOW ...
Membrane Transport: Animation Illustrating the Action of an Antiporter
www.microbelibrary.org/library/resources/3122-antiporters
Jun 14, 2007 - Antiporters are transport proteins that simultaneously transport two
substances across the membrane in opposite directions; one against the ...
Membrane Transport - Pearson
wps.aw.com/bc_martini_eap_5/211/54159/13864872.../index.html
When you are done, click "Submit Answers for Grading". Watch the Membrane
Transport animation. Screenshot of Membrane Transport animation. Download ...
Plasma Membrane & Cellular Transport - Town of Hull www.town.hull.ma.us/public_documents/hullma.../Cell%20Membrane
Click on the links below view graphics, animations, and tutorials regarding the
PLASMA MEMBRANE & CELLULAR TRANSPORT!! Everything: Cell Membrane ...
Membrane Transport - KScience
www.kscience.co.uk › Animations
Membrane Transport. Home > Animations > Membrane Transport. G. Download the
file. ATP. Na. K. ADP. P. Download the file. W. Download the file. ATP. G. Na.
Diffusion, Osmosis, and Movement Across a Membrane
www.uic.edu/classes/bios/bios100/lectures/diffusion.htm
Factors Affecting Diffusion Across a Plasma Membrane. Diffusion ... Animation crossing a semi-permeable membrane. Osmosis, the Passive Transport of Water.
CELL MEMBRANE & CELL TRANSPORT (PASSIVE and ACTIVE ...
www.d214.org/assets/2/workflow_staging/Documents/10060.PDF
http://www.wiley.com/college/pratt/0471393878/student/animations/ ... Which part of
the membrane might function to transport hydrophillic or WATER. LOVING ...
WEB ANIMATIONS AND INFORMATION - Department of Chemistry
https://www.chem.purdue.edu/courses/chm333/web%20Site%202.htm
http://www.wiley.com/legacy/college/boyer/0470003790/animations/acideroids/ ....
Membrane Transport Tutorial from Pratt and Cornely Essential Biochemistry.
Membrane Transport | Anatomy and Physiology | Cellular Form ...
https://www.inkling.com/read/anatomy-and...6th/.../membrane-transport
Free interactive eBook preview | 3.3 Membrane Transport Expected Learning ... These
include active transport and vesicular transport. ... Explore: Animations.
Diffusion, osmosis and active transport - ABPI - Resources for Schools
www.abpischools.org.uk › Home › Interactive content › All topics
In active transport a special transport protein in the cell membrane picks up the
Membrane Transport Animations
www.everettsd.org/.../Membrane%20Transport%20Animations%201112...
Membrane Transport Animations Name. Using the following website to fill out and
answer the questions on this worksheet.
Page 2 of 16
Illustrations:
Lipid Transport And Storage - SlideShare
www.slideshare.net/drknpk/lipid-transport-and-storage
Feb 6, 2010 - An interactive lecture on lipid transportation and storage in humans. ...
Triacylglycerol Transport; Bood circulation Harper's Illustrated ...
MEMBRANE TRANSPORT
www2.yvcc.edu/Biology/.../MembraneTransport/membranetransport.htm
In simple diffusion, small noncharged molecules or lipid soluble molecules pass ...
Illustrations of simple diffusion. ... Illustration of primary active transport.
Principles of Membrane Transport - Molecular Biology of the Cell ...
www.ncbi.nlm.nih.gov › NCBI › Literature › Bookshelf
by B Alberts - 1994 - Cited by 5 - Related articles
The relative permeability of a synthetic lipid bilayer to different classes of molecules.
.... These molecules provide a simple illustration of some of the principles ...
Lipid Digestion, Absorption and Transport
www.unifr.ch/biochem/assets/files/schneiter/cours/Voet/Voet25.pdf
Transport. Major form of energy: triacylglycerol/fat/triglycerides o 90% of dietary lipid
... Hydrolyzed lipids are absorbed by the intestinal mucosa ...... Examples:.
Diffusional transport in responding lipid membranes†
www.uam.es/personal_pdi/ciencias/mvelez/.../TransportAcross.pdf
by E Sparr - 2009 - Cited by 7 - Related articles
Diffusional transport across lipid membranes can be highly complex and include
several parallel ... This is illustrated for a lipid membrane in the presence of.
Lipoproteins: Lipid Digestion & Transport
www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/lipoprot.htm
Digestion and transport of lipids poses unique problems relating to the ... Examples
include synthetic resins, as well as soluble fiber (e.g., oat bran fiber and fruit ...
Endogenous Lipid Transport System - Netter Medical Illustrations
www.netterimages.com/image/3170.htm
Rights-managed illustration of Endogenous Lipid Transport System from the Netter
Collection, drawn by Craig, Machado.
Material Transport Across Permeability Barriers by Means of Lipid ...
www.physics.uoguelph.ca/~dutcher/download/.../9.pdf
by G CEVC - 1995 - Cited by 54 - Related articles
Material transport with lipid vesicles. 469. Agents, additives and ..... From the
illustrated pressure profile the maximum resulting force is estimated to be of the ...
metabolism and lipid transport
www.pnas.org/content/87/3/909.full.pdf
by J Peterson - 1990 - Cited by 200 - Related articles
generating step in transport of fatty acids from lipoprotein triacylglycerols into ...
metabolism and handles more than 100 g of lipid per day in individuals on a ...
Page 3 of 16
Function of prokaryotic and eukaryotic ABC proteins in lipid transport
www.ibpc.fr/UMR7099/Publis/pdf/Pohl05.pdf
by A Pohl - 1733 - Cited by 114 - Related articles
Additionally, lipid transport by ABC proteins is currently being studied in non-human
.... Examples for the sphingolipid moiety Y are hydrogen (in ceramide), ...
How Are Lipids Transported Through the Body? | LIVESTRONG.COM
www.livestrong.com › Food and Drink
Jul 17, 2011 - The manner in which lipids are transported in your body is essential for ...
in the bloodstream Photo Credit Stockbyte/Stockbyte/Getty Images ... Because lipids
are insoluble in water, they require a special transport vehicle to ...
Chapter 25. Lipid Transport & Storage - AccessMedicine - McGraw ...
accessmedicine.mhmedical.com/content.aspx?bookid=389&sectionid...
Harper's Illustrated Biochemistry, 29e > ... Understand how the liver plays a central
role in lipid transport and metabolism and how hepatic VLDL secretion is ...
Lipids, Membranes & Vesicle Trafficking - BioChemWeb.org by ...
biochemweb.org/lipids_membranes.shtml
by Gabriel Fenteany ... dealing with lipids and membrane structure, function, dynamics
and transport, vesicle ... On-Line Biology Book - Information and illustrations by M.J.
Farabee.
Biological Membranes and Membrane Transport Mechanisms
themedicalbiochemistrypage.org/membranes.php
Nov 14, 2013 - Biological membranes are composed of lipid, protein and carbohydrate
that exist in a .... examples of various membrane transport mechanisms.
Golgi Apparatus, Proteins, Transport | Learn Science at Scitable
www.nature.com/.../how-do-proteins-move-through-the-golgi-1439731...
by PL Connerly - 2010 - Cited by 1 - Related articles
The Golgi apparatus is central to the transport and modification of proteins in ...
apparatus is the central organelle mediating protein and lipid transport within the ...
Two schematic illustrations show two models of protein movement through the ...
Passive Transport
programs.northlandcollege.edu/biology/biology1111/.../passive1.swf
transport. In this animation, we will be focusing on three. specific types of passive ...
lipid. bilayer. houses the proteins and limits. what goes in and out of the. cell.
Coordinated Lipid Transfer between the Endoplasmic Reticulum ...
www.molbiolcell.org/content/19/9/3871.full.pdf
by D Peretti - 2008 - Cited by 107 - Related articles
Lipid transport between intracellular organelles is mediated by vesicular and .....
Images were processed using Adobe Photoshop (Adobe Systems, Mountain.
Biology4Kids.com: Cell Function: Active Transport
www.biology4kids.com/files/cell2_activetran.html
Transport through the membrane Active transport usually happens across the cell
membrane. There are thousands of proteins embedded in the cell's lipid ...
Page 4 of 16
A Molecular Mechanism for the Transport of ... - thomashaines.org
www.thomashaines.org/publications/Liebovich.pdf
This added an important insight into the properties of lipid bilayers above the transition
.... He made several assumptions as illustrated in Figure l. I. For a linear ...
Video demonstrations:
Membrane Transport Video Lecture, IIT Kharagpur ►►
freevideolectures.com › ... › IIT Kharagpur
Membrane Transport Video Lecture, IIT Kharagpur Course, Bio Technology, Youtube
Free Download, video ...
Transport Across Cell Membranes - YouTube ► 13:58► 13:58
www.youtube.com/watch?v=RPAZvs4hvGA
Jul 11, 2011 - Uploaded by Bozeman Science
016 - Transport Across Cell Membranes Paul Andersen describes how cells move ...
You need Adobe Flash ...
Cell Membrane - Passive and Active Transport - (diffusion , osmosis ...► 13:54► 13:54
www.youtube.com/watch?v=gOxRXn5r9Jo
Nov 3, 2012 - Uploaded by Kabi. This Video Covers the following section Methods of
Transport across the Plasma Membrane - Role of ...
Video: cell membrane active transport | Educational Video ...
www.watchknowlearn.org › ... › Human Anatomy
An educational video for kids. This 1:26 video is about cell membranes. The cell
membrane is surprisingly flexible, despite it being the The lipids in the ...
Cell Transport - Biology Video by Brightstorm ► 6:43► 6:43
www.brightstorm.com/science/.../cell-transport/
Explanation. Cell transport is movement of materials across cell membranes. Cell
transport includes passive ...
Cell membrane transport - TeacherTube ►►
www.teachertube.com/viewVideo.php?video_id...
Introduction to active and passive transport. ... TeacherTube - Cell membrane
transport. Username: Password ...
BiologyCorner: 30S Membrane Transport Videos
biologycorner2013.blogspot.com/.../30s-membrane-transport-videos.ht...
Sep 22, 2013 - Crash course on Membrane Transport:
https://www.youtube.com/watch?v=dPKvHrD1eS4 2. Short video on Endocytosis and
Exocytosis: ...
Membrane transport proteins Protocols and Video Articles - JoVE
www.jove.com/keyword/membrane+transport+proteins
Video articles in JoVE about membrane transport proteins include "Models and
Methods to Evaluate Transport of Drug Delivery Systems Across Cellular ...
Page 5 of 16
Transport Videos - Use the Last Word on Page 125 of
www.linkpublishing.com/video-transport.htm
CELL TRANSPORT VIDEOS ... Links to Transport Videos and Animations. ... to an
area of low concentration) across a selectively permeable membrane.
Lecture - 15 Membrane Transport - Free Biology Video Lecture
www.learnerstv.com/video/Free-video-Lecture-1782-biology.htm
Free Lecture - 15 Membrane Transport video lecture.
Osmosis/Diffusion/Active Transport - SlideShare
www.slideshare.net/.../osmosisdiffusionactive-transport-presentation
Nov 26, 2008 - It goes through the cell membrane without it opening up. Examples ...
Video link; Effect on living cells Animal Plant; Active Transport. Cell uses ...
Cell Biology Interactive Video Animations - Bio-Alive
bio-alive.com/animations/cell-biology.htm
Amino acids and protein, cell function, cell anatomy, cell membranes, chromosome
structure, diffusion, DNA structure, replication, ... Electron Transport Chain.
Quadrant-3
Multiple choice questions – chose the correct answer:
1. Relative permeability of a phospholipid bilayer to various substances
a) Permeable to CO 2 , N 2 , O 2
b) Not permeable to Glucose and fructose
+
+
c) Not permeable to K , Na , Cl , HCO 3
d) All are correct
2. Which of the following molecules cannot move directly through the membrane by simple
diffusion?
a) O 2
b) N 2
c) CO 2
d) benzene
3. The facilitated diffusion of glucose into erythrocytes uses a mechanism called
a) active transport
b) antiport
c) symport
d) uniport
Page 6 of 16
4. The outward-facing conformation of E. coli lactose permease has a:
a) high affinity for lactose
b) high pK a for the active site Glu residue
c) low affinity for lactose
d) The first and second answers are both correct.
5. Active transport means:
a) The pumping of molecules or ions through a membrane against their concentration
gradient.
b) Requires transmembrane protein, transporter
c) It requires it requires ATP
d) All are true
6. The active transport of Na+ and K+ by the membrane Na+-K+ pump uses energy from:
a) ATP hydrolysis to ADP and P i .
b) ATP hydrolysis to AMP and PP i .
c) symport (or counter-transport) of Cl-.
d) The third and fourth answers are both correct.
7. Which type of membrane transport process uses ATP as a source of energy?
a) Facilitated diffusion
b) Simple diffusion
c) Osmosis
d) Primary active transport
8. Proteins destined for export from the cell are synthesized with a signal sequence and begin
their synthesis
a) on free ribosomes
b) in secretory vesicles
c) in the Golgi complex
d) on smooth ER
9. By a mechanism called cotransport
a) sodium moves outward against is concentration gradient while sugar moves inward
down its concentration gradient
b) sugar and sodium move inward down their concentration gradient
c) sodium moves inward down its concentration gradient while sugar moves inward up
its concentration gradient
d) sodium and sugar move outward against their concentration gradient
Page 7 of 16
10. Substances transported by facilitated diffusion
a) move passively through specific channels from an area of greater concentration to one
of lower concentration
b) must have movements coupled to those of other substances
c) may flow to a region of higher concentration by the expenditure of energy
d) are restricted to only one direction through the membrane
11. Threonine, an amino acid, and arabinose, a monosaccharide, cross the cell membrane
down their concentration gradients by:
a) diffusion.
b) endocytosis.
c) phosphorylation.
d) facilitated diffusion.
12. Which of the following substances normally fails to cross cell membranes under any
circumstances?
a) Water
b) DNA
c) a fatty acid
d) ethanol (ethyl alcohol)
13. What is the difference between active transport (AT) and facilitated diffusion (FD)?
a) AT requires protein carriers; FD does not.
b) AT requires energy; FD does not.
c) AT requires a concentration gradient; FD does not.
d) AT requires a membrane; FD does not.
e) all of the above
14. Symport Pumps functions:
a) the driving ion and the pumped molecule pass through the membrane pump in the
same direction.
b) the driving ion and the pumped molecule pass through the membrane pump in the
opposite direction.
c) It works by simple diffusion
d) None of the above
15. The diffusion velocity of a pure phospholipid membrane will depend on:
a) concentration gradient,
b) size of the substance
c) charge, if the molecule has a net charge.
d) All the above
Page 8 of 16
State whether True or False:
1. Membranes serve as a selective barrier for the cell
2. The outward-facing conformation of E. coli lactose permease has a high affinity for
lactose
3. In an isotonic solution there would be no net movement of water.
4. Differential permeability can also be described as: the allowance of only certain
substances to pass through a membrane.
5. Diffusion occurs when molecules move from a region of lower concentration to a
region of higher concentration
6. Active transport requires a cell to expend energy
7. Receptor-mediated endocytosis enables a cell to pick up and concentrate a specific
kind of molecule.
8. Selective permeability permits the selective uptake of nutrients and the elimination of
wastes.
9. Cellular transportation of molecules through vesicles are called bulk transportation.
10. Golgi apparatus and ER facilitate vesicular transport of molecules for secretion.
Fill in the blanks with appropriate words:
1. __________ molecules cannot move directly through the membrane by simple
diffusion
2. Transport across membranes can take several different forms. No energy input is
required for _________ transport, which has two forms: ________ diffusion, which
occurs without assistance from a protein, and ________ diffusion, which requires a
protein transporter. However, ________ transport requires an input of energy
3. The active transport of Na+ and K+ by the membrane Na+-K+ pump uses energy
from ____________
4. ___________ is a membranous cell organelle produces secretory vesicles
5. _____________ membrane is necessary in order for osmosis to occur.
6. An example for passive transport mechanisms is ______________________
7. The sodium-potassium pump (which carries sodium out of a cell and potassium into a
cell) is an example of ____________ transport.
8. The process of a cell engulfing a solid object is ________________
9. When a cell bursts due to osmosis, it is in a solution that is _____________
10. Plant cells behave differently to animal cells when placed in a hypotonic solution
because plant cells have ________________
11. _____________ determines whether a transport process is passive or active
12. ________________ the uptake of water and small solutes into the cell by formation of
vesicles at the plasma membrane.
13. The movement of molecules across a membrane against their concentration gradient,
at the expense of ATP energy, is called ______________
14. If an animal cell is placed into a drop of 100% pure water it will ________________
Page 9 of 16
Quadrant – 4
Assignments (questions and solutions):
1. What is membrane transport?
2. What is passive transport?
3. Explain the process of simple diffusion
4. What is osmosis?
5. What is facilitated diffusion?
6. Explain the voltage gated channel proteins
7. Explain the ligand gated channel peoeins
8. What is an active transport?
9. Discuss briefly the mechanism of primary active transport
10. Explain the secondary active transport
Supplementary reading:
1. Hille, B. Ion channels of excitable membranes, 3rd ed. Sinauer Associates:
Sunderland, MA, 2001.
2. Stein WD (1967) The Movement of Molecules Across Cell Membranes; Stein, W. D.,
Eds, Academic Press: New York.
3. Karp, G (2008) Cell and Molecular Biology,5th ed. John Wiley & Sons: Hoboken, NJ.
4. Garrett, R and Grisham C (2009) Biochemistry, 4th ed.; Brooks/Cole: Boston.
5. Nikaido, H.; Vaara, M. Molecular basis of bacterial outer membrane permeability.
Microbiological Reviews, 1985, 49, 1-32. PMCID: PMC373015
6. Fischer, H.; Gottschlich, R.; Seelig, A. Blood-brain barrier permeation: molecular
parameters governing passive diffusion. J. Membrane Biol.,1998, 165, 201-211. DOI:
10.1007/s002329900434
7. Cusslera, E.; Arisa, R.; Bhown, A. On the limits of facilitated diffusion. Journal of
Membrane Science, 1989, 2-3, 149-164. DOI:10.1016/S0376-7388(00)85094-2
8. Catterall, W. Structure and function of voltage-gated ion channels. Annual Review of
Biochemistry, 1995, 64, 493-531. DOI: 10.1016/0166-2236(93)90193-P
9. Sheng, M.; Pak, D. Ligand-gated ion channel interactions with cytoskeletal and
signaling proteins. Annual Review of Physiology, 2000, 62, 755-78.
DOI:10.1146/annurev.physiol. 62.1.755
10. Banghart, M.; Volgraf, M.; Trauner, D. Engineering light-gated ion channels.
American Chemical Society, 2006, 45, 15129–15141. DOI: 10.1021/bi0618058
11. Pivetti, C.; Yen, M.; Miller, S.; Busch, W.; Tseng, Y.; Booth, I.; Saier, M. Two
Families of Mechanosensitive Channel Proteins. Microbiology and Molecular Biology
Reviews, 2003, 67, 66-85. DOI: 10.1128/MMBR.67.1.66-85.2003
Page 10 of 16
12. Wimmer M, Rose I (1978). "Mechanisms of enzyme-catalyzed group transfer
reactions". Annu Rev Biochem 47: 1031–78.
doi:10.1146/annurev.bi.47.070178.005123. PMID 354490. Hendrickson W (2005).
"Transduction of biochemical signals across cell membranes". Q Rev Biophys 38 (4):
321–30. doi:10.1017/S0033583506004136. PMID 16600054.
13. Lienhard G, Slot J, James D, Mueckler M (1992). "How cells absorb glucose". Sci Am
266 (1): 86–91. doi:10.1038/scientificamerican0192-86. PMID 1734513.
Wiki development on the course/other resources:
Membrane transport - Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/Membrane_transport
In cellular biology the term membrane transport refers to the collection of mechanisms
that regulate the passage of solutes such as ions and small molecules ... Background Thermodynamics - Transport types - Membrane selectivity
Essential Biochemistry - Membrane Transport - Wiley
www.wiley.com/college/pratt/.../membrane_transport/index.html
LOADING... (later sections may not yet be loaded). 100 %. Introduction. 1. Choose a
Section. Section 1 of 11. Membrane Transport. Previous. Stop. Help ? Play.
Cell Membrane Transport
www2.yvcc.edu/Biology/.../MembraneTransport/membranetransport.htm
One of the functions of membranes is to control what passes into and out of the cell. In
this module you will review mechanisms of membrane transport.
Membrane Transport
www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/.../4-transport.ppt
Valinomycin is a passive carrier for K+. It can bind or release K+ when it encounters
the membrane surface. Valinomycin can catalyze net K+ transport because it ...
Cross‐ Membrane Transport - CliffsNotes
www.cliffsnotes.com › Sciences › Plant Biology
Cross ‐Membrane Transport. Concentration gradients by which diffusion and osmosis
operate are only partially effective when all needs of the plant are ...
Transport across Cell Membranes - Molecular Cell Biology - NCBI ...
www.ncbi.nlm.nih.gov › NCBI › Literature › Bookshelf by H Lodish - 2000 - Cited by 15
- Related articles. Three-dimensional structure of a recombinant cardiac gap junction
membrane channel determined by electron crystallography. These channels allow the
direct ...
Cell Membranes: Structures Responsible for Membrane Transport
www.sparknotes.com › ... › Biology Study Guides › Cell Membranes
A summary of Structures Responsible for Membrane Transport in 's Cell Membranes.
Learn exactly what happened in this chapter, scene, or section of Cell ...
Page 11 of 16
Biomembranes I: Membrane Structure and Transport
www.phschool.com/science/biology_place/.../biomembrane1/intro.html
This BioCoach activity will help you review the structure of membranes and the variety
of ways in which materials travel across membranes by active or passive ...
Membranes and membrane transport - SlideShare
www.slideshare.net/.../membranes-and-membrane-transport-presentation
Oct 26, 2008 - Membranes and membrane transport. by Stephen Taylor, IB Bio &
MYP Science Teacher, HOD Science, MYP Coordinator at Canadian ...
Molecular Mechanisms of Membrane Transport - Institut Pasteur
www.pasteur.fr › ... › Units and Groups
Our work is aimed at understanding the molecular mechanisms of neurotransmitter
transport across the plasma membrane. In the central nervous system, ...
Cell membrane transport - The Free Dictionary
www.thefreedictionary.com/Cell+membrane+transport
The movement of a chemical substance through a gradient of concentration or electrical
potential in the direction opposite to normal diffusion, requiring the ...
Active Transport Across Cell Membranes - HyperPhysics
hyperphysics.phy-astr.gsu.edu/hbase/biology/actran.html
Active Transport Across Cell Membranes. There are numerous situations in living
organisms when molecules move across cell membranes from an area of ...
Membrane Transport - Shmoop Biology
www.shmoop.com › Biology › Cells › Topics in Depth
Shmoop Biology explains Membrane Transport. Part of our Cells Learning Guide.
Learning and teaching resource for Membrane Transport written by PhD ...
Assisted Membrane Transport - University of Cyprus
www.eng.ucy.ac.cy/cpitris/courses/CIIPhys/.../Lecture%202.pdf
Assisted →impermeable molecules must be assisted by other proteins in order to cross
the membrane. • Energy expenditure. • Passive membrane transport.
Solution to Quiz:
Chose the correct answer
1.
D 6.
A 11.
2.
D 7.
D 12.
3.
D 8.
C 13.
4.
A 9.
A 14.
5.
A 10.
A 15.
D
B
B
A
D
State whether True or False
1. T 3. T 5. F 7. T 9. T
2. T 4. T 6. T 8. T 10 T
Page 12 of 16
Fill in the Blanks
1. Polar
2. Passive---simple ---facilitated-active
3. ATP
4. Golgi apparatus
5. Semi-permeable
6.
7.
8.
9.
10
Glucose transport
Active
Phagosytosis
Hypotonic
Cell wall
11
12
13
14
Use of energy
Pinocytosis
Active transport
Burst
Answers are only indicative expand on the outline given:
1. What is membrane transport?
Membrane transport is essential for cellular life. As cells proceed through their life
cycle, a vast amount of exchange is necessary to maintain function. Transport may
involve the incorporation of biological molecules and the discharge of waste products
that are necessary for normal function. Membrane transport refers to the movement of
particles (solute) across or through a membranous barrier. These membranous barriers,
in the case of the cell for example, consist of a phospholipid bilayer. Membrane transport
is dependent upon the permeability of the membrane, transmembrane solute
concentration, and the size and charge of the solute. Solute particles can traverse the
membrane via three mechanisms: passive, facilitated, and active transport. Some of these
transport mechanisms require the input of energy and use of a transmembrane protein,
whereas other mechanisms do not incorporate secondary molecules.
2. What is passive transport?
Passive transport is the simplest method of transport and is dependent upon the
concentration gradient, and the size and charge of the solute.2 In passive transport, small
uncharged solute particles diffuse across the membrane until both sides of the membrane
have reached an equilibrium that is similar in concentration. The direction of solute
travel is indicative of the concentration of that particular particle on each side of the
membrane. Based on the thermodynamics of the system, particles will move from an
area of high concentration to an area of low concentration in order to increase the
entropy of the cell. Additionally, this particle movement will occur spontaneously as the
free energy (Gibbs free energy; ∆G) of the system is negative.
G = H - TS
Where:
• G = Gibbs free energy (Joules)
• H = Enthalpy (Joules)
o
• T = Absolute temperature ( K)
o
• S = Entropy (Joules/ K)
Passive transport is independent of membrane proteins and the catabolism of biological
molecules for energy.
Page 13 of 16
4. Explain the process of simple diffusion
In simple diffusion, small noncharged molecules or lipid soluble molecules pass between
the phospholipids to enter or leave the cell, moving from areas of high concentration to
areas of low concentration (they move down their concentration gradient). Oxygen and
carbon dioxide and most lipids enter and leave cells by simple diffusion.
5. What is osmosis?
Osmosis is a type of simple diffusion in which water molecules diffuse through a
selectively permeable membrane from areas of high water concentration to areas of
lower water concentration.
6. What is facilitated diffusion?
Facilitated diffusion, not to be confused with simple diffusion, is a form of passive
transport mediated by transport proteins imbedded within the cellular membrane.
Facilitated diffusion allows the passage of lipophobic molecules through the cell
membrane’s lipid bilayer. Just as in passive transport, molecules, particles, and ions
travel freely across the cellular membrane from high concentration to low concentration
in an attempt to achieve equilibrium and thereby increase the entropy of the system. Also
like passive transport, the Gibbs Free Energy of the system is negative, allowing the
particle movement to be spontaneous. Facilitated diffusion, however, uses channel
proteins to facilitate solute movement.
7. Explain the voltage gated channel proteins
Voltage gated channel proteins are activated by a change in the electrical potential of the
cellular membrane in its vicinity. When a potential difference occurs across the cellular
membrane, its electromagnetic field causes a conformational change in the channel
protein, allowing it to open. Opening of the protein channel allows an influx or efflux of
ions which, in turn, depolarizes the cell membrane. Voltage gated protein channels play
a particularly important role in excitable neuronal and muscle tissues.
8. Explain the ligand gated channel peoeins
Ligand gated channel proteins are activated in response to the binding of a ligand.17
Typically, ligand binding occurs at an allosteric binding site independent of the channel
protein’s pore. The binding of a ligand at the allosteric binding site causes a
conformational change in the structure of the channel protein, subsequently causing an
influx or efflux of ions. Release of the ligand allows the channel protein to return to its
original shape. Structurally, ligand gated channel proteins generally differ from other
channels due to the presence of an additional protein domain that serves as the allosteric
binding site.2
The prototypical example of ligand gating is the nicotinic acetylcholine receptor located
on the postsynaptic side of the neuromuscular junction.
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9. What is an active transport?
Active transport is the movement of particles through a transport protein from low
concentration to high concentration at the expense of metabolic energy. The most
common energy source used by cells is adenosine triphosphate or ATP, though other
sources such as light energy or the energy stored in an electrochemical gradient are also
utilized. In the case of ATP, energy is chemically harvested through hydrolysis. ATP
hydrolysis in turn causes a conformational change in the transport protein which allows
mechanical movement of the particle in question. Active transport systems are, therefore,
energy-coupling devices as chemical and mechanical processes are linked to achieve
particle movement. Active transport is classified as either Primary Active Transport or
Secondary Active Transport.
10. Discuss briefly the mechanism of primary active transport
Primary active transport uses the energy found in ATP, photons, and electrochemical
gradients directly in the transport of molecules from low concentration to high
concentration across the cellular membrane.
1. Using ATP: The enzyme-catalyzed hydrolysis reaction removing a phosphate from
ATP, thereby forming ADP, causes a conformational change in the transport protein
allowing particles to influx or efflux. Enzymes catalyzing ATP-driven primary
active transport are called ATPases. The most universal example of ATP hydrolysis
driving primary active transport in cells is the sodium-potassium pump.
2. Using electrochemical gradient energy: An electrochemical gradient has two
components: 1) an electrical component caused by charge difference on either side
of the cellular membrane and 2) a chemical component resulting from differing
concentrations of ions across the cellular membrane. The electrochemical gradient is
generated by the presence of a proton (H+) gradient. A proton gradient is an
interconvertible form of energy that can ultimately be used by the transport protein
to move particles across the cellular membrane.
3. Using Photon Energy: The energy stored in a photon, the basic unit of light, is
used to generate a proton gradient through a process similar to that found in
electrochemical gradients. The stepwise passing of electrons in an electron transport
chain reduces a molecule like NADH and ultimately generates a proton gradient.
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11. Explain the secondary active transport
Secondary active transport achieves an identical result as primary active transport in that
particles are moved from low concentration to high concentration at the expense of
energy. Secondary active transport, however, functions independent of direct ATP
coupling. Rather, the electrochemical energy generated from pumping ions out of the
cell is used. Secondary active transport is classified as either symporter of antiporter.
1. Symports: It uses a downhill movement of one particle to transport another particle
against its concentration gradient. Symports move both particles in the same
direction through a transmembrane transport protein.
2. Antiports: It moves two or more different particles across the cellular membrane in
opposite directions. Antiport secondary active transport moves one particle down its
concentration gradient and uses the energy generated from that process to move
another particle up its concentration gradient.
12. Discuss briefly on endocytosis and exocytosis movement of large particles
It is possible for large molecules to enter a cell by a process called endocytosis, where a
small piece of the cell membrane wraps around the particle and is brought into the cell.
If the particle is solid, endocytosis is also called phagocytosis. If fluid droplets are taken
in, the processes is called pinocytosis. The opposite of endocytosis is exocytosis. Cells
use exocytosis to secrete molecules too large to pass through the cell membrane by any
other mechanism.
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