L5 - For Tuesday Ch 12 p695-704 723-745 Ch 6 p388-399...

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
All lectures are being podcast and available at https://media4.ucsc.edu/webcast/ For Tuesday: Ch. 6, p388-399 Chapter 13
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lipid bilayers are impermeable to many molecules cystinuria
Background image of page 2
In the case of single uncharged molecule, passive transport simply depends on the difference in concentration on 2 sides of the membrane * * pumps Such as ATP hydrolysis or ion gradient
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
3 types of transporter mediate movement e.g. Na+ Na+ then actively pumped out of the cell using ATP passive active
Background image of page 4
Epithelial cells use the energy stored in the Na+ gradient to transport glucose across and epithelial layer-transcellular transport 1) Glucose pumped into cell by Na+- powered symporter 2) Glucose passes out of the cell into the extracellular fluid and then onto the bloodstream down its concentration gradient by passive transport 3) The Na+ gradient driving the symporter is maintained by Na+/ K+ pumps on the basalateral surface. (keeps intracellular Na low) 6) Importance of the tight junction.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Binding of transported molecules induces conformational changes in carrier proteins Carrier flips betw 2 conformational states. Outside: H and lactose binding sites are accessible to extracellular space. Loading is favored due to R144 bonding with E126, leaving E269 free for H+. Conformational change induced by lactose Inside: Unloading is favored because R144 bonds with E269, destabilizing H+. Conformational change Conformational change Lactose drives the conformational change, linking the transport of lactose to the electrochemical gradient.
Background image of page 6
The Na+-K+ pump is an ATP-driven carrier protein that pumps Na+ out of the cell, and K+ into the cell
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 8
The mechanism of the Na+-K+ pump 3 Na+ removed from cell and 2 K+ imported with each ATP hydrolyzed 1) 3 Na+ bind to cytoplasmic side & ATP is hydrolyzed - generates ADP and covalently attaches phosphate to aspartate group on cytoplasmic side. Leads to a conformational change 2) 3Na+ released to the extracellular side My BAD
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
A membrane potential is created by the combined actions of the Na+-K+ (3 Na out/ 2K in) pump (minor) and K+ LEAK channels (140mM intra and 5mM extra) out in out in The net efflux of K halts when the membrane potential reaches a value at which the electrical driving force on K+ exactly equals the effect of its concentration gradient--the electrochemical gradient is ZERO. No net flow of ions=equilibrium potential which can be calculated by the Nernst equation Resting membrane potential -20 to -120 mV
Background image of page 10
In fact, almost all membranes have an electrical potential difference (voltage gradient) across them with the inside usually negative with respect to the outside. The flow of ions through a membrane channel protein is driven by the electrochemical gradient for that ion (i.e. the voltage gradient and the concentration gradient). When these two influences balance each other, the electrochemical gradient is 0. NO NET FLOW. Called the equilibrium potential and it is calculated by the Nernst Equation. V=RT/zF ln [C]out/[C]in
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/28/2010 for the course MCD BIO 110 taught by Professor Hinck during the Fall '09 term at UCSC.

Page1 / 91

L5 - For Tuesday Ch 12 p695-704 723-745 Ch 6 p388-399...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online