lecture 11 oct 21 2013 for posting

8/13/2019 Lecture 11 Oct 21 2013 for Posting

1/22

SAVE THE DATE! Midterm 1 is this Friday, October 25,

in this room. Midterm will cover through Membrane

Fluidity, the first part of todays lecture.

SAVE THE DATE! Dr. Hyman review session istomorrow,Tuesday, Oct. 22 5:10-6:30 pm in Sproul

1102.

Today: My office hours at 2:15 pm, Spieth 3365

Announcements:


2/22


3/22

Front Podium

Kelsey

Brian

Back

Please sit spaced in every other seat. People

sitting together will be moved


4/22

Membranes

Lecture outline:

-bilayers

-mosaicism

-fluidity

Learning outcomes:Identify what factors

contribute tomembrane fluidity

Later: membranetransport


5/22

The Fluid MosaicModel


6/22

A design or decoration made of of small pieces of

different colors and different materials.

Mosaic

Th Fl id M i M d l


7/22

The FluidMosaic Model?


8/22

The fluidityof membranes


9/22

You might expect membranes that are

fluid would have a high concentration of:

I. Saturated phospholipids

II. Unsaturated phospholipids

III. Fatty acids

A. I

B. IIC. III

D. I and III

E. II and IIILets review for next

Fridays midterm using

membrane structure!


10/22

The fluidityof membranes

How might high and low temperatures impact

membrane fluidity?


11/22

The fluidity of membranes

Variation in

phospholipidsplays a role!

Two themes from earlier

in the quarter!

Electrical

polarity playsa big role


12/22

Some functions of membrane proteins

later


13/22

Membrane transport

Lecture outline:

Thermodynamics ofreactions

(Simple) diffusionFacilitated diffusion

Active transport

Learning outcomes:

Predict if reactions arespontaneous

Predict directionality ofparticle movementacross membranesusing energetics

Distinguish betweentransport mechanisms


14/22

G = H - T S+means add energy to system, non-spontaneous-means energy released; favorable, spontaneous

ordered

disordered

-G

G= Free energy

available to do work

G is the change in free energy

+Gendothermic exothermic


15/22

Condition 1: Simple diffusion (permeable barrier)

Particles and water are both free to diffuse

Both move down their concentration gradients fromhigh to low concentration

System becomes more disordered

Net flow stops when particles and water at equilibrium:

concentration of particles ANDconcentration of water

on both sides of membrane is equal

Spontaneous, exothermic, -G

Does this mean that movement has stopped?


16/22

Only water free to move

=osmosis.

Water moves from a condition

of high free water concentration

to low free water concentration,until water concentrations

reach equilibrium

In this container, in which

direction will water move to try

to equalize its concentration?

Condition 2:Simple diffusion (semi-permeable

barrier)

= osmotic pressure

Fig 7 15 9th edition


17/22

Fig. 7-15 9thedition

Hypotonic solution

(a) Animal

cell

(b) Plantcell

H2O

LysedH2O

Turgid (normal)

H2O

H2O

H2O

H2ONormal

Isotonic solution

Flaccid

H2O

H2OShriveled

Plasmolyzed

Hypertonic solution

crenation


18/22

G < 0exothermic

spontaneous

becoming less

ordered (S>0)

Simple Diffusion

across the lipid bilayerO2, CO2, H20

CFTR i fib i


19/22

CFTR = cystic fibrosis

transmembrane regulator

By way of review: What are the different domains called?

By way of review: what protein structures are implyed? (1o etc.)

CFTR ti fib i


20/22

CFTR = cystic fibrosis

transmembrane regulator

By way of review: what protein structures do we see? (1o

etc.)


21/22

COOH

NH2


22/22

lecture 11 oct 21 2013 for posting

Documents