Chapter 9 & 10

Passive transport

moving in and out of a cell with no consumption of energy

• high to low concentration

active transport

movement of molecules across from low to high concentration requiring ATP

• ions sugars amino acids

Three types of passive transport

simple diffusion, facilitated diffusion, osmosis

facilitated diffusion

transport of substances ACROSS A MEMBRANE from high to low concentration with transport molecules

• water, glucose, amino acids

osmosis

the diffusion of water through a semipermeable membrane from high water conc to low water conc

• water only

best known passive transporters

GLUT prototeins

simple diffusion

movement of molecules from area of high to low concentration

• water, gases and steroid hormones

GLUT transporters 

consist of 12 membrane spanning alpha helices in 2 domains

confrontational states of GLUT

are at eq, moves glucose in either direction depending on conc

aquaporins

integral membrane ptoetins that aid in water transport

where are aquaporins found

kidney, salivary glands, and lacrimal glands in eye

what is aquaporin pore lined with

hydrophobic residues, except for 2 asp side chains

types of active transport

primary and secondary

primary active transport

usees ATP

Secondary active transport

use electrochemical gradients, established by atpase gradient

• K+ out Na+ in

types of membrane transport systems

uniporters

symporters

an antiporter

uniporter

moves a single substance at a time

a symporter

transports two different substances across the membrane

antiporter

moves two substances in opposite directions across membrane

primary active transport example

NA, K-ATPase pumping Na out and K into cell

• ATP hydrolysis provides energy

• 3 Na for 2 K

proton pump and gerd

H+/K+atpase pumps protons out of parietal cells and K nack in

chloride ions leave through ion chanel

omezperol helps

What proteins bind to signaling molecules

receptors- protein

transmembrane proteins are usually

receptors, bind to signaling moelcules outside cell and transmit signal

How do receptoirs bind to ligand

IMFS

ligands affinity

can be determined by Kd, low KD → high affinity

signal transduction

activated receptor transmits message into cell, leads to cellular response

signaling molecules can be

amino acid derivatives

proteins

nucleotide derivatives

lipids

small gas molecules

agonsit

ligand that binds to receptor giving similar response to endogenous ligand

antagonists

bind to receptor and block the action of an agonist

2 types of receptors

G protein coupled

receptor tyrosine kinases

G proteins

named for ability to bind guanine nucelotides GDP and GTP

secnodary messanger

diffuse away to activate or inhibit activity of target proteins in a cell

G protein

made of 3 subunits alpha beta gamma

• non covalent

steps of g protinen receptors

1. ligand binds and changes receptor shape

2. G protein with GDP bound binds to active site, changing to GTP

3. g protein alters shape, and gtp and alpha break off

4. alpha interacts with adenylate cyclase

5. active site opens atp turns into cyclic amp

   1. cyclic amp interacts with protein kinase activates enzyme

cyclic amp

acts as secondary messenger

beta 2 adregernic receptor

found in bronchial smooth mucle

-active= smoth muscle relaxation

bronchiodialators

agonist of b2 adrenergic receptor

• respons to noreprinephrine and epinephrin

albutarol

treats asma B2 agonist

Receptor tyrosine kinases

high affinity cell surface receptors for polypeptide growth factors, cytokines, and hormones

RTKS function

as homodimer or heterodimers

ligand binding to RTK

activates kinase activites, phosphorylates things

series of kinase receptors activae or inhibit proteins

by adding phosphoryl grousp