Page 228 - Color Atlas of Biochemistry

Biological membranes 219

A. Permeability of membranes B. Passive and active transport

Electrochemical gradient
Small molecules Charge gradient
Apolar O , N 2
2
Benzene
Polar, uncharged Free
diffusion High Low
H O
2
Urea concentration concentration
Glycerol
CO , NH 3
2
Free
diffusion
Channel
protein
Large molecules Pore
Polar, uncharged
e.g. glucose

Passive
Ions No transport
H , Na , K , Mg 2 membrane Facilitated
passage
2
Ca , NH 4 Transporter diffusion
HCO , Cl , H PO 4
2
3
Amino acids
Nucleotides
Confor-
mational
change
C. Transport processes

Glucose A
P P P

Uniport U A
P P

P
Glucose
P
Transport
ATPase
Na H O
2
S
Symport Confor-
mational Active
change transport

P
Cl Cl

HCO 3
HCO 3
A
Antiport

Koolman, Color Atlas of Biochemistry, 2nd edition © 2005 Thieme
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