Harvard-MIT Division of Health Sciences and Technology
HST.410J: Projects in Microscale Engineering for the Life Sciences, Spring 2007
Course Directors: Prof. Dennis Freeman, Prof. Martha Gray, and Prof. Alexander Aranyosi
HST.410J/6.021J
Lecture 3
February 13, 2007
Escherichia Coli (E. Coli)
Culture Medium
NH4Cl�
MgSO4�
KH2PO4�
Na2HPO4�
Glucose�
Water
Image removed due to copyright restrictions.
Photograph of an E. coli cell.
1.0 g�
0.13 g�
3.0 g�
6.0 g�
4.0 g�
1.0 L
Generic Eukaryotic Animal Cell
Culture Medium
Image removed due to copyright restrictions.
Essential Amino Acids�
(a dozen)�
Vitamins (eight)�
Salts (Na+, K+, Ca2+, Mg2+,�
Cl−, PO43−, HCO3−)�
Glucose�
Serum
Air
Respiratory system
Circulatory
CO2
Cells
Food, water
system
Digestive system
Waste
Inputs to Organism
• air�
• water�
• food�
− carbohydrates�
− fats�
− proteins
Inputs to Cells
• oxygen�
• water�
• ions�
• building block molecules�
− sugars�
− lipids�
− amino acids
Figure from Weiss, T. F. Cellular Biophysics,
Vol. I. Cambridge, MA: MIT Press, 1996.
Courtesy of MIT Press. Used with permission.
Water transport in digestive system
Salivary
glands
Pharynx
Daily traffic
Esophagus
Trachea
•
•
•
•
•
•
800 g food + 1.2 L water ingested daily
1.5 L saliva
2 L gastric secretions
0.5 L bile
7 L digestive fluids
1.5 L pancreatic secretions
1.5 L intestinal secretions
Stomach
Liver
Pancreas
Small
intestine
15 pounds of water (10% of body weight)
secreted and reabsorbed daily
Large
intestine
Rectum
Anus
Images removed due to copyright restrictions.
Images of inside an intestinal tract and an endothelial cell.
Figure from Weiss, T. F. Cellular Biophysics,
Vol. I. Cambridge, MA: MIT Press, 1996.
Courtesy of MIT Press. Used with permission.
Microvilli
Junctional�
complex
Apical (mucosal)�
surface
Lateral�
surface
Figure from Weiss, T. F. Cellular Biophysics,
Vol. I. Cambridge, MA: MIT Press, 1996.
Courtesy of MIT Press. Used with permission.
Intercellular� Basal (serosal)�
Transcellular� Paracellular� transport through�
surface
transport
transport
gap junctions
lipid�
bilayer
membrane
7 nm
cell
Concentration at a point�
in space and time
volume V
amount of substance in V�
concentration c(x,t) = lim
V
V →�0
Flux at a point�
in space and time
window�
area A
φ(x,t)
amount of substance flowing�
flux φ(x,t) = lim through test window A in Δt�
A →�0
AΔt
Δt→�0
Fick's First Law
Figure from Weiss, T. F. Cellular Biophysics,
Vol. I. Cambridge, MA: MIT Press, 1996.
Courtesy of MIT Press. Used with permission.
CH2OH
H
C
CH2OH
C
O
H
OH
H
C
C
H
OH
OH
H
OH
C
C
OH
H
C
CH2OH
O
H
OH
H
C
H
H
H
C
C
OH
OH
C
O
H
OH
OH
C
C
C
OH
H
H
H
C
OH
Figure from Weiss, T. F. Cellular Biophysics,
Vol. I. Cambridge, MA: MIT Press, 1996.
Courtesy of MIT Press. Used with permission.
D-glucose
D-mannose
D-galactose
CH�2OH�
�
H�
C�
CH�2�OH�
C�
O�
H�
H�
OH�
H�
C�
H�
O�
H�
C�
H�
C�
C�
OH�
OH�
H�
OH�
C�
C�
C�
OH�
OH�
H�
OH�
D-glucose
H�
Figure from Weiss, T. F. Cellular Biophysics,
Vol. I. Cambridge, MA: MIT Press, 1996.
Courtesy of MIT Press. Used with permission.
C�
OH�
L-glucose
integral�
membrane� solute lipid�
bilayer
protein
membrane
7 nm
cell
4
Hydrophobicity
3
2
1
0
1
2
3
4
5
6
7
8
9
10
11
Figure from Weiss, T. F. Cellular Biophysics,
Vol. I. Cambridge, MA: MIT Press, 1996.
Courtesy of MIT Press. Used with permission.
12
−1
−2
−3
−4
100
200
300
Residue position
400
500
Hydrophobic
Hydrophilic
Outside
1
2
3
4
5
6
7
8
9
10
11
12
Inside
NH2
COOH
Figures from Weiss, T. F. Cellular Biophysics,
Vol. I. Cambridge, MA: MIT Press, 1996.
Courtesy of MIT Press. Used with permission.
Image removed due to copyright restrictions.
Please see figure 5 in Mueckler, Mike, and Carol Makepeace. "Cysteine-scanning Mutagenesis and Substituted Cysteine
Accessibility Analysis of Transmembrane Segment 4 of the Glut1 Glucose Transporter." J Biol Chem 280 (2005): 39562-39568.
Pumps
3 Na+
ADP + P
ATP
2 K+
Inside
Membrane
Outside
integral�
membrane�
protein
lipid�
bilayer
membrane
7 nm
pore
cell
Y. Jiang, A. Lee, J. Chen, V. Ruta, M. Cadene, B. Chalt, and R. MacKinnon (2003),�
Nature 423:33-41.
Images removed due to copyright restrictions.
Dissolution� Transport�
and diffusion� through�
through�
water�
lipid bilayer channels
Intracellular
Membrane
Extracellular
Transport�
through�
gated ion�
channels
Carrier-�
mediated�
transport
Pumps
Figure from Weiss, T. F. Cellular Biophysics,
Vol. I. Cambridge, MA: MIT Press, 1996.
Courtesy of MIT Press. Used with permission.