Avogadro-Scale Molecular Self-Assembly in Biological Systems

Avogadro-Scale Engineering: Form and Function

November 18, 19 2003The Bartos TheaterBuilding E15, MIT

Shuguang Zhang

Center for Biomedical Engineering, Center for Bits & AtomsMassachusetts Institute of Technology

Cambridge, MA 02139, USA

Interior of a cell: billions of biomolecules formstructures & allow cells to function with little errors.

A walking Avogadro being

Each adult human is made of ~100 trillion cells (1014 cells)!

Guyton, A.C. & Hall, J.E. (2000) Text Book of Medical Physiology 10th ed. W.B. Saunders.

http://www.nobel.se/medicine/laureates/1999/press.html

Water Molecules Per PersonIf each person weighs ~70 kilograms, or 70,000 grams, ~ 70% of that is water, i.e. 70,000 grams x 70% = 49,000 grams of water. Each molecule of water has a molecular weight of 18 daltons (oxygen = 16) + (2 hydrogens). Therefore: 18 grams = 1 mole (6.023x1023 water molecules = the Avogadro number)And… 49,000 grams divided by 18 gram/mole = 2,722 moles, or

2,722 x 6.023x1023 water molecules per person!

A moleculeof water.

Numbers of Nucleotides in DNA per Person

Each cell in a person contains 2 copies of the genome(3.164x109 bases)-- one from the mother and one from the father: 2 x 3.1647x109 bases/cell, or ~6.33x109 bases/cell.

Each adult person is made of ~1014 cells, or 6.33x109 bases/cell x 1014 cells/person = 6.33x1023 bases/person!

Numbers of Protein in Cells per Personhttp://www.nobel.se/medicine/laureates/1999/press.html

Each cell contains ~ 1 billion (109) proteins. Each adult is made of 1014 cells, or

109 proteins/cell x 1014 cells/person = 1023 proteins/person!

The hemoglobin moleculehas 4 polypeptidechains -- 2 and 2 .

Number of Lipid per Cell per Person

Each cell plasma membrane is made of ~200 millionlipids. However, each cell also has a nuclear membrane, mitochondrial membranes, Golgi apparati, endo-plasmic reticulum, etc. Collectively, the number oflipids is ~109 per cell. Each person is made of ~1014 cells, or 109 lipids/cell x 1014 cells/person = ~1023 lipids/person!

Myelinsurroundsspinal cordnerve fibers.

The Ribosome

Steve Santoso Yang, Biology/CBA Ph.D. Student

Monomeric Surfactant Peptides: A6D, V6D, V6D2, L6D, KL6, KV6

Sylvain Vauthey & Steve Santoso (CBE)

V6D Peptide Nanotubes

100 nm

V6D

Sylvain VautheyPNAS, 4/2002, Steve Santoso, NanoLetters, 7/2002

Geoffrey von MaltzahnLangmuir, 5/2003

Peptide Nanotubes are made up of trillions of peptides

Vauthey, et al., PNAS, April 16, 2002

Billions of molecules self-assemble into ordered structures

What do they have in common?Made by Human Made by NatureMachines Molecular machinesTransportation HemoglobinAssembly lines RibosomesDigital database NucleosomesCopy machines PolymerasesBulldozer/Destroyer Proteases/proteosomeChain couplers LigasesTrain control center CentrosomeTrain tracks Actin filament network Mail sorting machine Protein sortingElectric Fences MembranesGates/keys & passes Ion channelsInternet/www Neuron synapse