1. Cells are fundamental units of life
2. Cells use chemical or solar energy to function and reproduce
3. Cells are macromolecular factories
4. Cells move, divide (mitosis), and sense environmental conditions
©1993. Used by permission of Springer-Verlag.

©1993. Used by permission of Springer-Verlag.
A prokaryotic cell

©1993. Used by permission of Springer-Verlag.

A eukaryotic cell

(b) ©1980. Used by permission of Elsevier Science.
Mitochondria are organelles that metabolize conversion of chemical energy from food into ATP.

Electron micrograph of D.Melanogaster chromatin: arrays of regularly spaced nucleosomes, each ~80 A across.

Courtesy of Dr. Julian Heath.

©1982. Used by permission of Jones and Bartlett Publishers, Sudbury MA.

Molecular composition of bacterial cells by weight :
Small molecules 74% water 70% amino acids, sugars, fatty acids, ions 4%
Macromolecules 26% proteins 15%
RNA 6%
DNA 1% lipids 2% polysaccharides 2%

©1991 Larry Gonick.

©1982, American Association for the Advancement of Science. Used by permission.

20 types of amino acids in proteins

Protein 3D structure
Protein Data Bank (PDB) http://www.rcsb.org

Protein Data Base accession code 1VII ({C.J. McKnight, D.S. Doering, P.T. Matsudaira, P.S. Kim, J. Mol. Biol . 260 126 (1996)).

DNA looping induced by a Lac repressor tetramer

Protein Data Base accession code 1EHZ (H. Shi and P.B. Moore, RNA 6 1091 (2000)).

©1993. Used by permission of Springer-Verlag.

Fatty acids
Cellulose (polysaccharide)

A single peptide (protein building block)
A polypeptide chain

A tyrosine (TYR) amino acid (one of 20 naturally occurring amino acids)

Peptide torsion angles and secondary structure
• omega = 180 deg, phi & psi are variable
• minimize E({phi,psi}) – protein folding problem

Secondary structure elements: alpha & 3-10 helices

Secondary structure elements: beta sheets

The Ramachandran plot

Turns of the polypeptide chain

Side chain conformations

Protein 3D structure (second look)
Protein functions: enzymes, gene regulation
Protein Data Bank (PDB) http://www.rcsb.org

DNA & RNA

The genetic code

• Microtubules (25 nm): cytoskeleton
• Actin filaments (F-actin; 7 nm): actin cortex

Cell membranes are crowded: channels, receptors, pumps, actin cortex attachment points

©1993. Used by permission of Springer-Verlag.

©1993. Used by permission of Springer-Verlag.