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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.
A prokaryotic cell
©1993. Used by permission of Springer-Verlag.
©1993. Used by permission of Springer-Verlag.
A eukaryotic cell
Mitochondria are organelles that
metabolize conversion of chemical
energy from food into ATP.
(b) ©1980. Used by permission of Elsevier Science.
Introduction to chromatin scales
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
water
amino acids, sugars, fatty acids, ions
74%
70%
4%
Macromolecules
proteins
RNA
DNA
lipids
polysaccharides
26%
15%
6%
1%
2%
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)).
Elastic rod model
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.