Readings for Lecture 2

Readings for Lecture 2 - Readings for Lecture 2 Chapter 1...

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Readings for Lecture 2 Chapter 1 pp. 10-11 20 different amino acids Cells string these amino acids together in a linear chain to form a protein Proteins commonly range in length from 100 to 1000 amino acids, some are shorter and others longer The essential amino acids (from a dietary standpoint) are the eight amino acids we cannot synthesize and therefore must obtain from food o Beans and corn together have all eight Once a chain of amino acids is formed it folds into a complex shape, conferring a distinctive three-dimensional structure and function on each protein Proteins that are similar are considered to be part of protein families, a few hundred of these families have been identified Most proteins are designed to work in particular places in a cell, or to be released into the extra-cellular space Elaborate cellular pathways ensure that proteins are transported to the proper intra-cellular location Protein functions include o Structural – by forming an internal skeleton o Sensory – that change shape as temperature, ion concentrations or other properties of the cell change o Transport – by importing and exporting substances across the plasma membrane o Enzymes- cause chemical reactions to occur more rapidly than they would without the aid of these protein catalysts o Can bind to a specific gene and turn it on or off o Extracellular signals – they communicate to other cells or other parts of the cell when released o Motors – move other molecules around, burning ATP while they do so There are 20^400 possible different protein sequences How many protein molecules does a cell need to operate and maintain itself o Typical eukaryotic cell (e.g. hepatocyte cell – liver cell) Roughly a cube 15 μ m a side Volume of 3.4 x 10^-9 cm ^3 Density of 1.03 g/ml Weight of 3.5 x 10^-9 Proteins typically account for 20 % of a cells weight Total weight of cellular protein is 7x10^-10 The average yeast protein has a molecular weight of 52700 g/mol
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Total number of protein molecules per liver cell is 7.9x10^9 o A liver cell contains about 10000 different proteins, thus a cell contains close to a million molecules of each type of protein on average o In fact the abundance of different proteins varies widely Chapter 2 pp. 31-40 Most cells are 70-80 percent water Water is the most abundant molecule in biological systems Biomolecules that dissolve rapidly in water are called hydrophilic (e.g. Sugars) Biomolecules that shun water are called hydrophobic (e.g. Cholesterol) Biomolecules that contain both hydrophobic and hydrophilic regions are called amphipathic (e.g. Phospholipids) 2.1 Covalent Bonds and Noncovalent Interactions Covalent bonds are strong forces where two atoms share a pair of electrons (single bond) Noncovalent interactions are weaker forces The Electronic Structure of an Atom Determines the Number and Geometry of Covalent Bonds it can make Hydrogen, Oxygen, Carbon, Nitrogen, Phosphorus and Sulfur are the most
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Readings for Lecture 2 - Readings for Lecture 2 Chapter 1...

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