Chemistry of Life G.Burgess 2012

In a nut shell  All matter is made of atoms; cells are matter; cells are made of atoms  Atoms have shape  Atoms interact chemically and physically making compounds  The interaction of compounds shapes life  three major compounds found in cells are; proteins, lipids and carbohydrates Each type differes in composition and shape.

Lipids  composed of C,H,and O (ie. C 57 H 110 O 6 )  Produced by both plants and animals as cell membranes, fats, oils, waxes and steriods.  Used for prompting chemical reactions of homeostasis, protection from environment, and storing excess energy.  Lipids are hydrophobic; they repell water

Saturated, Unsaturated and Transfats  Note, both saturated fats and transfats are linear and unsaturated have a bend  Saturated and transfats are solid at room temperature  Unsaturated fats are liquid at room temperature

Cell Membrane  Keeps the cell separate from the external environment and regulates materials that are able to enter and leave the cell.  Fluid mosaic model: Composed of lipids held together by cholesterols, and proteins  Lipids: act as barrier to water  Cholesterols: add strength to lipid membrane  Proteins: enable ions and water soluble materials to enter the cell, give the cell identity and may act as attachment sites for other cells or macromolecules.

Phospholipid  Note the polar head and fatty acid tails are connecdt ed by a glycerol

Cell Membrane tbn1.gstatic.com/images?q=tbn:ANd9GcTD_hYpU l6E5TneNniP9ixk_zYQs_6ioHOB4- auF44dx4ZO6_GZrghttps://encrypted- tbn1.gstatic.com/images?q=tbn:ANd9GcTD_hYpU l6E5TneNniP9ixk_zYQs_6ioHOB4- auF44dx4ZO6_GZrg, accessed Sept tbn0.gstatic.com/images?q=tbn:ANd9GcQkZmwhsfzPah80 ov8CA9T9laWv3UlpMZk2eQbr1NZ_lNA-aL9Phttps://encrypted- tbn0.gstatic.com/images?q=tbn:ANd9GcQkZmwhsfzPah80 ov8CA9T9laWv3UlpMZk2eQbr1NZ_lNA-aL9P, accessed September

Carbohydrates  composed of C,H, and O (ratio of 2H to 1O) Sugars are made of keytones or aldehydes combined with carboxyl groups.  primary source of molecular energy.  produced by plants in the form of simple sugars and polysaccharides.  Simple sugars C 6 H 12 O 6 are called monosaccharides Simple sugars; gluose, galactose, fructose  Two simple sugars form a disaccharide more than two molecules joined make a polysaccharide.

Glucose, Fructose and Galactose  Note the chemical formula is the same, but the shapes and structures are different GlucoseGalactoseFructose

Proteins  composed of C, H, O and N (nitrogen is a necessary element for forming amino acids, the building blocks of proteins)  a single protein may be formed from 100’s of amino acids  two amino acids make a dipeptide; more make up a polypeptide  RNA, DNA and hormones are examples of polypeptides.  The type of polypeptide formed depends on the number and sequence of the amino acids that make it.  there are 20 different amino acid groups. These acids form the code that controls an organisms basic behavior and appearance.

Amino Acid Groups  These are just a few.  Each has a different composition and shape. accessed August 2012

RNA, DNA Structure  Note both are made of nitrogen bases  RNA has ribose sugar  DNA has deoxyribos e sugar accessed August 2012

Transport Mechanisms  Materials need to be transported through out an organism or cell.  Hemoglobin is an example of a transport molecule. It transports oxygen from the lungs to tissues in the body.  Cells use transport molecules to allow materials to cross through the cell membrane. Either by passive or active transport.

Passive transport  Molecules enter a cell without the need for ATP.  Always from area of high concentration to area of low concentration 1.Diffusion: transport of lipid soluble materials across the cell membrane (ie. Vitamin A, K, alcohols, some metal compounds) 2.Facilitated transport: transport of water soluble materials with the help of transport proteins.

Diffusion  The passing of materials from the fluid environment across the cell membrane to the cytoplasm  Does not require ATP  Materials cross the membrane with out the need of transport proteins

Facilitated Transport  Passive transport that moves water soluble materials across the cell membrane ie. water molecules, glucose, cations, and anions  Why transport Proteins? Enable the cell to maintain and regain needed chemical components for metabolism and cell function. Help cell to maintain concentrations of chemicals and water To get rid of excess materials without interfering with continual cell processes.

Channel Protein Channel Proteins: form a hole through which materials may pass.

Carrier Protein Carrier proteins: capture molecules and ions, change shape and release materials into cytoplasm

Gate Protein Gate proteins: open when signal molecule attaches ‘opening the gate’ to allow materials to pass into the cytoplasm.

Cellular Homeostasis and water concentrations  Three basic types of cellular environments; 1.Isotonic solutions: these solutions have the same or similar amounts of dissolved materials as the cytoplasm of a cell 2.Hypotonic solutions: have a greater concentration of water than what is present in the cell 3.Hypertonic solutions: have greater amounts of dissolved materials than what is present inside the cell.  Each of the solutions describe have an effect on the cell’s ability to survive.

Cellular Homeostasis and water concentrations  Isotonic Solutions: do not have an effect on a cell, as they mimic the cell’s inner solution. Ie. saline solution for eyes.  Hypotonic Solutions: will cause a cell to enlarge or break. Since the concentration of water is greater outside the cell, the water will flow into the cell until equilibrium is found.  Hypertonic Solutions: will cause a cell to shrink or collapse. Since the environment has a greater concentration of dissolved materials, water from the cell will move to the environment until the environment has the same concentration of water as the cell.

 These proteins, called pumps, move molecules and ions against concentration gradients.  They move materials from areas of low concentration to high concentration.  To do this they require ATP.  The Na-K pump (sodium potassium pump) is an example of an active transport protein. Active Transport Proteins

Digestion and Synthesis of organic molecules  Digestion refers to the breakdown of organic molecules into smaller/ simpler pieces.  Synthesis refers to the formation or joining of simple organic pieces into larger more complex ones.  These processes are completed by condensation reactions and hydrolysis reactions. Condensation reaction: dehydration reactions occur when a hydroxyl is removed from one molecule and a hydronium is removed from another as the two molecules form a larger molecule. The combining of hydroxyl and hydronium forms water Hydrolysis: water is added to a reaction separating the hydronium and hydroxyl forming two smaller molecules.  **Hydroxyl and hydronium groups serve to complete the molecular charges of the smaller molecules.

Digestion and Synthesis Processes Condensation Reaction C 6 H 12 O 6 + C 6 H 12 O 6  C 12 H 22 O 11 + H 2 O Hydrolysis Reaction C 12 H 22 O 11 + H 2 O  C 6 H 12 O 6 + C 6 H 12 O 6 The body uses these reactions to form needed structural and chemical components.

Interesting Links  Robert Horvitz's Work on Cell Death, Horvitz, B. and M.Hengartner, Gene accessed Feb.2,