Chemical Basis for Life

1. Chemical Basis for Life And Biochemistry

2. Chemistry of Life • Chemistryis important to biologists because all of the life activities in our cells that keep us alive are the result of chemical reactions. • Matter—anything that has mass and takes up space. • Elements—found on Periodic Table. Cannot be broken down into simpler kinds of matter. • HONC (Honk)—hydrogen, oxygen, nitrogen, carbon. These are the most important elements in living things.

3. Atoms • Atom—simplest particle of an element that keeps all the properties of that element. • Parts of an atom • Protons—positive charge • Neutrons—no charge • Electrons—negative charge Inside Nucleus Orbit Nucleus

4. The atomic number is the number of protonsin an atom • The atomic mass is the number of protons plusthe number of neutrons. • The number of electronsin an atom is the same as the number or protons giving it a net charge of zero.

5. Isotopes • Isotopes—atoms of the same element with different number of neutrons.

6. Compounds • Compounds—atoms of two or more elements joined by chemical bonds. • Examples: H2O NaCl C6H12O6 • Three models below show a water molecule Electron Cloud model Stick model Bohr model http://www.lionden.com/graphics/AP/Water1.gif

7. Chemical Bonds • Chemical bonds are attractive forces that hold atoms together. They form so that elements can become more stable by filling their outer energy levels.

8. Types of Chemical Bonds • Covalent Bonds—two atoms SHAREelectrons

9. Carbonhas the ability to form multiple covalent bonds • Carbon has 4 electrons in its outer shell. The shell can hold 8. Carbon needs 4 more electrons to become stable. This can result in big biological molecules based around chains of carbon atoms. http://t1.gstatic.com/images?q=tbn:ANd9GcTDsTGWMhdl6_3izM7K7RCw6b5ueLWXpacSg91FXY8Tt6PoObw&t=1&usg=__fkitOKpfQ768Lo6SF7eDzZ0qobs= http://www.chemistrydaily.com/chemistry/upload/d/d9/Covalent.png

10. Many complex biological molecules will be formed using doubleand triple covalent bonds. • Double—share 2 pair of electrons • Triple—share 3 pair of electrons Ethane Ethylene Acetylene

11. Ionic Bonds—atoms LOSEor GAIN electrons creating charges that attract each other. • SALTS!!!!

12. Energy and Chemical Reactions • Chemical reactions occur when one or more substances change to produce one or more new substances. • Chemical equations show what happens during the reaction Reactants on left Products on right 6CO2 + 6 H2O C6H12O6 + 6O2 +energy

13. Reaction Speed • Most reactions need the addition of energy before they will begin. • Activation Energy —energy required for a reaction to begin • Catalyst—speed up chemical reactions by lowering the activation energy required. • Enzymesare common catalysts in living things • They remain unchangedthroughout the reaction. http://xnet.rrc.mb.ca/davidb/photogallery/activationenergy1.gif

14. Endothermic and Exothermic Reactions • Endothermic reactions result in a net absorptionof energy • Exothermic reactions results in the net releaseof energy

15. Oxidation Reduction Reactions • Also called Redox Reactions • Electrons are transferredbetween atoms • Oxidation reaction —a reactant loseselectrons resulting in a positive charge • Example—Na loses an electron to become more stable creating a sodium ion (Na+) • Reduction reaction —a reactant gainselectrons resulting in a negative charge • Example—Chlorine gains an electron to become more stable creating a chlorine ion (Cl-) • The two always occur together. One reactant gives up what the other needs.

16. Water and Solutions • Water’schemical structure is important in its vital role in life. http://www.lenntech.com/images/Water%20molecule.jpg http://www.ci.rockford.il.us/uploadedImages/government/PublicWorks/Water/willing%20water%20color.jpg

17. Properties of Water • Water is POLAR • Electrons in the covalent bond are not shared equally. Results in a partial negative charge on the oxygen end and a partial positive charge on the hydrogen end.

18. Being polar allows water to: • Dissolvemany substances • Form hydrogen bonds with other water molecules creating: • Cohesion • Surface Tension • Adhesion • Capillarity • High heat capacity • Less density when water freezes (ice floats!!)

19. Solutions • Solution—mixture in which one or more substances are uniformly distributed in another substance. • Solute—dissolved substance • Solvent—substance in which the solute is dissolved • Concentration—amount of solute dissolved in a fixed amount of solution • Saturated Solution —no more solute can be dissolved

20. Ionization of Water • Water molecules can collide and break each other apart H2O H+ + OH- OH- is known as the hydroxide ion Free H+ ions react with water molecules: H+ + H2O H3O+ H3O+is known as the hydronium ion

21. Acids and Bases • Acid—solution in which the number of hydronium ions is greater than the number of hydroxide ions • They have a value BELOW 7 on the pH scale. • Base—solution in which the number of hydroxide ions is greater than the number of hydronium ions (Alkaline) • They have a value ABOVE 7 on the pH scale

22. Biochemistry • Carbon—element of life • Organic compounds—contain carbon (and hydrogen) • Can form 4 covalent bonds with other elements so it is the backbone of all organic compounds.

23. Functional Groups • Various functional groups can be attached to these carbon backbones. These groups determine how these molecules will react with other molecules. • Functional groups can be seen on the following chart:

24. Functional Group Structural Formula Example Hydroxyl (Alcohols) -OH H Carbonyl (on end) (Aldehydes) - C=O Carbonyl (in middle) (Ketone) O C Carboxyl (Organic Acids) COOH Amino (Amino Acids) NH2 Phosphate (Nucleic Acids) PO43-

25. Large Carbon Molecules • The building of large molecules occurs as follows: • Monomers —small, simple carbon molecules • Polymers —consists of repeated, linked monomers • Macromolecules —large polymers: (Carbohydrates, lipids, proteins, nucleic acids) http://kenpitts.net/bio/human_anat/monomer.jpg

26. Condensation Reactions Polymers form during condensation reactions In these reactions; water is released

27. Example: Glucose and Fructose combine to form Sucrose

28. Hydrolysis Polymers break down by a hydrolysis reaction In these reactions;water is used http://imcurious.wikispaces.com/file/view/hydrolysis_reaction.jpg/113609729/hydrolysis_reaction.jpg

29. The Energy Molecule: ATP • Adenosine Triphosphate (ATP ) —the most important energy currency molecule of cells. • Made of Adenine; Ribose(a sugar) and 3 phosphate groups

30. http://kentsimmons.uwinnipeg.ca/cm1504/atp.htm -ATP can lose its end phosphate which releasesthe energy stored in it. and makes adenosine diphosphate (ADP). -This energy is used to do work in the cell. -Adding the phosphate back to make ATP requires that we addenergy The Hydrolysis of ATP is used by the cell to provide the energy needed to drive chemical reactions.

31. The Molecules of Life • Four main groups of organic compounds: • Carbohydrates • Proteins • Lipids • Nucleic Acids http://ez002.k12.sd.us/Chapter%20One%20Science.htm

32. Carbohydrates • Used for energy • Three types: • Monosaccharides(glucose and fructose) • Disaccharides (sucrose) • Polysaccharides (glycogen, starch and cellulose) Structure is too complex to show

33. Proteins • Made of chains of amino acids held together by peptide bonds. • Dipeptides(two amino acids) • Polypeptides(long chains of amino acids) that fold and bend into proteins. Typical amino acid

34. Form by condensation reactions.

35. Enzymes —special types of proteins that act as catalysts

36. Lipids • Lipids are fats. • Used for energy • Nonpolar • Fatty acids bonded to other molecules

37. http://www.biology.lsu.edu/introbio/Link2/fatty%20acids.gif Saturated Fatty Acids —each carbon is covalently bonded to four atoms (NO DOUBLE BONDS) Unsaturated Fatty Acids —not all carbons are bonded to four other atoms (HAS DOUBLE BONDS)

38. Classes of Lipids • Triglycerides (fats) —three molecules of fatty acid joined to one molecule of glycerol. • Saturated triglycerides —the 3 fatty acids are saturated: hard at room temp: found in butter and red meat: “bad fats” • Unsaturated triglycerides —the 3 fatty acids are unsaturated: soft at room temp: found in plant seeds: “good fats” • Phospholipids —two fatty acids joined to glycerol. They also have a phosphate group. • Important part of all cell membranes • Waxes —fatty acid chain joined to an alcohol chain: waterproof: form protective layers in plants and animals • Steroids —four fused carbon rings with a functional group: include many hormones and cholesterol

39. Nucleic Acids • Include DNAand RNA • Information molecules • Made of repeating monomers called nucleotides. • Phosphate, pentose sugar, nitrogenous base.