The Chemistry of Life

1. The Chemistry of Life Chapters 2 and 3

2. Atoms • Smallest unit of matter that retains physical properties • 3 Basic Parts • Proton • Neutron • Electron • Nucleus gives an atom its mass • Electrons give an atom is behavior

3. Elements • Made up of only 1 type of atom • Isotopes have same number of p+, but different numbers of n0, so atomic mass varies • Form compounds • Chemical Bonds • Formula tells the ratio of atoms in a compound • 98% of living things are made of CHNOPS

4. Chemical Bonds • The valence electrons are involved in the bond • Atoms are stable when their valence shell is filled

5. Covalent Bonds- atoms share valence electrons and are held together • Non-metal to non-metal • Molecule is the smallest part of a compound that retains the properties

6. Polarity • Covalent bonds share electrons between atoms • Electrons shared equally result in a non-polar bond • Electrons shared unequally between the atoms create regions of positive charge and negative charge, though the molecule is neutral, results in a polar bond • Polar molecules can interact with each other and with ions • Whole molecules can be polar or select bonds in a molecule can be polar

8. Ionic Bonds are a result of the transfer of valence electrons • Atoms that lose electrons have more p+ than e- and are called positive ions (cations) • Atoms that gain electrons have more e- than p+ and are called negative ions (anions) • Metals form cations and non-metals form anions • The positive ion is attracted to the negative ion and they stick together

10. Energy • Comes in many forms • Kinetic, Potential, Chemical, Thermal, Radiant • The ability to do work • Can be converted from one form to another • When atoms for chemical bonds energy can either be absorbed or released

11. Living Things and Energy • All living things require energy • 1000s of chemical reactions occur in living organisms a day • Energy is either stored in bonds formed during a reaction or it is released by the reaction • Living organisms use this energy to carry out life processes • Metabolism is all of the chemical reactions that occur in an organism

13. Activation Energy • Energy required for a chemical reaction to occur • Can be a large amount • Catalysts lower the activation energy for a reaction • They are not used up and can be used repeatedly • Enzymes are proteins or RNA that act as catalysts in living organisms- there are 1000s

15. Enzyme has a specific shape that will interact with a specific substrate • Substrate is reactant being catalyzed fits in active site on enzyme Enzyme’s shape is changed when substrate bonds at active site • Change in shape causes bonds in substrate to weaken and break • Products are released by enzyme • Enzyme is unchanged and reacts anew with another substrate • Enzymes require very specific temperature and pH ranges • Changes can cause the enzyme to denature

16. Enzyme Catalyzed Reaction

17. Oxidation Reduction Reactions • AKA- Redox reactions • Reactions that involve the transfer of electrons • LEO says GER • Lose electrons oxidize • Gain electrons reduce • Oxidation and Reduction are coupled together- something is oxidized because something else is reduced

19. Water and Solutions • Cells are mainly water and the water is an arena for the chemical reactions of life to occur • Water is polar • H is slightly +, O is slightly – • Allows water molecules to interact with each other, ions, and other polar molecules • Water is universal solvent because of its polarity- it dissolves a lot of stuff

20. Hydrogen bonds form between water molecules allowing them to stick together • Hydrogen bonds form between H with a slight + charge and areas of – charge or with anions • Can be formed or broken easily and repeatedly- weak independently, strong in great numbers • Many occur at one time in water • H bonds allow water to experience • Cohesion- water molecules stick together • Adhesion- water molecules stick to other things

22. When ionic compounds are dissolved in water they ionize- break apart into cations and anions

23. Water is less dense as a solid than as a liquid • Ice floats- pond ecosystems are conserved even in winter • Water has a high specific heat capacity • Water absorbs large amounts of heat with little temperature change

24. Solutions • Solutions are homogeneous mixtures • All substances are evenly distributed throughout • Composed of solute and solvent • Solute is what is dissolved (less of this) • Solvent does the dissolving (more of this) • Can have different concentrations • How much solute is dissolved in the solvent • Saturated- the max amount of solute is dissolved

25. Aqueous solutions have water as the solvent • Essential for life • Aqueous solutions are essential for cells • Blood is an aqueous solution • Many organisms live in aqueous solutions- The ocean! Ponds! Lakes! Rivers! Your gut!

26. Acids and Bases • Water can ionize (split into ions) • H2O H+ + OH - • OH - is the hydroxide ion • H+ is a proton • Water can also accept a proton (H+), forming hydronium ion (H30+) • H+ + H2O H30+ • This occurs all of the time in water

27. Acids and bases are determined by the ratio of hydronium ions to hydroxide ions • Acids H30+ > OH- • Bases H30+ < OH- • Compounds that are acids donate a H+ and it will react with H20 to form H3O+ • Bases produce OH- which will increase their concentration

28. pH scale is a way to measure the concentration of H3O+ • It is a logarithmic scale- so each number is a ten-fold difference in concentration of H3O+

29. Buffers are chemical substances that can absorb excess acids or bases to maintain pH • Very important job • Enzymes (biological catalysts) can only function in specific pH ranges • Cells must regulate their pH

30. Biochemistry • The study of the chemistry that allows life to exist and flourish • Biochemistry is centered around the element Carbon • Organic compounds are those that contain carbon • Inorganic compounds do not generally contain carbon

31. Carbon • Carbon has 4 valence electrons and needs 8 • Forms covalent bonds to complete its valence shell • Carbon is special because is will bond with up to 4 other carbon atoms • Can form rings, straight chains, and branched chains

32. A covalent bond is formed when two atoms share 2 electrons • Represented with a straight line • Carbon can form single, double, and triple bonds • Carbon can form almost endless compounds as a result

33. Functional Groups • Organic molecules all contain Carbon- so what makes one compound different from another- Functional Groups • Functional Groups are specific clusters of atoms attached to a carbon compound • Each functional group has specific properties that it gives the compound

35. Large Carbon Molecules • Monomers are small, simple molecules that can be bonded together to form polymers • Macromolecules are made from polymers

36. Condensation and Hydrolysis Reactions • Monomers are bonded together through condensation reactions • With the addition of each monomer a water molecule is lost

37. Polymers can be broken down into polymers through hydrolysis reactions • A water molecule must be added in order to split one monomer away from the polymer

38. Energy Currency • Remember chemical bonds contain energy • Breaking or making a bond can either absorb or release energy • Some compounds have a lot of energy stored in their bonds • This energy can be used to power cell functions

39. Adenosine Triphosphate (ATP) is a high energy compound • Bond between the second and third phosphate is hydrolyzed to release energy for cellular functions, leaving ADP and P • ATP + H2O ADP + P + Energy • ADP + P + energy  ATP + H2O

40. Molecules of Life • Carbohydrates, Lipids, Proteins, Nucleic Acids • Each type has different properties and responsibilities • All have C, H, O; some also have N, P, S • Put together in different ratios

41. Carbohydrates • Roles include energy source and structural components • Made of C, H, O in a 1:2:1 ratio (CH2O)n • Monomer- monosaccharide • Glucose (simple sugar), galactose (milk), fructose (fruits) • Disaccharides are made by a condensation rxn joining 2 monosaccharide • Glucose + Fructose  Sucrose

42. Polymers are polysaccharides- large molecules made by joining many monosaccharides • Animals store excess sugar as Glycogen • Plants store excess sugar as Starch • Cellulose is a polysaccharide made by plants that gives cell walls strength and rigidity • Can be broken down by hydrolysis reactions

44. Proteins • Have a diversity of structures, resulting in a wide range of functions • Account for ~50% dry mass of cells • Act as enzymes, play roles in defense, storage, transport, cell communication, movement, structural support • Each protein has a unique 3-D shape • Composed of mainly C, H, O, N

45. Monomer is amino acid • There are 20 amino acids used to build thousands of proteins • Amino Acids have same basic structure • Amino group, central C, Carboxyl group, and R group (variable- distinguishes 1 aa from another) • Polymer is polypeptide • Long chain of amino acids • Held together by peptide bonds • Covalent bonds formed via condensation rxn

47. 1 or more polypeptide chain(s) fold into complex shapes • Shape is essential to function • Chains held together via interactions like hydrogen bonds • Enzymes are important group of proteins • Act as biological catalysts • Enzyme has a specific shape that will interact with a specific substrate • Substrate is reactant being catalyzed fits in active site on enzyme

48. Lipids • Function as long term energy storage, in membranes, water proof coverings, steroids (hormones) as chemical messengers • Have C, H, O- higher ratio of C and H to O • Long chains of C and H store more energy

49. Fatty Acids • Carboxyl Group connected to a long carbon chain • Carboxyl group is polar and therefore hydrophilic • Hydrocarbon chain is non-polar and hydrophobic • Fatty acids that have each C bonded to 4 things are called saturated • Fatty acids that have double bonds between some C atoms are called unsaturated

50. Triglycerides have 3 fatty acids joined to a glycerol head • Saturated triglycerides have a high melting point and are solid at room temp- butter, fats, red meat • Unsaturated triglycerides are usually liquid at room temp- Plant oils (olive, sunflower, etc)