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Biology I Honors “Life depends on chemistry.” The Nature of Matter What is the basic unit of matter? Atoms! Elements are made of like atoms. Compounds are formed when two or more elements combine. Compound are held together by bonds. 2 Main Groups of Chemical Compounds Organic Inorganic Organic Compounds Contain carbon Large molecules (made up of lots of atoms) Complex Lots of carbon and hydrogen atoms bound covalently (sharing electrons) primary compounds that make up the working structures of living things! Inorganic Compounds Generally do NOT contain carbon CO2 is an exception Also tend to be Small Simple While NOT the major building blocks of life, they are absolutely necessary for life Think WATER and Carbon Dioxide! What’s so special about CARBON? It’s a great Tinker Toy! 4 outer (valence) electrons Can bind with 4 different atoms What’s so special about CARBON? Readily forms COVALENT bonds with other atoms that are strong and stable What’s so special about CARBON? Can form chains of almost unlimited length by bonding with other carbon atoms These long chains can then FOLD to make many complex shapes THE BOTTOM LINE about CARBON It has HUGE potential for making a WIDE VARIETY of different types of molecules! How to BUILD (and take apart) Organic Molecules Polymer – a large molecule made up of many smaller subunits Monomer – a small subunit (building block) that can be joined with other subunits to make a polymer FOUR MAJOR GROUPS of Organic Compounds Carbohydrates Lipids Proteins Nucleic Acids Carbohydrates Functions Quick ENERGY Energy STORAGE in PLANTS Energy STORAGE in ANIMALS Structural compounds for SUPPORT GENERAL CARB STRUCTURE: Monomers and Polymers Monomers Monosaccharides i.e. Individual car in the train Polymers Polysaccharides i.e. The whole train Monosaccharides Simple/single sugars Basic formula CH2O Example: GLUCOSE; C6H12O6 Sugar made by plants in photosynthesis Others: galactose (milk sugar); fructose (fruit) Why monosaccharides are important Energy in them can be made QUICKLY available to living things Energy is stored in the chemical bonds of the sugar molecules ○ In particular, bonds between CARBON and HYDROGEN atoms store lots of energy When these bonds are broken, energy is released This energy is then available to use ○ Cellular respiration converts this energy to a usable form! Monosaccharide - Glucose Note that there are lots of these C-H bonds in a sugar molecule Each has lots of potential energy stored in it Disaccharides DOUBLE sugars Two monosaccharides joined Examples: Sucrose (table sugar) ○ Glucose + fructose (corn, beets, sugar cane) Lactose (milk) ○ Galactose (dairy, beets) + glucose Why are Disaccharides useful? Not quite so easily broken down as monosaccharides Can by used by plants / animals for safe temporary storage of sugars Used in transport in plants ○ Sugar not consumed on its way from leaves to roots Makes milk harder to digest in animals ○ MOST adult animals cannot digest milk ○ Keeps it for YOUNG ONLY Polysaccharides Made by joining MANY monosaccharides Sugar (thus energy) is STORED in this form TYPES of Polysaccharides STARCH PLANTS store energy in this form LOTS of GLUCOSE molecules linked in LONG CHAINS Animals CANNOT store energy in this form, but they CAN digest and USE it! Starch TYPES of Polysaccharides GLYCOGEN Energy storage carbohydrate in ANIMALS Found in the liver, mostly. ALSO made of lots of glucose linked together As you consume sugar, your liver converts it to glycogen and stores it. ○ Through the day as you need energy, the liver breaks off sugars from the glycogen molecules for you to us Glycogen Cellulose STRUCTURAL carbohydrate in PLANTS ALSO lots of glucose linked together CELL WALLS in plant cells SUPPORT and PROTECTION UNDIGESTABLE BY ANIMALS WOOD Chitin STRUCTURAL carbohydrate Cell walls of fungi Exoskeleton of arthropods Carbohydrate Review Are we addicted to sugar?? Lipids Waxes Oils Fats Steroids Functions of Lipids Energy Storage animals and plants Insulation Keeps animals warm blubber Functions of Lipids Waterproofing Duck feathers are kept dry by a layer of oil Mammal fur (beaver, otter, etc.), too. Plant leaves Functions of Lipids shockabsorption/protection of organs formation of membranes in cells and organelles make important compounds called steroids - cholesterol and hormones (estrogen and testosterone, for example) Structure of Lipids Glycerol + 3 fatty acids Glycerol is just a “connector” 3 fatty acids are the most important part Why are Fatty Acids the “important part”? fatty acids are LONG chains of carbon and hydrogen atoms remember: bonds between carbon and hydrogen atoms STORE ENERGY! So fats (with their 3 fatty acids) are PACKED with energy and are GREAT at energy storage EFFICIENT energy storage Because there are SO MANY C-H bonds in fatty acids, lipids are VERY efficient ways of storing energy. Fats produce more energy per gram than carbohydrates do! more efficient means better for animals lots of energy without much "baggage“ for animals that need to move. Efficient energy storage Some plants do use oils for energy storage Corn oil, peanut oil, etc. Efficiency is just not as important for plants since they don’t have to move around - so starch is still often the primary energy storage molecule for them Saturated vs. Unsaturated Fats saturated fat - when each carbon in a fatty acid shares a single covalent bond with as many hydrogen atoms as possible Solid at room temperature Saturated vs. Unsaturated Fats unsaturated fat - a fatty acid that has at least two carbons double bonded to each other instead of to hydrogen atoms – liquid at room temperature oils Saturated vs. Nonsaturated Fats Protein Functions Structural – build structures in organisms muscle contraction communication between cells movement of cell parts MOST IMORTANT: ENZYMES!!! Structure of Proteins Monomers of Proteins are AMINO ACIDS ○ 20 different types ○ All have different characteristics Protein Structure A protein is a polymer of amino acids Amino acid monomers link together by covalent bonds called PEPTIDE BONDS. = Proteins are long chains of amino acids sometimes called polypeptides in reference to their peptide bonds. Peptide bonds are formed by DEHYDRATION reactions. Making Proteins from Amino Acids Nucleic Acids Functions tell the cell how to function transmit genetic information to offspring Nucleic Acids Structure Monomers of nucleic acids are nucleotides ○ Sugar ○ Phosphate ○ Base Many nucleotides linked together give a nucleic acid - RNA and DNA are the two main examples Chemical Reactions The process that changes or transforms one set of chemicals into another Mass and energy conserved Speed varies Some release energy, others absorb energy Chemical Reactions The elements or compounds that enter into a chemical reaction are known as reactants. The elements or compounds produced by a chemical reaction are known as products. Copyright Pearson Prentice Hall All living things require energy to stay alive! Energy is conserved Energy is required That’s why we eat and plants need the sun! Activation energy-energy required to get a reaction started (some rxns to occur spontaneously) Living systems require catalysts to speed up rxns because they occur too slowly Enzymes are catalysts-they speed up reactions! Enzymes Enzymes have unique shapes designed to fit the chemicals that they are to "speed up" (the SUBSTRATES of the REACTION) The region of the enzyme that FITS the substrate specifically is called the enzyme's ACTIVE SITE. The substrate BINDS with the enzyme at the enzyme's ACTIVE SITE. Enzymes Enzymes can either: bring two (or more) reactants together more quickly and force them to react stress bonds in a single substrate and cause it to break apart more easily Enzymes An enzyme itself is NOT CHANGED by the chemical reaction it catalyzes A single enzyme can repeat its catalytic activity with many, many substrate molecules - that is, it can be used over and over again. Enzyme catalyzed reaction Enzymes ENZYMES ARE VERY SPECIFIC! If the shape of the enzyme's active site becomes damaged, it will be unable to bind with its substrate so I will be unable to function. If an enzyme loses its shape it is said to be DENATURED. ○ enzymes can be denatured by HEAT ○ or by extremes in pH. Cells regulate enzyme activity Enzymes cont…. regulate chemical pathways Make essential chemical compounds Involved in energy transfer communication