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Transcript
The Chemistry of Life 1 Atoms All things are made of atoms Atom -basic unit of all matter Normally it is electrically neutral (no charge) Made up of Protons Neutrons Electrons 1 water molecule, H2O, has 3 atoms (2 H and 1 O) 2 Atoms The nucleus is the center of the atoms and it contains protons and neutrons Protons + charged particle Heavy 3 Atoms Neutrons Neutrally charged particle Heavy 4 Atoms The electrons zip around the outside of the nucleus Electrons - charged particle Light Most atoms are electrically neutral so the + protons = the - electrons 5 Elements Element-pure substance that consists of just one type of atom 114 elements in the periodic table Have a 1 or 2 letter symbol C = carbon N = nitrogen H = hydrogen S = sulfur O = oxygen, etc. Is water an element? 6 Elements Elements are identified by their number of protons Atomic Number= Different elements have a # of protons different number of protons 6 C Carbon 12.011 Atomic Mass= 7 Where is Sodium? What is its atomic number? 8 Elements Atomic Number= 11 # of protons 11 Na Sodium 22.990 Atomic Mass= 23 9 Elements The electrons of an element determine its properties and reactivity They move around the nucleus in energy levels Different energy levels hold different numbers of electrons Full and stable: 2 (1st), 8 (2nd), 8 (3rd) electrons, starting from the center Is the carbon atom stable? 10 Isotopes Isotopes--atoms of same element w/ a different # of neutrons Some are radioactive, some are not Isotopes of Carbon Nonradioactive carbon-12 6 electrons 6 protons 6 neutrons Nonradioactive carbon-13 6 electrons 6 protons 7 neutrons Radioactive carbon-14 6 electrons 6 protons 8 neutrons 11 Radioactive Isotopes Isotope with unstable nucleus due to extra neutrons Break down at a constant rate Give off dangerous radiation Have uses too C-14 dating Cancer treatment 12 Bonds Bonding -for some atoms to be stable they must gain, lose, or share electrons with another atom. Stability of atoms is based on electrons 2 types of bonds -Ionic -Covalent 13 Bonds Ionic bonds - electrons transferred from one atom to another Normal atoms are electrically neutral, so with this transfer they gain a charge and form ions- charged atoms The oppositely charged ions attract forming the ionic bond NaCl has ionic bonds 14 Bonds Covalent bonds --sharing electrons Stronger than ionic Molecule--formed when atoms are joined in a covalent bond 15 Water Water covers ¾ of Earth’s surface Most abundant molecule in living things Universal solvent…dissolver of many substances found on Earth Connects all parts of the world with others. 16 Properties of Water Water has polar, covalent bonds Covalent- H and O share electrons Polar- sharing is unequal Oxygen “pulls” harder on negative electrons and gives it slight negative charge. 17 Properties of Water Opposite charges of polar molecules can interact to form hydrogen bonds H (+) attracts O (-) like a magnet Gives water special properties 18 Solutions Many substances dissolve in water Solutions occur when one substance is dissolved in another Solute -gets dissolved Solvent -does the dissolving Saltwater 19 Acids, Bases, and pH Solutions have a pH Chemical property to describe how acidic or basic it is An acid releases a hydrogen ion (H+) when it dissolves; bases take them up pH scale from 0-14 Pure water neutral: pH7 Acids:<7 Bases: >7 20 21 Buffers Human homeostasis-human blood must be b/t pH 6.77.5 Body uses buffers, which are weak acids or bases, to neutralize sharp changes in blood pH 22 Carbon Carbon atoms are the building blocks of life Carbon atoms only have 4 electrons in their outer energy level (recall 8 is stable), so they want to bond They are the basis of most molecules that make up living things 23 24 Organic Macromolecules Long chains of carbon subunits are called organic macromolecules have C-C bonds large molecules Each smaller molecule is a subunit called a monomer 25 Organic Macromolecules 4 types of organic macromolecules found in living things Carbohydrates Lipids Nucleic Acids Proteins 26 Carbohydrate Structure Composed of C, H and O Carbs include sugars and starches Sugars Called monosaccharides Basic carbs that are simple sugar monomers Sucrose (table sugar), glucose (made in photosynthesis) MONOSACCHARIDES (SUGARS) 27 Carbohydrate Structure Starches Called polysaccharides Complex carbs that are polymers made of monosaccharide monomers Pasta, potatoes, cellulose (cell walls of plants) MONOSACCHARIDES (SUGARS) POLYSACCHARIDE (STARCHES) 28 Carbohydrate Function Main source of energy for living things Converted to ATP— gasoline for cells Monosaccharides = immediate E Polysaccharides = longer term E Plants store carbs as cellulose which gives their cells strength 29 Lipid Structure Composed of C and H Lipids are polymers made of fatty acid and glycerol monomers Fats, oils, waxes are lipids Saturated and unsaturated fats Nonpolar so hydrophobic or ”waterfearing”-not dissolvable in water FATTY ACIDS AND GLYCEROL LIPID 30 Lipid Function Store energy for use later Hormones Cell membranes Waterproof covering (skin) 31 How much fat does pop have? 32 What organic macromolecule is the main ingredient? Nucleic Acid Structure Made of C, H, O,P (phosphorus) and N (nitrogen) Nucleic acids are polymers made of nucleotide monomers NUCLEOTIDES NUCLEIC ACID 33 Nucleotides Each nucleotide is made of 3 parts Phosphate group 5 Carbon sugar Nitrogen base (A, C, T, G as they are known in DNA) 34 Nucleic Acid Function Store and transmit hereditary (genetic) info DNA RNA 35 Protein Structure Composed of C, N, O, and H Proteins are polymers made of amino acid monomers 20 different amino acids form 1000’s of different proteins AMINO ACIDS PROTEIN 36 Protein Structure Proteins differ in the number and sequence of the 20 different amino acids The sequence of amino acids determines a protein’s structure (shape), and therefore, function If the shape is ruined, so is the protein’s function This is the basis of many diseases 37 38 Protein Function Enzymes-special proteins that control chemical reactions Form bones and muscles Forms hair and nails (keratin) Also part of cell membrane with lipids Food source: steak, eggs, nuts, cheese PROTEINS ARE NOT MAJOR SOURCES OF ENERGY! 39 Inorganic Inorganic –molecules that don’t have C-C or C-H bonds NaCl, H2O 40 Chemical Reactions Everything occurring in an organism is based on chemical reactions- process that changes one set of chemicals into another set Slow (rusting) or fast (burning) Breaking and remaking of bonds Reactants-products 41 Chemical Reactions Reactant(s) Product(s) carbon + oxygen carbon dioxide + energy CO2 + energy C + O2 O C O C O + energy O black solid colorless gas colorless gas 42 Energy in Chemical Reactions Reactions involve changes in energy Some reactions release energy Burning Digestion of carbs and lipids Some must absorb energy to occur ATP- form of energy absorbed or released when bonds are made or broken (“cell gasoline”) Animals get our ATP and organic macromolecules for body processes from food Plants get it from? 43 Chemical Reactions and Enzymes Some reactions are too slow They need lots of energy (ATP) to jump start them This energy is called activation energy Others are too fast and need to be slowed or neutralized Activation energy Reactants 44 Products Chemical Reactions and Enzymes Enzymes are the specialized proteins that control, or catalyze, chemical reactions in living things Digestion, nervous system signals, etc. all require them Substrates are the particular reactants an enzyme acts on in a chemical reaction They fit like a lock and key If the shape is ruined, so is the protein’s function This is the basis of many diseases 45 What Are Enzymes? Most enzymes are Proteins (tertiary and quaternary structures) Act as Catalyst to accelerates a reaction Not permanently changed in the process 46 Enzymes Are specific for what they will catalyze Are Reusable End in –ase -Sucrase -Lactase -Maltase 47 How do enzymes Work? Enzymes work by weakening bonds which lowers activation energy 48 Enzymes Without Enzyme With Enzyme Free Energy Free energy of activation Reactants Products Progress of the reaction 49 Enzyme-Substrate Complex The substance (reactant) an enzyme acts on is the substrate Substrate Joins Enzyme 50 Active Site A restricted region of an enzyme molecule which binds to the substrate. Substrate Active Site Enzyme 51 Induced Fit A change in the shape of an enzyme’s active site Induced by the substrate 52 Induced Fit A change in the configuration of an enzyme’s active site (H+ and ionic bonds are involved). Induced by the substrate. Active Site substrate Enzyme induced fit 53 What Affects Enzyme Activity? Three factors: 1. Environmental Conditions 2. Cofactors and Coenzymes 3. Enzyme Inhibitors 54 Environmental Conditions Enzyme activity can be affected by many variables, some of which due to altering the protein’s shape pH can alter shape and function Temperature can alter shape and function Enzyme concentration can affect how many reactions can occur: more enzyme=more activity 55 2. Cofactors and Coenzymes Inorganic substances (zinc, iron) and vitamins (respectively) are sometimes needed for proper enzymatic activity. Example: Iron must be present in the quaternary structure - hemoglobin in order for it to pick up oxygen. 56 Two examples of Enzyme Inhibitors a. Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Substrate Competitive inhibitor Enzyme 57 Inhibitors b. Noncompetitive inhibitors: Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site. Substrate active site altered Enzyme Noncompetitive Inhibitor 58