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UNIT II - BIOCHEMISTRY

UNIT II - BIOCHEMISTRY. Big Campbell ~ Ch 2-5 Baby Campbell ~ Ch 2-3. I. CHEMICAL BASIS OF LIFE. Elements Cannot be broken down without losing characteristic properties Six elements in greatest concentration in living things are S ulfur P hosphorus O xygen N itrogen C arbon H ydrogen

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UNIT II - BIOCHEMISTRY

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  1. UNIT II - BIOCHEMISTRY Big Campbell ~ Ch 2-5 Baby Campbell ~ Ch 2-3

  2. I. CHEMICAL BASIS OF LIFE • Elements • Cannot be broken down without losing characteristic properties • Six elements in greatest concentration in living things are • Sulfur • Phosphorus • Oxygen • Nitrogen • Carbon • Hydrogen • Defined by Atomic # which is = #of protons and the #of electrons in most cases

  3. I. CHEMICAL BASIS OF LIFE, cont • Atoms • Smallest unit of matter that retains properties of that element • Protons (+); found in nucleus • Neutrons (neutral); found in nucleus • Electrons (-); found in electron clouds. • Atomic Mass = p + n • Isotopes – when an atom has a different atomic mass, Ex: C12, C13, C14

  4. I. CHEMICAL BASIS OF LIFE, cont • Chemical Bonds • Chemical behavior of atom determined by valence electrons • Atoms interact with other atoms to complete their valence shells, either by transferring or sharing electrons

  5. I. CHEMICAL BASIS OF LIFE, cont • Types of Chemical Bonds • Ionic – Results when one atom has a much stronger attraction for electrons than another; one atom has a greater electronegativity. Electron(s) are transferred resulting in formation of ions. Bond forms due to charge attraction. Strength is dependent on environment

  6. I. CHEMICAL BASIS OF LIFE, cont • Covalent Bonds – More stable; results from sharing a pair of valence electrons. Forms a molecule. One pair of electrons shared = single covalent bond; two pair of electrons shared = double covalent bond. • Non-polar covalent bond – formed when electronegativity of atoms is the same • Polar covalent bond – formed when one atom is more electronegative; unequal sharing of electrons results in slight charges at either end of molecule

  7. II. WATER • Properties of Water Due to its Polarity • Hydrogen “bonds”

  8. II. WATER • “Stickiness” • Cohesion • Surface Tension • Adhesion • Capillary Action

  9. II. WATER, cont • Regulation of Temperature • High specific heat • High heat of vaporization • Density of “solid” water _<_ density of liquid water

  10. II. WATER, cont • Solvent of Life • Hydrophilic • “Water-loving” • Polar molecules “pull apart” ionic compounds & other polar molecules • Hydrophobic • “Water-hating” • Non-ionic and non-polar substances are repelled by water

  11. II. WATER, cont • Dissociation of Water • Rare, but measurable phenomenon • (2)H2O → H3O+ + OH- → H+ + OH- • In aqueous solution at 25˚C, total conc of [H+] [OH-] = 1x10-14 • Neutral solution → [H+] = [OH-]; therefore [H+] = 1 x 10-7 • pH = Provides a means for a compressed measurement of [H+] • -log10[H+] • Acid – Substance that dissolves in water to __increase_ [H+] • [H+] _>___ 1 x 10-7; pH __<__ 7 • Base - Substance that dissolves in water to _decrease_ [H+] • [H+] _<___ 1 x 10-7; pH _>_ 7 • pH of Water = 7

  12. II. WATER, cont • Buffers • Maintain a constant pH by donating, accepting H+ • Bicarbonate Buffer System • Very important buffer system in blood • pH of blood = _7.4_

  13. III. ORGANIC CHEMISTRY – THE STUDY OF CARBON • Atomic Structure of C • Atomic Number of C = 6 • 6 protons • 6 electrons • __4___ valence electrons • Hydrocarbon – composed on only C-H; impt in fossil fuels. Hydrophobic • Isomer – compounds with the same #of elements/atoms, but a different structural arrangement. See Ex…

  14. Four Ways Carbon skeletons can vary

  15. III. ORGANIC CHEMISTRY, cont

  16. III. ORGANIC CHEMISTRY, cont

  17. IV. THE BIOMOLECULES • Most are polymers made up of single units called monomers • Four Main Groups • CARBOHYDRATES • LIPIDS • PROTEINS • NUCLEIC ACIDS

  18. Dehydration Synthesis Also called _CONDENSATION REACTION__ Reaction that occurs to build polymers Forms __COVALENT_ bond between 2 monomers _WATER_lost as waste product Requires energy input, enzymes IV. BIOMOLECULES, cont

  19. Hydrolysis “__WATER BREAKING/SPLITTING_” Covalent bonds between monomers broken Releases energy; reaction accelerated with enzymes IV. BIOMOLECULES, cont

  20. V. CARBOHYDRATES • Provide fuel, act as building material • Generally, formula is a multiple of CH2O • Contain carbonyl group & multiple hydroxyl groups • Monomer = monosaccharides • Monosaccharides – usually found as ringed structures • Pentoses • Ribose • Deoxyribose

  21. V. CARBOHYDRATES, cont • Hexoses • Glucose • Fructose • Galactose

  22. V. CARBOHYDRATES, cont • Disaccharides • 2 monosaccharides covalently bonded together through dehydration synthesis • Example • Sucrose • Lactose • Maltose

  23. V. CARBOHYDRATES, cont • Polysaccharides • Many monosaccharides covalently bonded together through dehydration synthesis • Two main groups • Energy Storage Polysaccharides • Starch – Plants store glucose as starch in cell structures called plastids. Humans have enzymes to hydrolyze starch to glucose monomers. • Glycogen – Storage form of glucose in animals. More highly-branched than starch. In humans, found mainly in liver, muscle cells

  24. V. CARBOHYDRATES, cont • Structural polysaccharides • Cellulose – polymer of glucose. Every other glucose is upside down – forms parallel strands of glucose molecules held together with H-bonds

  25. V. CARBOHYDRATES, cont Structural polysaccharides • Chitin – found in arthropod exoskeleton, cell walls of fungi

  26. Very diverse group Non-polar, hydrophobic molecules Hydro_phobic__ Not true polymers Four groups Fats & oils phospholipids steroids waxes VI. LIPIDS

  27. Fats& Oils Composed of glycerol + 3 fatty acids Glycerol = 3-C alcohol Fatty acids – long hydrocarbon chains ending with carboxyl group AKA triglycerides Used for energy storage VI. LIPIDS, cont

  28. Saturated fats – “Saturated with hydrogens”; contain all single bonds. Typically from animal source, solid at room temp. Associated with greater health risk. Unsaturated fats – Contain double bonds, fewer H-atoms. Results in “kinked” hydrocarbon chain. Typically from plant source, liquid at room temp. VI. LIPIDS, cont

  29. Fats, cont. • Saturated fat • Unsaturated fat

  30. Phospholipids 2 fatty acids attached first 2-carboxyl groups of glycerol. Negatively-charged phosphate group is attached to 3rd carboxyl Partially polar and partially non-polar Found in all cell membranes. VI. LIPIDS, cont

  31. Phospholipid, cont.

  32. Waxes – One fatty acid attached to an alcohol. Very hydrophobic. Used as coating, lubricant Steroids – Consist of 4-rings with different functional groups attached. Cholesterol – steroid found in animal cell membranes; precursor for sex hormones VI. LIPIDS, cont

  33. Steroids, cont.

  34. VII. PROTEINS • Important part of virtually all cell structures, processes, reactions • Amino Acids – Proteins are large polymers made up of amino acid monomers. All amino acids have the same basic structure: • Amino group • Carboxyl group • Carbon, known as alpha carbon • R group → variable component; gives each amino acid its unique properties. Determines whether amino acid is classified as polar, non-polar, acidic, or basic.

  35. VII. PROTEINS, cont

  36. VII. PROTEINS, cont

  37. VII. PROTEINS, cont

  38. VII. PROTEINS, cont • Amino Acid → Protein • Dehydration synthesis results in formation of a peptide bond • Polypeptide – many amino acids covalently bonded together

  39. VII. PROTEINS, cont • Protein Conformation • Protein’s shape is related to its function. Generally, a protein must recognize/bind to another molecule to carry out its function. • Denaturation - A change in a protein’s shape. Results in a loss of protein’s ability to carry out function. • Four levels of protein structure • Primary • Secondary • Tertiary • Quaternary

  40. Primary – Sequence of amino acids VII. PROTEINS, cont

  41. Secondary – Coiling of polypeptide chain due to formation of H-bonds between H of amino end of one aa and OH of carboxyl end of another aa Alpha helix – created from H-bonds forming within one pp chain Beta pleated sheet – H-bonds form between aa in parallel pp chains VII. PROTEINS, cont

  42. Tertiary - Involves interactions between R groups of amino acids. Helps to give each protein its unique shape. VII. PROTEINS, cont

  43. Quaternary – Proteins that are formed from interactions between 2 or more polypeptide chains folded together. Examples include hemoglobin, collagen, chlorophyll VII. PROTEINS, cont

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