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Chemical Evolution. Carbohydrates and Lipids. Biochemistry. Systematic study of the molecular nature of life processes: the chemicals that make up of living systems (biochemicals), their organization into cells, and their chemical interactions Biochemicals have no life in themselves

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Chemical Evolution

Carbohydrates and Lipids


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Biochemistry

  • Systematic study of the molecular nature of life processes: the chemicals that make up of living systems (biochemicals), their organization into cells, and their chemical interactions

  • Biochemicals have no life in themselves

  • Chemical interactions which sustain life occur only when biochemicals become organized into cells in tissues


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Biochemicals

  • The major biochemicals are carbohydrates, lipids and proteins which provide energy and materials; and nucleic acids, which provide hereditary information needed to sustain life

  • According to Oparin, each was first produced abiotically by chemical evol-ution and then assembled as first cell


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Carbohydrates

  • Carbohydrates - substances having alcohol (-OH) and either aldehyde (CHO) or ketone (C=O) functional groups

  • Function: provide energy and materials

  • Structures: Chain and ring forms coexist with the ring form usually predominating in aqueous solutions


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(4 C)

Abiotic Synthesis of Carbohydrates (sugars)

(3 C)

(5 C)

(6 C)

Mason, Chemical Evolution,Oxford, UK, 1991, 241


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Carbohydrates - polyhydroxy aldehydes or ketones

Hill/Kolb, "Chemistry for Changing Times", 7th,Prentice Hall, NJ, 19995,456


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Ring Structure for Glucose

Brady/Holum, "Fundamentals of Chemistry", Wiley, NY, 1988, 1029


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Monosaccharides - One Ring

Joesten, World of Chemistry: Essentials, Saunders FL, 1993, 206


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Monosaccharides - one ring

Disaccharide - two rings

Disaccharides

Joesten, World of Chemistry: Essentials, Saunders FL, 1993, 206


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Polysaccharide - Many Rings

Glucose is stored in the human body as glycogen which is a polysaccharide having a structure similar to that for starch

Hill/Kolb, "Chemistry for Changing Times", 7th,Prentice Hall, NJ, 19995,457


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Structure/Property Generalizations

  • Chemical, physical, and biological properties of biochemicals are determined by their structures

  • Structurally, biochemicals involve large molecules frequently composed of repeating components (polymers)


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Energy-providing Function of Carbohydrates

  • Glucose is produced in plants by solar energy and chlorophyll catalyst: 6 CO2 + 6H2O => C6H12O6 + 6 O2; DH > 0

  • Glucose is water soluble (H-bonding) and is transported to cells where it serves as the source of energy by means of the reaction:

  • C6H12O6 + 6O2 => 6CO2 + 6H2O;DH < 0


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Flow of Energy and Matter Between Plants and Animals

Reduction of Carbon

Oxidation of Carbon

Joesten/Wood, World of Chemistry, 2nd, Saunders, NY, 1996, 491


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Lipids

  • Lipids are the components of cells that are insoluble in water but soluble in non-polar solvents

  • Include fats, oils, fatty acids, steroids, and some vitamins

  • Only fats, oils, and fatty acids will be considered in this course


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Fatty Acids

  • Fatty acids are organic acids RCOOH having 7-21 carbon atoms in R group

  • Fatty acids are classified according to the number of double bonds in the R-group (saturated, if no double bonds; mono-unsaturated, if one double bond; and poly-unsaturated if more than one double bond)


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(All C to C single bonds)

(One C to C double bond)

(More than one C to C double bond)

Tro,394


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Geometric Isomers

  • Geometric isomers have the same atoms and the same bonds, but different spatial orientations around a double bond

  • Differentiated by drawing an imaginary plane perpendicular to the plane containing the C=C (shown as red dotted lines on next slide)


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Examples of Geometric Isomers

Two like groups located on adjacent C atoms- both above or both below the  red plane: cis-isomer

Two like groups located on adjacent C atoms- one above and one below the  red plane: trans-isomer

http://www.wpbschoolhouse.btinternet.co.uk/page06/AlkeneStructure.htm



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Fats and Oils

  • Fats are tri-esters of saturated fatty acids and glycerol - solids at room temperature

  • Oils are tri-esters of unsaturated fatty acids - liquids at room temperature - kinks at double bonds decrease effectiveness of London Forces between chains


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Abiotic Synthesis of Fats and Oils from Fatty Acids

Joesten, World of Chemistry: Essentials, Saunders FL, 1993, 210


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Membrane Function of Lipids

  • One function of lipids is to serve as a membrane which separates compon-ents of an animal cell

  • A fat or oil is converted to a glycero-phospholipid by replacing one non-polar fatty acid unit with a polar unit - combination of a phosphate unit and an amino alcohol unit


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Lipids of Cell Membranes

Brady/Holum, Chemistry, 3rd, Wiley,NY, 2000, 1060.


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Hydrophilic: water-loving

Hydrophobic: water-avoiding

Glycerophospholipid Representation

Brady/Holum, Chemistry, 3rd, Wiley,NY, 2000, 1060.


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The Lipid Bilayer of Animal Cell Membranes

Structural integrity of an animal cell depends entirely on the sum of many weak forces: London dispersion, dipole, and hydrogen bonding

Brady/Holum, Chemistry, 3rd, Wiley,NY, 2000, 1061.