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Building Blocks of Life
Chemistry of Carbon Building Blocks of Life
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Why study Carbon? All of life is built on carbon Cells ~72% H2O
~25% carbon compounds carbohydrates lipids proteins nucleic acids ~3% salts Na, Cl, K… Why do we study carbon -- is it the most abundant element in living organisms? H & O most abundant C is the next most abundant
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Chemistry of Life Organic chemistry is the study of carbon compounds
C atoms are versatile building blocks bonding properties 4 stable covalent bonds Carbon chemistry = organic chemistry Why is it a foundational atom? What makes it so important? Can’t be a good building block if you only form 1 or 2 bonds. H C H H H
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Complex molecules assembled like TinkerToys
Figure 3.2 Molecular Shape Molecular Formula Structural Formula Ball-and-Stick Model Space-Filling Model (a) Tetrahedral: methane CH4 (b) More than one tetrahedral group: ethane C2H6 Figure 3.2 The shapes of three simple organic molecules (c) Plane: ethene (ethylene) C2H4
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© 2016 Pearson Education, Inc.
Figure 3.3 Hydrogen (valence = 1) Oxygen (valence = 2) Nitrogen (valence = 3) Carbon (valence = 4) H O N C Figure 3.3 Valences of the major elements of organic molecules The electron configuration of carbon gives it covalent compatibility with many different elements © 2016 Pearson Education, Inc.
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Hydrocarbons Combinations of C & H non-polar Stable
carbon-to-hydrogen linkages not soluble in H2O hydrophobic Stable Ex) fats very little attraction between molecules a gas at room temperature methane (simplest HC)
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Hydrocarbons can grow
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Isomers Molecules with same molecular formula but different structures (shapes) different chemical properties different biological functions Same formula but different structurally & therefore different functionally. Molecular shape determines biological properties. Ex. Isomers may be ineffective as medicines 6 carbons 6 carbons 6 carbons
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(a) Structural isomers trans isomer: The two Xs
Figure 3.5 Pentane 2-methyl butane (b) Cis-trans isomers cis isomer: The two Xs are on the same side. trans isomer: The two Xs are on opposite sides. (c) Enantiomers Figure 3.5 Three types of isomers, compounds with the same molecular formula but different structures CO2H CO2H C C H NH2 NH2 H CH3 CH3 L isomer D isomer
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Form affects function Structural differences create important functional significance amino acid alanine L-alanine used in proteins but not D-alanine medicines L-version active but not D-version sometimes with tragic results… stereoisomers
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Form affects function Thalidomide
prescribed to pregnant women in 50s & 60s reduced morning sickness, but… stereoisomer caused severe birth defects
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Diversity of molecules
Substitute other atoms or groups around the carbon ethane vs. ethanol H replaced by an hydroxyl group (–OH) nonpolar vs. polar gas vs. liquid biological effects! ethane (C2H6) ethanol (C2H5OH)
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Functional groups Parts of organic molecules that are involved in chemical reactions give organic molecules distinctive properties hydroxyl amino carbonyl sulfhydryl Carboxyl Methyl phosphate Affect reactivity makes hydrocarbons hydrophilic increase solubility in water
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Viva la difference! Basic structure of male & female hormones is identical identical carbon skeleton attachment of different functional groups interact with different targets in the body different effects For example the male and female hormones, testosterone and estradiol, differ from each other only by the attachment of different functional groups to an identical carbon skeleton.
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Hydroxyl –OH organic compounds with OH = alcohols
names typically end in -ol ethanol
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Carbonyl C=O O double bonded to C if C=O at end molecule = aldehyde
if C=O in middle of molecule = ketone
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Carboxyl –COOH C double bonded to O & single bonded to OH group
compounds with COOH = acids fatty acids amino acids
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carboxyl and amino group!
Notice the carboxyl and amino group! -NH2 N attached to 2 H compounds with NH2 = amines amino acids NH2 acts as base ammonia picks up H+ from solution
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Sulfhydryl –SH S bonded to H compounds with SH = thiols
SH groups stabilize the structure of proteins
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Phosphate –PO4 P bound to 4 O connects to C through an O
lots of O = lots of negative charge highly reactive transfers energy between organic molecules ATP, GTP, etc.
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component of DNA that has been modified by addition of
Figure 3.6-2c Methyl group (―CH3) Methylated compound 5-Methyl cytosine, a component of DNA that has been modified by addition of a methyl group Figure 3.6-2c Some biologically important chemical groups (part 2c: methyl) © 2016 Pearson Education, Inc.
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Building Blocks of Life
Macromolecules Building Blocks of Life
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Macromolecules Smaller organic molecules join together to form larger molecules macromolecules 4 major classes of macromolecules: carbohydrates lipids proteins nucleic acids
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© 2016 Pearson Education, Inc.
Figure 3.1 Figure 3.1 Why is the structure of a protein important for its function? © 2016 Pearson Education, Inc.
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Dehydration synthesis
Polymers Long molecules built by linking repeating building blocks in a chain monomers building blocks repeated small units covalent bonds H2O HO H • great variety of polymers can be built from a small set of monomers • monomers can be connected in many combinations like the 26 letters in the alphabet can be used to create a great diversity of words • each cell has millions of different macromolecules Dehydration synthesis
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You gotta be open to “bonding!
How to build a polymer You gotta be open to “bonding! Synthesis joins monomers by “taking” H2O out one monomer donates OH– other monomer donates H+ together these form H2O requires energy & enzymes H2O HO H enzyme Dehydration synthesis Condensation reaction
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How to break down a polymer
Breaking up is hard to do! Digestion use H2O to breakdown polymers reverse of dehydration synthesis cleave off one monomer at a time H2O is split into H+ and OH– H+ & OH– attach to ends requires enzymes releases energy H2O HO H enzyme Most macromolecules are polymers • build: condensation (dehydration) reaction • breakdown: hydrolysis An immense variety of polymers can be built from a small set of monomers Hydrolysis Digestion
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© 2016 Pearson Education, Inc.
(a) Dehydration reaction: synthesizing a polymer Figure 3.7 1 2 3 Short polymer Unlinked monomer 1 2 3 4 Longer polymer (b) Hydrolysis: breaking down a polymer Figure 3.7 The synthesis and breakdown of polymers 1 2 3 4 © 2016 Pearson Education, Inc. 1 2 3
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