The Star of The Show arbon and the Molecular Diversity of Life hapter 4 Pgs. 58-67 arbon is the Backbone of Life arbon enters the biosphere via plants It is the most vital atom in proteins, DNA, carbohydrates, and other molecules that distinguish living from nonliving things all life is built on carbon arbon is unparalleled in its ability to form molecules that are large, complex, and varied In cells About 72% is 2 Approx. 25% is carbon compounds Roughly 3% is salts rganic hemistry The hemistry of Life rganic compounds are those that contain a high number of carbon and hydrogen atoms The study of carbon compounds is organic chemistry arbon atoms can form diverse molecules by bonding to four other atoms arbon compounds range from simple to complex molecules rganic ompounds Name and omments (a) Methane (b) Ethane Molecular Formula 4 2 6 Structural Formula Ball-and-Stick Model Space-Filling Model rganic compounds often form polymers Long chains of smaller molecules called monomers, bind to form huge macromolecules Four types: carbohydrates, lipids, proteins, and nucleic acids (c) Ethene (ethylene) 2 4 1
rganic v. Inorganic Molecules ontains carbon Large covalent molecules Plays a role in living things, necessary element of life Does not contain carbon Smaller ionic molecules arbon Skeletons The bonding versatility of carbon allows it to form many diverse molecules, including carbon skeletons The electron configuration of carbon gives it covalent compatibility with many different elements arbon has four valence electrons and may form single, double, triple, or quadruple bonds an form FUR stable covalent bonds at same time (=tetravalence) ommon partners =,, N Four main elements are N arbon may bond to itself, forming carbon chains, which may vary in length and shape 8 TETRAVALENE makes large complex molecules with a variety of shapes possible (a) Length (b) Branching (c) Double bonds (d) Rings Ethane Butane yclohexane 1-Butene Propane 2-Butene Benzene isobutane rganic Molecules and the rigin of Life on Earth In 1953, Stanley Miller concluded that complex organic molecules could arise spontaneously under conditions thought to have existed on the early Earth is experiments support the idea that abiotic synthesis of organic compounds (maybe near volcanoes) could have been an early stage in the origin of life See details about his experiment on pg. 59 11 2
ydrocarbons arbon chains form the skeletons of most organic molecules ydrocarbons are organic molecules that only consist of carbon and hydrogen (other molecules may include other atoms, like N,, and P) nly have covalent bonding, and are nonpolar Major components of petroleum Not found independently in large amounts in living organisms, but they make up parts of some fats and oils an undergo reactions that release a relatively large amount of energy Isomers Isomers are compounds that have the same numbers of atoms of the same elements, but different structures and thus different properties and functions rganisms are sensitive to even the most subtle variations in molecular architecture, so sometimes only one isomer is biologically active Three types Structural isomers is-trans (geometric) isomers Enantiomers Types of Isomers Structural isomers differ in the covalent arrangements of their atoms Example: there are 3 forms of 5 12, 18 variations of 8 18, and 366,219 possible isomers of 20 42 is-trans isomers (also called geometric isomers) have atoms that differ in spatial arrangement around an inflexible double bond This only occurs when two carbons are double-bonded and each also has two different atoms (or groups of atoms) attached to it Enantiomers are isomers that are mirror images of each other; they differ in shape around an asymmetric carbon (attached to 4 different atoms or groups of atoms) They are left-handed and right-handed versions of the molecule Structural is-trans (geometric) Enantiomer Types of Isomers 6 12 6 6 12 6 6 12 6 trans- form cis- form Form/Structure Affects Function Importance of Structure Structural differences create important functional differences Two molecules can have the same amount of atoms but different structures would result in different functions Thalidomide Prescribed to pregnant women in 50s & 60s Reduced morning sickness, but caused severe birth defects 3
Functional Groups Functional groups are chemically reactive groups of atoms that affect function by being directly involved in chemical reactions These contribute to function by affecting the molecule s shape, and gives the molecule special chemical properties There are seven groups most important in biological processes ydrophilic, affect reactivity of molecule ydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate Nonreactive, usually serves as a recognizable tag on biological molecules Methyl What are the Functional Groups? Importance of Functional Groups Basic structure of male and female hormones are identical Identical skeleton with the attachment of different functional groups Interact with different targets in the body or Name: alcohols Example: ethanol Names of these molecules typically end in -ol ydroxyl Polar due to, which attracts 2 an -bond with water, helps dissolve organic compounds like sugars arbonyl Names: Ketones and aldehydes Ketones (if it is INSIDE a carbon may be structural isomers skeleton) with different properties Aldehydes (if at the END of a carbon skeleton) Found in sugars ketoses Example: acetone and propanal and aldoses 4
Name: carboxylic acids (or organic acids) Example: acetic acid, fatty acids, amino acids ompounds are acids and typically end in -oic arboxyl Properties Acts as an acid (donates + because of polar covalent bond) Found in cells in ionized form harge of 1- alled a carboxylate ion N Name: amines Example: glycine Typically ends in -ine Amino Acts as a base; picks up + from surrounding solution (water) Found in cells in ionized form harge of 1+ Sulfhydryl Phosphate S Name: thiols Example: cysteine ross-linking helps stabilize protein structure by building bridges between 2 S groups ccurs in curly hair P - - Name: organic phosphates Examples: glycerol phosphate Properties ontributes to negative charges in the molecules it is involved in (2- at the end of or above a molecule; 1- when it is internal) Transfers energy between organic molecules Acid lots of negative charges make it highly reactive A more complicated organic phosphate ATP adenosine triphosphate Adenine + ribose sugar + three phosphate molecules Used to store energy in the cell When it is time to use the stored energy The cell removes a phosphate group from the molecule When the bond is broken, it releases energy that does work The ATP molecule becomes ADP adenosine diphosphate ADP returns to the mitochondria in the cell to be recharged (phosphate is added back to make ATP) Name: methylated compounds Methyl May affect expression of genes when in DNA Affects shape and function of male and female sex hormones May not always attach to carbon 5