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Carbon-based MoleculesAlthough a cell is mostly water, the rest of the cell consists mostly of carbon-based molecules
Organic chemistry is the study of carbon compounds
Copyright Cmassengale
Organic molecules are complex molecules of life, built on a framework of carbon atoms
•Carbohydrates
•Lipids
•Proteins
•Nucleic Acids
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Carbon is a Versatile Atom
It has four electrons in an outer shell that holds eight
Carbon can share its electrons with other atoms to form up to four covalent bonds
Copyright Cmassengale
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Hydrocarbons
The simplest carbon compounds …
Contain only carbon & hydrogen atoms
Copyright Cmassengale
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Uses of Organic MoleculesA typical cell in
your body has about 2 meters of DNA
A typical cow produces over 200 pounds of methane gas each year
Copyright Cmassengale
Isomers
Isomers are compounds with the same molecular formula but different structures and properties:Structural isomers have different covalent arrangements
of their atomsGeometric isomers have the same covalent
arrangements but differ in spatial arrangementsEnantiomers are isomers that are mirror images of each
other
Animation: IsomersAnimation: Isomers
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 4-7
Pentane
(a) Structural isomers
(b) Geometric isomers
2-methyl butane
cis isomer: The two Xs areon the same side.
trans isomer: The two Xs areon opposite sides.
(c) Enantiomers
L isomer D isomer
Enantiomers are important in the pharmaceutical industry
Two enantiomers of a drug may have different effects
Differing effects of enantiomers demonstrate that organisms are sensitive to even subtle variations in molecules
Animation: L-DopaAnimation: L-Dopa
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 4-8
Drug
Ibuprofen
Albuterol
Condition
Pain;inflammation
Asthma
EffectiveEnantiomer
S-Ibuprofen
R-Albuterol
R-Ibuprofen
S-Albuterol
IneffectiveEnantiomer
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Carbon can use its bonds to::
Attach to other carbons
Form an endless diversity of carbon skeletons
Copyright Cmassengale
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Large Hydrocarbons:
Are the main molecules in the gasoline we burn in our cars
The hydrocarbons of
fat molecules provide energy for our bodies
Copyright Cmassengale
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Shape of Organic Molecules
Each type of organic molecule has a unique three-
dimensional shape
The shape determines its function in an
organism
Copyright Cmassengale
Space-filling models show howAtoms sharing electrons overlap
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Functional Groups are:Groups of atoms that give
properties( such as polarity, acidity) to the compounds to which they attach
Gained Electrons Lost ElectronsCopyright Cmassengale
What cells Do to Organic Compounds•Metabolism
–Activities by which cells acquire and use energy to construct, rearrange, and split organic molecules
–Allows cells to live, grow, and reproduce
–Requires enzymes (proteins that increase the speed of reactions)
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What cells Do to Organic CompoundsLarge molecules are called polymersPolymers are built from smaller molecules called monomers
Biologists call them macromolecules
Copyright Cmassengale
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Most Macromolecules are Polymers
Polymers are made by stringing together many smaller molecules called monomers
Nucleic Acid
Monomer
Copyright Cmassengale
Structural model: each line is a covalentbond; two lines are double bonds;three lines are triple bonds.
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Linking Monomers
Cells link monomers by a process
called condensation or dehydration synthesis (removing a molecule of
water)
This process joins two sugar monomers to make a double
sugar
Remove H
Remove OH
H2O Forms
Copyright Cmassengale
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Breaking Down PolymersCells break
down macromolecules by a process called hydrolysis (adding a molecule of water)
Water added to split a double sugar
Copyright Cmassengale
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Macromolecules in Organisms
There are four categories of large molecules in cells:
Carbohydrates
Lipids
Proteins
Nucleic Acids
Copyright Cmassengale
Structure Dictates Function
•We define cells partly by their capacity to build complex carbohydrates, lipids, proteins, and nucleic acids
•All of these organic compounds have functional groups attached to a backbone of carbon atoms.
•Most biological molecules have at least on functional group ( a cluster of atoms that imparts specific chemical properties to a molecule)