Chapter 2

Organic Chemistry

Why Is Carbon So Important to Life?

•       Organic Molecules = molecules that contain C-C or C-H bonds

•       Life’s diversity is based on the properties of carbon.

•       The enormous diversity of organic molecules emerge from the ability of carbon to form large, complex, diverse molecules

Why Is Carbon So Important to Life?

•       The carbon atom is a central point from which molecules branch off into four directions.

•       These bonds are strong yet flexible

Why Is Carbon So Important to Life?

•       Complex organic molecules can be thought of as carbon skeletons with different functional groups. The functional groups are just compounds of other elements (oxygen, nitrogen, phosphorous, hydrogen).

 

Molecules of Life

•       Organic molecules are mostly four types

–    Carbohydrates

–    Lipids

–    Proteins

–    Nucleic Acids

•       Macromolecules are synthesized by a dehydration reaction, and degraded by a hydrolysis reaction.

 

Dehydration Synthesis and Hydrolysis of Maltose

 

Carbohydrates

•       Carbohydrates function for energy storage and structure.

–    Monosaccharide (simple sugar)

v Ex: Glucose

–    Disaccharide

v Ex: Sucrose

 

Complex Carbohydrates

•       Polysaccharides.

–    Starch (plants).

–    Glycogen (animals).

–    Cellulose (plant cell walls).

–    Chitin (insect exoskeleton)

 

Lipids

•       Lipids contain more energy per gram than any other biological molecule.

–     Do not dissolve in water.

v  Absence of polar groups.

–     Triglycerides

v  Fats.

Ψ  Animal origin, solid at room temperature.

v  Oils.

Ψ  Plant origin, liquid at room temperature.

–     Oils, Fats, and Waxes Contain Only  Carbon, Hydrogen, and Oxygen

 

 

Saturated and Unsaturated Fatty Acids

•        A fatty acid is a carbon-hydrogen chain ending with -COOH.

–    Saturated fatty acids contain only single bonds between the carbon atoms.

–    Unsaturated fatty acids contain one or more double bonds in the carbon chain.

 

 

Phospholipids and Steroids

•       Phospholipids contain a phosphate head and fatty acid tails.

•       Water-Soluble Heads and Water-Insoluble Tails

 

•       Steroids are lipids with a backbone of four fused carbon rings.

–    Estrogen and testosterone.

Phospholipids

 

Proteins

•       Structural proteins “R” us!

Proteins

•       Proteins are macromolecules with amino acid subunits

–     Amino acid - Central carbon, amino group & acid group.

 

 

 

•       Peptide bond - Any bond joining two amino acids – Dehydration synthesis

Ψ  Polypeptide - Single amino acid chain.

 

 

Levels of Protein Organization

•       Primary Structure.

–    Linear sequence of amino acids.  (polypeptide)

–    Secondary Structure.

–    Repeating helix or pleated sheet

•       Tertiary Structure.

–    Final three-dimensional globular shape – combination of secondary structure

•       Quaternary Structure.

–    Proteins with more than one polypeptide.

Three-Dimensional Shapes Give Proteins Their Functions

Nucleic Acids

•       DNA and RNA, the Molecules of Heredity, Are Nucleic Acids

•       Other Nucleotides Perform Other Functions

 

Nucleic Acids

•       Nucleic acids are huge macromolecules composed of nucleotides.

–    A nucleotide is constructed of a phosphate, a pentose sugar, and a nitrogenous base.

–    Deoxyribonucleic acid (DNA).

v Double-stranded helix.

–    Ribonucleic acid (RNA).

v Single stranded.

 

DNA Structure

(ATP) Adenosine Triphosphate

•       ATP is the primary cellular energy carrier.

–    Energy currency of cells.

–    Breaks down to adenosine diphosphate (ADP) and a molecule of inorganic phosphate, releasing energy to drive cellular metabolism.

 

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