5.1) The main ingredient of organic molecules - Carbon!

THIS UNIT'S WORDS TO KNOW>>

• Organic molecule - Carbon-based molecule. (Bonds with hydrogen, oxygen, nitrogen ...etc)
• Inorganic molecule - Non-carbon-based molecule (Water, oxygen, amonia ...etc)
• Hydrocarbon - Organic molecule composed of only carbon and hydrogen atoms. Many of these are important fuels. (Methane) Our body's energy storing fat molecules contain long chains of these.
• Functional Group - Group of atoms within a molecule that interacts in predictable ways with other molecules.
• Hydrophilic - Attracts water molecules.
• Monomer - Small molecular unit that is the building block of a larger molecule.
• Polymer - Long chain of small molecular units (monomers).
  
  (Partly from the book, "BIOLOGY, Exploring Life" Glossary)

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Carbon Skeletons, Functional Groups, Monomers, and Polymers..

• Most molecules of a cell are carbon-based, other than water.
• Backbone of carbon atoms bonds to one another, and may brach off with atoms of other elements. This basic structure is the foundation of a wide range of molecules in life.
• The reason why the carbon atoms are so common in living things is because carbon's highest energy level are just 4 electrons. To satisfy it by holding 8 electrons in the outer energy level, carbon can form up to 4 bonds with other atoms, branching off in up to four directions.
• The carbon skeleton and the attached functional groups determine the properties of an organic molecule.

• Thousands of different kinds of polymers exist in every living cell, and they are all formed by only as fewer than 50 kinds of monomers.
• Life's large molecules are grouped as four main categories, which are carbohydrates, lipids, proteins, and nucleic acids.

Building and Breaking Polymers

• Every time a water molecule is released when two monomers bond to each other, making a polymer chain longer. This reaction is called dehydration, which basically means removing water.
• When cells break a polymer chain, either to obtain energy, or use them to build new polymers, they add water between the bonds of monomers. This process is called a hydrolysis reaction, which means that water is used to break down.


• Building polymer - water released.
• Breaking polymer - water added.
  

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Concept Check

Q. How many bonds in the most, can a carbon have, and why?
Q. What is the difference between organic and inorganic molecules?
Q. What are the four main categories of large molecules in life?
Q. Give one common functional group.
Q. Waht is the difference between a dehydration reaction and a hydrolysis reaction?

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Picture taken from:
http://www.biology.lsu.edu/ http://www.chemheritage.org/EducationalServices/pharm/tg/asp/ester/ester01.gif