Chapter Three: The Molecules of the Cells

 Questions: 

1. What are the seven functional groups?
2. Why does carbon create some of the most diverse and complex molecules?
3. What are the four types of macromolecules?  

Answers: 

1. The five functional groups are the hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, and methyl group.  The hydroxyl group is a hydrogen atom bonded to a on oxygen atom and it can form water molecules thus helping to dissolve organic compounds such as sugars.  It is polar.  The carbonyl group consists of carbon joined to oxygen with a double bond.  Its functional properties vary based on its structure and it is often found in sugars.  The carboxyl group is an oxygen atom double bonded to a carbon atom that is bonded to a hydroxyl group.  It has acidic properties.  The amino group consists of nitrogen bonded to two hydrogen atoms and to the carbon skeleton.  This group acts as a base.  The sulfhydryl group is made up of a sulfur atom bonded to an atom of hydrogen atom.  When two of these groups react and form a covalent bond they stabilize protein structure.  The phosphate group is a phosphorus  atom bonded to four oxygen atoms.  It has the potential to react with water thus releasing energy.  The methyl group consists of carbon bonded to three hydrogen atoms.  This group can affect the expression of genes.  
2. Carbon has four valence electrons meaning that it can form up to four covalent bonds.  These bonds can be single, double, or triple covalent bonds.  This means that it can form really large molecules whether they are chains, ring-shaped or branched meaning that carbon compounds can have many different isomers.    
3. The four different types of macromolecules are carbohydrates, lipids, proteins and nucleic acids.  Carbohydrates serve as fuel and building material.  Lipids are hydrophobic molecules that provide energy.  Proteins are polymers made up of amino acid monomers and have a variety of different functions.  Nucleic acids store and transmit hereditary information.  

Important Facts:

1. A protein consists of one or more polypeptide chains folded into a distinctive shape.  This determines the proteins function.  The primary structure of the protein is a polypeptide chain.  The secondary structure is the coiling/folding of the chain.  Tertiary structure is a three dimensional shape of a polypeptide,  while the quaternary structure is made up of more than one polypeptide.  
2. DNA and RNA are the two nucleic acids or nucleotides.  They are made up of a nitrogenous base (adenine, thymine, cytosine, guanine, uracil), a pentose (deoxyribose-DNA, ribose-RNA), and a phosphate group.
3. Denaturation occurs when a protein loses its shape and ability to function because of heat, a change in pH etc. 
4. Structural support polysaccharides are cellulose and chitin.  Cellulose is a major component in cell walls.  Chitin is commonly found in the exoskeleton of lobsters and insects.  Some energy storage polysaccharides are starch and glycogen.  Starch is often found in plants and stores substances.  Glycogen is used as storage in in animals.
5. A carbon skeleton is the chain of carbon atoms in an organic molecule.  They can be unbranched or branched and can contain double bonds.  This means that they can form many different isomers.  

Summary: This chapter focuses on organic compounds and the importance of carbon in life.  It talks about the hydrophilic functional groups.  The chapter also explains polymers and how they can be created by dehydration reactions as well as separated by hydrolysis.  The chapter then focuses on the structure and function of the organic macromolecules essential to living things: carbohydrates, lipids, proteins, and nucleic acids.

Diagram: This shows glucose and fructose forming sucrose through a dehydration reaction.  A molecule of water is released in order for the monosaccharides to bond.  

Key Terms:  
Hydrocarbons- Compounds made of only carbon and hydrogen atoms (methane, butane).
Polymers- smaller molecules bonded into chains.
Dehydration Reaction- a reaction that removes a molecule of water in order to link monomers together to form polymers.
Hydrolysis- The reverse of a dehydration reaction.  The bonds between monomers are broken by adding water to them.
Monosaccharides- carbohydrate monomers
Polysaccharides- carbohydrate polymers, long chains of sugar units
Unsaturated- fatty acids and fats with double bonds in the carbon chain.
Saturated- Fats with the maximum number of hydrogens.
Amino Acids- have an amino group and a carboxyl group and make up proteins.
Peptide Bond- amino acids joined together in a dehydration reaction.
Gene- distinct unit of inheritance



Relevant Video:
http://videos.howstuffworks.com/hsw/25354-compounds-organic-compounds-video.htm