Biology

Chapter 4.2

Lipids/Proteins

Concepts/Ideas/Facts:

1.  lipids store more energy than carbohydrates
2.  Large non polar molecules
3.  Insoluble in water
4.  Store large amounts of energy
5.  Of all the large molecules, proteins are the most diverse
6. Proteins are built of usually twenty amino acids
7. Twenty kinds of amino acids build peptide chains
8. DNA specifies the order of the amino acid sequences in proteins
9.  Peptide bonds form by way of condensation reactions
10. Proteins come in many thousands of different shapes
11. The longer the peptide chain the more chance mutations may occur
12. enzymes are the "keys" to protein functions

Definitions:

1. FATTY ACIDS – long straight chains of carbon with a carboxyl group – COOH attached at one end (head) making the head of the fatty acid polarized.  The hydrocarbon tail end is non-polar.
2. HYDROPHILIC – “water loving” when a molecule is attracted to water (the carboxyl group).
3.  HYDROPHOBIC – “water fearing” when a molecule is not attracted to water (the tail end of fatty acid molecule)
4. SATURATED FATTY ACIDS – each carbon atom is covalently bonded four atoms (no double bonds).  These tend to be solid at room temperature.  Found in animal fats.
5.  UNSATURATED FATTY ACIDS – there are double bonds with the carbon chain. These tend to be liquid at room temperature. Found in plant seeds.
6.  COMPLEX LIPIDS:

A.      TRIGLYCERIDES – three molecules of fatty acids joined to one molecule of the alcohol Glycerol.  This happens through a condensation reaction.

a.       saturated triglycerides – three molecules of saturated fatty acids joined to a alcohol glycerol molecule.

b.      unsaturated triglycerides composed of unsaturated fatty acids.

B.       PHOSPHOLIPIDS – two fatty acids joined by a glycerol molecule.  Cell  membranes are composed of two layers phospholipids with their hydrophilic “head”  facing outward or opposite of each other and their hydrophobic “tails” inward adjacent to each other.  The inability of lipids to dissolve in water allows the cell membrane to from a barrier between inside and outside of the cell.  This forms an affective a barrier for a cell.

C.      WAXES – a structural lipid made up of long fatty acid chains joined to a long alcohol chain.  Waxes are highly waterproof.

7. STERIODS – molecules composed of four fused carbon rings with various functional groups attached to them.  Examples are various hormones such as testosterone and molecules like cholesterol
8.  NUCLEIC ACIDS – large complex organic molecules that store hereditary information.
9.  DNA (Deoxyribonucleic Acid) – holds information essential for almost all of a cell’s activities.
10.  RNA (Ribonucleic Acid) – stores and transfer information essential for the making of  proteins.
11.  NUCLEOTIDES – monomers made up of a phosphate group, a five carbon sugar (pentose), and a ring shaped nitrogen base.

Amino Group

                                                   H− N−        

                                                          |

                                                         H

Carboxyl Group

                                              −  C − OH

                                                   ||

                                                   O

GLYCEROL MOLECULE                                                                                                               

      H             H           H

       |              |             |

H −C---------C−−−−−C−H

       |              |             |

     OH         OH        OH

TRIGLYCERIDE MOLECULE