3.2 Molecules of Life (Show PPT w/clips) What four main classes of organic compounds are essential to life processes? carbs lipids proteins nucleic acids. Carbohydrates. Carbohydrates include: Small sugar molecules in soft drinks Long starch molecules in pasta and potatoes.
-monosaccharides is a carb monomer.
This simple sugar is 1:2:1 and the general formula is (CH2O)n
n is a whole number from 3 to 8
So, (CH2O)6 = C6H12O6
The most common sugars/monosaccharides are:
Include glucose, fructose, & galactose
Have the same chemical, but different structural formulas
All three have the same formula but have difference structures. These are known as Isomers pg 55
Fructose is found in fruits
Honey contains both glucose & fructose
Galactose is called “milk sugar”
They’re made by joining two monosaccharides
Involves removing a water molecule (dehydration)
Maltose is composed of 2 glucose molecules
Lactose is made of galactose + glucose
Plant cells store starch for energy
Potatoes and grains are major sources of starch in the human diet
Animals store excess sugar in the form of glycogen
Glycogen is similar in structure to starch
All proteins are made of 20 different amino acids linked in different orders
Proteins are used to build cells, act as hormones & enzymes, and do much of the work in a cell
Changes in temperature & pH can denature (unfold) a protein so it no longer works
Cooking denatures protein in eggs
Milk protein separates into curds & whey when it denatures
Thousands of different enzymes exist in the body
Enzymes control the rate of chemical reactions by weakening bonds, thus lowering the amount of activation energy needed for the reaction
Enzymes are globular proteins.
Their folded conformation creates an area known as the active site.
The nature and arrangement of amino acids in the active site make it specific for only one type of substrate.
FATTY ACIDS- unbranched carbon chains that make up most lipids. These have long carbon chains with a –COOH carboxyl group.
Saturated fatty acidshave the maximum number of hydrogens bonded to the carbons (all single bonds between carbons)
Single Bonds in Carbon chain
Double bond in carbon chain
Composed of Glycerol & 3 fatty acid chains
Glycerol forms the “backbone” of the fat
TRIGLYCERIDES-saturated=butter and fats-unsaturated =found in plant seeds for germination
Fatty Acid Chain
Dehydration links the fatty acids to Glycerol
FAT SUBSTITUTES were approved by the FDA in 1996. It passes through the body without being digested or absorbed. For some, it created cramps, diarrhea, and loss of fat-soluble vitamins and betacarotene. Try to weigh the benefits of this against the side effects. What do you think?
PHOSPHOLIPIDS-have 2 fatty acids attached to a molecule of glycerol. How is this different than Triglycerides? They have a phosphate group attached to the third carbon of the glycerol. Our cells have a cell membrane that is composed of two layers of phospholipids called the LIPID BILAYER. It acts like a club bouncer and only allows certain things in and out of the cell. Pg 59.
WAXES-a type of structural lipid that is a long fatty acid chain joined to a long alcohol chain. They are waterproof. What benefits do plants have by having a cuticle that is a waxy layer on its leaves? Why do we have earwax?
Cholesterol is the “base steroid” from which your body produces other steroids
Estrogen & testosterone are also steroids
Some athletes use them to build up their muscles quickly
They can pose serious health risks
Contain information for making all the body’s proteins
Two types exist --- DNA & RNA
(A,G,C, or T)
Nucleic acids are polymers of nucleotides