1. AP Bio Chapter 3
Organic chemistry

2. Carbon compounds
Living organisms consist mostly of water and carbon-based compounds
This is because carbon can form many different large, complex molecules
A compound containing carbon is called an organic compound
Critically important molecules in living things are:
Carbohydrates
Lipids
Proteins
Nucleic acids
The first three form huge molecules called macromolecules

3. Carbon bonds
Carbon has four valence electrons – it can form four covalent bonds
It can form single, double, and even triple bonds
It can form straight or branched chains or even rings
Carbon bonds most frequently with hydrogen, oxygen, and nitrogen

5. Functional groups
These are the components of the molecule that are most commonly involved in chemical reactions
The number and arrangement of functional groups give the molecule its properties
Seven important functional groups:
hydroxyl
carbonyl
carboxyl
amino
sulfhydryl
phosphate
methyl

6. Macromolecules Building block molecules are called monomers
Many monomers joined together – these are polymers
Cells make and break down polymers
Dehydration reaction – two monomers bond together through the loss of a water molecule
Hydrolysis – polymers are broken down into their monomers by addition of a water molecule
These processes are facilitated by enzymes which speed up chemical reactions

7. Carbohydrates Sugars and the polymers of sugars
Simple sugars – monosaccharides
Glucose is the most common monosaccharide (C6H12O6)
Serve as major fuel for cells and as raw materials for building other molecules
Disaccharide – two monosaccharides
Table sugar (sucrose)
Complex sugars – polysaccharides
Energy storage:
Starch – storage in plants
Glycogen – storage in animals
Structural compounds:
Cellulose – the major component in plant cell walls
Chitin – found in the exoskeleton of arthropods and the cell walls of fungi

8. Lipids Lipids do not form true polymers
Lipids are nonpolar and therefore hydrophobic
The most biologically important lipids are fats, phospholipids, and steroids
Fats: contain glycerol and fatty acids
Saturated fatty acids have the maximum number of hydrogen atoms and no double bonds
Saturated fats are solid at room temp.
Most animal fats are saturated
Unsaturated fatty acids have one or more double bonds
Unsaturated fats are liquid at room tem
Plant fats and fish oil are usually unsaturated

10. Lipids… Major function of lipids is energy storage
They can also have structural functions
Phospholipids are major components of cell membranes
Phospholipids are amphipathic –hydrophilic head and hydrophobic tails
When in a water solution they self-assemble into a bilayer, hydrophobic tails toward the center and away from the water
Steroids are also lipids
Cholesterol – in animal cells; helps to maintain membrane fluidity

13. Proteins
Enzymatic proteins, defense, storage, transport, cellular communication, movement, structural support
Proteins are polymers of the amino acid monomers
There are 20 amino acids
Amino acids differ in their side chains, called R groups
The sequence of amino acids in a protein are coded for in the DNA
Each protein has a unique sequence of amino acids from a few to 1000s
Amino acids are joined together with peptide bonds - polypeptides
Enzymes – biological catalysts which speed up chemical reactions

14. Proteins…
The functional protein must be twisted, coiled, and folded into its unique shape
The shape of the protein determines its function
There are four levels of protein structure – all proteins have the 1st 3
Primary structure – the unique sequence of amino acids
Secondary structure – coils and folds within the polypeptide chain
Tertiary structure – interactions among the R-groups which may make the polypeptide bend into peculiar shapes
Quaternary structure – when multiple polypeptide chains clump together
Changes in the primary structure (the sequence of amino acids) can alter the other levels of structure and affect the protein’s ability to function

15. Proteins… Physical and chemical conditions can affect structure
pH, salt concentration, temperature – can cause the structure to unravel
This is called denaturation
Denatured proteins are biologically inactive

16. Nucleic acids Make up nucleic acids – the monomers are nucleotides
Two types: DNA, RNA
Nucleotide consists of a nitrogenous base, a pentose (5-C) sugar, and a phosphate group
Nitrogenous base – either one or two rings; these pair in a particular way – adenine with thymine; cytosine with guanine
Pentose – in DNA is deoxyribose; RNA has ribose
A prime (‘) is used to show the carbon atoms in the pentose
Adjacent nucleotides are joined by covalent bonds