Chemical Compounds for Life

• All living things are mostly composed of 4 elements: H, O, N, C "honk"
• Compounds are broken down into 2 general categories:
o Inorganic Compounds:
 Do not contain carbon
o Organic compounds
 Contain significant amounts of carbon.
 Often found with common "functional groups"
Carbon: The "swiss army knife" of chemistry.

• Carbon is essential to life for several reasons:
1. It can form strong stable (usually nonpolar) covalent bonds
2. It can form up to 4 chemical bonds
3. It can form multiple bonds

• Organic Compounds often form Polymers
o Long chains of smaller molecules (not atoms) called monomers, bind to form huge Macromolecules.
Organic Compounds of life:
• 4 Types: Carbohydrates, Lipids, Proteins & Nucleic acids
________________________________________
CARBOHYDRATES:
• Includes: Sugars, starches, cellulose & glycogen
• Made of Carbon ( C ), Hydrogen ( H ), and Oxygen (O )
• Following ratio of elements CnH2nOn
o Sugars: Provide & store energy for cells
o Simple sugars include Glucose & Fructose since these are made of only 1 Carbohydrate molecule they are known asMonosaccharides.


• Monosaccharides can be linked together through the process of Dehydration Synthesis
o Water is removed from 2 monocaccharides - resulting in a covalent bond between the 2 molecules
• Sucrose (table sugar) is made of 2 sugars linked together and these are called Disaccharides
o Often referred to as transport saccharides
o Require some digestion to be used by cells

Dehydration Synthesis
• Starches are many monosaccharides linked together in a single chain. These are called Polysaccharides.
o Plants use this for energy storage e.g. Potatoes
o Two types
 Amylose - Long strait unbranched chains
 Pectins - many linked short Amylose chains

Starch
• Cellulose is made of long polysaccharide chains
o Plants use this for structure (e.g. Wood) - not very digestible
o Due to the reverse orientation of the monosaccharide sububnits, digestive enzymes cannot hydrolize the bonds between them

Cellulose

• Glycogen is a moderately branched polysaccharide
o Animals use this for energy storage.

Glycogen

________________________________________
Lipids:
• Lipids are macromolecules including fats, waxes & oils
o Primary function is energy storage.
 Energy is stored in C-H bonds.
 More efficient in storing energy
o Lipids are made of 2 parts
 Glycerol - an alcohol - Serves as backbone of the molecule
 3 Fatty acids - Long hydrocarbon chains

• Saturated fats have long chains with no double-bonds
• Unsaturated fats have double bonds
• Polyunsaturated fats have many double bonds
• Each time a double bond is encountered, the molecule "Bends" slightly, resulting in a lower density of the lipid. This makes the molecule more likely to remain liquid at room or body temperatures.
• 4 Major types of biologically important Lipids
• Phospholipids - Important for membrane structure
• Steroids - eg. Cholesterol & testosterone. Provide membrane support / serve as hormones
• Terpenes - serve as important components of pigments
• Prostaglandins - appear to act like localized hormones to induce cellular/tissue responses.


________________________________________
Proteins
• Proteins are made of Amino Acids
• There are 20 different amino acids. Each having a similar general structure - Differ only in their "R" groups


example amino acids
• Amino acids form proteins via deyhdration sythesis forming peptide bonds
• Two amino acids linked together are called dipeptides
• More than 2 linked together are called polypeptides - polypeptides can be thousands of amino acids long

• Protein types include globular proteins which are usually enzymes and Fiberous proteins which usually serve for structure (eg. Hair)
• Proteins Exhibit 4 "levels of structure.

o Primary Structure of a protein is it’s sequence of amino acids.

o The Sequence (primary structure) causes parts of a protein molecule to fold into sheets or bend into helix shapes - this is a protein’s Secondary Structure.

o The protein then can compact and twist on itself to form a mass called it’s Tertiary Structure

o Several Proteins then can combine and form a protein’s Quaternary Structure.

• Various conformations are usually caused by the formation of hydrogen or disulfide bonds
• PH, changes or heat can disrupt these bonds, permanently denaturing the protein.

________________________________________
Nucleic Acids
• Two types of Nucleic acids
• DNA (Deoxyribonucleic Acid)
• RNA (Ribonucleic acid)
o DNA is Formed of in a "Double Helix" - like a spiral staircase.

DNA Molecule-note "double helix" shape
• DNA is formed by Nucleotides
o These are made from 3 components
 A 5-Carbon Sugar
 A Nitrogenous base
 A Phosphate group

• Nucleotides form a backbone through linkages from the OH group of the 3rd carbon to a phosphate group of the adjoining nucleotide. These are called Phosphodiester bonds

• For DNA There are 4 different Nucleotides categorized as either Purines (double ring) or Pyramidines (single ringed). These are usually represented by a letter. These Are:
o Adenine (A)
o Cytosine (C)
o Guanine (G)
o Thymine (T)


• Each "Rung" of the DNA "staircase" is formed by the linking of 2 Nucleotides through Hydrogen Bonds.
• These Hydrogen bonds form only between specific Nucleotides. This is known as Base Pairing. The rules are as follows:
o Adenine (A) will ONLY bond to Thymine (T)
o Cytosine (C) will ONLY bond to Guanine (G)


• RNA differs from DNA in several important ways.
1. It is much smaller
2. It is single-stranded
3. It does NOT contain Thymine, but rather a new nucleotide called Uracil which will bind to Adenine.


Comparison of DNA & RNA

• ATP is closely related to nucleic acids.
• Composed of Ribose, Adenine & a phosphate group
o Phosphate group has ability to bind/release additional phosphate group allowing it to store or release energy.