4 Macromolecule

Carbonhydrates 

• Structures: C_m(H₂O)_n
• Three main functions: energy for cells, structural support, cell-cell communication

1. Monosaccharides

Three common sugars share the same molecular formula: C₆H₁₂O₆. Because of their six carbon atoms, each is a hexose:

      Glucose: grape sugar, corn sugar, dextrose

      Fructose: honey

      Galactose: part of milk sugar (lactose)

Three common disaccharides:

      Lactose = glucose - galactose (milk sugar) 2. Polysaccharides

      Sucrose = glucose - fructose (table sugar)
      Maltose = glucose - glucose (brewing beer)

  Starches are polymers of glucose. Two types are found:

• amylose consists of linear, unbranched chains of several hundred glucose residues (units). The glucose residues are linked by a glycosidic bond between their #1 and #4 carbon atoms.
• amylopectin differs from amylose in being highly branched. At approximately every thirtieth residue along the chain, a short side chain is attached by a glycosidic bond to the #6 carbon atom (the carbon above the ring). The total number of glucose residues in a molecule of amylopectin is several thousand.

Glycogen

Animals store excess glucose by polymerizing it to form glycogen. The structure of glycogen is similar to that of amylopectin, although the branches in glycogen tend to be shorter and more frequent.
Glycogen is broken back down into glucose when energy is needed

Lipids
Triacylglycerols  (store energy)
Three main categories: fats, steroids, and phospholipids

• A fat is composed of a glycerol molecule (a short hydrocarbon) bonded to three fatty acids through dehydration synthesis. Saturated fats are solids at room temperature and are found mostly in animals, while unsaturated fats are liquids (oils) at room temperature and occur chiefly in plants.
• Steroids are made of four interconnecting carbon rings and cholesterol is the most common steroid.
• Phospholipids are composed of a glycerol molecule bonded to two fatty acids and a phosphate group.This phosphate group is polar although the rest of the molecule is hydrophobic.

Proteins

    They are constructed from one or more unbranched chains of amino acids( polymers) linked together by peptide .

    Functions: structure, support, movement, energy transfer, and defense

    Proteins have many levels of structure.

• Primary level of structure is the sequence of amino acids linked together in a peptide chain.There are only 20 amino acids, each with a hydrogen, an amino group (NH2 -), a carboxyl group (COO -), and an R group. This R group is known as a side chain and is composed of varying molecules.
• The secondary level of structure in proteins is the bending of this peptide chain into either an alpha helix (coil) or a beta sheet (plaited sheet) as a result of hydrogen bonding.
• The tertiary structure is based on the folding of the secondary structure caused by interactions between amino acid side chains. These include ionic and covalent bonds, disulphide bonds, and hydrophobic interactions.
• A protein's quaternary structure is based on the interaction between many peptide chains.

Deoxyribonucleic Acids

• Nucleic acids
• is composed of a nitrogenous base, a fvie-carbon sugar (a pentose), and a phosphate group.
• Five nitrogenous bases: Adnine, Guanine, Thymine and Cytosine. Cytosine will only bond with Guanine and that Adnine will only bond with Thymine.
• A phosphate group is linked to the sugar via a phosphodiester bond and the three nucleotides have become a nucleic acid.
• holds the generic information necessary for protein synthesis