MACROMOLECULES
Four Classes of Organic Molecules: Lipids, Carbohydrates, Proteins, Nucleic Acids
Organic molecules contain carbon and hydrogen.
Covalently bound
Based on carbon chains or rings
The diversity of organic molecules makes the diversity of life possible.
Remember molecules have shapes
Polymers (Greek = many parts), composed of (usually) many monomers
Formed by condensation synthesis, or dehydration – the net loss of a water molecule
Disassembled by hydrolysis (Greek = breaking with water)
With the help of specific enzymes
Isomer (Greek = same part): Same molecular formula but different atomic arrangement, shape
Functional Groups: determine polarity and reactivity
Carbohydrates: C, H, O
Monosaccharides, disaccharides, polysaccharides; generally some multiple of CH2O
Simple sugars (one ring) or polymers of sugars
Glucose: E now, Polysaccharides: stored E
Glycogen: stored E in animals, Starch: stored E in plants
Both polymers of glucose
Structural Polysaccharides
Cellulose in plants
Chitin in fungi and animals
Peptidoglycan in bacteria
Lipids: Fats
Fatty Acid: Glycerol + Three Fatty Acids (-COOH, carboxyl group)
Saturation: no double C=C bonds; the carbons are “saturated” with bonded hydrogen.
Unsaturation: one or more C=C double bonds resulting in kinking
Longer term E storage than glycogen
Phospholipids: two hydrophobic fatty acid tails and a hydrophilic phosphate head
Compose the fluid mosaic of membranes
Steroids: four carbon rings with various functional groups
Proteins
Polymers of amino acids: amino group and carboxyl (acid) group on organic molecule
20 types of commonly found, naturally occurring amino acids.
Peptide bonds (dehydration) join amino acids into polypeptides.
Peptides compose proteins.
Primary Structure: amino acid sequence
Secondary Structure: helical or sheet shape due to internal hydrogen bonds
Tertiary Structure: folding due to H, covalent, and/or ionic bonds resulting in
biologically relevant shape
Quaternary Structure: two or more polypeptides comprising one protein
Nucleic Acids
Polymers of nucleotides
Nucleotide: phosphate, sugar, N base
Sugar is ribose in RNA, deoxyribose in DNA
Five types of N bases
Cytosine, uracil, adenine, and guanine in RNA
Thymine, rather than uracil, in DNA
T=A, G=C
RNA is single stranded, DNA double helix with bases held together by H bonds
ATP
Ribose and adenine plus three phosphate groups
End phosphate bond is hydrolyzed, giving off E and forming ADP