Macromolecules

Carbohydrates

• Carbohydrates: molecules made of carbon, hydrogen and oxygen(rone carbon+one H20 ratio)
• carbohydrate chains: 
• monosaccharides
• disaccharides
• polysaccharides

Monosaccharides

• the position of the carbonyl(C=O) group categorize the sugars:
• glucose has an aldehyde(H-C=O) group, it is aldose
• fructose has the carbonyl group with its #2 C, it is ketose(forms a ketone group)
• Glucose and its isomers
• monosaccharide: glucose, galactose, fructose have the same chemical formula(C6H12O6)
• isomers: differ in the organization of their atoms
• glucose and galactose=stereoisomers

Ring forms of sugars

• glucose's main configuration: 6-membered ring(pyranose)
• fructose's main configuration: 5-membered ring(furanose)
• glucose's alpha form and beta form

Disaccharides and dehydration reaction

• Dehydration reaction=condensation reaction, dehydration synthesis <-> Hydrolysis
• the hydroxyl(OH) group+H of another > releasing H2O and forming a glycosidic linkage(kind of covalent bond)
• glucose-O-fructose=sucrose highlight is a glycosidic linkage
• 1-2 glycosidic linkage=1 carbon of glucose-O-2 carbon of fructose

• disaccharides: lactose(glucose+galactosee), maltose(glucose+glucose), sucrose(glucose+fructose)
• Polysaccharides: starch, glycogen, cellulose, chitin.. 

Storage polysaccharides

• starch: the stored form of sugars in plants
• a mixture of amyose and amylopectin *alpha form
• Amylose: unbranched chains of glucose monomers connected by 1-4 linkages
• Amylopectin: branched chains of glucose monomers, most is 1-4 but 1-6 occur periodically
• *cellulose is made of glucose monomers in their beta form
• *chitin resembles cellulose

Lipid

Triglycerides

• triglycerides(in blood)=fat=trayacylglycerol: a glycerol backbone+3 fatty acid tails
• glycerol: an organic molecule with 3 hydroxyl(OH) groups
• fatty acid: a long hydrocarbon chain attached to a carboxyl(C=O-OH) group
• the hydroxyl groups(on the glycerol backbone)-"dehydration synthesis reaction"-the carboxyl group(of fatty acids)

• it yields 3 fatty acid bound to glycerol via ester linkage

• *acyl group is a kind of carbonyl group
• *as a whole, fatty acid is not soluble despite it has a polar head but also has a longer non-polar carbon chain

Saturated and unsaturated fatty acids

• saturated: only single bonds between neighboring C in the hydrocarbon chain
• solid at room temperature, dense like butter
• unsaturated: hydrocarbon has a double bond(monounsaturated) or double bonds(polyunsaturated)
• liquid form at room temperature, less dense like oil
• cis configuration: 2 H on the same side, makes bent
• trans configuration: 2 H on the opposite side, makes no bent, bad for health

Other lipids 

• (bees)waxs, phospholipids, steroids, cholesterol(the most common steroids)...
• phospholipids: major components of the membrane
• has a backbone of glycerol and 2 fatty acid tails
• 3rd C of the glycerol backbone is occupied by a phosphate group
• amphipathic molecule means: has a hydrophobic part and hydrophilic part

Proteins

Amino acids

• the building block of proteins
• consists of: alpha carbon, amino group(NH2), carboxyl group(COOH) and H

• in physiological pH condition: 
• amino group is protonated(grab H), bears a positive charge
• carboxyl group is deprotonated(throw H), bears a negative charge
• R group defines amino acids

Peptide bonds

• carboxyl group(of the amino acid) reacts with the amino group(of an incoming amino acid)+releasing a water molecule

• directionality: amino terminus(N-terminus)on the left and carboxyl terminus(C-terminus) on the right

Protein structure

• Primary structure: the sequence of amino acids in a polypeptide chain
• Secondary structure: local folded structures within a polypeptide, due to interactions between atoms of the backbone
• a(alpha) helix, B(beta) pleated sheet: carbonyl O+amino H

• in an a helix: the carbonyl O is (hydrogen)bonded to amino H that is 4 down the chain(amino acid #1+amino acid #5)
• B pleated sheet has parallel and antiparallel form
• Tertiary structure: 3D structure of a polypeptide, due to interactions between the R groups(side chains)
• R group interactions: the whole series of non-covalent bonds
• Disulfide bonds: one special type of covalent bond in tertiary structure, between the sulfur-containing side chains of cysteines
• Quaternary structure: for some proteins made up of multiple polypeptide chains(subunits)
• same interactions that contribute to tertiary structures hold the subunits, form quaternary structure

Nucleic acids

• nucleic acids made of nucleotides
• 2 varieties: deoxyribonucleic acid(DNA), ribonucleic acid(RNA)
• in eukaryotes DNA found in the nucleus(in membrane-bound vault)
• and DNA broken up into chromosomes
• in prokaryotes DNA found in the nucleoid(not in membrane-bound container)
• central dogma: DNA-RNA copy(messenger RNA, mRNA)-ribosomes(molecular machine to build proteins)

Nucleotides

• Nucleotides made up of: nitrogenous base, five-carbon sugar, at least one phosphate group

• nitrogenous bases: adenine(A), guanine(G), cytosine(C), thymine(T)
• A, G is purines and C, T(U in RNA) is pyrimidines
• purines must pair with pyrimidines, A-T and G-C
• the five-carbon sugar in DNA is deoxyribose, in RNA, ribose
• polynucleotide chains by phosphodiester linkage: 5' to 3' direction and 3' to 5' direction(antiparallel)

sugar-phosphate backbone

• mRNA: intermediate between a protein coding gene&protein product
• rRNA: ribosomal RNA, a major components of ribosomes
• tRNA: transfer RNA, carry amino acids to the ribosome