Lecture Handout: Biochemistry I-III

MIT Department of Biology 7.014 Introductory Biology, Spring 2005 7.014 Handout Biochemistry I-III












































Carbohydrates Monosaccharides: CH2 OH

























H O H H OH H OH OH OH OH OH H CH2 OH O OH OH CH2 OH O OH a-Glucose CH2 OH OH b-Galactose Fructose Disaccharides: CH2 OH CH2 OH O O H H H OH H H H OH O OH CH2 OH OH H H OH






















Sucrose (Glucose( a1 2)Fructose) CH2 OH CH2 OH O OH H OH O OH H O H H OH H H H OH H H OH OH Lactose ( b-form)
















(Galactose( b1 4)Glucose) Polysaccharides: CH2 OH O H H H OH O H H H OH H O O H H H OH H O H CH2 OH CH2 OH CH2 OH H H H OH H H OH O O O OH O H H H OH OH Starch (Unbranched polymer of Glucose (a1 4) linkage) (Amylose is an example of a branched starch molecule) O H H H OH CH2 OH CH2 OH CH2 OH O H H H OH H H H H OH OH CH2 OH H OH H H OHO O H H H OH H O O H H H OH H O H CH2 OH CH2 CH2 OH O H H H OH O O O O H H H H OH H OH Glycogen (Branched polymer of Glucose in (a1 4) linkage with (a1 CH2 OH H O H H OH OH H H H H O H O OH CH2 OH OH H O CH2 OH H O H H OH H H OH H H OH O O O OH O H H H OH H H H OH O H O 6) branch points) OH Cellulose (Unbranched polymer of Glucose in (b1 H H O CH2 OH 4) linkage) O Nucleic Acids Nitrogenous Bases found in Nucleic Acids: Purines Pyrimidines NH 2 CH3 HN N O O O N H Cytosine O HN O N H N N N H H2 N HO CH2 OH O OH H H H H OH O H H H H OH H OH Ribose ( in RNA) Deoxyribose ( in DNA) A Nitrogenous Base plus a Sugar plus Phosphate forms a Nucleotide: NH 2 N O- O P N O CH2 O Phosphate group N N Base H O H H H HO H N Guanine Adenine Sugars found in Nucleic Acids: HO CH2 N HN N H N Uracil (in RNA) Thymine (in DNA) O NH 2 Sugar Deoxyribonucleoside monophosphate = Deoxyribonucleotide (found in DNA) N H Structures of Amino Acids at pH 7.0 Non-Polar OC H O O- O C H H C CH3 O H H O C H O H NH3 + H H NH3 + CH3 H H C CH2CH2 CH3 METHIONINE (met) O- H H O C H H C CH2 OH H CH3 C C CH3 VALINE (val) TYROSINE (tyr) H - NH3 H + H H H H O C NH3 + TRYPTOPHAN (trp) S NH3 + O C C CH2 C H Polar Special Cases: O- O O OC H C H C CH2 OH NH OH + 3 - O C O H NH2 H C CH2 C O H - - C ARGININE (arg) C O- GLUTAMIC ACID (glu) H C C C NH2 + NH2 H C CH2CH2CH2CH2 NH3 + LYSINE (lys) O- O O O C CH2CH2CH2 N NH3 + O C CH2CH2 NH3 + ASPARTIC ACID (asp) H PROLINE (pro) OC O NH3 + O GLYCINE (gly) NH2 O C O C H C CH2 CH2 H N CH2 H + C H NH3 + CYSTEINE (cys) O O O Acidic C CH2 SH NH + 3 C CH2CH2 C C H O- O O- O GLUTAMINE (gln) ASPARAGINE (asn) Basic H - NH3 + Charged O - C C O C CH2 C NH3 + O THREONINE (thr) SERINE (ser) O C C CH3 H NH3 + H C CH3 NH3 + PHENYLALANINE (phe) O C CH2 N C C CH2 H LEUCINE (leu) H - O O C H ISOLEUCINE (ile) ALANINE (ala) O C C CH2CH3 NH3 CH3 + NH3 + O- O NH3+ H H N + C H C CH2 NH3 + C H HISTIDINE (his) N H













Proteins General formula for amino acids (the building blocks of proteins): H amino end H2N C COOH carboxyl end a carbon R side chain : Polymerization of amino acids to form polypeptides with amide (peptide) linkage H H R1 C C H2 N O O N H C C O H R2 H + H O aa2 aa1 H2O H H2 N R1 C H C O O N C C O H R2 H + aa3 H2O peptide bond H H2 N amino terminal of polypeptide R1 C C O O H R3 + aa4 O N C C N C C H R2 H H O carboxyl end H2O H of polypeptide Polypeptide (Proteins are long polypeptides)

























Lipids H H H H H H H O H C C C C C C C C OH H H H H H H H A Fatty Acid To make a Triacylglycerol (triglyceride): O C OH O C OH H + O C OH HO C H HO C H HO C H H 1 glycerol 3 Fatty acids O C O O C O O C O Triacylglycerol (triglyceride) CH2 CH CH2 3 H2 O Phospholipids General structure of a phospholipid: HC 3 H 3C O (CH2 ) 9 C O CH2 O (CH2 ) C O CH O 9 CH2 O P OOR Common phospholipids: O R O P O O- Phosphatidyl choline: Phosphatidyl ethanolamine: O + R O P O (CH2)2 N H 3 OO Phosphatidyl inositol: (CH ) N+ (CH3 )3 22 R O P O O- OH OH OH OH OH