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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
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
Lactose ( b-form)
4)Glucose)
(Galactose( b1
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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
H
OH
OH
Glycogen
4) linkage with (a1
(Branched polymer of Glucose in (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
O
CH2 OH
4) linkage)
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Nucleic Acids
Nitrogenous Bases found in Nucleic Acids:
Purines
Pyrimidines
CH3
HN
N
O
O
O
NH 2
N
H
Cytosine
O
HN
O
N
H
N
N
N
H
N
HN
N
H
N
H2 N
N
Guanine
Adenine
Uracil
(in RNA)
Thymine
(in DNA)
O
NH 2
Sugars found in Nucleic Acids:
HO CH2
HO CH2
OH
O
H
H
H
OH
H
H
H
H
OH
O
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
Sugar
Deoxyribonucleoside monophosphate = Deoxyribonucleotide
(found in DNA)
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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
O
C CH2 C
O
NH3
+
H
-
-
C
H
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)
Basic
PROLINE
(pro)
O-
O
C
O
GLYCINE
(gly)
NH2
O
O
O
NH3
+
CYSTEINE
(cys)
O
C
H C CH2
CH2
H
N
CH2
H +
C H
GLUTAMINE
(gln)
ASPARAGINE
(asn)
Acidic
H
NH
+ 3
C CH2CH2
C
C
C CH2 SH
H
-
NH3
+
Charged
O
O-
O
O-
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
N
H
H
HISTIDINE
(his)
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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)
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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
3 H2 O
1 glycerol
3 Fatty acids
O
C O
O
C O
O
C O
CH2
CH
CH2
Triacylglycerol (triglyceride)
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Phospholipids
General structure of a phospholipid:
HC
3
H 3C
O
(CH2 ) 9 C O CH
2
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 (CH ) N H 3
22
O
O
Phosphatidyl inositol:
(CH ) N+ (CH3 )3
22
R O P O
O-
OH OH
OH
OH
OH
7