II. Biochemical Building Blocks

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II. Biochemical Building Blocks

• A. Carbohydrates
• B. Lipids
• C. Proteins
• D. Nucleic Acids

2
Carbohydrates

• 1. Vocabulary
• 2. Stereochemistry
• 3. Ring Formation
• 4. Biologically Important Monosaccharides

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Carbohydrates

• Carbohydrates- Polyhydroxy aldehydes and ketones
  or compounds that yield these upon hydrolysis
• General Formula Cx(H2O)y
• Monosaccharides - Simplest sugar unit
• Disaccharides - Two monosaccharide units
  connected together by a glycosidic bond
• consequence of condensation reaction
• Oligosaccharides - Several (2-10) monosaccharide
  units bonded together
• Polysaccharides - Polymers containing huge
  numbers of monosaccharide units bonded together.

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Classification of Monosaccharides

• By the number of carbon atoms
• triose 3
• tetrose 4
• pentose 5
• hexose 6
• By aldehyde or ketone functional group
• aldose aldehyde
• ketose ketone
• An aldopentose is a 5-carbon aldose
• A ketohexose is a 6-carbon ketose.

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Enantiomers of glyceraldehyde
C
H
O
H
O
H
C
H
O
H
2
L-glyceraldehyde
D-glyceraldehyde
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D- and L-Glucose
C
H
O
C
H
O
O
H
H
H
O
H
H
O
H
O
H
H
O
H
H
H
O
H
O
H
H
H
O
H
C
H
O
H
C
H
O
H
2
2
D-glucose
L-glucose
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Cyclic Forms - How to get
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Haworth Projections

• Haworth Projections are illustrations of the
  cyclic forms of carbohydrates.
• Draw a polygon containing the ring C and O atoms
  with the O atom at the upper right (6-membered
  ring) or the top (5-membered ring) with the
  -CH2OH group (the flag) up (all D
  enantiomers)
• -OH groups on the right of chiral carbons in
  Fischer projections go down and those on the left
  go up
• LURD
• The anomeric carbon atom is the carbon of the
  ring that was originally the aldehyde or ketone
  carbon (the hemiacetal C) this OH group on the
  anomeric C may go either up or down to form two
  anomers, called a and b .
• The b- anomer has the -OH group on the anomeric
  carbon on the same side as CH2OH group
• b b both on same side of ring

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The Anomeric Carbon
a-anomer
b-anomer
6
6
C
H
O
H
C
H
O
H
2
2
O
H
O
O
5
5
1
O
H
O
H
1
4
4
2
2
O
H
O
H
O
H
3
3
O
H
O
H
Anomeric carbon
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Relative Amounts of the a and b Anomers and the
Chain Form of D-Glucose.

• The two cyclic forms of D-glucose and the
  aldehyde open chain form are at equilibrium.
• About 37 is the a-anomer, about 63 the
  b-anomer, and less than 1 in the open chain form.

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Formation of Acetals and Ketals

• Since the cyclic forms of monosaccharides are
  hemiacetals or hemiketals, they can react with
  alcohols to form acetals and ketals.
• The -OH group on the anomeric carbon is always
  involved in the reaction.
• Sugar acetals are called glycosides.
• The bond from the anomeric carbon to the -OR
  group of the acetal is called the glycosidic bond.

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Biologically Important Monosaccharides
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Formation of Phosphate Esters

• D-glucose, and other monosaccharides, can form
  phosphate esters.
• These substances have enhanced biological energy

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Carbohydrates - Evaluation

• 1. highly polar monomers therefore water soluble
• 2. parent monosaccharides do not have any
  ionizable groups
• 3. several different potential connect or
  reactive points
• 4. can be derivatized and oxidized easily
• condensation to make polymers
• oxidation for extraction of energy content
• 5. biochemical energy content is substantial

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Lipids

• 1. Fatty Acids
• 2. Fats and Oils
• 3. Phosphoacylglycerols (Phosphoglycerides)

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Fatty Acids

• Fatty Acid - A long chain carboxylic acid having
  an even number of carbon atoms.
• Most common have 18 or 16 carbon atoms
• Saturated
• 12 lauric CH3(CH2)10COOH
• 14 myristic CH3(CH2)12COOH
• 16 palmitic acid CH3(CH2)14COOH
• 18 stearic acid CH3(CH2)16COOH

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Unsaturated Fatty Acids

• 16 palmitoleic
• CH3(CH2)5CHCH(CH2)7COOH
• 18 oleic
• CH3(CH2)7CHCH(CH2)7COOH
• 18 linoleic CH3(CH2)4CHCHCH2CHCH(CH2)7COOH
• 18 linolenic CH3CH2CHCHCH2CHCHCH2CHCH(CH2)7C
  OOH

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Melting Points of Fatty Acids

• Saturated fatty acids have higher melting points
  than unsaturated fatty acids.

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Triacylglycerides

• Fat - A triacylglycerol that is a solid at room
  temperature.
• Generally has an animal origin (animal fat)
• Contains primarily saturated fatty acids
• Oil - A triacylglycerol that is a liquid at room
  temperature.
• Has a vegetable origin
• Contains predominantly unsaturated fatty acids

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Fats and Oils
Typical fat
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Phosphoglycerides

• Phosphoglycerides - Diglycerides that are also
  phosphate esters of glycerol

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Lipids - Evaluation

• 1. highly nonpolar monomers in uncharged form
• water insoluble
• 2. parent fatty acids have ionizable groups
• enhanced water solubility in charged form
• 3. connect point ONLY at carboxyl group
• 4. can be derivatized and oxidized easily
• condensation to make various products but not
  polymers
• oxidation for extraction of energy content
• 5. biochemical energy content is substantial

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Proteins - Amino Acids
1. Generalized Amino Acid 2. Classes of
Amino Acids
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Generalized Amino Acid
Neutral form - solid
basic form
zwitterion form
acidic form
Dissolved forms
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Neutral, Nonpolar Amino Acids
Alanine (Ala, A)
Valine (Val, V)
Phenylalanine (Phe, F)
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Neutral, Nonpolar Amino Acids
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Neutral, Polar Amino Acids - I
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Neutral, Polar Amino Acids - II
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Acidic Amino Acids
O
O
C
Aspartic Acid (Asp,D)
C
H
2

N
H
C
H
C
O
3
O
O
O
C
C
H
2
Glutamic Acid (Glu,E)
C
H
2

N
H
C
H
C
O
3
O
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Basic Amino Acids
Lysine (Lys, K)

N
H
3
C
H
2
Histidine (His, H)
C
H
2
C
H
2
C
H
2

N
H
C
H
C
O
3
O
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Amino Acids - Evaluation

• 1. highly variable polarity of monomers
  depending on side chain structure
• variable solubility in water
• 2. All parent amino acids have 2 ionizable groups
  
• 3. two key connect points on each monomer
• complementary connect points can form polymers
• huge variability in possible structures depending
  on numbers and orders of amino acids
• huge potential differences in properties and
  potential of polymers depending balance and order
  of amino acids
• 4. biochemical energy content is variable but
  average

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Nucleic Acids Components

• 1. Bases
• 2. Nucleosides, Nucleotides
• 3. DNA RNA

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Pyrimidines
Pyrimidine
Cytosine (C)
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Purines
Purine
Adenine (A)
Guanine (G)
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Nucleic Acids

• Nucleoside - A purine or pyrmidine base joined to
  b-D-ribose or b-D- 2-deoxyribose by replacing
  the -OH group on the anomeric carbon by a N atom
  from the base.
• Nucleotide - A 5 phosphate ester of a nucleoside
• Nucleic Acid - A polymer composed of repeating
  nucleotide units
• RNA Ribonucleic Acid
• DNA Deoxyribonucleic Acid

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Nucleotides
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Nucleotides - Evaluation

• 1. Parent purines and pyrimidines made more
  soluble by addition of polar O and N groups
• 2. Highly polar sugar and ionic phosphate groups
  makes nucleotides very water soluble
• 3. Two key connect points on each monomer
• complementary connect points can form polymers
• huge variability in possible structures depending
  on numbers and orders of nucleotides lots of
  information
• not a lot of variability in terms of chemical and
  physical properties since nucleotides are very
  similar
• 4. biochemical energy content is quite low

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Fuel Value of Biological Substances