Chapter 3
Chemical Building Blocks of Life
I. Organic Molecules
Carbon
Functional Groups
Isomers
Making & breaking polymers
II. Carbohydrates
mono-, di- & polysaccharides
III. Lipids
fatty acids
triglycerides
phospholipids
cholesterol
steroids
IV. Proteins
amino acids
structural levels
V. Nucleic Acids
nucleotides
DNA, RNA
ATP
BIO150, Chapter 3, Raven & Johnson 8th ed.
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I. Organic Molecules
Organic means…??
Carbon
6
Atomic #
Valence =
12.001
Atomic Wt.
4
BIO150, Chapter 3, Raven & Johnson 8th ed.
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Functional Groups
All organic molecules have carbon & hydrogen.
Why are they so unique?????
Functional groups:
; Biochemical “accessories”
; Give molecules their unique properties.
7 main types:
Hydroxyl
Carbonyl
OH
C=O
(aldehyde or ketone)
OH-C=O
(COOH)
Carboxyl
Amino
Sulfhydryl
NH2
SH
(thiol)
Phosphate
Methyl
PO4
CH3
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Draw:
C5H11PO4
Isomers: Same molecular formula, different
structure
; Structural Isomers
; Stereoisomers
Making & breaking an organic “polymer”:
What is a “polymer” ?
monomer
Assemble via:
Break via:
Dehydration synthesis
Hydrolysis
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II. Carbohydrates
monomers: monosaccharides (simple sugars)
mono - one,
common monosaccharides
6-carbons
Glucose
Fructose
Galactose
sacchar(um) - sugar
include:
5-carbons
Ribose (RNA)
Deoxyribose (DNA)
2 monosaccharides = disaccharide
common disaccharides include:
Maltose = glucose + glucose
Sucrose = glucose + fructose
Lactose = glucose + galactose
More than 2 monosaccharides = polysaccharide
common polysaccharides include:
Starch (glucose storage in plants)
Glycogen (glucose storage in animals)
Cellulose (plant cell walls)
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Numbering the carbon atoms in a sugar:
#1
The bond that hooks monosaccharides together:
Glycosidic bond (linkage)
glyco = sugar
Function of carbohydrates????
Average Bond Energies (kcal/mol)
C-H ……… 98
C-O ……… 78
C-C ……… 80
C-N ……… 65
H-O ……… 110
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Carbohydrates can attach to proteins & lipids....
Glycoproteins:
sugar
sugar
protein
protein
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III. Lipids (fats, oils)
Lower oxygen content than carbs.
What would that imply ?????
Nonpolar, hydrophobic
Fats:
Contain fatty acids
saturated
All C-C single covalent bonds
unsaturated
Some C-C double covalent bonds
To make a “fat”, fatty acids attach to glycerol:
Glycerol
+ 1 fatty acid = monoglyceride
+ 2 fatty acids = diglyceride
+ 3 fatty acids = triglyceride
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Function of lipids/fatty acids ????
(~2x as much energy as sugars!)
Phospholipids :
CH2OH
Fatty Acid
CHOH
Fatty Acid
CH2OH
PO4
Amphipathic: amphi pathic -
two sided; double
feeling
Both hydrophobic & hydrophilic
Function of phospholipids?
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Steroids : sex hormones
Cholesterol
Testosterone
Estrogen
Function of steroid hormones??
Sex determination, differentiation
Secondary sex characteristics
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IV. Proteins
; 50% of a cell’s dry weight is
protein ! ! !
Proteins - polymers made of amino acids.
20 different types:
R = a side chain w/ O, C, H, S
Side chains give amino acids different properties:
• Polar
• Nonpolar
• Charged (ionic)
Essential vs. non-essential amino acids
ESSENTIAL = Must obtain in the diet.
NONESSENTIAL = Naturally made w/in the cell.
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The bond btw. amino acids:
Peptide Bond
peptide = protein
2 amino acids = dipeptide
many amino acids = polypeptide
Repeating elements in a protein (polypeptide) chain:
N C C NCC NCC N C CN C C N C C…
Once made, a protein folds. Structural levels are:
1o Structure:
Linear arrangement of amino acids.
2o Structure:
Linear chain coils &/or folds.
3o Structure:
Coils &/or folds form globular mass.
4o Structure:
Mass of many globular proteins.
What forces keep a protein folded?
Bonds.....
(ionic, covalent, hydrogen, etc.)
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What components w/in the protein are “bonding”?
R (side chains)
Folds create domains: functional regions of a protein
Domains preserved @ optimum:
; temperature
; pH
; salt concentration
Every protein can has different:
; #’s of amino acids
; types of amino acids
; arrangements of amino acids
Every protein has a unique:
;
;
;
;
size (molecular weight)
3-D shape
charge
solubility
Some Functions of Proteins: table 3.2
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To make a protein, how does a cell know:
- which amino acids to assemble?
- in what order to assemble them?
IV. Nucleic Acids
Amino acid sequence Æ encoded by DNA sequence
Genes: segments of DNA that
encode “recipes” for proteins.
DNA = DeoxyriboNucleic Acid
RNA = RiboNucleic Acid
What are DNA & RNA made of ? ? ?
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Nucleotides: Phosphate + Base + 5-carbon sugar
PO4
N-containing BASE
Pentose
Sugar
Sugar: 5 carbons (pentose)
Phosphate:
1-3
Base: Purine or pyrimidine (fig. 3.14)
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How do nucleotides join together?
Phosphodiester
linkage
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Nucleotides with >1 phosphate:
Adenine
Tri(ATP)
Phosphate
A major energy source ! ! !
2 nucleotides together:
Nicotinamide Adenine
(NAD)
Dinucleotide
Electron transporter (energy “voucher”)
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