Chapter 3 Chemical Building Blocks of Life Isomers

Chapter 3 1
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.

I. Organic Molecules

Organic means…??

Carbon 6 12.001

Atomic # Atomic Wt.

Valence = 4

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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 OH
Carbonyl
Carboxyl C=O (aldehyde or ketone)
Amino
Sulfhydryl OH-C=O (COOH)
Phosphate
Methyl NH2 (thiol)
SH

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: Dehydration synthesis
Break via: Hydrolysis

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II. Carbohydrates

monomers: monosaccharides (simple sugars)

mono - one, sacchar(um) - sugar

common monosaccharides include:

6-carbons 5-carbons

Glucose Ribose (RNA)

Fructose Deoxyribose (DNA)

Galactose

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) 6
C-H ……… 98
C-O ……… 78
C-C ……… 80
C-N ……… 65
H-O ……… 110

BIO150, Chapter 3, Raven & Johnson 8th ed.

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 - two sided; double
pathic - feeling

Both hydrophobic & hydrophilic
Function of phospholipids?

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Steroids : sex hormones Testosterone
Cholesterol

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 15
Base: Purine or pyrimidine (fig. 3.14)

BIO150 Chapter 3, Raven & Johnson 8th ed.

How do nucleotides join together?

Phosphodiester
linkage

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