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Organic and Inorganic Molecules
Inorganic Molecules
Organic Molecules:
- Carbohydrates
- Proteins
- Lipids
- Nucleic Acids
Inorganic Molecules
Inorganic molecules do not contain carbon.
General categories/examples of inorganic molecules
include:
- water
- minerals, salts
- acids and bases
- oxygen
MINUTE QUIZ
 Organic
molecules are ones which contain
_____________.
Organic Molecules
Organic molecules are those that contain carbon.
Carbon has interesting chemical properties:
- it can exchange 4 electrons at a time
(binds four other atoms)
- carbons can bind to each other to form
long chains
Functional groups binding to carbon include:
- hydroxyl group (-OH)
- carboxyl group (-COOH)
- amino group (-NH2)
-C-
Categories of Organic Molecules
 Carbohydrates
 Proteins
 Lipids
 Nucleic
acids
Carbohydrates

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Composed of carbon, hydrogen, and oxygen
General chemical formula = (CH2O)n
Used for energy production and storage
Carbohydrates are polar, so they’re soluble in water
They exist as monosaccharides, disaccharides, and
polysaccharides
Monosaccharides

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Monosaccharides are simple sugars
They can be:
- trioses (contain 3 carbons)
- tetroses (4 carbons)
- pentoses (5 carbons; ribose, deoxyribose)
- hexoses (6 carbons)
The hexoses are most common (glucose, fructose,
galactose)
Structures of Common Hexoses
The chemical composition of glucose, fructose, and galactose
is identical. What differs is location of the hydrogen,
hydroxyl, and oxygen groups.
CH2OH
OH
HO
CH2OH
HO
O
O
OH
HO
OH
OH
glucose
CH2OH
HO
CH2OH
OH
fructose
O
OH
OH
galactose
Dissaccharides
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Dissaccharides are composed of two monosaccharides
bonded together.
For example: glucose + fructose ----> sucrose + H2O
lactose = glucose + galactose
maltose = glucose + glucose
CH2OH
CH2OH
OH O
HO
OH
OH
CH2OH
CH2OH
OH O
O
HO
O
+
HO
HO
OH
CH2OH
HO
OH
O
OH
+ H2O
CH2OH
Polysaccharides
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Many simple sugars joined together to form long chains
Chains may be straight or branched
The most common form is glycogen, the storage form of
glucose (also called “animal starch”).
In our diet, we take in starch and cellulose. Starch is
broken down into glucose, but cellulose is not digested.
Proteins
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Proteins are large molecules with complex formulas
(include carbon, hydrogen, oxygen, nitrogen, sulfur)
Proteins are made up of amino acids (the basic building
block of proteins).
- 20 common amino acids used in the body
- consist of a carbon attached to a carboxyl group, an
amino group, and an R group.
- the R group differs between amino acids (and thus
determines their unique qualities).
General Structure of an Amino Acid
R
H2N - C - C - OH
H O
Properties of Amino Acid Groups
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Acidic amino acids: R group contains a carboxyl (-COOH)
group (example: aspartic acid, glutamic acid)
Basic amino acids: R group contains an amino group or
nitrogen-containing group (example: lysine, histidine)
Polar amino acids: R group contains lots of hydroxyl
groups (-OH; very soluble in water)
Nonpolar amino acids: R group has lots of carbon and
hydrogen (less soluble in water)
The R group can also contain sulfur (methionine, cysteine)
Building Proteins from Amino Acids
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The structure of the protein depends on the amino acid
content and the order of the amino acids.
Amino acids attach to each other by joining the carboxyl
group of one with the amino group of the next.
The attachment results in formation of water.
Recognize a peptide bond when you see one!
H R1
H R2
H R1
H R1
N - C - C - OH + N - C - C -OH
N - C - C - N - C - C - OH
H H
H H
O
H H
O
O
H
O
Structure of Peptides
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The properties of a protein depend upon the amino acid
composition, and the resulting three dimensional structure.
The structure of peptides can be defined at various levels:
- primary structure: the amino acid sequence
- secondary structure: the coiling of proteins into
pleated sheets or alpha helices
- tertiary structure: how the pleated sheets or alpha
helices fold upon themselves
- quaternary structure: if the protein is composed of
two or more subunits
Levels of Structure
Tertiary
Primary
Secondary
Quaternary
Natural Conformation of Proteins
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The natural conformation of a protein is how it exists in
3D space, resulting from secondary, tertiary and quaternary
structure.
The natural conformation can be strenghened by bonds
between sulfide groups, if the R group contains sulfur.
The natural conformation is destroyed (“denatured”) if a
protein is exposed to excessive heat or acidic conditions.
Types of Proteins in the Body
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structural proteins: collagen, elastin, keratin, etc.
contractile proteins: actin, myosin
hormones (luteinizing hormone, etc: see next quarter)
enzymes (catalyze reactions in the body; makes them
easier to happen)
Characteristics of enzymes
- Very specific for the reaction helped
- Enzyme is not consumed during the reaction
- Name usually ends in “-ase”
- oxidase: adds oxygen
- hydrolase: adds water
- dehydrogenase: removes hydrogen
- aminase: removes amino group
- decarboxylase: removes carbon
- isomerase: moves position of group on a molecule
- protease: breaks down protein
- lipase: breaks down fat
The types of enzymes in a cell determines the cell’s function!
Lipids
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Lipids are large chains or rings of carbon with some
oxygen (less than that in carbohydrates).
Lipids may also contain nitrogen, phosphorus, and sulfur.
Lipids contribute to structure of cells, and are important in
energy storage.
We will consider fatty acids, triglycerides, phospholipids,
and steroids.
Fatty acids
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Composed of long chains of carbon with
hydrogen atoms attached, and a
carboxyl group group at the end.
If all carbon-carbon bonds are single
bonds, the fatty acid is referred to as
being saturated.
If there are double bonds between
carbons, its an unsaturated fatty acid.
- If there is one double bond, its a
monounsaturated fatty acid.
- If there is more than one double
bond, its a polyunsaturated fatty acid.
Triglycerides
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Fatty acids are usually attached to glycerol, with a -COOH
group at the end.
glycerol + 3 fatty acids = triacylglycerol
Triglycerides can be broken down into fatty acids and
glycerol.
Triglycerides represent 95% of stored fat.
They are important in
- energy storage
- insulation (prevent heat loss)
- protection (surrounding delicate organs)
Phospholipids
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Phospholipids are formed by
joining glycerol with 2 fatty acids,
a phosphate group, and a nonlipid
group.
The fatty acids are hydrophobic,
while the phosphate end is polar
and hydrophilic.
Phospholipids form a major part of
the plasma membrane.
Steroids
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Steroids have a characteristic ring structure.
Cholesterol is the most common form
- a component of the cell membrane
- serves as precursor for other forms
general structure
cholesterol
Nucleic Acids
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Contain the genetic information for protein structure
Two types: DNA and RNA
The basic building block is the nucleotide
phosphate group + sugar + organic base
In RNA the sugar is ribose, in DNA its deoxyribose
PO4 + ribose + organic base = RNA
Organic bases used
Bases are characterized as purines or pyrimidines
 The purines are:
adenine (used in both DNA and RNA), and
guanine (DNA and RNA)
 The pyrimidines are:
cytosine (DNA and RNA)
thymine (DNA only) and
uracil (RNA only)
(Don’t memorize the structure of these.....)
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Building DNA and RNA
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To build DNA and RNA, nucleotides are joined by
hydrogen bonds between sugar and phosphate groups (see
text)
DNA is double-stranded, and coils up in a double helix
Purines bind to pyrimidines, and vice versa
RNA is single-stranded
The sequence of nucleotides determines the protein
produced
Examples
DNA: ATCATTGCGCAA
TAGTAACGCGTT
RNA: AUCAUUGCGCAA
Next Lecture.....
Metabolic Pathways