THE STUDY OF MOLECULES FOUND IN
LIVING ORGANISMS
ORGANIC
CHEMISTRY
Outline:
I.
Origin of Life (organic molecules)
II.
Carbon
A. Hydrocarbons
III.
Isomers
B. Stereoisomers
IV.
V.
Functional Groups
Macromolecules
A. Carbohydrates
B. Lipids
C. Proteins
D. Nucleic Acids
I. Origin of Life
• Miller concluded:
organic molecules could
arise spontaneously
under conditions of
early Earth
ABIOTIC
SYNTHESIS OF
ORGANIC
MOLECULES
Miller-Urey Experiment
I. Carbon
• Form the backbone of biological molecules
Reason for enormous variety of biological molecules
Can form up to 4 covalent bonds
C, O, N, S, P, H
Can take on many different shapes: SHAPE DETERMINES FUNCTION
I.A. Hydrocarbons
• Organic molecules consisting only of C & H
METHANE
ETHANE
Covalent bonds within hydrocarbons store LOTS of
 good fuel source
PROPANE
ENERGY!
Length of C-H chain can be … UNLIMITED!
I.A. Hydrocarbons
EN of C = 2.5
EN of H = 2.1
RULE: If EN diff. b/w atoms is >
0.4 = POLAR molecules
H-C regions of any organic molecule are nonpolar regions
Fats do not dissolve in
water b/c mainly made
of H-C chain  fats are
nonpolar molecules
Fats are HYDROPHOBIC
I.A. Hydrocarbons
 Different shapes and sizes
II. Isomers
3 Types
1. Structural Isomers:
Molecules with SAME
formula (same elements) but
DIFFERENT structure
(shape)
 caused by different bond
connections
6 carbons
6 carbons
Different chemical
properties
Different biological
functions
6 carbons
II. Isomers
3 Types
2. Cis-trans Isomers:
Differ in spatial arrangement due to
double bonds  inflexible
II. Isomers
3 Types
2. Cis-trans Isomers
Light-induced
Conformational
Change
II. Isomers
3 Types
3. Stereoisomers (AKA enantiomers):
Isomers that are mirror images of one another  differ in
shape due to presence of asymmetric carbon, C attached to 4
different atoms/groups of atoms
II. Isomers
3 Types
3. Stereoisomers (AKA enantiomers):
Effective b/c
fits into cells
protein
receptor
Uneffective
b/c does not
fit protein
receptor
Stereoisomers
…that can cause MAJOR sometimes harmful results!
1950’s  Thalidomide was given
to pregnant women to suppress
morning sickness
EFFECTIVE
Isomer
MUTAGENIC
Isomer
RACEMIC MIXTURE
III. Functional Groups
Create Molecular Diversity!!
• Most biological molecules
contain a C-H core with attached
functional groups
Give molecules diff. chemical
properties
Involved in chemical reactions
•
•
•
•
Hydroxyl • Sulfhydryl
Carbonyl • Phosphate
Carboxyl • Methyl
Amino
Molecular Diversity in ACTION
• Male hormone Testosterone vs. female hormone Estradiol
• basic carbon skeleton is identical
• different functional groups  different effects
Hydroxyl
-OH
• Organic molecules that contain an –OH group
ALCOHOLS (name usually ends in –ol)
Properties:
Polar, can form H bonds with
H2O to help dissolve
compounds (e.g. sugars)
Found in:
ETHANOL
Carbohydrates
Proteins,
Nucleic acids,
Lipids
Carbonyl
• Consists of carbon atom joined to an oxygen atom by a double bond
KETONES: carbonyl
group within carbon
skeleton
ALDEHYDE: carbonyl
group at the end of
carbon skeleton
ACETONE
PROPANAL
Properties:
Found in:
Ketones and aldehydes can be structural
isomers (e.g. acetone and propanal)
Sugars (ketoses
and aldoses)
Carboxyl
-COOH
• O double-bonded to C that is also bonded to OH group
Carboxylic acids, or organic acids
Properties:
Acts as an acid; can donate an H+ b/c
covalent bond b/w O and H is polar
ACETIC ACID
gives vinegar sour taste
Found in:
Amino
-NH2
• N bonded to 2 H atoms and to the C skeleton
Amines
Properties:
Acts as a base; can pick up an H+ f/
surrounding solution
H+
+
Found in:
GLYCINE
A compound that is both an
amine and carboxylic acid
 these compounds are
called AMINO ACIDS
Sulfhydryl
-SH
• S atom bonded to atom of H
Thiols
Properties:
2 sulfhydryl groups can form a
covalent bond  “cross-linking”
helps stabilize protein structure
(tertiary structure)
Found in:
CYSTEINE
An important S containing
amino acid
Phosphate
• P atom is bonded to 4 O atoms; 1 O atom is bonded to C
skeleton; 2 O atoms carry neg. charges
Organic phosphates
Properties:
Have potential to react with
water  releasing energy
Found in:
GLYCEROL PHOSPHATE
Plays very important role in cellular
chem. rxns.; provides backbone for
phospholipids  most prevalent
molecule in cell membrane
Methyl
-CH3
• C bonded to 3 H atoms
Methylated compounds
Properties:
Arrangement of methyl
groups in male and female
sex hormones affects their
shape and function
Found in:
5-METHYL CYTOSINE:
A component of DNA
modified by a methyl group
 this modificaton affects
expression of genes