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V. Organic Compounds
Introduction:
 Organic compounds = carbon
 organisms=organic
 Why carbon?
1. 4 valence e- = 4 covalent bonds
2. can form single, double or triple bonds
3. can bond to other carbon atoms, making long
chains, branched molecules or rings.
Structural
formula
Ball-and-stick
model
Space-filling
model
Methane
The four single bonds of carbon point to the corners
of a tetrahedron.
Ethane
Length.
Propane
Carbon skeletons vary in length.
Butane
Isobutane
Branching. Skeletons may be unbranched or branched.
1-Butene
Double bonds.
2-Butene
Skeletons may have double bonds,
which can vary in location.
Cyclohexane
Rings.
Benzene
Skeletons may be arranged in rings.
 organic compounds unique properties depend on
 size & shape of the molecule
 groups of atoms (functional groups) attached to it
 compounds containing functional groups are
hydrophilic (water-loving)
 makes them soluble in water
 Functional groups (pg. 35 formulas)
1) Hydroxyl group
2) Carbonyl group
3) Carboxyl group
4) Amino group
5) Phosphate group
* Methyl group (non-polar)*affects shape & function
Estradiol
Female lion
Testosterone
Male lion
VI. Macromolecules
 large organic molecules
 also called polymers
 made of smaller “building blocks” called
monomers
 Monomers link together to form polymers
through dehydration reactions, which
remove water
 Polymers are broken apart by hydrolysis, the
addition of water
Short polymer
Unlinked
monomer
Short polymer
Dehydration
reaction
Longer polymer
Unlinked
monomer
Hydrolysis
A. Carbohydrates – (polysaccharides)
1. monosaccharide (simple sugar) = monomer
• glucose, fructose (fruit), galactose (milk)
• made of C, H, O (1:2:1)
• functional group(s): hydroxyl, carbonyl
• used for energy in cells & as raw materials to
manufacture other organic molecules
Glucose
(an aldose)
Fructose
(a ketose)
Structural
formula
Abbreviated
structure
Simplified
structure
2. disaccharide -two monomers (sugars) joined
by dehydration reaction
• sucrose (glucose + fructose) = table sugar
• maltose (2 glucose) = grain sugar
• lactose (glucose + galactose) = milk sugar
Glucose
Glucose
Maltose
3. Polysaccharides – many monomers (sugars)
• function in cells as a storage molecule or a
structural compound
a) Starch- storage molecule in plants made of
glucose
b) Glycogen- storage molecule in animals
made of glucose
c) Cellulose- polymer of glucose that forms
plant cell walls
d) Chitin- used by insects & crustaceans to
build an exoskeleton
Starch granules in
potato tuber cells
Glycogen
granules
in muscle
tissue
STARCH
Glucose
monomer
GLYCOGEN
CELLULOSE
Cellulose fibrils in
a plant cell wall
Hydrogen bonds
Cellulose
molecules
B. Lipids
• not true polymers
• non-polar, water insoluble (hydrophobic)
• made of C, H, few O
• hydroxyl & methyl groups
• long term energy storage, insulation, cushion/protect
organs, prevent water loss, chemical messengers, cell
membranes
• contain twice as much energy as a polysaccharide
1. Fats/Oils (triglycerides)
• made from glycerol and
3 fatty acids (monomers)
linked by dehydration reaction
Glycerol
Fatty acid
a. unsaturated fats - have fewer than
the maximum number of hydrogen
atoms (good)
• made of fatty acids that contain
double bonds, causing kinks or
bends in the carbon chain
• usually liquid at room temp
• plants, fish
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b. saturated fats – have maximum number of
hydrogens, no double bonds (bad)
• solid at room temp
• animal fat (lard), butter
2. Phospholipids -important part of cell membrane
3. Steroids -lipids made of fused ring structures
• cholesterol a steroid that plays a significant role in
the structure of the cell membrane & sex hormones
4. Waxes – cuticle coating on plants
Hydrophilic
heads
Phospholipid
Water
Hydrophobic
tails
Water
cholesterol
Carboxyl
group
Amino acid
Amino
group
Amino acid
Peptide
bond
Dehydration
reaction
Dipeptide
Leucine (Leu)
Hydrophobic
Serine (Ser)
Aspartic acid (Asp)
Hydrophilic
C. Protein (polypeptide)
•
amino acids (20) = monomers
 central C atom & 4 other things:
1) amino group
2) carboxyl group
3) another chemical group
represented as “R”
4) H
 peptide bonds holds amino acids
together
•
made of C, H, O, N
Amino
group
Carboxyl
group
1. Functions of Proteins (8) – determined by shape
a. Structural – hair, nails, fibers in tendons
b. Contractile (movement) - found in muscles
c. Signal (regulation) – hormones
d. Storage – egg white (albumin)
e. Transport – hemoglobin carries O2 in blood
f. Defense - antibodies of the immune system
g. Receptors - built into cell membranes
h. Enzymes – control chemical reactions
Four Levels of Protein Structure
Primary structure
Amino acids
Hydrogen
bond
Secondary structure
Alpha helix
Tertiary structure
Quaternary structure
Pleated sheet
Polypeptide
(single subunit
of transthyretin)
Transthyretin, with
four identical
polypeptide subunits
D. Nucleic Acids (DNA & RNA)
•
Nucleic acid = monomer
•
Made of C, H, O, N, P
 3 parts
1) five-carbon sugar
(pentose)
Nitrogenous
base
(adenine)
 ribose in RNA
 deoxyribose
in DNA
Phosphate
group
2) phosphate group
3) nitrogenous base
(1 of 4)
Sugar
• 4 nitrogenous bases
 adenine (A)
 thymine (T) (DNA only)
 cytosine (C)
 guanine (G)
 uracil (U) (RNA only)
Nucleotide
Sugar-phosphate
backbone
1. DNA = 2 strands wrapped around each other
forming a double helix
• A pairs with T
• C pairs with G
 Functions: compose genes, determine
the structure of proteins
2. RNA = single strand
 Functions: copy & transfer DNA so
proteins can be made
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Base
pair
VII. Enzymes
A. Properties
1. large proteins
2. end with –ase
3. very specific to a reaction
4. reusable
B.
Function
1. act as biological catalysts (speed up rate of a
reaction without being used up)
• lower activation energy needed to start a
reaction by weakening chemical bonds
C. Enzyme-Substrate Complex
1. Active site- specific shape on enzyme
2. Substrate- reactant(s) that can attach to active site
to react
• lock & key design - shape of active site is so
precise that only the intended substrate(s) can
attach. Also called induced fit.
D. Factors Affecting Enzyme Activity (Rate)
1. temperature – too high will denature
(unfold) enzyme, too low will slow down rate
2. pH – needs to be around 6-8; other levels
can denature enzyme
3. concentration of substrate – if more
substrate than enzymes, rate slows down
4. Inhibitors – can stop/slow rate
a. competitive – resemble substrate & compete
for active site
b. non-competitive – attach to enzyme some
place other than active site, altering shape of
active site; substrate cannot fit