Chapter 3- Organic Molecules
CHNOPS• Six of the most abundant
elements of life (make up 95% of the weight of all living things)!
• What are they used for?• Structures, enzymes, energy,
hormones, DNA…
• How do we get them?• Eating, drinking, and breathing
The Almighty Carbon• All life is built on carbon (cells are 75% water, 25% carbon compounds, and 3% water)
• C atoms are versatile• 4 stable covalent bonds• Must be constantly bonding with CHNOPS
for stability
• Especially important is carbon’s ability to bond with other carbons• VERY STABLE• Hydrocarbons (exclusively carbons and
hydrogen)• Non-polar• Hydrophobic• stable
Function Groups• Carbon chain = skeleton of
backbone
• Diversity of organic molecules comes from the attachment of functional groups• Specific combination of bonded
atoms that always reacts the same way
Polar, forms hydrogen bonds
Polar
Polar, acidic
Polar, basic, forms hydrogen bonds
Forms disulfide bonds
Phosphate group Polar, acidic
Polymers• Long molecules built by linking
repeating building blocks in chains• Building blocks = monomers• Covalent bonds
• 4 Major classes of macromolecules:• Carbohydrates• Lipids• Proteins• Nucleic acids
• Four groups of macromolecules can be broken down into polymer and monomer subunits • Easier to digest• Also easier to take the building blocks to
build what you need
B-I-O-L-O-G-Y
Biomolecule Synthesis and Degradation
• Dehydration Reaction• Building of biomolecules
• As subunits are joined together water is released
• Requires energy
• Hydrolysis/ Digestion• Break down biomolecules with water• Opposite of dehydration• Must add water to break down molecules• Releases energy- we are breaking a bond• Requires enzymes
Enzymes
• Molecule that speeds up a reaction by bringing the reactants together
• Remains unchanged by reaction
• Think of it as a dating site (dehydration) or a divorce attorney (hydrolysis) for biomolecules
H2O
HO
HO H
H HHO
enzyme
Carbohydrates• “Carbon water”- Some form of CH20
• Monomer: monosaccharide• Simple sugar
• glucose, ribose
• Functions:• Energy
• Raw materials
• Energy storage
• Structural compounds
• Examples• Glucose- C6H12O6
• Starch• Cellulose• glycogen
Sugars
• Most names for sugars end in –ose
• Classified by carbons:• 6C= hextose (glucose)
• 5C= pentose (ribose)
• 3C =triose (glyceraldehyde)
OH
OH
H
H
HO
CH2OH
H
H
H
OH
O
Glucoseglyceraldehyde
Building sugars• Dehydration synthesis
|
fructose
|
glucose
monosaccharides
|sucrose
(table sugar)
disaccharide
H2O
CARBOHYDRATES• Carbon to hydrogen to oxygen ratio of 1:2:1
• Monomer= Monosaccharides• Single sugar molecule (aka simple sugar)
• Some form of CH20
• Ex. Glucose• C6H12O6
• Disaccharide- 2 monosaccharides• Joined in dehydration reaction
• Ex. Sucrose and lactose
• Polysaccharides• Large polymers
• Ex. Starch
Lactose
Polysaccharides
• Polymers of Sugars• Cost little energy to build• Easily reversible = easy energy• Energy is stored in the C-C bond
• Harvested in cellular respiration
• Functions:• 1) Energy storage
• Glycogen- animals (muscles)• Starch- plants
• 2) Structure• Cellulose- plants• Chitin- arthropods
Linear vs. branched polysaccharides
starch
(plant)
glycogen
(animal)
energy
storage
slow release
fast release
Polysaccharide Diversity
• Molecular structure determines function
• Isomer- identical molecular formulas, but different arrangement of atoms
in starch in cellulose
Cellulose
• Most abundant organic compound on Earth• herbivores have evolved a mechanism to digest
cellulose
• most carnivores have not• that’s why they eat meat to get their energy &
nutrients
• cellulose = indigestible roughage
Lipids
• Lipids are composed of C, H, and O
• ALL hydrophobic
• Do not form polymers• Big molecules of small units (NOT A
CONTINUING CHAIN)
• “Family” Types:• Fats and Oil
• Phospholipids
• Steroids
• Waxes
1) Triglycerides (fats and oils)
• Glycerol (3C alcohol) + fatty acids• Fatty acid= long HC tail with carboxyl
(COOH) head
• Long HC chain• Polar or non-polar?
• Hydrophilic or hydrophobic?
• FUNCTION:• Energy storage (2x carbs)
• Cushion organs
• Insulationdehydration synthesis
H2O
enzyme
Saturated vs unsaturated fats
• Saturated fatty acid= no double bonds between carbon• Long straight chain
• Most animal fasts
• Solid at room temperature
• Unsaturated fatty acids= double bonds with carbon• Plant and fish fats
• Vegetable oils
• Liquid at room temperature• Natural peanut butter
2) Phospholipids• Constructed like fat but contains a
phosphate group instead of a third fatty acid chain
• Hydrophilic head and hydrophobic tail
• Tend to form two layers (bilayer)• Polar heads associated with other
polar heads
• BIOLOGICAL IMPORTANCE• Makes up the majority of the plasma
membrane of cells
3) Steroids• Entirely different structure
compared to other lipids• Four fused carbon rings• Steroid type is based on
functional group attached to carbon ring
• BIOLOGICAL IMPORTANCE• Physical stability (cholesterol)• Hormones (testosterone)
4) Waxes• Long-chain fatty acids bonded with
long-chain alcohols
• Solid are room temperature
• BIOLOGICAL IMPORTANCE• Form protective cuticles
• Plants use to reduce water loss• Ducks use to remain buoyant on water
cholesterol
Proteins• Monomer: Amino acids
• Amino and acid functional group
• 20 different amino acids
• Polymers:a)Peptides- 2+ amino acids
b)Polypeptides- chains (usually <50 amino acids)
c) Protein: 1+ polypeptides formed into a shape
H2O
—N—
H
H
C—OH||O
R
|
—C—|
H
Building Proteins
• Peptide Bond• Covalent bond between NH2 (amine) of
one amino acid and the COOH (carboxyl) of another
• C-N bond
• Polar• Allows for H bonding
• Polypeptide chains have direction• N-terminus = NH2 end
• C-terminus = COOH end
• repeated sequence (N-C-C) is the polypeptide backbone• can only grow in one direction
Shapes of Proteins• Primary
• Sequence of amino acids• Determine by DNA• Sickle cell anemia
• Secondary• Coil or folding of protein caused by the position of
hydrogen bonds• α helix (coil): bond between every fourth amino acid• Β pleat (sheet): turns back on itself and forms bonds
• Tertiary• Final 3D shape resulting from coils and pleats• Mostly caused by interactions with hydrophobic
amino acids and water and hydrogen bonds of amino acids
• Determines protein’s specificity
• Quaternary• Some proteins consist of more than one
polypeptide• Ex. Hemoglobin has 4 polypeptides attached to each
other
structure determines function
Protein denaturation
• Unfolding a protein• conditions that disrupt H bonds,
ionic bonds, disulfide bridges• temperature
• pH
• salinity
• alter 2° & 3° structure• alter 3-D shape
• destroys functionality• some proteins can return to their
functional shape after denaturation, many cannot
Protein-Folding Diseases• Protein chaperones: proteins in the
cell that fold new proteins into their shape
• A malfunctioning protein chaperone can improperly fold proteins resulting in a non-functional protein
• Possible diseases related to improper folding:• Alzheimer’s Disease• Fatal brain disease, TSE
• Mad cow disease
Proteins
• BIOLOGICAL IMPORTANCE:
1) Metabolism: enzymes
2) Support: hair/nail
3) Transport: carrier proteins, hemoglobin
4) Cell communication: insulin
5) Defense: antibodies
6) Regulation: Some hormones epinephrine
7) Motion: contractile proteins in muscles
Hemoglobin
Insulin
Nucleic Acids
•Monomer: nucleotide•Composed of:
• pentose (5) sugar• Ribose in RNA
• Deoxyribose in DNA
• phosphate• Nitrogen carbon ring
• The A,T,C,G part
Complementary Base Pairs
• Pyrimidines (single ring)• DNA
• Cytosine and Thymine
• RNA• Cytosine and uracil
• Purines (double ring)• Adenine and Guanine
• Held together by hydrogen bonds
Adenosine Triphosphate (ATP)
• Nucleotide composed of adenine, ribose, and three phosphates
• Last two phosphates are unstable and easily broken
Nucleic Acids
• Biological Importance:• genetic material
• stores information• genes
• blueprint for building proteins
• DNA RNA proteins
• transfers information• blueprint for new cells
• blueprint for next generation
DNA
proteins