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