Biomolecules

The Chemical Building Blocks of Life

The Chemistry of Carbon

• Organic molecules contain carbon• Carbon’s four valence electrons allow

it to form up to four covalent bonds• Hydrocarbons consist only of C and H

– Propane CH8

• It can easily bond to itself and form long chains– Linear - Cyclic - Branched

Functional Groups

• Chemical properties and reactivity are a result of functional groups

• Functional groups maintain chemical properties no matter where they occur

• Polar molecules are hydrophilic• Nonpolar molecules are hydrophobic• The degree to which organic molecules

interact with water affects their function• Hydroxyl group (-OH) is one of the most

common functional groups, it will make a molecule water soluble

Macromolecules – The Sum of the Parts

• Many complex biological activities require large macromolecules

• Macromolecules are polymers built by linking together small subunits called monomers– Proteins are polymers of amino acids– Nucleic acids are polymers of nucleotides– Starches are polymers of simple sugars

CondensationIt’s not just for the water cycle anymore

• Macromolecules are constructed by covalently bonding monomers by condensation reactions where water is removed from the functional groups of the monomers

• Dehydration synthesis (water is removed)• A hydroxyl (-OH) from one monomer and a

hydrogen (-H) from another are removed• Anabolic reaction

Hydrolysis• Hydrolysis is the reverse of condensation• Results in the break down of polymers• Hydration reactions add water and break

bonds releasing energy

Macromolecules

•Perform complex tasks with precision

•Basic structure and function of each family similar in all organisms (bacteria – humans)

Families of Biomolecules

• Carbohydrates

•Lipids

•Proteins•Nucleic Acids

Basic Function

Carbo’s Lipids N. Acids ProteinsEnergyStorageStructure

Long term storageInsulationProtection

InheritanceBlueprint for metabolism

CatalystsHormonesStructure

StarchGlycogenGlucoseSucroseCellulose

LipidFatsOilsWaxes

DNARNAATP

ProteinsEnzymes

CarbohydratesHow Sweet It Is!

• General formula (CH2O)n

• Simple sugars or large molecules made of sugar monomers

• Monosaccharides (monomer) are covalently linked by condensation reaction to form polysaccharides (polymers)

Sugars• Monosaccharides

– Five carbon: Ribose– Six carbon: glucose and fructose

•Disaccharides–Sucrose–Lactose

•Polysaccharides–Starch–Cellulose–Glycogen

PolysaccharidesThree Types

• Glycogen – animal storage product that accumulates in the liver

- Highly branchedGlucoseGlycogenglucosebloodstream

• Starch – plant energy storage- Helical- Easily digested by animals through

hydrolysis

Cellulose

• Polysaccharide found in plant cell walls• For humans cellulose is indigestible and

forms dietary fiber• Made up entirely of β glucoses

– Structure is constrained into straight microfibrils

• Not an energy source for animals• Chitin – insect exoskeletons

Lipids

• Long-term energy storage• Generally insoluble in water• Structural components of cells

(phospholipids)• Cellular messengers (hormones)

More FAT• Triglycerides are composed of three fatty acids

covalently bonded to one glycerol molecule

•Fatty acids are composed of CH2 units and are hydrophobic

•Fatty acids can be saturated (all single bonds) or unsaturated (one or more double bonds)

•A fat (mostly saturated) is solid at room temp. while an oil (mostly unsaturated) is liquid at room temp.

Phospholipids

• Important structural component of cell memranes

• Phosphate group (head) is polar and water soluble (hydrophilic)

• Fatty acid tails are hydrophobic

•This allows the phospholipids to form bilayers and membranes

Other Lipids• Steroids

– Insoluble in water– Built around a four ringed skeleton

• Cholesterol– Component for animal cell membranes– Formation of myelin sheath covering nerves

• Hormones– Chemical messengers

• Waxes– Many fatty acids linked to a long backbone– Waterproofing in plants, ears, beehives

Proteins• 50% dry weight of body• Mammal cell contains 10,000 proteins• Control elements (enzymes)

– Organic catalysts– Mediators of metabolism– Direct development, maintenance, and

growth• Structural elements (cell membrane,

muscles, ligaments, hair, fingernails)• Regulate what goes into/out of cells

Building Blocks of ProteinsAmino Acids

• Amino acids (monomers) are linked together to form proteins (polymers)– Each unique sequence of amino acids forms a

different protein– All living things (even viruses) use the same 20

amino acids

• 20 different Amino Acids– Amino end (NH2)

– Carboxyl end (COOH)– Hydrogen– R group – variable component

Amino Acids• Amino Acids are grouped by

whether R- group is polar or non-polar

•Positively charged side chain•Negatively charged side chains•Polar but uncharged side chains•Hydrophobic side chains•Special cases

Protein Assembly• AA’s are linked together by joining

the amino end of one molecule to the carboxyl end of another

•Peptide bond forms a chain called a polypeptide•Transcription in nucleus

–DNA code mRNA•Translation on ribosomes

–mRNA protein

Protein Structure• Primary structure

– Specific linear sequence of AA’s in a polypeptide

– Determined from code in inherited genetic material

– Changes in primary structure can alter proper functioning of the protein

• Secondary structure- the tendency of the polypeptide to coil or pleat due to H-bonding between R- groups- -helix, -pleated sheet, or random coil

• Tertiary structure- shape of entire chain; folded, twisted, or

globular

- shape related to function and properties

•Quaternary structure- more than one polypeptide chain

Nucleic Acids• Polymers composed of monomer

units known as nucleotides• Information storage

– DNA (deoxyribonucleic acid)• Protein synthesis

– RNA (ribonucleic acid)• Energy transfers

– ATP (adenosine tri-phosphate) and NAD (nicotinamide adenine dinucleotide)

Nucleotides• Nucleotide structure

– Phosphate – Nitrogenous base

Purines (double-rings)Adenine and Guanine

Pyrimidines (single-rings)Cytosine, Thymine, and Uracil

– Sugar – either ribose or deoxyribose pentoses in ring formDeoxyribose lacks one oxygen

Functions of Nucleic Acids• DNA – Physical carrier of genetic

information– Restricted to nucleus

• RNA – key component of protein synthesis– Messenger RNA (mRNA) – blueprint

for construction of a protein– Ribosomal RNA (rRNA) – construction

site where the protein is made– Transfer RNA (tRNA) – truck delivering

the proper AA to the site of construction

The End