The Structure and Function of Large Biological MoleculesWhat is a macromolecule?

What is a macromolecule?

Macromolecules are polymers- large molecules formed by joining many subunits together (monomers - "building blocks").

Four main macromolecules:

- carbohydrates (sugars)

- lipids (fats, oils)

- proteins (enzymatic, structural, storage etc. function)

- nucleic acids (DNA/RNA)

What are the levels of protein structure?

• PRIMARY - unique sequence of amino acids
• SECONDARY - alpha helix or beta pleated sheets
• TERTIARY - overall shape of a polypeptide resulting from
• QUATERNARY - overall protein structure

What is the difference between DNA and RNA?

DNA - deoxyribonucleic acid

- sugar: deoxyribose

- double helix

- nucleotides (nitrogenous bases): C (cytosine), G (guanine), A (adenine), T (thymine)

RNA - ribonucleic acid

- sugar: ribose

- single helix

- nucleotides: C, G, A,U (uracil)

Facts:

• Macromolecules are polymers, made of monomers
• Carbohydrates serve as fuel and building materials
• Triacylglicerols (fats or oils) are important energy source
• The two ends of phospholipids show different behavior toward water (hydrophilic / hydrophobic)
• A protein's specific structure determines how it works

Key terms:

Macromolecules (polymers) = Large molecules formed by joining many subunits together

Polymer = molecule that consists of a single unit (monomer) repeated many times

Monomer = A building block of a polymer

Dehydration/ Condensation synthesis = the chemical reaction that joins monomers into polymers. Covalent bonds are formed by the removal of a water molecule between the monomers

Hydrolisis = Reverse of

condensation synthesis. Breaks polymers into monomers by adding water.

Polypeptide = polymers of amino acids

Proteins = polypeptide chains of Amino Acids linked by peptide bonds

Fatty acid = a long carbon chain (12-18 C) with a -COOH (acid) on one end and a -CH₃ (fat) at the other.

Denaturation = pH shifts, high salt concentrations, heat

Nucleotide = monomer

of nucleic acid, consisting of a nitrogen base, deoxyribose (five-carbon sugar) and a phosphate group

Summary:

Organic molecules are those that have carbon atoms. In living systems, large organic molecules, called macromolecules, may consist of hundreds or thousands of atoms. Most macro

molecules are polymers, molecules that consist of a single unit (monomer) repeated many times.

Four important classes of organic molecules - carbohydrates, lipids, proteins and nucleic acids - are discussed below.

Carbohydrates - classified into 3 groups according to the number of sugar molecules present : monosaccharide, disaccharide, polysaccharide - and are all serving as fuel and building material.

Lipids are class of substances that are insoluble in water (and other polar solvents) but are soluble in no

npolar substances (ex. ether). There are 3 major groups of lipids: tryglicerides (fats, oils, waxes), phospholipids and steroids.

Proteins can be gr

ouped according to their functions: structural, storage, transport, defensive, enzymes.

Although the functions of proteins are diverse, their structures are similar (polymers of amino acids, covalently bonded).

Nucleic acids are divided into two groups: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). The genetic information of a cell is stored in molecules of DNA. The DNA, in turn, passes its genetic instructions to RNA for directing various metabolic activities of

the cell.

Extra:

Roger Kornberg --> Nobel Prize in Chemistry for using Xray crystallography to determine the 3D shape of polymerase II