Molecules of Life Polymers Are Built of Monomers

Molecules of Life

Polymers Are Built of Monomers • Organic molecules are formed by living organisms – have a carbon-based core – the core has attached groups of atoms called functional groups • the functional groups confer specific chemical properties on the organic molecules

Polymers Are Built of Monomers • The building materials of the body are known as macromolecules because they can be very large • There are four types of macromolecules: 1. 2. 3. 4. Proteins Nucleic acids Carbohydrates Lipids Large macromolecules are actually assembled from many similar small components, called monomers • – the assembled chain of monomers is known as a polymer

Macromolecule Formation • There are 4 major categories of organic molecules in living organisms: – Carbohydrates – Lipids – Protein – Nucleic acids

Macromolecules • A macromolecule is built upon repeating subunits called polymers. • Macromolecules are large and complex. • An organic molecule is based on long chains of carbon with functional groups on the ends that give the molecule its unique chemical properties.

Macromolecules • All four macromolecules consist of a covalent bond between two subunits. . a hydroxyl group is removed from one end a hydrogen group from the other end. • This process is called dehydration. • Dehydration requires the action of an enzyme to facilitate chemical binding. • Adding of water to the polymer too break them into subunits is called hydrolysis.

Carbohydrates • Carbohydrates are energy sources and are made of polymers of simple carbohydrates. – Simple carbohydrates include monosaccharides and disaccharides. – Complex carbohydrates are polysaccharides formed from glucose. • Component of plant cell walls, outer skeletons of insects. • Ex. : chitin, cellulose, glycogen, starch.

Carbohydrates • Carbohydrates are monomers that make up the structural framework of cells and play a critical role in energy storage – a carbohydrate is any molecule that contains the elements C, H, and O in a 1: 2: 1 ratio – the sizes of carbohydrates varies • simple carbohydrates – consist of one or two monomers • complex carbohydrates – are long polymers

Carbohydrates • Simple carbohydrates are small – monosaccharides consist of only one monomer subunit • an example is the sugar glucose (C 6 H 12 O 6) – disaccharides consist of two monosaccharides • an example is the sugar sucrose, which is formed by joining together two monosaccharides, glucose and fructose

Formation of sucrose

Carbohydrates • Complex carbohydrates are long polymer chains – because they contain many C-H bonds, these carbohydrates are good for storing energy • these bond types are the ones most often broken by organisms to obtain energy – the long chains are called polysaccharides

Carbohydrates • Plants and animals store energy in polysaccharide chains formed from glucose – plants form starch – animals form glycogen • Some polysaccharides are structural and resistant to digestion by enzymes – plants form cellulose cell walls – some animals form chitin for exoskeletons

Carbohydrates and their function

Lipids • Fats and all other biological materials that are not soluble in water, but are soluble in oil are lipids. • Used for long term energy storage. • Fats: – Triglycerols are made of glycerol and three fatty acids. – Fatty acids may be saturated or unsaturated with hydrogen along the carbon chain.

Lipids • Fats are used for: – Energy storage; – Components of cell membranes (phospholipids); – Message transmission (steroids); – Pigmentation.

Lipids • Fatty acids have different chemical properties due to the number of hydrogens that are attached to the non-carboxyl carbons – if the maximum number of hydrogens are attached, then the fat is said to be saturated – if there are fewer than the maximum attached, then the fat is said to be unsaturated

Saturated and unsaturated fats

Proteins • Proteins may serve as enzymes, play a structural role, and act as chemical messengers. • They are polypeptides made up of amino acids joined by peptide bonds. • Act as catalysts.

The formation of a peptide bond

Proteins • Protein structure: – The sequence of amino acids within the protein is called the primary structure. – Any folding of the primary chain structure is called the secondary structure. – Globular shapes are the tertiary structure of a protein. – When more than one polypeptide chain composes the protein, it has quaternary structure. – The shape of a protein can be denatured (poor function results).

Proteins • There are four general levels of protein structure 1. Primary 2. Secondary 3. Tertiary 4. Quaternary

Proteins • Primary structure – the sequence of amino acids in the polypeptide chain • This determines all other levels of protein structure Figure 4. 7 Levels of protein structure: primary structure

Proteins • Secondary structure forms because regions of the polypeptide that are nonpolar are forced together; hydrogen bonds can form between different parts of the chain • The folded structure may resemble coils, helices, or sheets Figure 4. 7 Levels of protein structure: secondary structure

Proteins • Tertiary structure – the final 3 -D shape of the protein • The final twists and folds that lead to this shape are the result of polarity differences in regions of the polypeptide Insert Figure 4. 7 from TLW 6 e

Proteins • Quaternary structure – the spatial arrangement of proteins comprised of more than one polypeptide chain Figure 4. 7 Levels of protein structure: quaternary structure

Protein • The shape of a protein affects its function – changes to the environment of the protein may cause it to unfold or denature • increased temperature or lower p. H affects hydrogen bonding, which is involved in the folding process – a denatured protein is inactive

Nucleic Acids • Nucleic acids (polynucleotides) store information for cells. • DNA (Deoxyribonucleic acid) exists as a double helix of polynucleotides, using base pairing within the helix. – Base pairing dependent upon hydrogen bonding. – DNA encodes genetic materials and ribonucleic acid (RNA) is involved in protein synthesis.

The Double Helix • The reason for DNA to assume its double helix is because only two base pairs are possible: Adenine-Thymine and Guanine. Cytosine. • The advantage of the double helix is that it contains two copies of the information —one the mirror image of the other.

The DNA double helix