Molecules of Life All living things are made up of four classes of large molecules: Carbohydrates, lipids, proteins, and nucleic acids. Macromolecules are large molecules composed of thousands of covalently connected atoms. Structure of the molecule affects its function.

Macromolecules are polymers built from monomers Polymer- long molecule consisting of many similar building blocks The small building blocks are called monomers. Carbohydrates, Proteins, and Nucleic acids are polymers.

Building and Breaking down Polymers A dehydration reaction occurs when two monomers bond together. Loss of a water molecule. Polymers are broken apart by hydrolysis. Addition of a water molecule

(a) Dehydration reaction: synthesizing a polymer Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond. Longer polymer (b) Hydrolysis: breaking down a polymer Hydrolysis adds a water molecule, breaking a bond. 1 2 3 4

Carbohydrates Serve as fuel and building material Include sugars and the polymers of sugars. Simplest are called monosaccharides (single sugars) Classified by location of the C=O and number of carbons Carbohydrate macromolecules are polysaccharides Disaccharides- two sugar monomers linked.

Carbohydrates Store Energy Starch- a storage polysaccharide of plants, consists of glucose molecules. Simplest form is amylose Found in the chloroplasts Glycogen- is a storage molecule in animals Mainly in muscle cells

Carbohydrates Provide Structure Cellulose- major component of the tough wall of plant cells Chitin- found in the exoskeleton of arthropods and supports the cell walls of many fungi

Lipids Hydrophobic molecules that do not form polymers. Hydrophobic = Water fearing Consist mostly of hydrocarbons, which form nonpolar covalent bonds This group consists of: Fats Phospholipids Steroids

Fats Fats are constructed from two types of smaller molecules: glycerol and fatty acids Glycerol- Three-carbon alcohol with a hydroxyl group on each carbon Fatty acid- carboxyl group attached to a long carbon skeleton

Fatty acid (in this case, palmitic acid) Figure 5.10 Fatty acid (in this case, palmitic acid) Glycerol (a) One of three dehydration reactions in the synthesis of a fat Ester linkage Figure 5.10 The synthesis and structure of a fat, or triacylglycerol. (b) Fat molecule (triacylglycerol)

Two Kinds of Fats Saturated Fatty acids- Have the maximum number of hydrogen atoms possible and no double bonds Unsaturated fatty acids- Have one or more double bonds Fats store energy and are stored in adipose cells

Phospholipids Two fatty acids and a phosphate group are attached to glycerol Fatty acid tails are hydrophobic Phosphate group and attachments for hydrophilic head

Formation of Bilayers When in water, these phospholipids form bilayers Hydrophilic heads face water Hydrophobic tails face each other Found in cell membranes

Nucleic Acids Nucleic acids store, transmit, and help express hereditary information. DNA and RNA are examples of nucleic acids. Made of monomers called nucleotides Nucleotides are made up of a nitrogenous base, a sugar, and a phosphate group

DNA and RNA RNA molecules are single polynucleotide chains Single stranded DNA molecules have two polynucleotides spiraled in a double helix Each strand runs antiparallel (opposite directions) One DNA molecule can include many genes

Proteins Includes a diversity of structures that have a wide range of functions. Functions include: Structural support Storage Transport Cellular communications Movement Defense against foreign substances

Proteins Proteins consist of one or more polypeptides Polypeptides are unbranched polymers built from the 20 amino acids that are linked by peptide bonds Amino Acids are the monomers of proteins Amino Acids are organic molecules with carboxyl and amino groups Differ in their properties because of the differing side chains

Protein Structure A functional protein consists of one or more polypeptides twisted, folded, and coiled into a unique shape. The sequence of Amino Acids determines the structure, and that determines its function

Four Levels of Structure The primary structure- its unique sequence of amino acids (Information in genes) Secondary structure- consists of coils and folds in the polypeptide chain Alpha helix and Beta pleated sheet Tertiary structure is determined by interactions among various side chains Quaternary structure results when a protein consists of multiple polypeptide chains

Animation Protein Structure Animation (Resources Page)

Loss of Structure Alterations in pH, temperature, salt concentration can cause a protein to unravel. The loss of a protein’s structure is called denaturation. Once denatured, the protein is inactive.

Enzymes Enzymes are a type of protein that acts as a catalyst and speeds up chemical reactions. Enzymes can perform their functions repeatedly. Without enzymes, many of life’s processes would not be possible.

Bozeman Video Molecules of Life- Bozeman Science (Resources Page)