Biology 211 Anatomy & Physiology I Macromolecules of Importance in Human Anatomy & Physiology

Many molecules in the human body are very large, consisting of hundreds or even thousands of atoms. These are called macromolecules. Four types of macromolecules are particularly important in the human body: Proteins Carbohydrates / Polysaccharides Lipids Nucleic Acids

All of these macromolecules are polymers which consist of repeating smaller subunits called monomers Polymer: Monomers Protein Amino acids Carbohydrate/ Monosaccharides Polysaccharide Lipid Fatty acids & Glycerol Nucleic Acid Nucleotides

Rather than draw out these large molecules, we typically use a set of shorthand figures for them Amino acids are usually shown as circles Monsaccharides are usually shown as polygons showing the number of carbons Fatty acids are usually shown as wavy lines Nucleotides are usually shown with three parts

Polymer: Monomers: Protein Amino acids

Some important functions of proteins in the human body: Membrane Proteins Enzymes Structural proteins Some Hormones Antibodies Contractile Proteins Blood Clotting

Proteins are composed of unbranching chains of amino acids arranged in different sequences. There are 21-22 different amino acids, all of which have the same basic structure: Where "R" is different for each amino acid

Glycine - Alanine - Glutamine - Alanine – Serine – Lysine -Valine and The sequence of amino acids in a protein is called its primary structure Thus, the proteins Glycine - Alanine - Glutamine - Alanine – Serine – Lysine -Valine and Alanine – Valine - Alanine - Glycine – Lysine - Serine - Glutamine have different primary structures even though they contain the same seven amino acids (Scientists are lazy: Amino acids are often shown as circles instead of drawing out all the atoms)

The chain of amino acids in a protein will fold into specific patterns, called its secondary structure Different parts of each chain fold in different ways; Thus, they have different secondary structures

This folded protein folds even further to form its tertiary structure Since proteins with different primary structures will fold into different secondary structures, they will also fold into different tertiary structures

Obviously, proteins with different primary structures These folded proteins may group together, providing the protein with its quaternary structure. Obviously, proteins with different primary structures will have different secondary structures and thus different tertiary structures which will group into different quaternary structures Hemoglobin Immunoglobulin (antibody)

The specific function of any protein depends on its three-dimensional shape (secondary, tertiary, and quaternary structures) If the shape of the protein is changed, it will no longer function as it should. This is called denaturing the protein

Polymer: Monomers: Protein Amino acids Carbohydrate Monosaccharides

Different monosaccharides have different structures, but all share the same basic formula: Cn H2n On Most common monosaccharides: C6 H12 O6 Also found: C3 H6 O3 C4 H8 O4 C5 H10 O5

Two monosaccharides linked by dehydration synthesis = disaccharide

2 monosaccharides = disaccharide 3 monosaccharides = trisaccharide Many monosaccharides = polysaccharide (too many to count) Monosaccharides Disaccharides = sugars Fuzzy terminology: Sometimes: All monosaccharides disaccharides called "carbohydrates" polysaccharides

Two Important Functions of Carbohydrates: 1) Storage of fuel for energy: Amylose (starch) in plants; Glycogen in animals Human cells can digest starch but not synthesize it. They can both synthesize & digest glycogen

Two Important Functions of Carbohydrates: Digestion of starch or glycogen in the digestive system produces Glucose (Scientists are lazy: Glucose & other monosaccharides are often shown as hexagons instead of drawing out all the atoms) which is further broken down within cells to release lots of energy. Waste products: Carbon dioxide Water

Two Important Functions of Carbohydrates: (1. Storage of fuel for energy) 2) Structural carbohydrates Many in extracellular matrix of all tissues Receptors on cell surfaces (usually bound to proteins or lipids) (Cell walls in plants / bacteria = cellulose & others) (Exoskeletons of invertebrates = chiton) We will discuss the use of carbohydrates for producing energy and for use as structural molecules at various times throughout this course and BIOL 212

Lipid Fatty acids & Glycerol Polymer: Monomers: Protein Amino acids Carbohydrate Monosaccharides Lipid Fatty acids & Glycerol

Lipids: Molecules which are hydrophobic and do not mix with water Two major types: Fats (& Oils) Steroids

If it’s solid at room temperature it’s a fat Fats & Oils: Monomer (basic repeating units) are fatty acids bound to a 3-carbon molecule called glycerol If it’s solid at room temperature it’s a fat If it’s liquid at room temperature it’s an oil Fatty acids Glycerol (Scientists are lazy: Fatty acids are often shown as wavy lines instead of drawing out all the atoms)

Fatty acids are long carbon chains (up to 20 or more carbons) with a carboxyl group at one end. If they have no double Bonds between carbons, they are called saturated fatty acids If they have one or more double bonds between carbons, they are called unsaturated fatty acids Always an even number of carbons

Glycerol is a 3-carbon molecule to which fatty acids bond by dehydration synthesis

Most common: Diglycerides (2 fatty acids bound to glycerol) Triglycerides (3 fatty acids

Diglycerides and triglycerides are energy-storage molecules. They can be found in most type of cells, but are primarily found in adipocytes, in which they form large fat droplets in the center. When needed for energy, fatty acids can be released from triglycerides and diglycerides and broken down to release energy. (we’ll discuss the details in BIOL 212)

Related to triglycerides are phospholipids, in which one fatty acid is replaced by a phosphate-containing group.

Phospholipids are major components of cellular membranes because the phosphate-containing group is highly hydrophilic while the fatty acids are highly hydrophobic (Scientists are lazy: Instead of drawing out all the atoms, phospholipids are often shown as a circle for the phosphate group with wavy lines for the two fatty acids) Phospholipids are also the surfactant molecules which allow the small air sacs (alveoli) of the lungs to stay open

Fats and oils are one type of “lipid” Another type of lipid: Steroids Do not contain glycerol or fatty acids Hormones from adrenal gland testes ovaries Cholesterol Vitamin D Bile Salts (help absorb fat) (other places)

Polymer: Monomers: Protein Amino acids Carbohydrate Monosaccharides Lipid Fatty acids & Glycerol Nucleic Acid Nucleotides

Each nucleotide has three parts:

There are five different base groups in nucleic acids Both DNA & RNA Adenine Cytosine Guanine DNA RNA Uracil Thymine

Ribonucleic acid (single chain of nucleotides)

Deoxyribonucleic acid (double chain of nucleotides)