Biology 211 Anatomy & Physiology I Dr. Thompson Macromolecules of Importance to 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 Lipids Nucleic Acids

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

All of these monomers and polymers consist of chains or rings of covalently bonded carbon atoms, with other atoms (primarily hydrogen, oxygen, nitrogen, and phosphorus) attached. Therefore, these are defined as organic molecules. Example: Phospholipid Example: Fatty Acid

Rather than draw out these large organic 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 Carbohydrate Monosaccharides Lipid Fatty acids & Glycerol Nucleic Acid Nucleotides

Proteins form parts of cell membranes enzymes antibodies some hormones molecules which produce movement in muscle fibers in the extracellular matrix... many other molecules Some proteins exist alone, but many are combined with carbohydrates to form glycoproteins

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

Amino Group Carboxyl Group

The sequence of amino acids in a protein is called its primary structure Thus, the proteins Glycine - Alanine - Glutamine - Alanine - Serine and Alanine - Alanine - Glycine - Serine - Glutamine have different primary structures even though they contain the same 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

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 Lipid Fatty acids & Glycerol Nucleic Acid Nucleotides

Different monosaccharides have different structures, but all share the same basic formula: C n H 2n O n Most common monosaccharides: C 6 H 12 O 6 Also found: C 3 H 6 O 3 C 4 H 8 O 4 C 5 H 10 O 5

2 monosaccharides = disaccharide

3 monosaccharides = trisaccharide Many monosaccharides = polysaccharide (too many to count) Fuzzy terminology: Monosaccharides Disaccharides = sugars Sometimes: All monosaccharides disaccharides called "sugars" polysaccharides 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 which is further broken down within cells to release lots of energy. Waste products: Carbon dioxide Water (Scientists are lazy: Glucose & other monosaccharides are often shown as hexagons instead of drawing out all the atoms)

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

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

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

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)

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

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 bound to glycerol)

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 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 Phospholipids are also the surfactant molecules which allow the small air sacs (alveoli) of the lungs to stay open (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)

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:

Ribonucleic acid (single chain)

Deoxyribonucleic acid (double chain)

There are five different base groups in nucleic acids AdenineCytosineGuanine Thymine Uracil Both DNA & RNA DNARNA