Anatomy & Physiology I Macromolecules
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 Carbrohydrates Lipids Nucleic Acids
All of these macromolecules are polymers which consist of repeating smaller subunits called monomers Polymer: Protein Carbohydrate Lipid Nucleic Acid Monomers Amino Acids Monosaccharaides Fatty Acids 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
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 21 different amino acids, all of which have the same basic structure: Where "R" is different for each amino acid
Amino Group Carboxyl Group
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: Protein Monomers: Amino acids Carbohydrate Lipid Nucleic Acid Fatty acids & Glycerol Nucleotides
Different monosaccharides have different structures, but all share the same basic formula: 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 =
Functions of carbohydrates: 1) Storage of fuel for energy Amylose (starch) in plants Glycogen in animals Human cells can digest amylose but not synthesize it. They can both synthesize & digest glycogen
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)
Polymer: Protein Carbohydrate Monomers: Amino acids Monosaccharides Lipid Nucleic Acid Nucleotides
Lipids: Molecules which are hydrophobic and do not mix with water Two major types:
Fats & Oils: Monomer (basic repeating units) are bound to a 3-carbon molecule called triglyceride.
Fatty acids are long carbon chains (up to 20 or more) 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.
Glycerol is a 3-carbon molecule: to which fatty acids bond by dehydration synthesis
Most common: (2 fatty acids bound to glycerol) (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 and broken down to release energy to form ATP
Phospholipids are the major component of all cellular membranes Phospholipids are also the surfactant molecules which allow the small air sacs (alveoli) of the lungs to stay open
Other type of lipid: Steroids Do not contain glycerol or fatty acids Basic unit = sterol Cholesterol
Other steroids include Vitamin D Bile Salts (help absorb fat) Hormones from adrenal gland testes ovaries
Polymer: Protein Carbohydrate Lipid Monomers: Amino acids Monosaccharides Fatty acids & Glycerol Nucleic Acid
Each nucleotide has three parts:
Rribonucleic acid (single chain)
Deoxyribonucleic acid (double chain)
There are five different base groups in nucleic acids Both DNA & RNA A C G DNA RNA T U