Lec-6,7 Biological Macromolecules Lecture Notes PDF

BIO-103: Biological Macromolecules LECTURE: 06-07 1  Lecture Outline Introduction & basic terminologies Carbohydrate Protein Lipid Nucleic Acid 2  Introduction/ at a glance...

BIO-103: Biological Macromolecules LECTURE: 06-07 1  Lecture Outline Introduction & basic terminologies Carbohydrate Protein Lipid Nucleic Acid 2  Introduction/ at a glance Living Systems Carbon Inorganic Organic compoun And the containin compounds rest! ds g! Assembling Macromolecule into complex s form Carbohydrate s Lipids Building Blocks of living Proteins organism Nucleic Acids Terminologies/Definitions Macromolecule:  Small molecules assemble in different orientation to make large molecule or Macromolecules.  Example: Glucose molecules assemble to make cellulose (a carbohydrate). glucose glucose glucose glucose cellulose glucose glucose glucose glucose 4 Terminologies/Definitions Monomers are small molecules or building blocks which may be joined together in a repeating fashion to form more complex molecules called polymers. A polymer may be a natural or synthetic macromolecule comprised of repeating units of a smaller molecule (monomers). glucose glucose glucose glucose cellulose glucose glucose glucose glucose glucose Monomer Polymer 5 Terminologies/Definitions Polymerization is the linking together of monomers to form polymers. A condensation reaction occurs via the loss of a small molecule, usually from two different substances, resulting in the formation of a covalent bond. Need the Input of energy 6  Terminologies/Definitions Hydrolysis, which is the reverse of condensation, breaks apart large organic molecules into smaller ones. By breaking the bonds between monomers, Hydrolysis liberates the energy that polymers contained during condensation; thus, some of the energy required to polymerize is returned upon hydrolysis. Liberation of energy Try to link up with the context of Metabolism that we’ve learned earlier… 7  Terminologies/Definitions Carbohydr ates Glucose Building Blocks/monomers Proteins Macromole Amino acids cules Lipids Fatty acid and glycerol Nucleic Acids Nucleotide 8  CARBOHYDRATE Common symbol: (CH2O)n Most common is Glucose. In glucose, Carbon, Hydrogen and Oxygen makes a molecule of glucose in 1:2:1 ratio. Chemical formula: C6H12O6. or (CH2O)6 Structural materials, storing and transporting energy Three types: monosaccharides, oligosaccharides, and polysaccharides. 9  CARBOHYDRATE Two monosaccharide's will make disaccharide. Examples: Sucrose (glucose+fructose) (Table Sugar) Lactose (glucose+galactose) (Milk Sugar) Maltose (glucose+glucose) (Barley/germinating seeds) olysaccharides: Long chains of monosaccharide units bound together 10  Starch and Cellulose Chitin Glycogen Starch is Different Partly energy bond formed derived from storage than starch non-sugars molecule in Structural (nitrogen) plants component Composes Glycogen is in plants exoskeletons energy Cannot be of insects storage digested by molecule in animals animals. Starch and glycogen can be digested by animals. 12  Functions of Carbohydrates Providing energy and regulation Sparing the use of proteins for energy Preventing ketosis and breakdown of fatty acids and Biological recognition processes Flavor and Sweeteners Dietary fiber, which is also a form of carbohydrate, is essential for the elimination of waste materials and toxins from the body 13  PROTEINS Most diverse in both structure and function Proteins are the polymers of amino acids Thousands of different kinds of proteins are made from only twenty monomers, called amino acids. Monomer Polymer 14  Amino Acids: Building Block of Proteins Contains an amine group (NH3) (basic/positive) A carboxyl group (COOH) (acidic/negative) One or more atoms called an “R group” All three groups are attached to the same carbon atom Amino Acids: Building Block of Proteins  Amino acids are divided into two groups- Essential: must be supplied in the diet. Non-essential: not supplied in the diet.  Amino acids are bonded together by peptide bonds to form protein. 16  Peptide Bonds The bond that forms between two amino acids is called a peptide bond. 17  Levels of protein structure Primary structure: The linear arrangement of amino acids in a protein Secondary structure: Areas of folding or coiling within a protein. e.g. α-helices and β-pleated sheets Tertiary structure: Final three- dimensional structure of a protein, which results from a large number of non-covalent interactions between amino acids. Quaternary structure: Non-covalent interactions that bind multiple polypeptides into a single, larger protein. e.g. Hemoglobin 18 Levels of protein structure 19  Main functions of proteins Protein's main function is to build, maintain and repair all our body tissues Protein can also be used as energy source by body Biological functions of proteins Protein acts as storage material of food and energy. Many proteins are enzymes that catalyze biochemical reactions Proteins are molecular instrument through which genetic information is expressed. They act as antibodies to prevent disease. The milk proteins help the growth of infant mammals. For detail functions see the notes underneath… 20  Lipids Composed of Carbon, Hydrogen, and Oxygen Differ from carbohydrates: no specific ratio (C:H:O) Building blocks are fatty acids and glycerol. Energy storage molecules “stores the most energy” 2X of Carbohydrates Structurally heterogeneous, Not soluble in wate Are soluble in hydrophobic solvents. Examples: 1. Fats 2. Oils 3. Phospholipid 4. Waxes 5. Steroid hormones21 6.  Synthesis of triglycerides Glycerol Fatty acids Can be saturated/unsaturated Relate with the melting points and physical states…….. 22  Fats Fats are solid at ordinary temperatures. Generally, fats are produced by animals. In animals, fats are stored in adipose cells. Fats are also important as cushions for body organs and as an insulating layer beneath skin. Oils Oils are liquid at ordinary temperatures. Generally, oils are produced by plants. Some common vegetable oils are peanut, soybean, and corn oil. Waxes Both plants and animals produce waxes. The waxy coating on some plants leaves is an example of plant waxes. Beeswax is an example of a wax produced by an animal. FA in this context…. Recall the saturated and unsaturated 23  Phospholipids  Phospholipids are a variation on the triacylglycerol theme in which – One fatty acid is replaced with a phosphate group, which in turn is bound to additional functional groups.  Structurally and functionally, the important thing about phospholipids is that – These molecules are simultaneously hydrophobic (at one end, the fatty acid end) and hydrophilic (at the other end, the phosphate end). Amphiphile 24 Recall the cell membrane in this context… Here it goes…let’s think latera 25  Steroids All steroids possess a common ring structure. These ring structures vary by attached functional groups. Cholesterol is example of a steroid; cholesterol is a membrane component The common steroid structure is the basis of sterol hormones including the human sex hormones (the estrogens and the androgens, including testosterone). 26  Nutrition and Health Most of the lipid found in food is in the form of triacylglycerols, cholesterol and phospholipids A minimum amount of dietary fat is necessary to facilitate absorption of fat- soluble vitamins (A, D, E and K) and carotenoids Essential Fatty Acids Trans Fat 27  The fat guidelines Limit total fat intake to less than 25–35% of your total calories each day; Limit saturated fat intake to less than 7% of total daily calories; Limit trans fat intake to less than 1% of total daily calories; The remaining fat should come from sources of monounsaturated and polyunsaturated fats such as nuts, seeds, fish and vegetable oils; and Limit cholesterol intake to less than 300 mg per day, for most people 28  Nucleic Acids The chemical link between generations The source of genetic information in chromosomes Dictate amino-acid sequence in proteins Simple units called nucleotides, connected in long chains Nucleic acids are composed of long chains of nucleotides linked by dehydration 29  Nucleic Acids Two types: a. Deoxyribonucleic acid (DNA-double helix) b. Ribonucleic acid (RNA-single strand) Nucleotides have 3 parts: 1- phosphate group (P) 2- pentose sugar (5-carbon) 3- nitrogenous bases: adenine (A) thymine (T) DNA only uracil (U) RNA only cytosine (C) 30  Nucleic Acids The secondary structure is similar to the proteins The concentration of adenine equals that of thymine The concentration of guanine equals that of cytosine Why? 31 Cells Genes Chromosomes DNA 32  DNA RNA Structural Name: Deoxyribonucleic Acid Ribonucleic Acid Function: Medium of long-term Transfer the genetic storage and code needed for the transmission of genetic creation of proteins from information the nucleus to the ribosome. Without RNA, proteins could never be made. Structure: Typically a double- A single-stranded stranded molecule with molecule in most of its a long chain of biological roles and has nucleotides. a shorter chain of nucleotides. Bases/Sugars: Long polymer with a Shorter polymer with a deoxyribose and ribose and phosphate phosphate backbone backbone and four and four different bases: different bases: adenine, 33 adenine, guanine, guanine, cytosine, and Thank you. Any Questions? 34