BIOL 111 Lecture 1 - Carbohydrates & Lipids PDF

Biology for Health Sciences BIOL 111  General Information Course title: Biology for Health Sciences Course code: BIOL 111 Textbook: Biology A Global Approach 11th edition by Campbell, Reece, et, all. Credit hours: 2 hours (1-hou...

Biology for Health Sciences BIOL 111  General Information Course title: Biology for Health Sciences Course code: BIOL 111 Textbook: Biology A Global Approach 11th edition by Campbell, Reece, et, all. Credit hours: 2 hours (1-hour lecture and 1-hour lab) Course duration: 10 weeks  BIOL 111 Lecture 1: Macromolecules of the cell I & II (Carbohydrates & Lipds) Learning Objectives At the end of this lecture, students should be able to: Distinguish between monosaccharides, disaccharides and polysaccharides Distinguish between saturated and unsaturated fats Describe phospholipids and steroid Overview: The Molecules of Life All living things are made up of four classes of large biological molecules : carbohydrates, lipids, proteins, and nucleic acids Macromolecules are large molecules (polymers) composed of thousands of covalently connected (monomers). Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 5.1: Macromolecules are polymers, built from monomers Three of the four classes of life’s large organic molecules are polymers: – Carbohydrates/ polysaccharides – Proteins – Nucleic acids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Synthesis and Breakdown of Polymers A condensation reaction or more specifically a dehydration reaction occurs when two monomers bond together through the loss of a water molecule Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Figure 5.2(a) Dehydration reaction: synthesizing a polymer 1 2 3 Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond. H2O 1 2 3 4 Longer polymer (b) Hydrolysis: breaking down a polymer 1 2 3 4 Hydrolysis adds a water H2O molecule, breaking a bond. 1 2 3 H Concept 5.2: Carbohydrates serve as fuel and building material Carbohydrates include sugars and the polymers of sugars The simplest carbohydrates are monosaccharides, or single sugars Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Monosaccharides/Sugars Monosaccharides have molecular formulas that are usually multiples of CH2O Glucose (C6H12O6) is the most common monosaccharide Monosaccharides are classified by – The location of the carbonyl group (as aldose or ketose) – The number of carbons in the carbon skeleton Monosaccharides serve as a major fuel for cells and as raw material for building molecules Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-3: Classification Trioses (C3H6O3) Pentoses (C5H10O5) Hexoses (C6H12O6) Aldoses Glyceraldehyde Ribose Glucose Galactose Ketoses Dihydroxyacetone Ribulose Fructose  Disaccharides A disaccharide is formed when a dehydration reaction joins only two monosaccharides This covalent bond is called a glycosidic linkage / bond Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Figure 5.5 Examples of Disaccharide Synthesis a) Dehydration reaction in the synthesis of maltose b) Dehydration reaction in the synthesis of sucrose  Disaccharides Clinical relevance Lactose intolerance Inability to breakdown lactose (glucose + galactose) in dairy products due to lactase deficiency Clinical symptoms: abdominal pain, diarrhea, gas and bloating Use dairy-free alternatives or Lactose-free milk Polysaccharides Polysaccharides :polymers of sugars, have storage and structural roles The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Storage Polysaccharides Starch, a storage polysaccharide of plants, consists entirely of glucose monomers Plants store surplus starch as granules within chloroplasts and other plastids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Storage Polysaccharides Glycogen is a storage polysaccharide in animals (in liver and muscle cells) Liver Muscle Hydrolysis of glycogen in these cells releases glucose when the demand for sugar increases Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Figure 5.6a,b Structural Polysaccharides The polysaccharide cellulose is a major component of the tough wall of plant cells Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  BIOL 111 Lecture 2: Macromolecules of the cell II (Lipids) Carbohydrates Proteins Lipids Nucleic Acids Learning Objectives At the end of this lecture, students should be able to: Distinguish between saturated and unsaturated fats Describe phospholipids and steroid Concept 5.3: Lipids are a diverse group of hydrophobic molecules Lipids are the one class of large biological molecules that do not form polymers (not a real Macromolecule) Lipids are hydrophobic They don’t mix well with water! Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 5.3: Lipids are a diverse group of hydrophobic molecules Lipids are the one class of large biological molecules that do not form polymers (not a real Macromolecule) Lipids are hydrophobic because they consist mostly of – hydrocarbons, which form nonpolar covalent bonds Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 5.3: Lipids are a diverse group of hydrophobic molecules The most biologically important lipids are Fats Phospholipids Steroids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  1- Fats Fats are constructed from two types of smaller molecules: I- glycerol II- fatty acids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  1- Fats Glycerol: is a three-carbon alcohol with a hydroxyl group attached to each carbon A fatty acid consists of a carboxyl group attached to a long carbon skeleton (hydrocarbon) Glycerol Fatty acid Carbon skeleton Carboxyl group (hydrocarbon) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-11 Fatty acid (palmitic acid) Glycerol (a) Dehydration reaction in the synthesis of a fat Ester linkage (b) Fat molecule (triacylglycerol)  Fats separate from water because water molecules hydrogen-bond to each other and exclude the fats In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride The fatty acids in a fat can be all the same or of two or three different kinds  Fatty acids vary in length (number of carbons) and in the number and locations of double bonds Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds Unsaturated fatty acids have one or more double bonds Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Fats made from saturated fatty acids are called saturated fats, and are solid at room temperature Most animal fats are saturated Fats made from unsaturated fatty acids are called unsaturated fats or oils, and are liquid at room temperature Plant fats and fish fats are usually unsaturated Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Figure 5.10 Saturated and Unsaturated Fats and Fatty Acids a) Saturated fat b) Unsaturated fat  A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits Hydrogenation is the process of converting unsaturated fats to saturated fats by adding hydrogen Hydrogenating vegetable oils also creates unsaturated fats with trans double bonds These trans fats may contribute more than saturated fats to cardiovascular disease © 2018 Pearson Education Ltd.  The major function of fats is energy storage Humans and other mammals store their long- term food reserves in adipose cells Adipose tissue also cushions vital organs and insulates the body © 2018 Pearson Education Ltd. Phospholipids In a phospholipid, two fatty acids and a phosphate group are attached to glycerol The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Figure 5.11 The Structure of a Phospholipid  When phospholipids are added to water, they self-assemble into a bilayer, with the hydrophobic tails pointing toward the interior The structure of phospholipids results in a bilayer arrangement found in cell membranes Phospholipids are the major component of all cell membranes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-14 Hydrophilic WATER head Hydrophobic tail WATER Video: Phospholipids  Steroids Steroids are lipids characterized by a carbon skeleton consisting of four fused rings Cholesterol, a type of steroid, is a component in animal cell membranes and a precursor from which other steroids are synthesized A high level of cholesterol in the blood may contribute to cardiovascular disease © 2018 Pearson Education Ltd. Fig. 5-15 Cholesterol Q: What makes lipids/fats hydrophobic? A) their long carbon skeleton B) the carboxyl group at one end of the molecule C) the glycerol moiety D) presence of relatively nonpolar C—H bonds