Lecture 1 - Lipids and Sugars PDF

Welcome to the cell biology section of biol1010 Lecture 1 - N. González Chapter 5  Organs Tissues Levels of organization Cells Molecules Orga...

Welcome to the cell biology section of biol1010 Lecture 1 - N. González Chapter 5  Organs Tissues Levels of organization Cells Molecules Organelles A cell is the smallest unit that can live on its own and that makes up all living organisms and the tissues of the body. Biologists use microscopes to study cells Most cells are between 1 and 100 µm in diameter (yellow region of chart) and their components are even smaller, as are viruses. Light microscopes use visible light and magnifying lenses to allow us to see cells light Journey to the Microcosmos  Fluorescent light microscopes capture fluorescence (a form of glow). Green fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. The locations of specific molecules in the cell can be revealed by labelling the molecules with fluorescent molecules. Electron microscopes use beams of electrons Transmission electron microscopes Scanning electron microscopes A transmission electron microscope (TEM) is used to study the internal structure of thin sections of cells. A scanning electron microscope (SEM) is used to study the fine details of cell surfaces.  5 talk to each other 2 min 1. Identify the type of microscope 3 1 6 2 4 7 A guide to study using the lecture slides Very likely will be in the exam Some of these will be in the exam The illustrations help you understand  The Structure and Function of Large Biological Molecules Lipids and sugars Lecture 1 - N. González Chapter 5 Campbell Biology Lecture 1 and 2 are about macromolecules 1. Polysaccharides (sugars) 2. Lipids 3. Nucleic acids (DNA, RNA) 4. Proteins Most of a cell is water (70%). The remaining 30% contains varying proportions of structural and functional molecules. Large molecules are either lipids or polymers 1. Polysaccharides = polymers 2. Lipids = not true polymers but can be large molecules 3. Nucleic acids (DNA, RNA) = polymers 4. Proteins = polymers On the molecular scale, members of three of these classes— carbohydrates, proteins, and nucleic acids—are huge and are therefore called macromolecules Macromolecules are polymers, built from monomers polymers A polymer is a long molecule consisting of many similar or identical building blocks linked by covalent bonds In addition to forming polymers, some monomers also have other functions of their own monomers Polymers grow by dehydration reactions reaction. Polymers are disassembled to monomers by hydrolysis Hydrolysis is essentially the reverse of the dehydration reaction Hydrolysis means water breakage (from the Greek hydro, water, and lysis, break).  Polysaccharides serve as fuel and as building material sugars Monosaccharides generally have molecular formulas that are some multiple of the unit CH2O. Glucose (C6H12O6), In aqueous solutions, glucose molecules, as well as most other five- and six-carbon sugars, form rings Rings are the most stable form of these sugars. The carbons of the sugar are numbered 1 to 6, as shown. To form The glucose ring, carbon 1 (magenta) bonds to the oxygen (blue) attached to carbon 5. A disaccharide consists of two monosaccharides joined by a glycosidic linkage Polysaccharides are macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages. Both plants and animals store sugars in the form of storage polysaccharides Animals store glycogen Plants store starch, a mix of amylopectin and amylose Vertebrates store glycogen in liver and muscle cells. Hydrolysis of glycogen in these cells releases glucose when the demand for sugar increases Organisms build strong materials from structural polysaccharides Organisms build strong materials from structural polysaccharides Chitin is the carbohydrate used by arthropods to build their exoskeletons The differing glycosidic linkages in starch and cellulose give the two molecules distinct three-dimensional shapes.  discuss 5 min A dehydration reaction joins two glucose In the 1970s, a process was molecules to form maltose. The formula developed that for glucose is C6H12O6. What converts the glucose in corn is the formula for maltose? syrup to its sweeter isomer, fructose. High Fructose corn syrup, a common ingredient in soft drinks and processed food, is a mixture of glucose and fructose. What type of isomers are glucose and fructose? (See Figure 4.7). Lipids are a diverse group of hydrophobic molecule Lipids are grouped with each other because they share one important trait: They mix poorly, if at all, with water. Lipids are the components of cell membranes Lipids are fats, phospholipids, and steroids A fatty acid has a long carbon skeleton, usually 16 or 18 carbon atoms in length. The carbon at one end of the skeleton is part of a carboxyl group, the functional group that gives these molecules the name fatty acid. The rest of the skeleton consists of a hydrocarbon chain. A fat is constructed from two kinds of smaller molecules: glycerol and fatty acids Triacylglycerols are three fatty acid molecules are each joined to glycerol phospholipids are only two fatty acids attached to glycerol. The third hydroxyl group of glycerol is joined to a phosphate group The terms saturated fats and unsaturated fats refer to the structure of the hydrocarbon chains of the fatty acids. Hint = saturated with hydrogen A phospholipid has a hydrophilic (polar) head and two hydrophobic (nonpolar) tails. phospholipids are essential for cells because they are major constituents of cell membranes. Steroids are lipids characterized by a carbon skeleton consisting of four fused rings ← Cholesterol is the molecule from which other steroids, including the sex hormones, are synthesized. Estradiol and testosterone are sex hormones responsible for the contrasting features of male and female vertebrates → CONCEPT CHECK 1. Compare the structure of a fat (triglyceride) with that of a phospholipid. 2. Why are human sex hormones considered lipids? 3. WHAT IF? Suppose a membrane surrounded an oil droplet, as it does in the cells of plant seeds and in some animal cells. Describe and explain the form it might take.