Macromolecules Essentially the functions of life Jocie Cormier &Maryann Kotoch

1. MacromoleculesEssentially the functions of lifeJocie Cormier &Maryann Kotoch

2. Why are they important?!? • Macromolecules inhabit a cell and provide it with important functions for life! • “How?” you ask? • Well… • They provide structural support • They are a source of stored fuel • They have the ability to store and retrieve genetic information • And ability to speed biochemical reactions.

3. Four Major Types: • Proteins • Carbohydrates • Nucleic acids • Lipids • In terms of overall structure, all macromolecules except lipids are called polymers!!

4. Why are Lipids different? • Lipids are insoluble molecules! (meaning they do not dissolve in water) • This group of molecules includes fats and oils, waxes, phospholipids, steroids (like cholesterol), and some other related compounds. • All Lipids are hydrophobic (“water-hating”) and thus much harder to break down for energy, that’s the one property they have in common. • Fats and oils are triglycerides, composed of 3 fatty acids covalently bonded to a glycerol molecule.

5. Types of Lipids Storage Lipids: Fatty acids, Triacylglycerols, and Sterols Structural Lipids: Complex Lipids in Membranes, Phospholipids, and Saccharolipids

6. Storage Lipids Fatty Acids- are the defining constituents of lipids and are in large part responsible for the distinctive physical and metabolic properties. • In the body these are released from triacylglycerols during fasting to provide a source of energy. • Fatty acids in diet are short and medium chain length are not usually esterified. Once within the body they are oxidized rapidly in tissues as a source of ‘fuel’. • Longer chain fatty acids are usually esterified first to triacylglycerols or structural lipids in tissues. Triacylglycerols-These form the primary storage form of long chain fatty acids for energy and structure formation of cells. • These are composed of glycerol and 3 fatty acids to form a triester. • Triglycerides are found in blood tests. • Complete hydrolysis of triacylglycerols yields three fatty acids and a glycerol molecule. • Polyunsaturated fatty acids are important as constituents of the phospholipids and form the membranes of the cells. • Most of the natural fats and oils of commerce consist of triacylglycerols

7. Saturated/Unsaturated fats: are commonly used in the context of nutrition. These terms refer to the structure of the hydrocarbon chains of the fatty acids. If there are no double bonds between carbon atoms composing a chain, then as many hydrogen atoms as possible are bonded to the carbon skeleton. Such a structure is said to be saturated with hydrogen. An unsaturated fatty acid has one or more double bonds, with one fewer hydrogen atom on each double-bonded carbon. Sterols-Cholesterol is a ubiquitous component of all animal tissues. • Most of it is present in the membranes. • It occurs in the free form and esterified to long chain fatty acids (cholesterol esters) in animal tissues, including the plasma lipoproteins. • Cholesterols are precursor of bile acids, vitamin D and steroidal hormones.

8. Structural Lipids Complex Lipids in Membranes: • Cellular membranes control the transport of materials, including signaling molecules and can change in form to enable budding, fission and fusion. • The cell membranes have a water loving or hydrophilic constituent and a hydrophobic or water repelling constituent making them amphiphilic. Phospholipids: • There are two classes of phospholipids. • The first are the glycerophospholipids, which are themselves subdivided into two groups. • Phosphatides, is molecules composed of glycerol substituted with two fatty acid esters. • Three alcohols that form phosphatides are choline, ethanolamine, and serine. • Sphingolipids, have a long-chain or sphingoid base, such as sphingosine, to which a fatty acid is linked by an amide bond. • Sphingomyelin is by far the most abundant sphingolipid in animal tissues. Sphingomyelin is an important building block of membranes.

9. Saccharolipids: • These are molecules wherein fatty acids are linked directly to a sugar backbone. • These form part of the cell membrane bilayer as well. In the saccharolipids, a monosaccharide substitutes for the glycerol backbone present in glycerolipids and glycerophospholipids.

10. The structure of a Phospholipid-A phospholipid has a hydrophilic (polar) head and two hydrophobic (nonpolar) tails. The kink in one of its tails is due to a cis double bond. Cholesterol, a steroid- Attach in four interconnected rings. Saturated fatty acid- At room temperature, the molecules of saturated fat, are packed closely together, forming a solid. (ex. Butter) Unsaturated fatty acid- At room temperature, the molecules of an unsaturated fat cannot pack together closely enough to solidify because of the kinks in some of their fatty acid hydrocarbon chains. (ex. Oils)

11. VIDEO TIME! • http://www.youtube.com/watch?v=7k2KAfRsZ4Q

12. Citations Campbell, Neil A., Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A Wasserman, Peter V. Minorsky, and Robert B. Jackson. Campbell Biology. San Francisco, CA: Benjamin Cummings, 2011. Print. "Types of Lipids." Types of Lipids. N.p., n.d. Web. 10 Sept. 2013. All images found using “google image search” "Google." Google. N.p., n.d. Web. 10 Sept. 2013.