MCB100 Introductory Microbiology September 14, 2018

1. MCB100 Introductory Microbiology September 14, 2018 Lipids and Polysaccharides

2. MCB100 Exam 1 Fall 2018 Friday, September 28, 2018 2:00 – 2:50 pm Covers: chapters 1, 2, 4, 3 & 6 (Chapter 5 is not on exam 1!) Place: If your last name starts with A – M: please take the exam in room 2079 NHB If your last name starts with N – Z: please take the exam in room 100 Noyes Lab Review Session: 7:00 – 7:50 pm, Wednesday, Sept. 26 Place: Room 161 Noyes Lab

3. MCB100 Exam 1 Fall 2018 Practice Exam 1 has been updated. To find the link to the practice exam, go to:www.life.illinois.edu/mcb/100 - Click on: “Exam Information” - Scroll down to find the link to the practice exam. (It downloads as a MS Word Document.)

4. Proteins – polymers of amino acids held together by peptide bonds Lipids – amphipathic molecules that form the matrix of cell membranes – fatty acids and glycerol components are held together by ester bonds Polysaccharides (also known as complex carbohydrates) – polymers of sugars held together by glycosidic bonds Nucleic Acids – polymers of nucleotides held together by phosphodiester bonds

5. Fatty acids and Lipids hydrophilic end hydrophobic end

6. (Top) Two Dimensional Diagram of a Segment of a Cell Membrane (Lipid Bilayer Only) (Bottom) Three Dimensional Diagram of a Segment of a Cell Membrane (Lipid Bilayer with embedded proteins)

7. Fats are long-term energy storage molecules that are more hydrophobic than phospholipids.

8. Sterols are lipids that are found in the membranes of eukaryotic cells. Cholesterol is found in animal cell membranes. Ergosterol is found in fungal cell membranes. Phytosterol is found in plant cell membranes. Bacteria generally don’t have sterols in the membranes, except Mycoplasma and Ureoplasma have ergosterol. CholesterolErgosterolA Phytosterol (Sitosterol)

9. What Good Are Lipids? • Which one of the following is NOT roles of lipids in living organisms? • A. the materials of the matrix of a cell membrane • B. starting material for the synthesis of steroid hormones • C. long term storage of amino acids that can be used later to make nucleotides • D. long term storage of hydrocarbon chains that can be broken down to produce energy • in mammals, fats can act as insulation to help retain heat

10. Proteins – polymers of amino acids held together by peptide bonds Lipids – amphipathic molecules that form the matrix of cell membranes – fatty acids and glycerol components are held together by ester bonds Polysaccharides (also known as complex carbohydrates) – polymers of sugars held together by glycosidic bonds Nucleic Acids – polymers of nucleotides held together by phosphodiester bonds

11. Sugars and Polysaccharides Simple sugars have the general formula (CH2O)n. That is: a certain number of carbon atoms with an equal number of water molecules worth of hydrogen and oxygen. Hence sugars are called carbohydrates. Glucose (or dextrose) is an example of a small sugar, or monosaccharide with the formula C6H12O6. Polysaccharides such as starch and cellulose are formed by linking together dozens or even hundreds of simple sugar units.

13. Sugars have many polar groups: hydroxyls & carbonyls. This makes sugars very soluble in water. Sugars can be broken down (oxidized) to yield energy. Sugars can be joined to each other by glycosidic bonds. A disaccharide is made by joining two simple sugars. A trisaccharide is made by joining three simple sugars. Polysaccharides are made by joining manysugars. Polysaccharides can be sugar storage molecules. (starch) Polysaccharides are important components of cell walls. Polysaccharides can be slimy or sticky substances.

14. Sugars can be linked by glycosidic bonds. The suffix used in the name of a sugar is: -ose.

15. A modified sugar has some change from the standard (CH2O)n formula. Examples: glucosamine has an amino group on carbon-2, N-acetylglucosamine has an acetic acid (ethanoic acid) attached to that amine, N-acetylmuramic acid is like n-acetyl- glucosamine with an additional group attached to carbon-3. Chitin, the cell wall material in fungi, is a polymer of N-acetyl- glucosamine. Bacterial cell walls contain N-acetylmuramic acid.

16. Starch

17. Polysaccharides Cellulose a component of plant cell walls, a glucose polymer held together by beta-1,4-linkages Chitin a component of the exoskeleton of insects and other arthropodsChondroitin a component of cartilage

18. Which one of the following statements about sugars and polysaccharides is FALSE? A. Sugars are typically very hydrophillic. B. Sugars can be broken down to yield energy. C. Polysaccharides never have branching chains. D. A sugar molecule with 5 carbon atoms is called a pentose. E. Polysaccharides are important components of bacterial and fungal and plant cell walls.

19. Glycoproteinsglyco- : pertaining to sugar A glycoprotein is a protein with sugar groups attached.

21. Glycolipids One or more sugar groups attached to fatty acid chains.

22. Lipopolysaccharide LPS bacterial endotoxin O - antigen LPS is a complex glycolipid found on the outer surface of the outer membrane of Gram-negative bacteria.