Unit 1 Seminar Luis Lowe AIM account: Luis.Lowe SC246: Microbiology Fundamentals of Microbiology SC 246

About Me MS Biology and Maters in Public Health Work at Centers for Disease Control in Atlanta, Georgia Bioterrorism agents Molecular Assays, epidemiology, etc… Instructor for Microbiology, General Biology and Anatomy and Physiology Science Geek Into fitness and nutrition Questions

Agenda tonight Course overview Syllabus, Grading, How to, Answers for those new to online address should be Kaplan IMPORTANT NUMBER Eukaryotic vs. Prokaryotic What in the world does that mean? Bacteria Walls Gram stains Science center tour at 8:45 Questions

Prokaryotic –Eukaryotic Cells Comparing Prokaryotic and Eukaryotic Cells Prokaryote comes from the Greek words for prenucleus. Eukaryote comes from the Greek words for true nucleus. What do the terms Prokaryotic and Eukaryotic mean? What are some of the major differences between Prokaryotic and Eukaryotic cells?

ProkaryoteEukaryote One (usually) circular chromosome, not in a membrane No membrane-enclosed organelles Peptidoglycan cell walls (usually) Binary fission Paired chromosomes, in nuclear membrane Organelles Simple cell walls (IF present) Mitosis

Question to think about? From an evolutionary prospective, Prokaryotic cells are much less complex than Eukaryotic cells. It seems that we wouldn’t have much of a problem fighting them off, right? However, this is obviously not the case. Offer an explanation for this. WHY do you think we still get infections and illnesses?

Gram stain What is it? What is it used for? The Gram stain was developed by Christian Gram in 1884 Primary stain of identification in microbiology lab Used to classify bacteria as either gram positive or gram negative. What does that mean? Most, but not all, bacteria can be stained using this method Which one(s) can’t. Why does it stain differently? Why is it a fundamental part of identifying bacteria? What are the major differences between Gram negative and Gram positive cells?

Gram Stain Mechanism Staining procedure: 1.Crystal violet and Gram’s iodine: Primary stain 2. Stain is decolorized with 95% ethanol 3. Counterstain: Safranin 4. Water rinse Gram + retain CV and remain purple Gram – retain safranin * Based on cell physiology

Figure 4.13b, c

Differential Stains: Gram Stain Figure 3.11b

Gram + Streptococcus Pyogenes (What is strep pyogenes?) Other clinically relevant Gram +?

Gram-positive cell walls Thick peptidoglycan Teichoic acids In acid-fast cells, contains mycolic acid Gram Stain Anthrax

Gram - Spirillum volutans (harmless bacteria) Other clinically relevant Gram -?

Gram-Negative Outer Membrane Lipopolysaccharides, lipoproteins, phospholipids. Forms the periplasm between the outer membrane and the plasma membrane. Protection from phagocytes, complement, antibiotics. O polysaccharide antigen, e.g., E. coli O157:H7. Lipid A is an endotoxin. Porins (proteins) form channels through membrane

Something to think about? The medical and scientific communities use their knowledge of Prokaryotic cells to target infectious microbes and clear out infections. Given just what you have learned so far, how do you think they might go about this?

KU Science Center Tour Go to the following link Afterwards, you are free to go with any questions you may have.

Questions??

References Tortora, G., Funke, B., & Case, C. (2007). Microbiology: An Introduction (8th ed.). San Francisco, CA: Pearson.

Peptidoglycan Polymer of disaccharide N-acetylglucosamine (NAG) & N-acetylmuramic acid (NAM) Linked by polypeptides Figure 4.13a

Gram-Positive cell walls Thick layer of peptidoglycan Figure 4.13b

Gram-Negative Outer Membrane Figure 4.13c