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Unit 1 SeminarLuis [email protected] account: Luis.Lowe
SC246: Microbiology
Fundamentals of Microbiology SC 246
About MeMS Biology and Maters in Public HealthWork at Centers for Disease Control in
Atlanta, GeorgiaBioterrorism agentsMolecular Assays, epidemiology, etc…
Instructor for Microbiology, General Biology and Anatomy and Physiology
Science GeekInto fitness and nutritionQuestions
Agenda tonightCourse overview
Syllabus, Grading, How to, Answers for those new to onlineEmail address should be KaplanIMPORTANT NUMBER 877-623-0272
Eukaryotic vs. ProkaryoticWhat in the world does that mean?
BacteriaWallsGram stains
Science center tour at 8:45Questions
Prokaryotic –Eukaryotic CellsComparing Prokaryotic and
Eukaryotic CellsProkaryote 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?
Prokaryote EukaryoteOne (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 stain2. Stain is decolorized with 95% ethanol3. Counterstain: Safranin4. Water rinse
Gram + retain CV and remain purpleGram – 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 acidsIn 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 linkhttp://khe2.adobeconnect.com/kusc_tour/ Afterwards, you are free to goEmail with any questions you may have.
Questions??
References
Tortora, G., Funke, B., & Case, C. (2007). Microbiology: An Introduction (8th ed.). San Francisco, CA: Pearson.
PeptidoglycanPolymer 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