Unit 1 SeminarLuis Lowe404-981-6570LLowe@kaplan.eduAIM 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