Comparing Prokaryotic and Eukaryotic Cells
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Transcript Comparing Prokaryotic and Eukaryotic Cells
SC246: Microbiology
Fundamentals of Microbiology SC 246
Unit 1 Seminar
Luis Lowe
404-981-6570
[email protected]
AIM account: Luis.Lowe
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
Email address should be Kaplan
IMPORTANT NUMBER 877-623-0272
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?
Prokaryote
One (usually) circular
chromosome, not in a
membrane
No membrane-enclosed
organelles
Peptidoglycan cell walls
(usually)
Binary fission
Eukaryote
• 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
Other clinically relevant Gram +?
(What is strep pyogenes?)
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
http://khe2.adobeconnect.com/kusc_tour/
Afterwards, you are free to go
Email 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