2What do the terms Prokaryotic and Eukaryotic mean What do the terms Prokaryotic and Eukaryotic mean? What are some of the major differences between Prokaryotic and Eukaryotic cells?
3Prokaryotic Cells Comparing Prokaryotic and Eukaryotic Cells Prokaryote comes from the Greek words for prenucleus.Eukaryote comes from the Greek words for true nucleus.
4Prokaryote Eukaryote Paired chromosomes, in nuclear membrane One (usually) circular chromosome, not in a membraneNo membrane-enclosed organellesPeptidoglycan cell walls (usually)Binary fissionPaired chromosomes, in nuclear membraneOrganellesSimple cell walls (IF present)Mitosis
5From 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?
6What is the Gram stain, and why is it a fundamental part of identifying bacteria? What are the major differences between Gram negative and Gram positive cells?
7Gram stain The Gram stain was developed by Christian Gram in 1884 Primary stain of identification in microbiology labUsed to classify bacteria as either gram positive or gram negativeMost, but not all, bacteria can be stained using this method
8Gram Stain Mechanism Staining procedure: 1.Crystal violet and Gram’s iodine: Primary stain2. Stain is decolorized with 95% ethanol3. Counterstain: Safranin4. Water rinseGram + retain CV and remain purpleGram – retain safranin* Based on cell physiology
15Gram-Positive cell walls Thick layer of peptidoglycanFigure 4.13b
16Gram-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
18The 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?