Lab Report : The Gram Stain

The outer membrane in the cyanobacterium cell (Phormidium uncinatum) is the structure that makes the cell gram negative. On the other hand, the characteristic that makes the cell gram positive is the thick peptidoglycan layer.

The main idea of this experiment was to correctly identify the unknown bacteria, #3. Identification of unknown bacteria yields multiple benefits in many different areas in the research of microorganisms. In this experiment I performed many different test dealing with things such as the presence of enzymes, fermentation abilities and different chemical reactions. Observations made from the tests were then compared to a gram negative unknown chart in order to identify the bacteria. Based off of my results and the chart, I concluded the bacteria #3 was the bacteria Escherichia coli. E. coli is most commonly found in the intestines of warm blooded organisms. Most E. coli strands are non pathogenic however, there are strands

The Gram-positive cell wall is composed of peptidoglycans, a thick layer of protein-sugar complexes taking up 60-90% of their cell wall. Peptidoglycan is composed of two glucose derivatives, N-acetylmuramic acid and N-acetylglucosamine alternated and cross-linked by tetrapeptides that is composed of L-alanine, D-glutamine, L-lysine

Gram negative and gram positive bacteria differ from each other in many ways especially in the composition and size of their cell walls. Unlike Gram-positive bacteria, Gram-negative bacteria have a thin peptidoglycan layer surround by an outer membrane. This outer membrane contains many proteins one of them being lipopolysaccharides (LPS), which contributes to the bacteria’s negative charge. One part of this protein is a lipid, called Lipid A, which is considered an endotoxin because this lipid triggers an immune response stimulating fever

n.d.). Gram-negative bacteria have a cell wall made up of a thin layer of Peptidoglycan, which is covered with an outer membrane of Lipoprotein and Lipopolysaccharide, and a bipolar-staining coccobacillus is an oval shaped bacterial cell with two poles that is in between coccus and bacillus forms (Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. 2003.). It is also known as an obligate intracellular pathogen, meaning that it is a microorganism causing disease that is only able to survive in a particular environment or by taking on a particular role. This particular pathogen can only survive when concentrated in blood (Sutyak, Katia. n.d.). This fermentative, motile organism produces a thick antiphagocytic, or a cell that prevents the action of phagocytes, slime layer as it moves (Sutyak, Katia. n.d.). Phagocytes are cells that absorb detrimental microorganisms, unwanted material, and other foreign bodies within the bloodstream and tissues (The American Heritage® Dictionary of the English Language, Fourth Edition, Mifflin, Houghton.

It was a pleasure of mine to work on this report and would appreciate feedback. If you have any questions, you can reach me at 469-449-8853 or email me at b.mathew23@Gmail.com

This report was written entirely by me and has not received any previous academic credit at this or any other institution.

Gram Staining             Gram Staining is a procedure used to distinguish between gram-positive and gram-negative bacteria, where one of the main differences is the cell wall. Gram-positive bacteria contain multiple layers of peptidoglycans and gram-negative lacks of peptidoglycans in the cell wall. Overall, is a short procedure that consists of the following steps: first apply the primary stain (crystal violet), second apply the mordant (Gram’s iodine), third apply decolorizing agent (ethanol or ethanol acetone) and finally apply secondary stain (safranin). Another purpose of gram staining is to determine the bacteria’s morphology.

One of the most prominent differences is the amount of peptidoglycan in the cell walls of both cells. In gram positive cells, PTG is abundant and numerous, creating a thick layer, and in gram negative cells, PTG is usually in small amounts or completely absent. In gram negative cells, teichoic acids are absent and present in gram positive cells, providing rigidity to the cell wall. Gram positive cells have no outer lipopolysaccharide membrane whereas the gram negative cells do giving the cells protection against certain chemicals as well as structural integrity. Conclusively, the flagella in both gram positive and gram negative cells have a different amount of rings in the basal body that anchor the flagellum to the cell. In gram positive cells, there are two basal bodies and four basal bodies in the gram negative

How does the Ph of colas affect teeth staining? It’s important to know this because it relates to something common in our daily lives, our teeth. Also, knowing there are people that drink cola on the regular, it is best for them to be aware of how of much it harms their teeth. Understanding how the ph of colas affect teeth staining will help determine what colas should be avoided to keep teeth in best conditions. For this experiment, the hypothesis is the following; the lower the ph of the cola is, the more staining will be present on the tooth representative because the acids that make the ph of the cola lower, also weaken the protective layer of teeth.

The cell structure of salmonella gastroenteritis consists of: gram-negative bacilli, the cell envelope of salmonellae contains a complex lipopolysaccharide structure. The lipopolysaccharide can work as an endotoxin, and may be important in determining virulence of the organisms. The endotoxin complex consists of several components, an outer O-polysaccharide coat, a middle portion, and an inner lipid A coat. This structure is important for various reasons. Firstly, the environment of the sugar units in the outer O-polysaccharide chains is in charge of O antigen specificity; this may also help determine the virulence factor. Salmonellae missing the complete sequence of O-sugar repeat units are called rough because of the bumpy appearance of the colonies; they tend to be less virulent than the smooth strains which contain a complete complement of O-sugar units. Secondly, antibodies that are against the middle portion will protect against infection by a wide range of Gram-negative bacteria; this may moderate their lethal effects. Lastly, the endotoxin factor of the cell wall has an important role in the pathogenesis of several clinical phenomena’s of Gram-negative

Gram negative bacteria have two layers of peptidoglycan which make import and export molecules (protein, enzymes and toxins) through them difficult, for that reason they have special mechanizes which known secretion systems .There are six type of these secretions type I, type II, type III, type IV, type V and type VI .The latter is the resent type has been discovered.

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