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In the late 1800s, Hans Christian Gram developed the gram staining procedure. Gram staining is a valuable diagnostic tool used in the clinical and research world. The gram stain is a method used to determine the identification of unknown bacteria. (BIO215, 2017)
According to, typically when you’re sick, you go to the doctors. If your doctor or you happen to think that you may have an infection, the doctor can order a culture to be performed, a gram stain or even both. If it happens to be that you do have a bacterial infection, your doctor can then have a gram stain done on the bacteria to see if the bacteria in your infection are gram negative bacteria or gram positive bacteria. Gram staining can be done on different specimens such as blood, tissue, stool, urine, and sputum. Determining whether the bacteria is gram negative or gram positive bacteria can play a huge role in what treatment your doctor may or may not recommended for you take to fight the infection off to kill the bacteria. What type of bacterial infection you may have can also be determined through the gram staining process. Having a gram stain done can help your doctor decide if the bacteria is responsible for your symptoms and to see what type of bacteria is present. After determining if the bacteria present is gram negative or gram positive bacteria, the size, shape, and the quantity of the bacteria, can also provide more information about your infection you may have and be very helpful for you medical provider. (Healthline, 2016)
Gram negative bacteria are more resistance to antibiotics and can build resistance much sooner, while gram positive bacteria are more susceptible to antibiotics. Gram negative bacteria become more resistant to antibiotics because of the lipopolysaccharide layer in their outer membrane. Lipopolysaccharide has a portion of lipids that act as an endotoxin. (Diffen, 2018) Knowing what antibiotic to use when having an infection is very important when trying to overcome the bacterial infection to get better and not let the bacterial infection get out of hand.
According to, the six-gram positive genera of bacteria are known to cause disease in humans are Streptococcus, Staphylococcus, Corynebacterium, Listeria, Bacillus, and Clostridium. A few that fall under gram negative would be Pseudomonas aeruginosa, Neisseria gonorrhoeae, Chlamydia trachomatis, and Yersinia pestis. (Diffen, 2018)
There are a few steps you must follow to do a gram stain. According to BIO215 Lab Book, first the gram negative or gram positive cells are stained by a primary stain, crystal violet, for 30 seconds and then rinsed with water. Then, iodine is added to the smear for one minute and then rinsed. Iodine is a mordant the combines with crystal violet which forms an insoluble complex in gram positive cells. Both, gram negative and gram positive bacteria will appear purple as of now. Then you’ll drip decolorizer with alcohol to the smear for no more than 20 seconds and rinse. Gram positive still appears purple under the microscope because it’s cell wall retains the crystal violet, but the decolorizer removes the mordant complex in gram negative cells, letting them appear colorless. Then, safranin is added to the smear for a minute and then rinsed. Safranin is the counterstain that colors the gram negative cells pink. Safranin sticks to gram positive cells as well but their appearance isn’t changed because the crystal violet is more intense than the safranin. (BIO215, 2017)
Question 4: Oxidative vs substrate level phosphorylation
First, I’ll start off with a few differences between oxidative phosphorylation and substrate level phosphorylation from the website. Oxidative phosphorylation releases energy by chemical oxidation of nutrients that is used for the creation of ATP, Adenosine Triphosphate. In substrate level phosphorylation, transfers a phosphate group directly from the substrate, a phosphorylated compound, to ADP, Adenosine Diphosphate, to create more ATP to be used. In substrate level phosphorylation, a coupled reaction makes the energy during this process. In oxidative phosphorylation, the electron transport chain generates the energy that is need for this process to happen. (Difference Between, 2017) I will further explain the electron transport chain in detail later. During substrate level phosphorylation, the redox difference is very much smaller compared to in oxidative phosphorylation where there is a much bigger gap of redox potential that is generated to power this. Substrate level phosphorylation can happen with either anaerobic or aerobic conditions. (Difference Between, 2017) Aerobic means that oxygen is present or needed. Anaerobic is meaning when little or no oxygen is present or needed. (Anderson, D. G., et al., 2016) Substrates are partially oxidized during substrate level phosphorylation and in oxidative phosphorylation, electron donors are fully oxidized. Substrate level phosphorylation takes place in mitochondria and cytosol. Oxidative phosphorylation occurs in the inner membrane of mitochondria. Substrate level phosphorylation can be utilized in the Krebs cycle and glycolysis. Oxidative phosphorylation can only be seen during the electron transport chain. Unlike oxidative phosphorylation, substrate level phosphorylation is not interacting or communicated with electron transport chain or ATP synthase whereas oxidative phosphorylation is with both. (Difference Between, 2017) The enzyme ATP synthase uses the energy of the proton motive force to drive the synthesis of ATP. (Anderson, D. G., et al, 2016) In substrate level phosphorylation, nicotinamide adenine dinucleotide and oxygen isn’t used to form ATP. Oxidative phosphorylation uses nicotinamide adenine dinucleotide and oxygen to produce ATP. (Difference Between, 2017) In substrate level phosphorylation the net ATP production is four ATP and after oxidative phosphorylation the net ATP production is thirty four ATP. (PEDIAA, 2017)
Now, what energizes oxidative phosphorylation? The electron transport chain is what energizes oxidative phosphorylation process. But where does all of this occur? According to Science Prof Online, the electron transport chain is obliqated to have a membrane to operate accordingly. In bacteria and archaea’s, prokaryotic cells, in the mesosomes of the cells plasma membrane is where the electron transport chain happens. In eukaryotic cells, such as plants, animals, and fungi, the electron transport chain occurs in the mitochondria. This is where eukaryotic power factories create ATP by breaking down all of the food. Plants make food into ATP with their mitochondria as well and have organelles called chloroplasts with an internal thylakoid membrane, where the electron transport chain uses sunlight to make ATP. (Science Prof Online, 2016)
The electron transport chain is so important because it creates ATP. ATP is a big form of energy. If we don’t have any energy, how can anything get done? We just wouldn’t be able to. According to, the transport chain is where the majority of the ATP is created. A whole whopping thirty-four ATP molecules are formed from the products of one molecule of glucose. This is the movement of electrons going from high energy to low energy is what makes the proton gradient happen. The only way for the electron transport chain to happen is if there is readily oxygen available. (DBriers, 2012)
Question 5: Oxygenic vs. Anoxygenic
First, I’ll start off with some differences between oxygenic photosynthesis and anoxygenic photosynthesis. According to, algae, plants and cyanobacteria photosynthesize by oxygenic photosynthesis. Oxygenic photosynthesis final electron acceptor is water. Anoxygenic photosynthesis is used by some bacteria. Anoxygenic photosynthesis does not produce any oxygen. Nonsulf bacteria, green sulfur bacteria, heliobacteria, purple bacteria, and acidobacteria photosynthesize by anoxygenic photosynthesis. In oxygenic photosynthesis, photosystems I and II are used, whereas only photosystem I is used in anoxygenic photosynthesis. Oxygenic photosynthesis uses water has the electron source and hydrogen, hydrogen sulfide or ferrous ions are used as the electron donor in anoxygenic photosynthesis. If not obvious enough in oxygenic photosynthesis, oxygen is produced during the light reaction. In anoxygenic photosynthesis, oxygen is not being produced during the light reaction like in oxygenic. In oxygenic photosynthesis, chlorophylls are used and in anoxygenic photosynthesis, bacteriochlorophylls or chlorophylls are used. NADPH is produced in oxygenic photosynthesis because ADP is the terminal electron acceptor. Anoxygenic photosynthesis doesn’t produce NADPH like oxygenic does because the electrons are reentered into the system. In oxygenic photosynthesis, ATP is produced by noncyclic photophosphorylation whereas cyclic photophosphorylation produces ATP in anoxygenic photosynthesis. Oxygenic photosynthesis equation is shown as 6CO2 + 6H2O ?Light C6H12O6 + 6O2. Anoxygenic photosynthesis is shown as 6CO2 + 12H2S + Light ? C6H12O6 + 12S + 6H2O. (PEDIAA, 2018)
According to our text book, in light reactions in cyanobacteria and photosynthetic eukaryotic cells, photosystem I and photosystem II work together as part of the light reactions. The energy that is absorbed by photosystem I and photosystem II raise the energy of electrons stripped from water to a high enough level that it can be used to generate a proton motive force and produce reducing power. This is why it is considered oxygenic photosynthesis because it does just that, it generates oxygen. (Anderson, D. G., et al., 2016) According to, “All living and breathing organisms inhale oxygen from the air to produce energy and exhale carbon dioxide into the atmosphere. Oxygenic photosynthesis replaces oxygen in the air with the assistance of energy from sunlight.” In our text book, the Tandem Photosystems of Cyanobacteria and Chloroplasts, energy that is captured by antennae pigments excites a reaction center chlorophyll. This causes it to emit a high energy electron, which is passed to an electron transport chain. In cyclic photophosphorylation, electrons emitted by photosystem I are returned to that photosystem. In non-cyclic photophosphorylation, the electrons used to replenish photosystems I are donated by radiant energy, excited photosystem II. Then, photosystem II replenishes its own electrons by stripping them from water, in return, producing oxygen. (Anderson, D. G., et al., 2016) On, I found if there wasn’t oxygenic photosynthesis, eventually our atmospheric oxygen would be completely gone. After an oxygenic photosynthesis reaction, six carbon dioxide molecules come together with twelve molecules of water with the use of sunlight. The sunlight is required for this reaction to occur. Oxygenic photosynthesis reacts to form six oxygen molecules, one glucose molecule and six water molecules. (News, 2017)
According to Anderson, D. G. et al., anoxygenic photosynthetic bacteria have only a single photosystem. It cannot use water as an electron donor for reducing power. This is exactly why it is considered anoxygenic, it does not generate oxygen. Hydrogen gas, hydrogen sulfide, and organic compounds is what anoxygenic photosynthetic bacteria use as electron donors. (Anderson, D. G., et al., 2016) The way anoxygenic photosynthesis uses light energy resembles how plants use light energy as well. Anoxygenic photosynthesizing bacteria and plants are photoautotrophs because they use carbon dioxide to create energy. But aside from having that in common they do differ from how anoxygenic photosynthesis only uses the use of photosystem I for collecting energy from the sunlight and plants use both photosystems.(Study) According to our text book, there are two groups of anoxygenic photosynthetic bacteria, purple bacteria and green bacteria. The purple bacteria will use a photosystem that resembles photosystem II in oxygenic photosynthesis of cyanobacteria and eukaryotes to use ATP. They have to use the reverse electron transport because the photosystem odes increase the electrons to a high enough standard level to decrease NAD+. The reverse electron transport is what it sounds, it’s the electron transport chain ran in reverse by the use of ATP. Green bacteria use a photosystem close in relation to the photosystem I in oxygenic photosynthesis of cyanobacteria and eukaryotes. A reduction of NAD+ or generation of a proton motive force is caused from the electrons being released. (Anderson, D. G., et al., 2016)

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