1. If the reaction XA + Y XY + A has a ΔG of +7.3 kcal/mol, could this reaction be driven in the cell by coupling it to ATP hydrolysis? Why or why not? (10 pts)
The ΔG value for ATP hydrolysis is approximately -30 kcal/mol (Milo, R., & Phillips, R. (n.d.)). The reaction could be driven in the cell by coupling it using ATP hydrolysis because the ΔG value of the reaction would be about -22.7 kcal/mol (Ahern, K. (n.d.).). The products (XY+A) can be used as the reactants in another reaction.
2. Using two of the steps in glycolysis, explain how a favorable reaction is linked to an unfavorable reaction to allow the unfavorable reaction to occur. Be specific in your description. Include products and reactants, ΔG values, and whether
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Step 8 to 9 is also unfavorable because the delta G value is +0.4, but step 9 to 10 has a delta G value of -7.5. These reactions are able to take place because of coupling—the product of one unfavorable reaction is the reactant of a different favorable reaction. According to Le Chatelier's principle, since the product of the unfavorable reactions are always being used as the reactant of a favorable reaction, the unfavorable reaction will always take place because the removal of a product will result is a shift in equilibrium to make more product. The product of step 2, glucose 6-phosphate, is used in the next reaction as a reactant and favorably forms fructose 6-phosphate. Similarly, from steps 8 to 9, 2-phosphoglycerate is used as a recant to form phosphoenolpyruvate. Step 9 still results in a positive delta G, but step 10 (formation of pyruvate) has a delta G value of -7.5. the formation of ATP drives the unfavorable reaction in the forward …show more content…
3. Using a reaction from the citric acid cycle, please explain oxidation and reduction. Be specific in your description. Include products and reactants, which molecules are oxidized and reduced, and what the oxidizing and reducing agents are in reaction. Why must we speak of oxidation and reduction together? (10 points)
In the first step of the citric acid cycle, NAD+ is reduced to NADH. The oxidizing agent is NAD+ because it accepts electrons and NADH is the reducing agent because it is able to give up electrons. In the reverse reaction, NADH is oxidized to form NAD+, so NADH is still the reducing agent and NAD+ is the oxidizing agent. Oxidation and reduction must go together because, for example, when a substance loses electrons, there must be another substance that is able to accept those electrons.
Citation: Slides 6 and 25 from Week 6 lecture
gars. These are then split into two three-carbon sugar phosphates and then these are split into two pyruvate molecules. This results in four molecules of ATP being released. Therefore this process of respiration in cells makes more energy available for the cell to use by providing an initial two molecules of ATP.
3. Pyruvate is converted in two steps; firstly pyruvate releases CO₂ which is converted to acetaldehyde. Then secondly acetaldehyde is reduced by NADH to ethanol.
The citric acid cycle is an amphibolic pathway. It utilises both anabolic and catabolic reactions; the first reaction of the cycle, in which oxaloacetate (a four carbon compound) condenses with acetate (a two carbon compound) to form citrate (a six carbon compound) is typically anabolic. The production of the isomeric isocitrate is simply intramolecular rearrangement. The subsequent two reactions are typically catabolic, producing succinate (a four carbon compound), which is then oxidised, forming fumarate (a four carbon compound). Water addition produces malate and then oxidised for regeneration of oxaloacetate. Thus the cycle can be seen to exhibit both anabolic and catabolic processes to form its intermediates.
The [ES] complex can then undergo two different pathways; the complex can dissociate to [E] and [S], at a rate of k or it can shift equilibrium to the left with a rate constant of k2 to form [E] and product [P]1. In this model, the breakdown of the ES complex to yield P is the overall rate-limiting step. Three assumptions of a Michaelis-Menton plot are that a specific [ES] complex in rapid equilibrium between [E] and [S] is a necessary intermediate, the amount of substrate is more than the amount of enzyme so the [S] remains constant, and that this plot follows steady state assumptions. Steady state assumptions states that the intermediate stays the same concentration even if the starting materials and products are constantly changing.2 The rapid equilibrium between enzyme and substrate, and the enzyme-substrate complex yields a mathematical description regarded as the Michaelis-Menton
Metabolic pathways are a series of reactions catalysed by multiple enzymes. Feedback inhibition, where the end product of the pathway inhibits an earlier step, is an
That is when muscles switch from aerobic respiration to lactic acid fermentation. Lactic acid fermentation is the process by which muscle cells deal with pyruvate during anaerobic respiration. Lactic acid fermentation is similar to glycolysis minus a specific step called the citric acid cycle. In lactic acid fermentation, the pyruvic acid from glycolysis is reduced to lactic acid by NADH, which is oxidized to NAD+. Lactic acid fermentation allows glycolysis to continue by ensuring that NADH is returned to its oxidized state (NAD+). When glycolysis is complete, two pyruvate molecules are left. Normally, those pyruvates would be changed and would enter the mitochondrion. Once in the mitochondrion, aerobic respiration would break them down further, releasing more
... the reaction to shift to the right would be to remove products. A third way is to change the temperature. Since this is an endothermic reaction, +∆H, we can imagine that “heat” is a reactant. Thus, if we add heat, it will shift to the right. To be classified as a redox reaction, we need at least two elements to change oxidation states. The easiest way to look at a reaction and determine this is if you have an element by itself on one side of the reaction and it is in a compound on the other side. Most of the time, the oxidation number of each element in a compound is their common charge. The sum of oxidation numbers must equal the compounds overall charge. Elements in the natural state (by themselves) have an oxidation number of 0. The reducing agent is the species responsible for reducing the other chemical. Therefore, the reducing agent is oxidized itself.
In cellular respiration, glucose with ADP and Phosphate group will be converted to pyruvate and ATP through glycolysis. NAD+ plays a major role in glycolysis and will be converted
If cells are denied energy, they will die. The second law of thermal dynamics says energy is lost in the form of heat whenever energy changes form. ATP is stored in the c. Glucose produced by C02, water and ATP. Respiration may be said to be a controlled breakdown of glucose that produces ATP for cell activities to be carried out. The purpose of the lab was to show the effect of temperature on the rate of respiration.
In our Biology Lab we did a laboratory experiment on fermentation, alcohol fermentation to be exact. Alcohol fermentation is a type of fermentation that produces the alcohol ethanol and CO2. In the experiment, we estimated the rate of alcohol fermentation by measuring the rate of CO2 production. Both glycolysis and fermentation consist of a series of chemical reactions, each of which is catalyzed by a specific enzyme. Two of the tables substituted some of the solution glucose for two different types of solutions.
Jim Clark. (2007). The effect of changing conditions in enzyme catalysis. Retrieved on March 6, 2001, from http://www.chemguide.co.uk/organicprops/aminoacids/enzymes2.html
Blood glucose levels are the measurement of glucose in an individual’s blood. This is important because glucose is the body’s main source of fuel and the brains only source of fuel. Without energy from glucose the cells would die. Glucose homeostasis is primarily controlled in the liver, muscle, and fat where it stored as glycogen. The pancreas is also a significant organ that deals with glucose. The pancreas helps regulate blood glucose levels. Alpha-islet and beta-islet pancreatic cells measure blood glucose levels and they also regulate hormone release. Alpha cells produce glucagon and beta cells produce insulin. The body releases insulin in response to elevated blood glucose levels to allow the glucose inside of cells and
Although not shown in the fermentation reaction, numerous other end products are formed during the course of fermentation Simple Sugar → Ethyl Alcohol + Carbon Dioxide C6 H12 O6 → 2C H3 CH2 OH + 2CO2 The basic respiration reaction is shown below. The differences between an-aerobic fermentation and aerobic respiration can be seen in the end products. Under aerobic conditions, yeasts convert sugars to
This lab attempted to find the rate at which Carbon dioxide is produced when five different test solutions: glycine, sucrose, galactose, water, and glucose were separately mixed with a yeast solution to produce fermentation, a process cells undergo. Fermentation is a major way by which a living cell can obtain energy. By measuring the carbon dioxide released by the test solutions, it could be determined which food source allows a living cell to obtain energy. The focus of the research was to determine which test solution would release the Carbon Dioxide by-product the quickest, by the addition of the yeast solution. The best results came from galactose, which produced .170 ml/minute of carbon dioxide. Followed by glucose, this produced .014 ml/minute; finally, sucrose which produced .012ml/minute of Carbon Dioxide. The test solutions water and glycine did not release Carbon Dioxide because they were not a food source for yeast. The results suggest that sugars are very good energy sources for a cell where amino acid, Glycine, is not.
The molecule ATP (adenosine triphosphate) can function as a coenzyme. When a phosphate group is removed, turning ATP into ADP (adenosine diphosphate), energy is released. Since several chemical reactions require energy, cells can use ATP to give energy to a reaction to help in altering the substrate to product. The substrate can be temporarily phosphorylated, or have an added phosphate group. The phosphate group can then be removed and the product is formed partly through the addition and removal of a phosphate.