Ch 9 Cellular Respiration and Fermentation
2.)Explain how ATP is recycled in cells.
-ATP can be restored by adding a phosphate group back to ADP (takes energy: recompressing spring). (Food) Cellular respiration harvests sugars from other molecules makes energy and is put to work by regenerating a cell's supply of ATP. (Energy is given off because it comes from the bond)
24.)Consider the NADH in glycolysis. What is it's final electron acceptor in Fermentation?
A derivative of pyruvate, such as acetaldehyde during alcohol fermentation, or pyruvate itself during lactic acid fermentation.
15.)Describe the process of chemiosmosis. (ATP synthase)
ATP synthase is the enzyme that makes ATP by chemiosmosis. It allows protons to pass through the membrane using the kinetic energy to phosphorylate ADP, making ATP
18.)Compare the fate of pyruvate in alcohol fermentation and lactic acid fermentation.
Alcohol Fermentation Pyruvate is reduced to ethanol in two steps:Pyruvate loses carbon dioxide and is converted to the two-carbon compound acetaldehyde.NADH is oxidized to NAD+ and acetaldehyde is reduced to ethanol.Many bacteria and yeast carry out alcohol fermentation under anaerobic conditions. Lactic Acid Fermentation Pyruvate is reduced to lactate.NADH is oxidized to NAD+.Commercially important products of lactic acid fermentation include cheese and yogurt.When oxygen is scarce, human muscle cells switch from aerobic respiration to lactic acid fermentation. Lactate accumulates, but it is gradually carried to the liver where it is converted back to pyruvate when oxygen becomes available.
8.)Describe how the carbon skeleton of glucose changes as it proceeds through Glycolysis.
In glycolysis, the skeleton will change in two ways. The ring must be opened, and then the glucose will be cleaved into 2 3-carbon molecules known as glyceraldehyde. These are straight chained.
14.)Explain how the exergonic "slide" of electrons down the electron transport chainis coupled to the endergonic production of ATP by chemiosmosis.
As electrons pass or slide down the electron transport chain energy is released. This is an exergonic reaction because energy is being released as electrons pass from carrier to carrier in the ETC. This energy is used by ATP synthase to create ATP. This is an endergonic reactions because it needs energy to take place. Energy is needed to produce ATP.Chemiosmosis involves the pumping of protons through specific passageways in the membranes of the mitochondria from the inner to the outer space. This creates the H+ proton gradient. This influences the H+ to diffuse across the gradient, thus providing energy as the proton is passed down. A hydrogen gradient awaits on either side of the inner mitochondrial membrane and as the H+ are moved through the ETC, energy is released, thus the exergonic reaction. Then when this energy is consumed by the ATP synthase, that would be the endergonic reaction.
5.)Explain why organic molecules that have an abundance of hydrogen are excellent cellular fuels.
Because their bonds are a source of "hilltop" electrons, whose energy is released when they are transferred to oxygen.
19.)Compare the processes of fermentation and cellular respiration.
Cellular respiration is more efficient because it can produce up to 32 ATP while fermentation can produce about 2 ATP
17.)Explain why fermentation is necessary.
Cellular respiration process as whole is aerobic (requires oxygen). While glycolysis and fermentation are anaerobic process (does not require oxygen). Especially in our muscle cell, enough oxygen is not always present for contraction, so they used glycolysis followed by lactic acid fermentation to generate ATP. It is used as immediate source of energy until blood can transport for energy from liver or other places.
13.)Describe the point (in all the steps of cell respiration) at which glucose is completely oxidized during cellular respiration.
Glucose is completely oxidized after chemiosmosis because that's when the final products of Glycolysis and The Citric Acid Cycle are used creating the final 36 to 38 ATP molecules. The final products that are used are NADH and FADH2 which are needed in the electron transport chain and ultimately Chemiosmosis.
20.)Describe how food molecules other than glucose can be oxidized to make ATP.
Each NADH and FADH2 molecule formed represents stored energy... contain high energy electrons from food molecules which are carried to an electron transport chain; Plants manufacture their own food by photosynthesis using energy from sunlight. Cells harvest the chemical energy stored in organic molecules and use it to regenerate ATP, the molecule that drives most cellular work. ADP + P + energy ATP
4.)Explain how redox reactions are involved in energy exchanges.
Electrons are transferred from one atom to another, or move to a lower energy orbital on the covalent bond of an atom.
21.)Explain how glycolysis and the Krebs cycle can contribute to anabolic pathways.
Glycolysis and the citric acid cycle contribute by making ATP, they also generate electrons for the Electron Transport Chain (ETC). The ETC then uses those electrons to make a proton gradient in the mitochondria which in turn powers the enzyme ATP-synthase to make a whole bunch of ATP.
16.)Summarize the net ATP yield from the oxidation of a glucose molecule by constructing an ATP ledger that includes coenzyme production during the different stages of glycolysis and cellular respiration.
Glycolysis makes 2 ATP; Krebs Cycle makes 2 ATP; Electron Transport Chain makes approximately 30 ATP.
6.)Describe the role of NAD+ and the electron transport chain during respiration.
It is a coenzyme and an electron carrier. NAD+ is a good electron carrier bc it can cycle easily between oxidized (NAD) and reduced (NADH) states. As an electron acceptor, NAD+ functions as an oxidizing agent during respiration
1.)Describe the summary equation for cellular respiration (chemical equation for thedegradation of glucose).
Organic compounds+Oxygen => Carbon dioxide+Water+Energy. C6H12O6+6O2 =>
3.)Define oxidation and reduction.
Oxidation is loss of electrons. Reduction is gain of electrons.
22.)Explain how ATP production is controlled by the cell and what role the allosteric enzyme, phosphofructokinase, plays in the process.
Phosphofructokinase (PFK) is a glycolytic enzyme that catalyzes the irreversible transfer of a phosphate from ATP to fructose-6-phosphate:fructose-6-phosphate + ATP fructose-1,6-bisphosphate + ADP In part because of the irreversible nature of this step in glycolysis, PFK is the key regulatory enzyme for glycolysis. When ATP levels are high in the cell, the cell no longer needs metabolic energy production to occur. In this case, PFK's activity is inhibited by allosteric regulation by ATP itself, closing the valve on the flow of carbohydrates through glycolysis.
11.)Describe where pyruvate is oxidized to acetyl CoA, what molecules are produced,and how this process links glycolysis to the Krebs cycle.
Pyruvate is oxidized to Acetyl-CoA in the cytoplasm The molecules produced are 2 carbon dioxide molecules, 2 NADH molecules, and 2 Acetyl CoA's. The process converts pyruvate to Acetyl CoA because otherwise, it cannot be introduced to the Citric Acid Cycle.
7.)Describe the cellular regions where glycolysis, the Krebs cycle, and the electron transport chain occur.
The Krebs cycle takes place in the matrix of the mitochondria.Glycolysis occurs in the cytoplasm of the cell, with the products of glycolysis entering the mitochondria to continue cellular respiration.The electron transport chain occurs across the inner membrane of the mitochondria.
12.)Describe the form and fate of the carbons in the Krebs cycle. Note the role ofoxaloacetate in this cycle.
They remain in the cycle, occupying a different location in the molecules on their next turn, after another Acetyl group is added. The oxaloacetate regenerated at the end is made up of different carbon atoms each time around.
9.)Explain why ATP is required for the preparatory steps of glycolysis.
Two molecules of ATP are consumed as glucose is split into two three-carbon sugars (glyceraldehyde 3-phosphate).The conversion of these molecules to pyruvate produces two NADH and four ATP by substrate-level phosphorylation.
10.)Identify where sugar oxidation, substrate-level phosphorylation, and the reduction of NAD+ occur in glycolysis.
substrate-level phosphorylation - steps 7 & 10 reduction of NAD+ - step 6.
