Chapter 9 Review- Cellular Respiration

Front 1

Explain Redox reactions, give examples. explain the meaning of the terms oxidation, reduction, oxidizing agent, and reducing agent.

Back 1

redox reactions involve the transfer of electrons. In a redox reaction, if electrons are lost from one substance, then it is oxidation. reduction is when a substance in a reaction gains electrons. a reduction agent is the electron donor (gives up the electron) the oxidizing agent is the electron acceptor.
An example of a redox reaction is Na+ +Cl---------> Na+ + Cl-, the sodium loses an electron and becomes oxidized, and the chloride becomes reduced and gains an electron.

Front 2

how does aerobic glucose catabolism compare with processes like the combustion of methane or wood? How is it different

Back 2

just as in the combustion of methane, in respiration; the fuel (glucose ) is oxidized and oxygen is reduced. The electrons lose potential energy along the way and energy is released. oxidation of glucose transfers electrons to lower energy state, liberating the energy that becomes available for ATP Synthesis.

Front 3

write out an equation that summarizes the process of cellular respiration as the complete oxidation of glucose. Explain when in the process of cell respiration each reactant or product is consumed or produced, respectively.

Back 3

C6H12O6 + 6O2 ---> 6 CO2 + 6 H2O + Energy:

The O2 and H2O are reduced and the C6H12O6 and CO2 become oxidized. the water and oxygen gain electrons while the glucose and carbon dioxide lose electrons.

Front 4

Contrast ATP production by substrate level phosphorylation and by oxidative phosphorylation. For each mechanism, give specific REACTANTS from which ATP is made and the SOURCE OF ENERGY used to make it (different in each case). Last, indicate in which stages of cellular respiration ATP is produced by each mechanism.

Back 4

ATP production in oxidative phosphorylation is made from ADP +Pi, and is powered by redox reactions with in the ETC, the energy released in each step of the chain is stored in the mitochondrion . The energy source is electrons carried by NADH and FADH2. ATP is produced during chemiosmosis and ETC

In substrate level- phosphorylation, rather than ATP being made from ADP +Pi, an enzyme transfers a phosphate group from a substrate molecule to ADP, rather than adding an inorganic phosphate. The energy source here is electrons carried by NADH. Here, ATP is produced during glycolysis.

Front 5

In what aqueous compartment in the cell do glycolysis, pyruvate oxidation and the citric acid cycle occur? Name the initial reactants and end products for all 3 pathways. What is OXIDIZE and what is REDUCED during all 3 processes?

Back 5

In the cytosol; the initial reactant in glycolysis during energy investment is 1 glucose molecule and 2 ATP and the end products are 2 pyruvate, 2 NET ATP, 2 NADH. In pyruvate oxidation the reactants are 2 pyruvate + 2 NAD + 2 CoA, and the end products are 2 acetyl CoA, 2 NADH, 2 H and 2 Co2. citric acid cycle the end products are 2 ATP, 6 NADH, and 2 FADH's, initial reactants are 2 ATP, 2 NADH. In glycolysis, the NAD is being reduced and the G3P is oxidized; in Pyruvate oxidation, pyruvate is oxidized while NAD is reduced to NADH; in the citric acid cycle, acetyl CoA gets oxidized and NADH/FADH gets reduced.

Front 6

What are coenzymes. Explain how coenzyme NAD+ is chemically altered when it is reduced, and when it is re-oxidized (what exactly is added and what is removed) Where does this happen on the molecule?

Back 6

a coenzyme is an organic molecule that serves as a cofactor (e.g.- vitamins) NAD is chemically altered when it is reduced by virtue of it gaining 2 electrons thus turning it into NADH. This occurs on the nicotinamide group of the molecule.

Front 7

how many steps do the pathways of glycolysis, pyruvate oxidation and the citric acid cycle have? what distinguishes a cyclic pathway from a linear one?

Back 7

glycolysis has 10 steps, pyruvate oxidation has 3 steps, and citric acid cycle has 8 steps. glycolysis is a linear pathway that occurs in the cell's cytoplasm, where as citric acid cycle is a cyclic pathway that occurs in the mitochondrial matrix. Glycolysis is both anaerobic and aerobic, whereas citric acid cycle is limited strictly to aerobic respiration.

Front 8

In glycolysis, what is meant by "energy investing" and "energy harvesting" and what all is invested and harvested in which steps?

Back 8

energy investing mean that the process must use energy before it can produce ATP. in the energy investing phase, 2 ATP are used (step 1) and 2 more are used in step 3. Energy harvesting means that energy is being produced, not used. In this case the energy pay off is 2 ATP in step 7 and 2 ATP in step 10.

Front 9

How many Co2 molecules are produced from the complete oxidation of glucose? Where is each on produced?

Back 9

since glucose is a 6 carbon structure 6 Co2 are produced.

Front 10

list all the products of pyruvate oxidation. How many of each product is produced per glucose? In what way are the enzymes catalyzing pyruvate oxidation "localized" ?

Back 10

the products of pyruvate oxidation are, Co2, and NADH, ZERO ATP are produced. Per glucose, 2 Co2 and 2 NADH are produced. they are localized by feedback inhibition, if ATP production lags behind its use, ADP accumulates and activates the enzymes that speed up catabolism, but at the same time if ATP supply exceeds demand, then catabolism slows down as ATP molecules accumulate and bind to the same enzymes, inhibiting them.

Front 11

Why is the cycle Hans Krebs discovered called the citric acid cycle? List 3 molecules produced by the cycle that store valuable chemical energy. In which decade did Krebs work out the cycle? When did he receive the Nobel Prize in Physiology or Medicine?

Back 11

Because citric acid is the 6 carbon molecule that starts the Krebs cycle NADH, FADH, and GTP store valuable chemical energy. Krebs worked out the citric acid cycle in the 1930's, and won the Nobel Prize in 1953

Front 12

How many Co2 molecules are produced in ONE cycle of the citric acid cycle? How many cycles are required to complete the catabolism of a molecule of glucose?

Back 12

2 Co2 molecules are produced per 1 cycle of citric acid cycle, 2 cycles of the citric acid cycle must occur for the complete catabolism of glucose, thus giving a net yield of 4 Co2.

Front 13

What is the Electron Transport Chair, and in which specific membrane is it found? How does potential energy of an electron change as it moves down the chain? How do the electronegativities of the chain molecules differ along the chain? How are the chain molecules localized to facilitate their functioning?

Back 13

it is a collection of molecules embedded in the inner membrane of the mitochondrion in eukaryotic cells, the potential energy of the ETC loses potential energy ("bucket brigade") as each component of the chain becomes reduced when accepting electrons from its uphill neighbor which has a lower affinity(attraction) for electrons (is less electronegative)- it returns to its oxidized form as it passes electrons downhill to its more electronegative neighbor. The chain molecules are localized within the mitochondria, but the enzymes that control the ETC are assembled in a multienzyme complex that will facilitate a sequence of reactions.

Front 14

describe how the energy stored in reduced coenzymes is used to create a proton gradient (proton motive force) and ultimately store ATP by chemiosmosis?

Back 14

As electrons are transferred ( by electron carriers such as NADH and FADH2) and cause H+ ions to be taken up and released into the surrounding solution, in Euks, the electron carriers are spatially arranged in the inner mitochondrial membrane in a such a way that H+ is accepted from the mitochondrial matrix and deposited in the intermembrane space, the H+ gradient that results is Proton Motor Force.

Front 15

In which stages of cellular respiration is ATP made? In which stages is it consumed? In which stages are coenzymes reduced? In which stages are coenzymes oxidized?

Back 15

In glycolysis, during energy investment ATP is consumed, during energy harvesting, 2 ATP are produced, pyruvate oxidation never produces ATP, however, the citric acid cycle does produce 1 ATP and the ETC produces 32 ATP. NAD and FAD are oxidized in pyruvate oxidation , and NAD is reduced to NADH during citric acid.

Front 16

in the absence of O2, some cells can subsist on ATP made by fermentation. Which reactant of glycolysis must be recycled in order to keep glycolysis running? Describe two ways this may be done (2 types of fermentation)?

Back 16

Pyruvate must be recycled from glycolysis- there is lactic acid fermentation(Pyruvate reduced directly by NADH to form lactate as an end product) and alcohol fermentation (pyruvate converted to ethanol)

Front 17

Aside from glucose, what other metabolic fuels can be used to make ATP? Summarize how each fuel is hydrolyzed, then enters into one of the first 3 stages of cellular respiration?

Back 17

glucose is turned to glycogen in the liver, once glycogen is used, then adipose tissues are broken down through lipolysis which produces glycerol which enters cells to restore glycolysis, once lipids in adipose tissues are broken down, all that's left is proteins and amino acids, amino acids are converted to pyruvate and respiration is restored.

Front 18

Beyond providing energy as ATP, what do catabolic pathways provide to anabolic pathways that enables them to build biomolecules?

Back 18

catabolic pathways break down the energy source to use it in anabolism- this can happen by: humans can make about half of the 20 amino acids in proteins by modifying compounds siphoned away from the citric acid cycle.

Front 19

which step of which pathway does the enzyme phosphofructokinase catalyze? explain how cellular respiration is regulated through PFK, including all metabolites involved and the role of feedback inhibition. Is competitive or non-competitive inhibition involved.

Back 19

in step 3 of glycolysis, phosphofructokinase catalyzes, If ATP accumulates within the cell, PFK is inhibited thus slowing the process of respiration; as ATP is consumed, PFK becomes active again and respiration increases. PFK feedback is non-competitive as it binds allosterically.