Ch.07- KEY Cellular respiration & Ferment In Focus-1 PDF

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Name : Mr. Key

AP Biology: CH 7 7 Cellular Respiration and Fermentation Cellular Resp. Big Picture (Freeman)

1. The three key pathways of cellular respiration are: a. Glycolysis b. The citric acid cycle (Krebs Cycle) c. Oxidative phosphorylation at the ETC 2. Catabolic Pathways are pathways that break down organic molecules, releasing stored energy. 3. Organic molecules possess potential energy as a result of the arrangement of electrons in the bonds between their atoms. 4. Fermentation is the partial breakdown of sugars without O2 (anaerobic) 5. Aerobic respiration is the most efficient catabolic pathway. This occurs in the presence of O2 which makes this an aerobic process.

6. The term cellular respiration includes both aerobic and anaerobic processes. However, it originated as a synonym for aerobic respiration because of the relationship to respiration and the act of breathing oxygen. Therefore, cellular respiration is often used to describe the aerobic process. 7. The basic breakdown of sugar can be represented through the chemical equation: C6H1206 + 6 O2 6 CO2 + 6 H2O + NRG 8. ***This reaction is an Exergonic reaction. G is negative in this reaction which means: Energy is released and this reaction is spontaneous. 9. Draw a graph that shows this reaction (show reactants, products, activation NRG, G)

10. When cells break down glucose, the relocation of electrons releases energy stored in organic molecules, and this energy is used to synthesize ATP. Oxidation / Reduction Reactions (OIL RIG) 11. In a redox reaction, the loss of electrons from one substance is called oxidation, and the addition of electrons is called reduction. 12. The electron donor is called the reducing agent while the electron acceptor is called the oxidizing agent. 13. An electron loses potential energy when it shifts from a less electronegative atom toward a more electronegative atom (energy is released, -G) – remember that oxygen is VERY electronegative.

14.

In the process of cellular respiration Glucose is being oxidized while O2 is being reduced which allows Energy to be released.

15.

Why are organic molecules with many hydrogen atoms great sources for energy? These types of molecules are high in energy (hydrocarbons) because they are a source of “hilltop” (high energy) electrons (e-) with the potential to fall closer to O2.

16.

If electrons and H+ ions were transferred directly to Oxygen what would occur? This reaction would result in an uncontrolled release of energy. This release of energy would cause the cells of living organisms to immediately die.

17.

Therefore, the coenzyme, NAD+ (nicotinamide adenine dinucleotide) functions as an oxidizing agent. When this molecule, NAD+, is reduced it becomes NADH because of the addition of 2 electrons (2e-) and 1 Proton (H+).

18.

Enzymes called dehydrogenases remove a pair of hydrogen atoms (2 electrons and 2 protons) from the substrate, thereby oxidizing it.

19.

The above molecule is a great intermediate because very little energy is lost when electrons (e-) are transferred from food to NAD+.

20.

Electrons do not move directly from sugar to oxygen to harness energy to make ATP. The primary electron acceptor is NAD+ which delivers 2 electrons and 1 proton to the electron transport chain. FAD is another electron acceptor, but will deliver less energy to the electron transport chain.

21.

Rocket fuel contains H2 and O2 and the energy used to power a rocket comes when the electrons from hydrogen “fall” closer to the more electronegative oxygen.

22.

The basic “downhill” path that electrons follow as their energy is harnessed to produce ATP is: Food_ NADH or FADH2 ETC O2

OVERVIEW OF CELLULAR RESPIRATION (CAMPBELL)

23.

Fill in the diagram below indicating the three stages of respiration. Indicate the molecule produced and method of production of ATP in each process.

24.

The first two stages of cellular respiration, glycolysis and Krebs cycle are catabolic pathways that break down Glucose and other organic fuels.

25.

Glycolysis which occurs in the cytosol begins the degradation process by breaking glucose into two molecules of pyruvate (pyruvic acid) GYCOLYSIS OVERVIEW (CAMPBELL)

26.

The citric acid cycle (Krebs cycle) which takes place in the mitochondrial matrix of eukaryotic cells or the cytosol of prokaryotic cells, completes the breakdown of glucose by oxidizing pyruvate into carbon dioxide and water.

Through cellular respiration the energy currency (ATP) of the cell can be produced through two reactions: 27. Oxidative Phosphorylation which occurs in the electron transport chain with oxygen as the final electron acceptor. (accounts for 90% of ATP production)

28.

Substrate level Phosphorylation which occurs in glycolysis and the Krebs cycle. This involves the direct transfer of a phosphate group from an organic substrate to an ADP by an enzyme.

Glycolysis 29. Glycolysis is the first step in harnessing of energy. * occurs in the cytosol * Means “ sugar splitting” * oxygen is not needed (anaerobic) * Can be divided into two phases I) Energy investment phase where the cell invests 2 ATPs. II) Energy payoff phase where the cell makes 4 ATPs by Substrate level Phosphorylation and 2 NADH LABEL

30.

The (net) energy result of this process is 2ATP plus 2NADH which will be used later by the electron transport chain to produce ATP if oxygen is present.

After pyruvate is oxidized, the Citric Acid Cycle (Krebs Cycle) completes the energy yielding oxidation of organic molecules CITRIC ACID CYCLE (CAMPBELL) 31.

Glycolysis will release less than 25% of the energy stored in glucose while most of the energy will be stockpiled in the 2 molecules of pyruvate, which will be OXIDIZED/ REDUCED (CIRCLE ONE) if oxygen is present, or it will go through the process of fermentation if no oxygen is present.

32.

Krebs Cycle: occurs in the mitochondrial matrix of eukaryotic cells.

33.

The link stage between glycolysis and the Krebs cycle occurs when pyruvate is converted to actyl-Co A by the addition of coenzyme A.

Through this process: a. CO2 is released as a waste. b. NAD+ is reduced to produce NADH

The Krebs Cycle 34.

Krebs cycle- occurs in the mitochondrial matrix

35.

The one ATP molecule that is produced in each turn of the Krebs cycle is produced through Substrate level Phosphorylation.

36.

3 molecules of NADH and 1 molecule of FADH2 are formed in each turn of the cycle.

37.

It takes 2 turns of the Krebs cycle to completely oxidize one molecule of glucose because of the 2 molecules of pyruvate made in glycolysis

38.

Therefore, a total of 2 ATPs, 8NADHs and 2 FADH2s are produced during the Krebs cycle including the conversion of pyruvate to Acetyl-CoA.

39.

2 ATPs, 6 NADHs and 2 FADH2s are produced in Krebs ALONE.

During Oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesis ETC (CAMPBELL) 40. So far, glycolysis and the citric acid cycle have produced 4 net molecules of ATP per glucose, all by the process of Substrate level Phosphorylation. 41.

The electron transport chain (ETC) is a series of molecules embedded in the inner mitochondrial membrane (cristae)

42. How does form follow function when discussing the cristae? The cristae is a folded membrane which creates a great deal of surface area. Along this membrane there can be a great many areas in which ETC chains can exist therefore maximizing the amount of electron transport occurring and the amount of ATP produced through chemiosmosis. 43.

Most of the components of the ETC are made up of Proteins. Closely bound to these are prosthetic groups which are essential for the catalytic function of certain enzymes.

44.

As the electron carriers NADH and FADH2 reach the electron transport chain, they give up their electrons which then release energy as they move downhill through the chain.

45.

During electron transport along the chain, electron carriers alternate between reduced and oxidized states as they accept and donate electrons.  flavoprotein is the first molecule of the ETC  ubiquinone is the only non-protein member of the ETC  cytochromes are a class of proteins that make up the majority of the ETC

46.

The final electron acceptor is oxygen which is highly electronegative and becomes reduced to form water when it picks up a pair of hydrogen ions.

47.

As electrons drop down the ETC energy is released and H+ is pumped against its concentration gradient from the matrix to the inner membrane space (pH in the inner membrane space is lower than in the matrix)

48.

What is the difference between NADH and FADH2 with regard to the ETC? NADH donates its electrons to the first electron acceptor in the ETC allowing the electrons to fall a greater distance and release maximum energy before it is accepted by O2. Conversely, FADH2 donates its electrons in the middle of the ETC. These electrons fall a shorter distance to O2 and release less energy to drive chemiosmosis.

49.

The electron transport chain makes 26-28 ATP directly

Chemiosmosis : The Energy-Coupling Mechanism 50.

All over the inner membrane of the mitochondrion or the prokaryotic plasma membrane are many copies of protein complex called ATP synthase that actually makes ATP from ADP and inorganic phosphate.

51.

ATP synthase uses the energy of an existing ion gradient to power ATP synthesis.

52.

The power source for the ATP synthase is a difference in the concentration of H+ ions on opposite sides of the inner mitochondrial membrane which were pumped during electron transport.

53.

Chemiosmosis is the energycoupling process by which a H+ ion gradient is used to create energy to produce ATP.

54.

The H+ gradient is referred to as a proton motive force.

ETC AND CHEMIOSMOSIS (McGRAW_HILL)

Why the inexact # of ATP produced? a. NADH can facilitate the production of approx. 2.5 ATP b. FADH2 can facilitate the production of approx. 1.5 ATP c. The maximum # of ATP that can be produced through the ETC are 26-28. 55.

Why might less ATP be produced? Depending on the type of cell, the NADH from glycolysis might not travel easily into the mitochondrial matrix to donate its electrons to the ETC. This loss of potential energy may decrease the number of H+ ions it can help pump into the inner membrane space.

56.

40% (approx.) is the efficiency of respiration with regard to energy conversion. The remainder of the energy is lost as heat. By comparison the most efficient car converts only about 25% of the energy stored in gasoline. Oxidate it or Love It

57.

Hibernating animals contain a tissue called brown fat in which the mitochondria have an uncoupling protein which allow H+ to move across the cristae without the production of ATP. This generates heat.

58.

Why would a hibernating animal not want to use the proton motive force to produce ATP when hibernating?

No Oxygen, No ATP, Not True!!!!!!! FERMENTATION (CAMPBELL) 59.

Fermentation - is the process by which the anaerobic catabolism of nutrients can occur for an extended period of time.(it is an extension of glycolysis)

60.

In order for the above process to occur, addtional, reactions are needed that regenerate NAD+ by transferring electrons to pyruvate.

61.

The NAD+ can then be reused to oxidize the next glucose molecule by glycolysis.

62.

Fermentation produces NO additional ATP molecules but allows more energy to be produced by the continued breakdown of glucose in glycolysis.

63.

In alcohol fermentation, pyruvate is converted to ethanol (ethyl alcohol) and CO2 is given off as a waste gas. This regenerates NAD+ which is needed for the continuation of glycolysis.

64.

Many bacterial and yeast carry out alcoholic fermentation. Humans use these organisms for brewing, winemaking, and baking.

65.

During lactic acid fermentation, pyruvate is reduced directly by NADH to form lactate, with NO release of CO2. Human muscle cells use this process when Oxygen is scarce.

66.

The lactate that accumulates was previously thought to cause muscle fatigue and pain, but recent research suggests that increased levels of potassium (K+) ions may be to blame. Excess lactate is carried away by the blood to the liver where it is gradually converted back to pyruvate.

67.

Obligate anerobes are organisms that carry out only fermentation or anaerobic respiration and cannot survive in the presence of oxygen.

68.

Other organisms can make enough ATP by using either fermentation or respiration are called facultative anaerobes.

69.

Ancient prokaryotes probably used glycolysis to make ATP long before oxygen was present in the Earth’ atmosphere.

70.

Glucose is not the only source of energy. Carbohydrates, proteins and fats can all be used for fuel. Label the following diagram.

71.

The oxidation of fats will produce twice as much ATP as the same mass of carbohydrates.

BIOFLIX: CELLULAR RESPIRATION Photosynthesis & Cellular Respiration (Bozeman)...