Wednesday, October 31, 2012

October 31, 2012 Laps



I got through the science review for older boy and now I will start Unit 3 Human Systems.
It is a large section comprising of chapters 6-10 so it will be a hard trudge. It is useful for parents to do this sort of study so that they aren’t hard on their kids when they fall behind because it is a lot of stuff to learn.
Meanwhile younger boy has social studies to go over.

 I realize now that public education never really ends if you are a parent.


After dropping older boy at his Halloween party, I went and did 1 hour on the treadmill.
My right knee hurt so I wimped out and only did 3 laps around the track.
Nice indents of snow everywhere.
Not many kids dropped by for candy and so there were many pieces of candy left.  I will have to eat more candy I am afraid to ensure it doesn’t get stale.
I had to pick up thyroid pills at London Drugs and almost bought the leftover Halloween candy there that was already reduced but I somehow got out of the store without buying more chocolate.

Finally restarted my mum's exercise program. She is very tippy and so I am going to work on balance and strength.

Help tell the story of Defend Our Coast by sharing our new video!






Last week, people came together like never before to show a united and powerful wall of opposition to the expansion of tar sands pipelines and tankers.
12,000 of us joined protests in Victoria and in 70+ communities all across British Columbia to show our elected leaders that citizens are passionate and powerful, and will do whatever it takes to stop Big Oil and bullying governments from pushing their worst projects against our will.
Today we have something special to share: an inspiring video that captures the energy of last week. Let’s work together to spread the word even further by sharing the story of Defend our Coast. Please share in your social networks.
A big thank you to all the citizen photographers in Victoria and at rallies across the province for capturing such beautiful images, and a special shout out to local photographer / videographer Zack Embree for creating such a beautiful compilation.


Inquiry into Biology UNIT 3 Photosynthesis and Cellular Respiration Chapter 5 Photosynthesis and Cellular Respiration Section 5.3 Cellular Respiration Releases Energy from Organic Compounds






UNIT 3 Photosynthesis and Cellular Respiration
Chapter 5
General Outcomes


Chapter 5  Photosynthesis and Cellular Respiration

5.3       Cellular Respiration Releases Energy from Organic Compounds



August 10, 2012 –October 31, 2012 Section 5.3



Inquiry into Biology

UNIT 3 Photosynthesis and Cellular Respiration
Chapter 5
General Outcomes


5.3          Cellular Respiration Releases Energy from Organic Compounds


Section Outcomes

In this section you will

1)      distinguish in general terms –aerobic respiration/anaerobic respiration/ fermentation
2)      explain how carbohydrates are oxidized by glycolysis and the Krebs cycle to produce reducing power in NADH and FADH2 and chemical potential in ATP
3)      explain how chemiosmosis converts the reducing power of NADH and FADH2 to the chemical potential of ATP
4)      design an experiment to show that oxygen is used in aerobic cellular respiration and that heat is produced
5)      explain that science and technology are developed to meet needs
6)      investigate and integrate from different sources


Key Terms


aerobic cellular respiration
anaerobic cellular respiration
glycolysis
Krebs cycle
electron transport system
chemiosmosis
fermentation


The Process of Cellular Respiration (read page 182)

Refer to Figure 5.16 page 182
Read this section of the text because it is a repeat of previous sections.
Note the summary equations for photosynthesis and cellular respiration provided here and the fact that if you multiply the chemical formulas on both sides of the equations by six, you get the summary equations for this process.


Three Pathways for Energy Release

-there are three pathways for energy release
1)            organisms that live in oxic (oxygen-containing) conditions carry out aerobic cellular respiration
2)            organisms that live in anoxic (no oxygen) conditions carry out anaerobic cellular respiration
3)            some organisms ferment—this is an anaerobic process but is not technically classified as anaerobic cellular respiration.


1)      aerobic cellular respiration
-animals, plants, many types of fungi, protists, and bacteria

2)      anaerobic cellular respiration
-some types of bacteria
-archaea
-deep sea producers (chemosynthetic organisms)
-some nitrogen fixing bacteria and some other types of soil bacteria

3)      fermentation
-yeast and bacteria that cause milk to sour (Lactobacillus bulgaricus)


Questions

1)      Explain the difference between oxic conditions and anoxic conditions.
2)      Describe how aerobic cellular respiration is different from anaerobic respiration


Examining Aerobic Cellular Respiration

-aerobic cellular respiration is an oxidation reaction that breaks down glucose to produce energy in the form of ATP

-a series of enzyme-catalyzed reactions occur
-these reactions transfer electrons from high energy molecules (mainly glucose) to oxygen

-this releases energy in the form of ATP in plants/animals/most other eukaryotic cells


Refer to Figure 5.17 on page 186

This figure provides the main steps in cellular respiration.

This is a fairly involved section so we will go over it in small steps.
I find that when there is a large amount of text you need to use steps and repeat/review the section to get all the information clear in your head.

So first let us go over aerobic cellular respiration one way and then we will  go over it a second way.

1)      aerobic cellular respiration is an oxidation reaction in which a series of enzyme catalyzed reactions transfer electrons from high-energy molecules---mainly glucose to oxygen.
2)      This process is the main way that energy is released.
3)      Energy is released in the form of ATP.
4)      The process of cellular respiration begins with glycolysis.
5)      This is an anaerobic process (it can take place without oxygen) and it occurs in the cytoplasm of the cell.
6)      glycolysis produces a small amount of ATP.
7)      The product of glycolysis is pyruvate.
8)      This product still contains a large amount of energy and can be metabolized further.
9)      If oxygen is not available in eukaryotic cells--   pyruvate is fermented.
10)   If oxygen is present---pyruvate goes through the rest of the reactions of aerobic cellular respiration which means that it is transported into mitochondria.   In the mitochondria, pyruvate undergoes a reaction to prepare it for entry into the Krebs cycle.  Refer to Figure 5.17 page 186 to see this process.
11)   Pyruvate is used to make a molecule called acetyl CoA. Carbon dioxide is released.  The formation of Acetyl CoA is depicted in figure 5.19 page 187 (Forming Acetyl-CoA) at the top of the page. In this process NAD+ goes to NADH (reduction).
12)   The Krebs cycle takes the acetyl CoA and there is a series of reactions that extract electrons and hydrogen ions. Refer to Figure 5.17 page 186.
13)    The major function of the Krebs cycle is to transform the energy of glucose into the reducing power of NADH and FADH2.   These molecules supply high energy electrons to an electron transport system that produces ATP.  Water is the final end product of this process. There is ultimately a larger production of ATP by this aerobic cellular respiration process than by the anaerobic glycolysis process.



This is the first run through of the process of aerobic cellular respiration.
Now we will go through the second run through in more detail.



Outside the Mitochondria:  Glycolysis

1)      glycolysis occurs in all living cells
2)      for some types of cells---it is the only source  of energy because it can occur in anaerobic conditions
3)      for example, yeast can live without oxygen but our muscles cannot use glycolysis endlessly—they need oxygen eventually.
4)      Refer to Figure 5.18 now.  The role of glycolysis is to split glucose.  Glucose is a six carbon molecule and it is split into two molecules of a three carbon molecule called pyruvate.
5)      ATP is used at the start of glycolysis.
6)      Although glucose is a high energy molecule, energy in the form of ATP must be used to start the metabolism of glucose.
7)      After energy has been added to glucose, it splits and the two intermediate three-carbon molecules of pyruvate are formed.
8)      Several more reactions then occur that result in the production of a small amount of ATP and a molecule of NAD+ (nicotinamide dinucleotide) is reduced to NADH.
9)      The amount of ATP that is synthesized in glycolysis is 4 molecules.  It is greater than the amount of ATP used to start the process (2 molecules).  Thus, there is a net gain of 2 molecules of ATP for glycolysis.
10)   When glycolysis is complete there are two identical three-carbon molecules of pyruvate that are prepared for the Krebs cycle.
11)   when oxygen is not available ---or for species that cannot use oxygen---glycolysis is the only pathway by which the cell can extract energy from glucose
12)   the products of glycolysis---must still be processed further by fermentation
13)   when sufficient oxygen is present ---pyruvate is transported into the matrix of the mitochondria to be prepared for the Krebs Cycle



Inside the Mitochondria: Krebs Cycle Preparation

1)      pyruvate must undergo one reaction before a portion of it can enter the Krebs cycle
2)      as shown on page 187, pyruvate loses one carbon atom in the form of carbon dioxide and the other two carbon atoms bind to Coenzyme A (CoA).  In the process NAD+ goes to NADH.
3)      The CoA attaches to the two carbon compound to make a product called acetyl CoA
4)      The entire reaction is shown on Page 187 in this way:

C3H4)3  + CoA + NAD+-----C2H3)—CoA  +CO2 and NADH

or

pyruvate  + CoA ----acetyl CoA  +carbon dioxide


5)      Acetyl CoA enters the Krebs cycle for further processing. The CoA can be thought of as a sort of tow truck to move the 2 carbon compound (called the acetyl group) to where it is needed in the Krebs cycle where the CoA releases the acetyl group for processing


The Krebs Cycle

The Krebs cycle is outlined in Figure 5.19.

It is called a cycle because the last compound –the four-carbon compound that picks up a group of two carbons from acetyl-CoA must be regenerated so that it can continue doing its job of picking up the two carbon groups.


1)      During one complete cycle, a two carbon group is added to the Krebs cycle and two carbon atoms are fully oxidized to carbon dioxide. (The carbon dioxide is a waste product—the gas you exhale).
2)      Most of the energy released when the carbon atoms are oxidized is transformed into reducing power in the form of reduced NADH and FADH2 (flavin adenine dinucleotide).
3)      FADH2 is very similar to NADH and to NADPH.
4)      Also in the Krebs cycle an ATP molecule is generated.

Questions

1)      State where the reactions of the Krebs cycle occur in a cell.
2)      What compound that is derived from glucose actually enters the Krebs cycle?
3)      The carbon atoms that are derived from glucose are fully oxidized in the Krebs cycle. What becomes reduced during the Krebs cycle?


Electron Transport

1)      most of the ATP of aerobic cellular respiration is produced during electron transport
2)      the electron transport system in mitochondria is very similar to the one in chloroplasts
3)      high energy electrons are passed to a chain of electron carrying molecules that are attached to the inner membrane of mitochondria
4)      as the electrons are passed along these carriers there is energy release in small controlled amounts
5)      the energy is used to pump hydrogen ions across the membrane from the matrix (outside the mitochondrion)  to the intermembrane space (the space between the inner and outer membrane of the mitochondrian).
6)      the build up of ions in this intermembrane space creates a gradient of hydrogen ions with more hydrogen ions inside the space versus outside the mitochondrion
7)      the ions can diffuse back to the matrix across the membrane but only through special channels formed by the enzyme ATP synthase
8)      this enzyme uses the energy of the hydrogen concentration gradient to bind a phosphate group to ADP to form ATP –this process is called chemiosmosis
9)      as in the chloroplast, chemiosmosis is the process by which there is production of ATP from ADP and phosphate that is coupled to the movement of hydrogen ions across the mitochondrial membrane down their concentration gradient
10)   oxygen is the final electron accepting molecule in the electron transport system
11)   the oxygen accepts electrons and hydrogen ions to make water

The Role of Oxygen in Aerobic Cellular Respiration
Page 188
1)      oxygen is the final electron acceptor –without it none of the reactions of the electron transport system could occur.
2)      You have to look at the reactions before oxygen accepts the electrons to understand how important oxygen is.
3)      If oxygen is not present the whole process would fail.
4)      when oxygen is not present—the only part of the aerobic cellular respiration process that would occur would be glycolysis.  However it does not produce enough energy to sustain life.  See Figure 5.20 page 188 to understand how much ATP glycolysis results in compared to the Krebs cycle and the electron transport system.
5)      if we compare ATP production of glycolysis we see that 12 ATP are produced in glycolysis versus 24 ATP by the Krebs cycle and the electron transport system. The total production is 36 ATP of which only 2 ATP are produced by the Krebs cycle and 22 ATP are produced by the electron transport system.  Refer to Figure 5.20 on page 188


August 21, 2012

Anaerobic Cellular Respiration Uses a Different Final Electron Acceptor

1)      When oxygen is not present organisms such as various species belonging to domains Bacteria and Archaea—then anaerobic respiration takes place.
2)      What this means is that oxygen is not the final electron acceptor. You still have an electron transport system and a concentration gradient to generate ATP but less ATP is produced.
3)      Anaerobic respiration is less efficient.
4)      Since oxygen is not the final electron acceptor another one must be found.  For most anaerobic cells the final electron acceptor is an inorganic chemical such as sulfate, nitrate, or carbon dioxide.
5)      Depending on the inorganic chemical used—the byproducts of this reaction are elemental sulfur, nitrite, elemental nitrogen, or methan.

Questions

1)      Where, in the mitochondria, are the electron carriers located?
2)      What is the source of the high energy electrons for electron transport in mitochondria?
3)      Describe the function of oxygen in cellular respiration.

Fermentation
Pages 190-193

1)      Anaerobic organisms do not use oxygen, and some cells in aerobic organisms are sometimes without oxygen so must use fermentation.
2)      Fermentation is a metabolic pathway that includes glycolysis and one or two reactions in which NADH is oxidized to NAD+ by reducing pyruvate to other compounds.
3)      Fermentation is not as efficient as aerobic cellular respiration (produces less ATP by glycolysis)
4)      many single-celled organisms such as yeast and bacteria carry out fermentation.
5)      Fermentation also occurs in parts of an organism that are in an anaerobic environment –such as plants submerged in ponds or cells in multicellular organisms that do not have direct access to oxygen.
6)      There are many types of fermentation pathways.
7)      Two common ones are lactate fermentation and ethanol fermentation.





Lactate Fermentation

Ethanol Fermentation

October 31, 2012


Lactate Fermentation

1)      This occurs in some single-celled organisms and in some animal cells that are temporarily without oxygen.
2)      In the absence of oxygen, glucose undergoes glycolysis to produce pyruvate and ATP is produced. Pyruvate must be converted to lactate; this process requires NADH.
3)      See figure 5.21 page 190 to understand the flow of reactions.
4)      The resulting NAD+ is cycled to continue the process.
5)      In muscle cells, lactate fermentation occurs at times when the body is working hard. At such times, aerobic cellular respiration cannot produce enough energy to keep up with demand and so more energy is provided by glycolysis.
6)      Glycolysis is increased to the point where it exceeds the oxygen supply, creating an oxygen debt. Because of the lack of oxygen, the Krebs cycle and electron transport system cannot work fast enough to process the pyruvate and so pyruvate collects. 
7)      The only problem is that you can’t have pyruvate accumulating to excess because the Krebs cycle and the electron transport system cannot process it all. It has to be converted to a form that can be temporarily put away by the body for later use. The body solves this problem by converting pyruvate to lactate so that glycolysis will continue. 
8)      Lactate is stored in muscle cells.
9)      If too much lactate is stored, there is muscle fatigue and cramping.
10)   If oxygen levels are increased (breathing fast) then the lactate is converted back to pyruvate for use in aerobic cellular respiration.







Ethanol Fermentation

1)      Some organisms are able to function aerobically as well as anaerobically.
2)      When they function in anaerobic mode, these organisms carry out ethanol fermentation.
3)      Yeasts and some kinds of bacteria convert pyruvate to ethanol and carbon dioxide.
4)      This process takes two steps and is shown in Figure 5.22 page 191.
5)      In this process, pyruvate is converted first to a two-carbon compound and then to ethanol. Carbon dioxide is produced in the conversion of pyruvate to the two-carbon compound and NADH is required to convert the two carbon product to ethanol.
6)      Fermentation by brewer’s yeast---Saccharomyces cerevisiae –is used to make baked goods and alcohol.   See figure 5.22.   Yeast fermentation may be used to make alcohol products such as wine or champagne from grapes, or mead from honey and cider from apples.  Another alcohol product—beer is made by fermenting sugars in grain such as barley, rice or corn.
7)      In the case of bread, how is fermentation by brewer’s yeast used?  Refer to figure 5.23.  In photo A the bread dough with yeast is left in a warm place so that the yeast can ferment.  The bread dough increases in size due to the carbon dioxide produced in fermentation.  The photo B shows the dough doubling in size as a consequence.   When the dough is baked the carbon dioxide will be driven off, leaving small holes that give the bread its chewy texture.
8)      Other products of fermentation are possible besides ethanol.
9)      The product produced depends on the organism.
10)   See table 5.2 Selected Fermentation Products and their Uses page 191


Other fermentation products and their uses

1)      Depending on the organism, fermentation can yield other substances besides lactate and ethanol.
2)      These include acetic acid, diacetyl, lactic acid (lactate) and propionic acid + CO2.
3)      Acetone and butanol are two other fermentation products.
4)      Acetone was used in world war I to make cordite a smokeless gunpowder.
5)      Butanol was used in world war I (WWI) to make artificial rubber for tires.
6)      Inefficient means of making acetone existed prior to WWI.  A better way was developed by Chaim Weizmann. It used the anaerobic bacterium –Clostridium acetobutylicum.  100 tonnes of molasses or grain was converted to 12 tonnes of acetone or 24 tonnes of butanol. Now we produce  these products from petrochemicals.
7)      Refer to page 191 for the other possible sources of other fermentation products.


Questions

1)      What does it mean to say that glycolysis is an anaerobic process?
2)      Under what conditions does fermentation occur?
3)      Describe how lactate fermentation is similar to and different from ethanol fermentation.

Energy from Manure Pages 192-193

1)      Alberta raises about 3.5 million pigs each year.
2)      This is almost 15% of the Canadian total.
3)      Pork is an important resource.  Over $2 billion worth of pork per year is sold.
4)      Pig manure is the largest source of greenhouse gas emissions (Statistics Canada).
5)      Pig manure is a source of biogas.
6)      Biogas is methane from animal wastes.
7)      In other countries biogas is used as fuel.
8)      How is biogas made?  It is made by digestion of manure.




How Biogas is Made

1)      Manure is broken down by anaerobic digestion.
2)      An anaerobic chamber is used—this is an airtight tank with heating coils and sometimes a mechanical mixer.
3)      This digester does not have oxygen in it because it is poisonous to anaerobic bacteria.
4)      Anaerobic digestion is a two part process in these anaerobic digesters.
5)      It works best at a temperature of 35’C or better.
6)      In the first part—acid-forming organisms break down manure into simple organic compounds.
7)      In the second part—a second group of anaerobic organisms break down the acids into methane and carbon dioxide.
8)      Biogas is made of 60-80% methane gas, 20-40% carbon dioxide and trace amounts of other substances such as hydrogen sulfide, ammonia and water vapour.
9)      Costs for the process vary as there are different types and sizes of anaerobic digesters.

The Value of Biogas

1)      1 kg of hog manure produces about 0.5 m3-1 m3 of biogas (with 60-65 % methane).
2)      1 m3 of biogas is enough to cook three meals daily for a family of four to six people, replacing approximately 11 kg (one tank) of propane.
3)      5 mature pigs would be required to provide sufficient manure.
4)      Other factors influence production figures of biogas.
5)      In Vegreville, Alberta manure digestion is used to make electricity at Highmark Renewables.  Find out about this and other integrated manure utilization systems (IMUS).
6)      Some manure can be made into crude oil by scientists.  Investigative work continues. 


Ethanol

1)      in organisms that carry out ethanol fermentation, the ethanol produced is released as a waste product.
2)      In fact, ethanol waste is toxic to yeast.
3)      As its concentration approaches 12% the yeast die off.
4)      However, this “waste” can be used as energy by humans.
5)      Ethanol was a common lamp fuel during the 1800s and was used for early internal combustion engines and cars, also starting in the 1800s.
6)      In the past, gasoline cost less than ethanol to produce, thus ethanol was not produced in large quantities.
7)      This situation changed in the 1970s.  At that time, rising oil prices, dwindling reserves and environmental concerns resulted in research into alternate fuel sources.
8)      Whenever oil prices rises, these alternate fuels become commercially more attractive to produce.
9)      In cars, the use of gasohol ( mixture of 10% ethanol and 90% gasoline) is becoming more common.
10)   Cars made after 1980 can use gasohol without any engine modifications required.
11)   Car companies are designing cars that can use fuel with higher ethanol percentages—eg. Brazil has cars that burn pure ethanol or several combinations of ethanol and gasoline.


Ethanol Production

1)      In Canada, the most common source of ethanol –is the fermentation of corn and wheat.
2)      Grain is mixed with meal. Then it is mixed with water to form a slurry called “mash”.
3)      Enzymes are then added.   They convert the starches to glucose.
4)      The mash is heated to destroy bacteria.
5)      It is then cooled and placed in fermenters.
6)      Yeast is added.
7)      The yeast grows on the glucose under anaerobic conditions and releases the end products –ethanol, carbon dioxide.
8)      The product –called “beer” is approximately 10% ethanol and 90% water.
9)      If beer is distilled ---to eliminate as much of the water as possible—this give you nearly pure ethanol.
10)   A small amount of gasoline is then added to make the ethanol unfit for human consumption.
This is called denaturing.
11)   The solid residues of this process are used to make Distiller’s Dried Grains and Solubles (DDGS) which is used to feed poultry and cattle.  These are dried residues of the grain and yeast from this fermentation process.
12)   The combustion of ethanol produces carbon dioxide.
13)   This is one of the greenhouse gases that contributes to global warming.  However, unlike in the case of gasoline, the source of ethanol---grain---is a renewable resource.  
14)   Ethanol is made by the fermentation of corn, grain, sugar cane and other crops that can be grown quickly.
15)   Also these same crops absorb carbon dioxide in order to produce more sugars and, through processing, more ethanol. 
16)   Despite all these good aspects to the use of ethanol—it is still not “carbon-neutral”. In other words, the production and burning of ethanol releases more carbon dioxide than is absorbed by plants.   So why use it?  When ethanol is added to gasoline, ethanol increases the octane rating of the fuel—in other words---the gasoline burns more slowly and there is prevention of engine “ping.”  As well, the ethanol—with gasoline ---(ethanol/gasoline mixtures) reduces the amount of carbon monoxide produced in the exhaust emissions. 
17)   Burning pure ethanol on its own—also eliminates the release of partially burned hydrocarbons and volatile organic compounds (VOCs) that contribute to smog.

Section 5.3 Summary Pages 193-194


1)      Three metabolic pathways make up aerobic cellular respiration.
2)      The first set of reactions in aerobic cellular respiration is called glycolysis. Glycolysis is an anaerobic process that takes place in the cytoplasm of the cell.
3)      During glycolysis –a small amount of ATP is generated and NAD+ is reduced to NADH.
4)      The fate of pyruvate---which is the final product of glycolysis----depends on the availability of oxygen and on the type of organism involved.
5)      If oxygen is present ---pyruvate goes to the matrix of the mitochondrion.  In most organisms pyruvate in the mitochondrion is broken down to carbon dioxide and acetyl CoA. NAD+ is reduced to NADH.  Acetyl CoA then enters the Krebs cycle by combining with a four carbon compound. 
6)      During the Krebs cycle two carbon atoms are fully oxidized to carbon dioxide.  NAD+ and FAD are reduced to NADH and FADH2, and a small amount of ATP is produced.
7)      The reduced NADH and FADH that are formed during the Krebs cycle donate their electrons to electron carriers in electron transport.   As electrons are passed from one carrier to the next, the energy that is released is used to pump hydrogen ions across the mitochondrial inner membrane into the intermembrane space, creating a concentration gradient.  The energy stored in this gradient is used to make ATP by chemiosmosis.
8)      Organisms that carry out anaerobic cellular respiration use inorganic chemicals other than oxygen as the final electron acceptor.  This produces ATP for the cell, but not as much as that produced in aerobic respiration.
9)      In muscles that are working anaerobically---the pyruvate is converted to lactate.   The reduced NADH is reoxidized to NAD+ so that the glycolysis process can keep going. (see figure 5.21 page 190 to understand this process).
10)   In yeast growing anaerobically, pyruvate is converted to carbon dioxide and ethanol and the reduced NADH is reoxidized so that glycolysis can continue. See figure 5.22 page 191 to see this step of NADH---going to NAD+.
11)   Fermentation is used on an industrial scale to make ethanol.
12)   Ethanol is used as an additive to gasoline to reduce some environmental contaminants.


Section 5.3 Review  Page 194

1)      Summarize photosynthesis and cellular respiration in terms of reduction and oxidation of carbon-based molecules.
2)      Compare, in general terms, aerobic cellular respiration, anaerobic cellular respiration, and fermentation.
3)      Identify three energy-releasing metabolic pathways associated with aerobic cellular respiration.
4)      Use graphics or words to summarize glycolysis—the first stage of aerobic cellular respiration.  Include where this process takes place, whether or not oxygen is required for these reactions, the products that are formed as a result of glycolysis, and where these products go next.
5)      Use graphics or words to summarize the Krebs cycle, the second stage of aerobic cellular respiration. Include where this process takes place, whether or not oxygen is required for these reactions, the products that are formed as a result of the Krebs cycle, and where these products go next.
6)      Use graphics or words to summarize the electron transport system, the third stage of aerobic cellular respiration.  Include where this process takes place, whether or not oxygen is required for these reactions, the products that are formed as a result of the electron transport system, and where these products go next.
7)      Explain the term “chemiosmosis”.
8)      Identify the final electron acceptor in aerobic cellular respiration, and explain what happens if this molecule is not present in the cell.
9)      Explain why aerobic cellular respiration produces so much more ATP than does anaerobic cellular respiration.
10)   Describe the term “fermentation” and explain why this process is considered to be anaerobic.
11)   Compare lactate fermentation to ethanol fermentation in terms of starting and ending material and ATP production.

Summary Page 195


1)      The summary reactions for photosynthesis and respiration represent dozens of different reactions.
2)      The central function of photosynthesis and cellular respiration is to produce energy-rich compounds and to break these compounds down to release their stored energy.
3)      The energy is stored in ATP.  This is adenosine triphosphate.
4)      The energy in this product is contained in the bonds between the phosphate groups, leaving ADP (adenosine diphosphate) and a free phosphate group.  When the bond to the last phosphate group is broken, the energy released is available  to do cell work.
5)      The energy stored in energy rich compounds is used to add a phosphate group back to ADP to regenerate ATP.
6)      In photosynthesis, the carbon dioxide and water are involved in two separate sets of reactions.  Water is split into hydrogen ions, electrons, and oxygen in the light-dependent reactions; carbon dioxide is incorporated into carbohydrates in the light-independent reactions.
7)      In the light-dependent reactions, which take place in the thylakoid membranes---of the chloroplasts, pigments capture light energy and use it to excite electrons that are channelled away to produce ATP and NADPH. 
8)      During the light-independent reactions in the stroma of the chloroplasts, the chemical potential energy of ATP and the reducing power of NADPH are used to reduce carbon dioxide and form glucose and other carbohydrates via the Calvin-Benson cycle.
9)      The glucose produced by plants and other autotrophs (photosynthesizing organisms) is used by all other organisms.
10)   The glucose is processed to extract the energy in it.
11)   A series of reactions do this work.
12)   The reactions are those of glycolysis, the Krebs cycle, and electron transport.
13)   Glycolysis is an anaerobic process that occurs in the cytoplasm and breaks down glucose to form pyruvate.
14)   In most organisms ---pyruvate then passes into the mitochondria---where it is broken down into carbon dioxide and acetyl CoA in preparation for the Krebs cycle, which occurs in the matrix. Energy released from this cycle—is used to reduce NAD+ and FAD to NADH and FADH2. These reduced compounds contribute their electrons to electron carriers embedded in the inner mitochondrial membranes.
As the electrons are passed from one carrier to the next in electron transport, the energy that is released in a stepwise manner is used to pump hydrogen ions across the inner mitochondrial membrane, forming a concentration gradient that generates ATP through chemiosmosis.
15)   In some organisms, glycolysis is their only source of energy.  In these organisms, the pyruvate is broken down into carbon dioxide and alcohol (ethanol fermentation) or lactate (lactate fermentation). Humans have long been using the fermentation process to obtain ethanol, which is becoming popular as a fuel for transportation.
16)   See the graphic organizer on page 195 for reactions summary in a picture form.


Review Questions Page 198-199
Do these questions.