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Chapter 4: Cellular Respiration
You won't have to memorize chemical equations or structural formulas for most of the chemistry.
Instead, you need to provide names of major molecule, describe their sequence in a metabolic process, and describe how the process accomplishes its objective.
To do work requires energy.
It is possible to convert energy from one form to another.
The first law of thermodynamics states that "gone" is a violation of the word "lost".
Not all of the energy is passed from one usable form to another, that some of the energy becomes unusable or unable to do work.
In the form of heat, the energy is not usable.
As additional energy conversions occur, more energy becomes useless, and things become disorganized.
The second law of thermodynamics states that the universe will increase in size if energy is constantly moving from one form to another.
The earth and living things receive energy from the sun.
Some of the energy is not available for chemical reactions because it will be lost as heat.
6 CO2 + 6 H2O - C6H12O6 + 6 O2 is the overall equation for photosynthesis.
The energy comes from the sun.
The presence of a catalyst can lower the activation energy.
The free energy of a reaction is not changed by a catalyst.
Most endergonic reactions are done with the help of specific enzymes.
In order for life to continue, living things need a constant input of free energy.
As a result of chemical reactions, that energy is used to maintain order.
Without free energy, cells degrade and die.
The initial breakdown process of glucose is the subject of this chapter.
When electrons are transferred from one molecule to another in a chain of reactions, they give up energy for generating the molecule's energy.
The process of cellular respiration takes place in cells.
The energy is taken from the energy-rich glucose.
These are general formulas for food.
In the following section, each of these processes is discussed.
In addition to obtaining free energy directly from glucose, other carbohydrates, such as starch and glycogen, can also be used.
They all end up being a type of sugar calledfructose orglucose.
Free energy can come from the source of free energy.
Before they are absorbed into the bloodstream, they are eaten.
The body can be made to have more than one type of amino acids.
NH2 is stripped from the amino acids and then thrown away.
The remainders of the amino acids are converted to various substances in the Krebs cycle.
Fats can be sources of free energy.
Glycerol and fatty acids can be obtained from fats or from the digestion of fats.
After the conversion, glycerol enters the Krebs cycle.
There are 2 additional substances added.
The first few steps are dependent on the input of ATP.
This changes the amount of sugar in the body.
Two NADH are produced.
The energy-rich molecule is called NADH.
The 4 ATP are produced by the body.
Two pyruvate are formed.
A net of 2 ATP and 2 pyruvate are made from a single glucose molecule after it is turned into 2 pyruvate, 2 NADH, and a net of 4 ATP.
The process takes place in the cytosol.
pyruvate is the end product of glycolysis.
Remember that glycolysis produces 2 pyruvate, even though the Krebs cycle is described for 1 pyruvate.
Pyruvate to acetyl CoA.
In a step leading up to the Krebs cycle, pyruvate and CoA are combined to produce acetyl CoA.
1 CO2 and 1 NADH are also produced.
The Krebs cycle begins when acetyl CoA is combined with OAA.
There are seven products.
3 NADH, 1 FADH2, and 1 ATP are made along the way.
FADH2 accepts electrons during a reaction.
The animals exhale CO2 when they breathe.
The electrons are passed from one carrier to the next in the chain.
The electrons give up their energy along the way.
The electrons that are provided by NADH and FADH2 have enough energy to generate 2 and 3 ATP, respectively.
The water is formed by the 1/2 O2 and 2 H+.
There are two major processes of aerobic respiration that occur in the mitochondria.
There is a double layer oflipids in this membrane.
There is a narrow area between the inner and outer membranes.
There are H+ ion (protons) here.
This is where ovodative phosphorylation occurs.
The electron transport chain within the cristae removes electrons from FADH2 and H+ ion from the matrix to the intermembrane space.
The matrix is the fluid substance that fills the inside.
The conversion of pyruvate to acetyl CoA occurs here.
In addition, CO2 is generated.
NADH and FADH2 have electron removed.
The two molecule (2A, 2B) have electrons removed from them.
The shaded strip shows the electron transport chain from one complex to the next.
A pH and electrical gradient is created.
As electrons at the end of the electron transport chain combine with H+ and oxygen to form water, the concentration of H+ in the matrix decreases further.
The result is a positive and negative electric charge.
Similar to water behind a dam, these gradients are potential energy reserves.
ATP is generated.
The pathway for the protons in the intermembrane compartment to flow back into the matrix is provided by a channel in the inner membrane.
The protons lose energy when they are drawn through the channel.
When water passes through a turbine, it creates electricity.
2 pyruvate are converted to 2 acetyl CoA and 2 more NADH are produced.
6 NADH, 2 FADH2, and 2 ATP are produced from 2 acetyl CoA.
The total ATP count from 1 original glucose molecule appears to be 38 if each NADH produces 3 and FADH2 produces 2.
The number is reduced to 36 because the 2 NADH that are produced in the cytoplasm must be transported into the mitochondria.
The net yield of each NADH is reduced by the transport of the molecule.
It is thought that the totalATP production is 36.
No electron acceptor exists if oxygen is not present.
NADH accumulates if this happens.
The Krebs cycle and glycolysis both stop after the conversion of the NAD+ to NADH.
The cell may soon die if this happens.
There is anaerobic respiration in the cytosol.
Pyruvate to acetaldehyde.
CO2 and acetaldehyde are produced for each pyruvate.
Beer and champagne have a source of CO2 formed.
There is a substance to be 888-609- 888-609- 888-609- 888-609- 888-609- The energy in NADH is used to drive this reaction, releasing NAD+.
Each acetaldehyde has to be made with 1 ethanol and 1 NAD+.
Beer and wine are made from the ethyl alcohol produced here.
The objective of this pathway is important to you.
You should wonder why the energy in an energy-rich molecule like NADH is removed and put into the formation of a waste product that eventually kills the yeast that produce it.
The goal of this pathway is to free NAD+ so that glycolysis can continue.
In the absence of O2, all the NAD+ is bottled up.
The electrons of NADH cannot be accepted without oxygen.
The purpose of the pathway is to release some NAD+.
There is a reward for each pyruvate that is converted.
This is not much, but it is better than the alternatives.
There is only one step in the process.
NADH gives up its electrons in the process of converting a pyruvate to lactate.
The NAD+ can now be used for lysis.
In mammals, most lactate is transported to the liver, where it is converted back to sugar.
A review of the material presented in this chapter is provided by the questions that follow.
They can be used to evaluate how well you understand the concepts.
AP multiple-choice questions are often more general, covering a broad range of concepts.
The two practice exams in this book are for these types of questions.
Four possible answers or sentence completions are followed by each of the following questions or statements.
The one best answer or sentence is what you choose.
It produces a substance.
Lactic acid is produced.
The electron transport chain is produced by it.
It replenishes NAD+ so that glycolysis can occur.
Oxygen is needed to carry the waste CO2.
Oxygen is used to make sugar.
The oxygen molecule becomes part of the ATP molecule.
Three major biosynthetic pathways are represented in the boxes.
The following graph shows the amount of CO2 that is released by plant cells at various levels of atmospheric oxygen.
The amount of CO2 released is relatively high if the atmospheric O2 is less than 1%.
The Krebs cycle is active.
H2O is being converted to O2.
There is alcohol being produced.
There isn't enough coenzyme A.
The amount of CO2 released increases as atmospheric O2 increases.
Chemiosmosis talks about how ATP is generated.
H+ accumulates in the area between the cristae and the mitochondrion.
A voltages is created across the cristae.
A cristae is made of protons.
The energy from the electrons flowing through the channel is used to phosphorylate the ADP.
Some of the products from the breakdown are in the Krebs cycle.
Water is produced if oxygen is present.
The electrons that transform NAD+ + H+ to NADH are donated by oxygen in aerobic respiration.
Lactate is produced when there is no oxygen.
The questions that follow are typical of an entire AP exam question or just that part of a question that is related to this chapter.
There are two types of questions on the AP exam.
It takes about 20 minutes to answer a long free-response question.
Sometimes they offer you a choice of questions to answer.
6 minutes is the time it takes to answer a short free-response question.
diagrams can be used to supplement your answers, but a diagram alone is not adequate.
The energy from the NADH is used to drive the formation of Ethanol in the process of alcohol fermentation.
Explain in two or three sentences why there is a need to add energy to the process.
The mitochondrion has two layers of skin.
In two or three sentences, explain why two membranes are needed.
The location where these biosynthetic pathways occur is addressed.
Explain the process of aerobic respiration and how it extracts energy from starches, proteins, and lipids.
Explain why organisms need oxygen.
Explain how some organisms can survive in the absence of oxygen.
In the absence of oxygen, all of the NAD+ gets converted to NADH.
There is no NAD+ to accept electrons from the glycolytic steps.
By increasing the amount of alcohol, it is possible to continue the process of glycolysis.
1/2 O2 combines with 2 electrons and 2 H+ to form water at the end of the electron transport chain.
You should look at aerobic respiration by looking at the arrows: pathway A, pathway B, and pathway C. The first, second, third, fourth, fifth, sixth, seventh, and eighth arrows are ADP, NAD+, or FAD.
The Krebs cycle is one of the pathways in which ATP is produced.
Arrow 3 is used in the production of the NADH.
arrow 7 is a product of the Krebs cycle.
FADH2 cannot be represented by arrow 3.
Both arrows 3 and 7 can be used to represent NADH.
If arrow 7 represents NADH, then arrow 6 represents FADH2.
Arrow 9 represents the O2 that accepts the electrons after they pass through the electron transport chain.
Arrow 9 could also be ADP, but not among the answer choices.
The Krebs cycle is represented by pathway B.
The energy in pyruvate is used to generate FADH2 and NADH.
Each molecule has the potential to produce 36, 36, pyruvate, 15, acetyl CoA, 12 and NADH.
There is a variable pathway that breaks down the alcohol in the human body.
Answer choice A can be eliminated if you don't know how much of the molecule pyruvate can yield.
Anaerobic respiration is initiated when O2 is absent.
CO2 is released by alcohol fermentation.
It is obvious that photosynthesis is not happening.
The graph shows plant activity at night or during a heavily clouded day.
The Krebs cycle is where CO2 is produced.
As in the previous question, the production of CO2, rather than its consumption, indicates that photosynthesis is not occurring, and that the plant activity is taking place at night.
Lactic acid fermentation removes electrons from NADH to make NAD+.
No ATP is generated by this step.
The electrons move down the protons.
The number of positive charges in the intermembrane space is related to the number of positive charges inside the crista membrane.
During strenuous exercise, pyruvate is broken down.
CO2 is produced by aerobic respiration.
Anaerobic respiration would increase the formation of lactate.
O2 and H+ are combined with electrons to form water.
pyruvate, acetyl CoA, and intermediate carbon compounds are used in the Krebs cycle to convert products from the breakdown of lipids and proteins.
The transfer of electrons from NADH and FADH2 to electron acceptors that pump H+ across the inner mitochondria is called ozodative phosphorylation.
The final electron acceptor is Oxygen.
No CO2 is involved.
All of the remaining answer choices describe the processes that release CO2.
The same process is described by answer choices B and D.
The negative sign indicates that the coupled reactions are exergonic and that the reaction is random.
NADH accumulates when O2 is not present.
There isn't any NAD+ available for glycolysis.
The regenerated NAD+ can be used in lysis.
H+ is transported from the matrix to the intermembrane space where it accumulates.
This causes the movement of protons to go back into the matrix.
Oxygen is required for the Krebs cycle and the processes involved in obtaining it from pyruvate.
Pyruvate is derived from a process that does not require oxygen.
Before pyruvate enters the Krebs cycle, it combines with coenzyme A.
2 electrons and 2 H+ were removed from pyruvate and combined with NAD+ to form 1 NADH + H+.
There is enough energy in NADH to produce 3ATP.
A CO2 molecule is released.
The end product is acetyl CoA.
acetyl CoA is combined with oxaloacetate to form citrate, releasing the coenzyme A component.
The last product in the series of reactions is the substance that reacts with acetyl CoA.
The energy from the coenzymes is used to make the molecule.
2 electrons pass through an electron transport chain for each of these coenzymes.
3ATP are generated for each NADH when they originate in the Krebs cycle.
FADH2 is capable of generating 2 ATP.
O2 accepts the electrons and 2 H+) to form water at the end of the electron transport chain.
In the Krebs cycle, NAD+ and FAD can be used.
There is a total number of 15 ATP generated from a single pyruvate.
The matrix of the mitochondria contains the Krebs cycle.
The cristae is where the electron transport chain's carriers are embedded.
In these cristae membranes, oxidation occurs.
H+ is deposited on the outside of the cristae.
The intermembrane space has excess protons that creates a pH and electric gradient.
The energy provided by the gradient is used to generate ATP as protons pass back into the matrix through the cristae.
The answer to each part of the question should be labeled a, b, or c to help you organize your answer.
The question is similar to the first one.
You need to discuss glycolysis in detail.
You also need to know that 2pyruvate is produced by glycolysis.
Only one pyruvate is the answer to question 1.
The answer follows that.
Starches are made from sugar.
The stears enter the glycolytic pathway.
The sugars are catalyzed to the two sugars.
The sugars enter the pathway at the beginning, but the sugars enter after a couple of steps.
There are two types of Lipids: glycerol to hydrolyzed and fatty acids.
acetyl CoA is produced by both of these components.
There are some things that are to be found in the body.
Different products are produced when broken down.
Some of the products are converted to acetyl CoA.
NH3 is a toxic waste product that is exported from the cell.
There is an additional focus on the function of O2 in the first part of this question.
There are consequences if oxygen is not present.
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