Exam 3 Bio

The Photo Part of Photosynthesis

-Inside the chloroplast is a stack of thylakoid discs -On the thylakoid discs are chlorophyll molecules housed inside a Photosystem -Photons in sunlight hit the Photosystem and the energy from the photons is transferred to the chlorophyll molecules. There are 2 types of Photosystems (PSII & PSI) -This causes the excitation of electrons which move to the Primary Electron Acceptor.

Chlorophyll

-Plant pigment (chlorophyll A & B) in thylakoid membrane -Absorbs certain wavelengths of energy (photons) from the sun -Absorbed energy excites electrons in chlorophyll pigment

The Calvin Cycle

-Series of chemical reactions -Occurs in stroma -Enzymes are recycled

Electron Transport Chain part 2

-The lost energy pumps H+ ions into the space between the inner and outer membranes of the mitochondria causing a higher concentration of H+ ions here than in the mitochondrial matrix -Excess H+ ions move down the gradient from high to low concentration bringing them back to the matrix where they aid the phosphorylation of ADP into ATP

Using Figure 10.19 in your text as a guide, explain the three key events—indicated by the arrows below—in the C4 pathway.

1. In mesophyll cells, the enzyme PEP carboxylase adds carbon dioxide to PEP. 2. A four-carbon compound conveys the atoms of the CO2 into a bundle-sheath cell via plasmodesmata. 3. In bundle-sheath cells, CO2 is released and enters the Calvin cycle

Cholorplast consist of 6 componets

1. Outer membrane 2. Inner membrane 3. Granum 4. Lamella 5. Stroma 6. Thylakoids

List the three places in the light reactions where a proton-motive force is generated by increasing the concentration of H+ in the stroma

1. Water is split by photosystem II on the side of the membrane facing the thylakoid space 2. As plastoquinone (Pq), a mobile carrier, transfers electrons to the cytochrome complex, four protons are translocated across the membrane into the thylakoid space 3. A hydrogen ion is removed from the stroma when it is taken up by NADP+ .

Photosynthesis (Synthesis Reaction) part 2

2. Sugar Creation ATP and NADPH donate a phosphate and H+ ion (respectively) to the carbon molecule in the chloroplast to reduce 3-phosphoglycerate to the G3P (3-carbon) molecule Additional ATP and electrons from NADPH work to create glucose from two G3P molecules 3. Regeneration Some of the G3P molecules are recycled to make more rubisco to convert the carbon and continue the cycle

Use both chemical symbols and words to write out the formula for photosynthesis. (Use the one that indicates only the net consumption of water.) Notice that the formula is essentially the opposite of cellular respiration.

6 CO2 + 6 H2O + Light energy → C6H12O6 + 6 O2

Explain what is meant by a C3 plant.

A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.

The breakdown of glucose is linked to cellular work by a chemical driveshaft known as

ATP

Describe the roles of autotrophs and heterotrophs in the biosphere

Autotrophs (producers) sustain themselves without consuming anything derived from other organisms. EX) Algae, along with plants and some bacteria and fungi (An organism that obtains organic food molecules without eating other organisms or substances derived from other organisms. Autotrophs use energy from the sun or from oxidation of inorganic substances to make organic molecules from inorganic ones) Heterotrophs (consumers) live by eating compounds produced by other organisms. EX) Dogs, birds, fish, lions, humans, some bacteria, yeast, cows (An organism that obtains organic food molecules by eating other organisms or substances derived from them)

Compare and contrast C4 plants with CAM plants. In your explanation, give two key similarities and two key differences.

Both C4 and CAM plants thrive in hot, dry conditions. Both have evolved methods to reduce water loss and to "fix" carbon dioxide in an intermediate compound before it enters the Calvin cycle. C4 plants have Kranz anatomy, with thick-walled bundle-sheath cells. CO2 is added to PEP to make a four-carbon intermediate so that CO2 will not be lost through photorespiration. CAM plants prevent water loss by closing their stomata during the day, but in order to have CO2 available, it is fixed in crassulacean acid when the stomata are open at night. In C4 plants, the initial steps of carbon fixation are separated structurally from the Calvin cycle. In CAM plants, the two steps occur at different times (temporal separation of steps.)

Photosynthesis (Synthesis Reaction)

Calvin Cycle: 3 Steps 1. Fixation 2. Sugar Creation 3. Regeneration Fixation Rubisco (a 5 carbon sugar; rubilose bisphosphate carboxylase/oxygenase) in plant cell combines it with CO2 to create a carbon-containing molecule in the chloroplast (3-phosphoglycerate)

NAD+ is a coenzyme. What are coenzymes? (If you have forgotten, look at p. 158 in Chapter 8.)

Coenzymes act as cofactors and they are organic molecules, such as many vitamins.

Cyclic electron flow is thought to be similar to the first forms of photosynthesis to evolve. In cyclic electron flow no water is split, there is no production of , and there is no release of . (The Big Picture: Why did oxygen not accumulate in the atmosphere until cyclic electron flow evolved?)

Cyclic electron flow can be visualized in Figure 10.16. Cyclic electron flow is thought to be similar to the first forms of photosynthesis to evolve. In cyclic electron flow no water is split, there is no production of NADPH and there is no release of oxygen.

What happens when a plant undergoes photorespiration?

During photorespiration, which is a metabolic process, the plant consumes oxygen and ATP, releases carbon dioxide, and decreases photosynthetic output. Photorespiration generally occurs on hot, dry, bright days, when stomata close and the O2/CO2 ratio in the leaf increases, favoring the binding of O2 rather than CO2 by rubisco.

Krebs Cycle + Before the Krebs Cycle Begins Acetyl CoA enzyme is made

Each pyruvate molecule moves from cytoplasm to mitochondria to react with Coenzyme A to form Acetyl CoA, CO2 and 2 NADH 1. Pyruvates move from cytosol to mitochondrial matrix 2. Pyruvates split into CO2 and acetyl groups 3. Acetyl groups bind to coenzyme A to form Acetyl CoA 4. NAD receives 2 electrons and a H+ ion to make NADH (for each pyruvate that is split)

In this reduction stage, the low-energy acid 1,3-bisphosphoglycerate is reduced by electrons from NADPH to form the three-carbon sugar .

G3P

Where does glycolysis occur in the cell? Is oxygen required?

Glycolysis occurs in the cytoplasm of the cell and does not require oxygen.

Conceptually, it is important to know that the C4 pathway does not replace the Calvin cycle but works as a CO2 pump that prefaces the Calvin cycle. Explain how changes in leaf architecture (Figure 10.19) help isolate rubisco in regions of the leaf that are high in CO2 but low in O2.

In effect, the mesophyll cells of a C4 plant pump CO2 into the bundle sheath, keeping the CO2 concentration in the bundle-sheath cells high enough for rubisco to bind carbon dioxide rather than oxygen.

Cellular Respiration

In the Cytosol 1. Glycolysis - enzymatic breakdown of glucose to pyruvate and ATP In the Mitochondria 2. Krebs Cycle (Citric Acid Cycle) to create CO2 and ATP 3. Electron Transport Chain to form ATP

In cellular respiration, electrons are not transferred directly from glucose to oxygen. Following the movement of hydrogens allows you to follow the flow of electrons. What electron carrier is hydrogen transferred to first?

NAD+

Lactic acid fermentation starts with glucose and yields lactate. Explain this process and be sure to describe how NAD+ is recycled

NAD+ and lactate are formed in this process when pyruvate is reduced by NADH.

The step that converts pyruvate to acetyl CoA at the top of the diagram occurs twice per glucose. This oxidation of pyruvate accounts for two additional reduced molecules and two molecules of CO2.

NADH

What are the two electron carrier molecules that feed electrons into the electron transport system?

NADH and FADH2

In phase two, the reduction stage, what molecule will donate electrons, and therefore is the source of the reducing power?

NADPH

Krebs Cycle

Occurs in mitochondria Mitochondria have 2 compartments 1. Intermembrane compartment - between the outer membrane and inner membrane 2. Inner compartment - inside inner membrane, contains fluid matrix Mitochondrial Matrix Enzymes in matrix catalyze reactions aided by electron transport proteins, H+ ions and ATP-synthesizing-proteins

Summarize the catabolic degradation of food by aerobic respiration in words (rather than using chemical symbols).

Organic compounds, combined with oxygen, yields carbon dioxide, water, and energy.

Redox Reactions

Oxidation and Reduction always go together because you will always have one molecule that gives an electron (OXIDIZED) and one that accepts the electron (REDUCED)

Both cellular respiration and photosynthesis are redox reactions. In redox reactions, pay attention to the flow of electrons. What is the difference between oxidation and reduction

Oxidation is when something loses electrons and reduction is when something gains electrons.

NADH

Oxidized or Reduced? Reduced Higher Energy/Lower Energy Higher energy

The net production of one G3P requires molecules of ATP and molecules of NADPH.

The net production of one G3P requires 9 molecules of ATP and 6 molecules of NADPH.

Explain the role of PEP carboxylase in C4 plants, including key differences between it and rubisco.

This enzyme adds CO2 to phosphoenolpyruvate (PEP), forming the four-carbon product oxaloacetate. PEP carboxylase has a much higher affinity for CO2 than does rubisco and no affinity for O2. Therefore, PEP carboxylase can fix carbon efficiently when rubisco cannot—that is, when it is hot and dry and stomata are partially closed, causing CO2 concentration in the leaf to fall and O2 concentration to rise.

The breakdown of glucose in cellular respiration yields of energy, meaning this reaction has a positive/negative ΔG and is exergonic/endergonic. (Circle the correct choices.)

This reaction has a negative delta G and is exergonic.

Describe what happens when NAD+ is reduced. What enzyme type is involved?

When NAD+ is reduced, it becomes NADH and the enzyme involved is dehydrogenase.

What is the role of the electron transport chain in forming the H+ gradient across the inner mitochondrial membrane?

When energy is released, the electrons here go down the electron transport chain and then a gradient is present when the H+ can move from the matrix of the mitochondria to the intermembrane space.

Two key terms are chemiosmosis and proton-motive force. Relate both terms to the process of oxidative phosphorylation.

With the electron transport chain also comes the presence of a H+ concentration gradient and the potential energy here is proton-motive force, while chemiosmosis utilizes this factor in order to power the synthesis of ATP.

Cholorplast

a plastid that contains chlorophyll and in which photosynthesis takes place

Other way is say glycolysis is

citric acid cycle

cofactors

non- protein chemical compound that is bound to a protein and is required for enzyme activity

Disadvantages

requires more energy

Photosynthesis ...

uses energy from sunlight to make food

Redox Reactions: Oxidation and Reduction

-The transfer of electrons during chemical reactions releases energy stored in organic molecules -This released energy is ultimately used to synthesize ATP

Be able to label a cholorplast

...

Explain how photorespiration can be a problem in agriculture.

Rice, wheat, and soybeans are C3 plants that are important in agriculture. When their stomata partially close on hot, dry days, C3 plants produce less sugar because the declining level of CO2 in the leaf starves the Calvin cycle, limiting growth.

Using 18O as the basis of your discussion, explain how we know that the oxygen released in photosynthesis comes from water.

Scientists confirmed van Niel's hypothesis that oxygen released from photosynthesis comes from water with the use of 18O, a heavy isotope, as a tracer to follow the fate of oxygen atoms during photosynthesis. The experiments showed that the O2 from plants was labeled with 18O only if water was the source of the tracer. If the 18O was introduced to the plant in the form of CO2, the label did not turn up in the released O2.

Suppose a large meteor hit the earth. How could smoke and soot in the atmosphere wipe out life far beyond the area of direct impact?

Smoke, soot, and dust in the atmosphere could block sunlight, and plants may not conduct photosynthesis at high enough levels to survive. No food source for all the other living organisms on the planet

Product of Photosystem II (P680): ATP

Some electrons from Photosystem II (P680) move on to PSI (P700) PSII in the chlorophyll molecules of the reaction-center complex. These electrons are sent to the primary electron acceptor and the ETC of PSII, and then to PSI where they are passed through the electron transport chain associated with PSI PSI makes NADPH by accepting the electrons from PSII and sending them to it's ETC

Inner membrane

fills the role of the inner mitochondrial membrane in electron transport and the chemiosmotic generation of ATP

Outer membrane

freely permeable to small molecules and ions which allows the concentration of molecules within the intermembrane space to be the same as within the cytosol.

The starting product of glycolysis is the six-carbon sugar and the ending products are two -carbon molecules of .

glucose, 3, pyruvate

Granum

increase the surface area of the thylakoids, which results in more light being absorbed into the chlorophyll (stack of pigment containing thylakoids)

Lamella

keeping all of the sacs a safe distance from each other and maximizing the efficiency of the organelle

Energy movement through cholorphyll

light energy bumps an electron in the cholorphyll molecule to a higher, excited energy level

Thylakoid

location of "photo" reactions, where light energy is converted into chemical energy

When compounds lose electrons, they _____ energy; when compounds gain electrons, they _____ energy.

lose, gain

the "photo" reaction

occurs in the thylakoids of the leaves cholorplasts

Stomata

open at night to take in CO2 and bind it ; completely closed during the day - think desert plants

As the citric acid cycle is completed what compound is regenerated?

oxaloacetate

Which strongly electronegative atom, pulling electrons down the electron transport chain, is the final electron acceptor?

oxygen

Fermentation allows the production of ATP without using either _____ or any .

oxygen, electron transport chain

Higher energy state

potential energy increases

What three organic macromolecules are often utilized to make ATP by cellular respiration?

proteins, carbs, and fats

A photosystem is composed of a protein complex called a (blank) complex surrounded by several (blank) complexes.

reaction center light-harvesting

The enzyme responsible for carbon fixation in the Calvin cycle, and possibly the most abundant protein on Earth, is .

rubisco

Photo reaction needs

sunlight and water (cholorphyll) produces ATP and NADPH (energy storing molecules) produces oxygen

"SYNTHESIS"

the captured energy of sunlight is used to make food (glucose)

Advantages

water loss is minimized in warm climates

Advantageous

when light energy is abundant and water is scarce (natural drought)

Comparing Fermentation with Anaerobic and Aerobic Respiration

-All use glycolysis (net ATP = 2) to oxidize glucose and harvest chemical energy of food -In all three, NAD+ is the oxidizing agent that accepts electrons during glycolysis -The processes have different final electron acceptors: an organic molecule (such as pyruvate or acetaldehyde) in fermentation and O2 in cellular respiration -Cellular respiration produces 32 ATP per glucose molecule; fermentation produces 2 ATP per glucose molecule

(Fermentation/Anaerobic Respiration) part 2

-Anaerobic respiration uses an electron transport chain with a final electron acceptor other than O2, for example sulfate -Fermentation uses substrate-level phosphorylation instead of an electron transport chain to generate ATP - phosphate is put on directly to the ADP

Electron Transport Chain part 3

-At the end, the electrons are at a lower energy and combine with oxygen and H+ ions to create water and ATP is formed from the H+ ion concentration gradient

ADAPTATIONS

-C4 Photosynthesis Advantageous when light energy is abundant and water is scarce (natural drought) -CAM Photosynthesis Stomata open at night to take in CO2 and bind it ; completely closed during the day -Plants in complete darkness Use geothermal heat or electromagnetic radiation instead of sunlight to make their own food

Redox in Cellular Respiration

-Cellular Respiration involves the breakdown of glucose to form pyruvate and ultimately ATP -Glycolysis is the redox reaction that oxidizes glucose and reduces oxygen to form

The Principle of Redox

-Chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions, or redox reactions -In oxidation, a substance loses electrons, or is oxidized -In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced)

Electron Transport Chain + chain & Chemiosmosis

-ETC accepts electrons from NADH and FADH2 -Uses energy from electrons to move H+ through hydrogen pumps in ETC -Some electrons are used in formation of water -Chemisomosis: formation of ATP at the ATP synthase enzyme

Cellular Respiration: Harvesting Chemical Energy

-Energy flows into an ecosystem as sunlight and leaves as heat -Photosynthesis generates O2 and organic molecules, which are used in cellular respiration -Cells use chemical energy stored in organic molecules to regenerate ATP, which powers work

Electron Transport Chain part 1

-FADH2 and NADH bring excited electrons to the ETC -Carrier molecules (FMN, Cytochromes C1, C, A, A3) in the electron transport chain move the high-energy electrons along and these electrons release energy each time they move

Regulation of Cellular Respiration via Feedback Mechanisms

-Feedback inhibition is the most common mechanism for control -If ATP concentration begins to drop, respiration speeds up; when there is plenty of ATP, respiration slows down -Control of catabolism is based mainly on regulating the activity of enzymes at strategic points in the catabolic pathway

Types of Fermentation

-Fermentation consists of glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysis -Two common types are alcohol fermentation and lactic acid fermentation

Glycolysis + Glycolysis harvests chemical energy by oxidizing glucose to pyruvate

-Glycolysis ("splitting of sugar") breaks down glucose into two molecules of pyruvate -Glycolysis occurs in the cytoplasm and has two major phases Energy investment phase Energy payoff phase -Glycolysis occurs whether or not O2 is present

Glycolytic Pathway

-Glycolytic pathway (Glycolysis) Conversion of glucose to carbon dioxide, water, heat and ATP energy C6H12O6 + 6 O2 = 6 CO2 + 6 H2O + heat + ATP -Glucose is broken down in a series of steps Each step is catalyzed by an enzyme -At specific steps 2 electrons and 2 protons (and 2 hydrogen atoms) are stripped from the glucose molecule by dehydrogenase enzymes (Glucose is Oxidized) -Hydrogen atoms serve as an "intermediate" electron carrier -Hydrogen takes the stripped electron and transfers it to the official electron carrier of the cell (NAD or FAD) -Dehydrogenase brings the H

Fermentation + Lactic acid and ethanol production (Fermentation/Anaerobic Respiration) part 1

-Most cellular respiration requires O2 to produce ATP -Without O2, the electron transport chain will cease to operate -In that case, glycolysis couples with fermentation or anaerobic respiration to produce ATP - pyruvate can stay in cytosol and is converted to waste products like lactic acid

Photosynthesis

-Occurs mostly in plants and some bacteria and algae (organisms with pigments that capture light) -Photosynthesis is the capture of sunlight energy and conversion of the photons in the sunlight to stored glucose and ultimately forms ATP energy -Energy is stored in the bonds of the glucose and released when converted to the useable form of energy (ATP)

Redox Reactions part 2

-Oxidation part of redox reaction = loss of electrons from one substance Reducing agent is the molecule that donates the electron -Reduction part of redox reaction = addition of electrons to a substance (i.e. adding a negatively charged electron to the molecule reduces the amt of positive charges for that molecule Oxidizing agent is the molecule that accepts the electron

The Versatility of Catabolism

-Proteins must be digested to amino acids; amino groups can feed glycolysis or the citric acid cycle -Fats are digested to glycerol (used in glycolysis) and fatty acids (used in generating acetyl CoA) -Fatty acids are broken down by beta oxidation and yield acetyl CoA -An oxidized gram of fat produces more than twice as much ATP as an oxidized gram of carbohydrate - fats need more oxygen molecules than carbs so they are oxidized more and thus yield more ATP

Krebs Cycle part 3

-Succinic acid is then modified to re-form as oxaloacetate to go on to breakdown a 2nd acetyl CoA -(Essentially the Krebs Cycle happens twice; one time for each Acetyl CoA that was formed by the pyruvate molecules) -When the 4 carbon molecule is re-formed it results in the generation of NADH and FADH2 (another high-energy electron carrier)

Catabolic Pathways and Production of ATP

-The breakdown of organic molecules is exergonic -Anaerobic Respiration: Fermentation is a partial degradation of sugars that occurs without O2 -Aerobic respiration consumes organic molecules (such as glucose) and O2 and yields ATP -Anaerobic respiration is similar to aerobic respiration but consumes compounds other than O2

The last idea in this challenging concept is how chemiosmosis works in photosynthesis. Describe four ways that chemiosmosis is similar in photosynthesis and cellular respiration.

1. In photosynthesis and cellular respiration, an electron transport chain assembled in a membrane pumps protons across the membrane as electrons are passed through a series of carriers that are progressively more electronegative. 2. In photosynthesis and cellular respiration, ATP synthase complex couples the diffusion of hydrogen ions down their gradient to the phosphorylation of ADP. 3. The inner membrane of the mitochondrion pumps protons from the mitochondrial matrix out to the intermembrane space, which then serves as a reservoir of hydrogen ions. The thylakoid membrane of the chloroplast pumps protons from the stroma into the thylakoid space (interior of the thylakoid), which functions as the H+ reservoir. 4.In the mitochondrion, protons diffuse down their concentration gradient from the inter- membrane space through ATP synthase to the matrix, driving ATP synthesis. In the chloroplast, ATP is synthesized as the hydrogen ions diffuse from the thylakoid space back to the stroma through ATP synthase complexes, whose catalytic knobs are on the stroma side of the membrane.

Explain what is meant by a C4 plant.

A plant in which the Calvin cycle is preceded by reactions that incorporate CO2 into a four-carbon compound, the end product of which supplies CO2 for the Calvin cycle.

anabolic vs catabolic

Anabolism requires energy to grow and build. - Catabolism uses energy to break down (These metabolic processes work together in all living organisms to do things like produce energy and repair cells)

Photosynthesis is not a single process, but two processes, each with multiple steps. a. Explain what occurs in the light reactions stage of photosynthesis. Be sure to use NADP+ and photophosphorylation in your discussion. b. Explain the Calvin cycle, using the term carbon fixation in your discussion.

A. The light reactions are the steps of photosynthesis that convert solar energy to chemical energy. Water is split, providing a source of electrons and protons (hydrogen ions, H+ ) and giving off O2 as a by-product. Light absorbed by chlorophyll drives a transfer of the electrons and hydrogen ions from water to an acceptor called NADP+ (nicotinamide adenine dinucleotide phosphate), where they are temporarily stored. The light reactions use solar power to reduce NADP+ to NADPH by adding a pair of electrons along with an H+ . The light reactions also generate ATP, using chemiosmosis to power the addition of a phosphate group to ADP, a process called photophosphorylation. B. The cycle begins by incorporating CO2 from the air into organic molecules already present in the chloroplast. This initial incorporation of carbon into organic compounds is known as carbon fixation. The Calvin cycle then reduces the fixed carbon to carbohydrate by the addition of electrons. The reducing power is provided by NADPH, which acquired its cargo of electrons in the light reactions. To convert CO2 to carbohydrate, the Calvin cycle also requires chemical energy in the form of ATP, which is also generated by the light reactions.

To summarize, note that the light reactions store chemical energy in ________ and _____ , which shuttle the energy to the carbohydrate-producing _ ___ cycle.

ATP NADPH Calvin cycle

Use this same figure to explain the correlation between an absorption spectrum and an action spectrum.

Absorption spectrum is the range of a pigment's ability to absorb various wavelengths of light; also a graph of such a range. Action spectrum is a graph that profiles the relative effectiveness of different wavelengths of radiation in driving a particular process.

Krebs Cycle part 2

Acetyl CoA (2 carbons) and Oxaloacetate (4 carbons) join to form a 6-carbon molecule (citric acid; citrate) Citric acid is further broken down to α-ketoglutaric acid (α-ketoglutarate) and succinic acid (succinate) In these reactions ATP, NADH and CO2 are made NADH takes electrons to the Electron Transport Chain (ETC) to make ATP

Photosynthesis vs. Cellular Respiration

Essentially, photosynthesis is the formation of glucose while cellular respiration is the breakdown of glucose photosynthesis 6 CO2 + 6 H2O + sunlight energy = C6H12O6 cellular respiration C6H12O6 + 6 O2 = 6 CO2 + 6 H2O + heat + ATP

Explain what has happened to the six carbons found in the original glucose molecule.

It is oxidized and two pyruvate molecules are the result here and they form NADH, FADH2, and ATP.

Examine Figure 10.18 in your text while we tally carbons. This figure is designed to show the production of one net G3P. That means the Calvin cycle must be turned three times. Each turn will require a starting molecule of ribulose bisphosphate (RuBP), a five-carbon compound. This means we start with carbons distributed in three RuBPs. After fixing three molecules of CO2 using the enzyme , the Calvin cycle forms six G3Ps with a total of carbons. At this point the net gain of carbons is , or one net G3P molecule.

Examine Figure 10.19 in your text while we tally carbons. This figure is designed to show the production of one net G3P. That means the Calvin cycle must be turned three times. Each turn will require a starting molecule of ribulose bisphosphate (RuBP), a five-carbon compound. This means we start with 15 carbons distributed in three RuBPs. After fixing three molecules of CO2 using the enzyme rubisco, the Calvin cycle forms six G3Ps with a total of 18 carbons. At this point the net gain of carbons is 3, or one net G3P molecule.

Explain the difference between fermentation and aerobic respiration.

Fermentation : is a partial degradation of sugars or other organic fuel that occurs without the use of oxygen Aerobic respiration : with oxygen uses energy (ATP) to make sugars (carbohydrates)

Glycolysis is thought to have evolved very early in the evolution of life on Earth. Provide three pieces of evidence that justify this hypothesis.

Glycolysis evolved very early and evidence of this is that it is the most widespread metabolic pathway in organisms on Earth. Glycolysis occurs in the cytoplasm of the cell, which suggests that it is of great age. In the eukaryotic cell, there are organelles that have membranes and these came into evaluation about 1 billion years after the prokaryotic cell, glycolysis does not require these, which suggests that it evolved very early in the evolution of life on Earth.

What is the meaning of glycolysis? What occurs in this step of cellular respiration?

Glycolysis means "sugar splitting" and in this step of cellular respiration, glucose is split into two three carbon sugars.

Oxygen stabilizes the electrons by combining with two hydrogen ions to form what compound?

H2O

Describe how he determined an action spectrum long before the invention of a spectrophotometer.

In 1883, Theodor W. Engelmann illuminated a filamentous alga with light that had been passed through a prism, exposing different segments of the alga to different wavelengths. He used aerobic bacteria, which concentrate near an oxygen source, to determine which segments of the alga were releasing the most O2 and thus photosynthesizing most. Bacteria congregated in greatest numbers around the parts of the alga illuminated with violet-blue or red light.

Three turns of the Calvin cycle nets one G3P because the other five G3Ps must be recycled to three RuBPs. Explain how the regeneration of RuBP is accomplished.

In a complex series of reactions, the carbon skeletons of five molecules of G3P are rearranged by the last steps of the Calvin cycle into three molecules of RuBP. To accomplish this, the cycle spends three more molecules of ATP. The RuBP is now prepared to receive CO2 again, and the cycle continues

Explain the difference in energy usage between the catabolic reactions of cellular respiration and the anabolic pathways of biosynthesis.

In cellular respiration, ATP is synthesized via energy but in biosynthesis, other molecules are synthesized via the energy present in ATP.

What is the function of the electron transport chain in cellular respiration?

In cellular respiration, the electron transport chain is responsible for the moving of electrons down redox reactions which release that acts in the production of ATP.

Three types of phosphorylation (adding a phosphate) are covered in the text, and two of these occur in cellular respiration. Explain how the electron transport chain is utilized in oxidative phosphorylation.

In oxidative phosphorylation energy is released via redox reactions and the energy brings about a concentration gradient across the membrane on the inside of the mitochondria and ATP synthesis is caused by chemiosmosis.

Phosphofructokinase is an allosteric enzyme that catalyzes an important step in glycolysis. Explain how this step is a control point in cellular respiration.

It is a control point in cellular respiration because is aids in the synching of glycolysis and the citric acid cycle

Notice the colors and their corresponding wavelengths. Explain the relationship between wavelength and energy.

Light is a form of energy known as electromagnetic energy, also called electromagnetic radiation. Electromagnetic energy travels in rhythmic waves analogous to those created by dropping a pebble into a pond. Electromagnetic waves, however, are disturbances of electric and magnetic fields rather than disturbances of a material medium such as water. The distance between the crests of electromagnetic wave sis called the wavelength.

Stroma

Location of "synthesis reaction, where chemical energy is synthesized into sugar (calvin cycle)

For aerobic respiration to continue, the cell must be supplied with oxygen—the ultimate electron acceptor. What is the electron acceptor in fermentation?

NAD+

Na means Cl means

Na loses an electron = (+) charge Sodium is oxidized Cl gains an electron = (-) charge Chlorine is reduced

Some of the types of energy in the electromagnetic spectrum will be familiar, such as X-rays, microwaves, and radio waves. The most important part of the spectrum in photosynthesis is visible light. In order, what are the colors of the visible spectrum?

Red, Orange, Yellow, Green, Blue, Indigo, Violet

NAD+

Oxidized or Reduced? Oxidized Higher Energy/Lower Energy Lower energy

Explain why oxygen is considered the ultimate electron acceptor

Oxygen itself is very electronegative in nature.

What is the name of the chlorophyll a at the reaction center of PS I?

P700

Photosystem II (PSII) has at its reaction center a special pair of chlorophyll a molecules called P680. What is the explanation for this name?

Perhaps you caught that the reaction center molecules for photosystem I are a special pair of chlorophyll molecules called P700. So, the question has a mistake—but the response should be either to note this error, and explain what is meant by P700, or note the error and explain that P680 molecules form the reaction center for photosystem II. These reaction center molecules (either P680 or P700) are named for the wavelengths of light that are most effectively absorbed by each (680 nm or 700 nm)

What molecule is the "pacemaker" of cellular respiration?

Phosphofructokinase

Product #2 Photosystem I (P700): NADPH

Photosystems II and I work together to make ATP and NADPH: both are needed for the synthesis part of photosynthesis

Alcohol fermentation starts with glucose and yields ethanol. Explain this process, and be sure to describe how NAD+ is recycled.

Pyruvate becomes ethanol in this process because CO2 is released from pyruvate and then NAD+ and ethanol are present. After this, NAD+ is recycled because it has the ability to be used in glycolysis after this.

Completely label the following figure and then explain why pyruvate is a key juncture in metabolism.

Pyruvate is a key juncture in metabolism because in regards to fermentation and aerobic cellular respiration, it is what decides what will occur based upon the presence or lack of oxygen in this process.

Explain how and where each of these molecules may enter the process of cellular respiration:

Starch - during glycolysis Glycogen - during glycolysis Proteins - outside the mitochondrion (mitochondria) + during glycolysis Fats - during glycolysis

Explain this statement: "Only the green cells of a plant are the autotroph while the rest of the plant is a heterotroph."

Technically, green cells are the only autotrophic parts of the plant. The rest of the plant depends on organic molecules exported from leaves via veins. In most plants, carbohydrate is transported out of the leaves in the form of sucrose, a disaccharide.

Explain the important events that occur in the carbon fixation stage of the Calvin cycle.

The Calvin cycle incorporates each CO2 molecule, one at a time, by attaching it to a five- carbon sugar named ribulose bisphosphate. The enzyme that catalyzes this first step is RuBP carboxylase, or rubisco. The product of the reaction is a six-carbon intermediate so unstable that it immediately splits in half, forming two molecules of 3-phosphoglycerate

Use Figure 9.13 in your text of ATP synthase to explain and label the five steps to the production of ATP.

The H+ ions that are going down their gradient go in a channel in a stator in the membrane. The H+ ions go into binding sites in a rotor and the subunit shapes are altered and allow the rotor to rotate along with the membrane. The H+ ions go around once and then leave the rotor and go through another channel to the matrix of the mitochondria. A rod spins due to the rotor spinning and the rotor extends in a knob underneath of it, which does not move because of the stator. Catalytic sites become active due to the rod rotating and this is in the knob and causes the production of ATP which comes from ADP and also Pi.

Study Figure 9.19 in your text. Explain how AMP stimulates cellular respiration, whereas citrate and ATP inhibit it.

The accumulation of AMP denotes that more ATP is needed which stimulates cellular respiration but the buildup of ATP impedes the enzyme and glycolysis so therefore cellular respiration is inhibited due to this.

Where is light-dependent reaction of a cholorplast and The light-independent reaction

The light-dependent reaction occurs: thylakoid membrane The light-independent reaction occurs: Stroma

Why is the total count about 30 or 32 ATP molecules rather than a specific number?

The ratio of NAD+ to ATP isn't a whole number therefore the yield is not a specific number. The result also can be different based on the shuttle used.

Use two key differences to explain how chemiosmosis is different in photosynthesis and cellular respiration.

There are noteworthy differences between oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts. In mitochondria, the high-energy electrons dropped down the transport chain are extracted from organic molecules (which are thus oxidized), whereas in chloroplasts, the source of electrons is water. Chloroplasts do not need molecules from food to make ATP; their photosystems capture light energy and use it to drive the electrons from water to the top of the transport chain. In other words, mitochondria use chemiosmosis to transfer chemical energy from food molecules to ATP, whereas chloroplasts transform light energy into chemical energy in ATP.

Track coaches used to think that lactic acid accumulated in the muscles as a result of intense exertion, and would have athletes slowly jog to move more oxygen into the muscles so lactic acid would be oxidized and there would be less soreness the next day. What is currently known about lactate production and muscle soreness?

When carbohydrate catabolism is faster than the supply of O2 that goes to the muscles, the lactate is not oxidized to pyruvate. According to research, lactate production can be good for the performance of a person when they work out

The citric acid cycle: a. How many NADHs are formed? b. How many total carbons are lost as pyruvate is oxidized? c. The carbons are lost in which molecule? d. How many FADH2 are formed? e. How many ATPs are formed? f. How many times does the citric acid cycle occur for each molecule of glucose?

a 3 b 2 c carbon dioxide d 1 e 1 f 2

Explain the three steps in the conversion process

a. -COO- becomes fully oxidized and is released as CO2 b. The two-carbon fragment that is left over becomes oxidized and the electrons from this move to NAD+ and energy is stored as NADH. C. CoA forms acetyl CoA and high a larger amount of potential energy.

Electron transport involves a series of electron carriers, mostly proteins. a. Where are these carrier molecules found in eukaryotic cells? b. Where are the carrier molecules found in prokaryotic cells?

a. In the mitochondrial membrane b. In the plasma membrane

Explain the role of the components of the photosystem listed below

a. Reaction-center complex (This complex of proteins associated with a special pair of chlorophyll a molecules and a primary electron acceptor. Located centrally in a photosystem, this complex triggers the light reactions of photosynthesis. Excited by light energy, the pair of chlorophylls donates an electron to the primary electron acceptor, which passes an electron to an electron transport chain) b. Light-harvesting complex (This complex of proteins associated with pigment molecules (including chlorophyll a, chlorophyll b, and carotenoids) that captures light energy and transfers it to reactioncenter pigments in a photosystem) c. Primary electron acceptor (In the thylakoid membrane of a chloroplast or in the membrane of some prokaryotes, the primary electron acceptor is a specialized molecule that shares the reaction center complex with a pair of chlorophyll a molecules and that accepts an electron from them)

The following set of questions deals with linear electron flow:

a. What is the source of energy that excites the electron in photosystem II? (light) b. What compound is the source of electrons for linear electron flow? (water) c. What is the source of O2 in the atmosphere? (splitting of water) d. As electrons fall from photosystem II to photosystem I, the cytochrome complex uses the energy to pump hydrogen ions. This builds a proton gradient that is used in chemiosmosis to produce what molecule? (ATP) e. In photosystem I, NADP+ reductase catalyzes the transfer of the excited electron and H+ to NADP+ to form .

aerobic and anaerobic processes

aerobic - presence of oxygen ( with oxygen) anaerobic - absence of oxygen (without oxygen)