Cellular Respiration: Harvesting Chemical Energy & Photosynthesis: Converting Light Energy to Chemical Energy Test

ATP

(adenosine triphosphate) Main energy source that cells use for most of their work It is made of an organic molecule called adenosine plus a tail of three phosphate groups.

What do people in favor of cutting down old trees argue?

That replacing the old trees with seedlings would increase photosynthesis and reduce atmospheric CO2.

How do special enzymes enable C4 and CAM plants to conserve water during photosynthesis?

By allowing photosynthesis to continue even when stomata are closed during dry conditions

What absorbs energy in the thylakoids?

Chlorophyll built into the thylakoid membranes

The green color in plants is from what?

Chlorophyll pigments in the chloroplasts

What is built into the thylakoid membranes and especially grana, where thylakoids are stacked?

Chloroplast pigments that are part of the light-harvesting complexes called photosystems

Photosystem

Cluster of chlorophyll and proteins found in thylakoids Includes a few hundred pigments, including chlorophylls a and b and carotenoids - functions as a light-gather antenna.

Cellular respiration is a type of

Combustion reaction that occurs very slowly

Creatine phosphate

Compound that serves as an alternative energy source for muscle tissue and can keep the muscles cells working for about 10 seconds

Light reactions

Converts solar energy to chemical energy, splits water, making O2 and NADPH

Examples of C4 plants

Corn, sorghum, and sugarcane All three of them evolved in hot regions of the tropics where there are dry seasons.

What does CAM stand for?

Crassulacean Acid Metabolism

What were the first organisms to undergo photosynthesis?

Cyanobacteria (added oxygen to the atmosphere)

Where does Glycolysis occur?

Cytosol

Extensive deforestation may...?

Decrease the amount of plants undergoing photosynthesis, thus reducing the amount of organisms counteracting carbon dioxide emissions.

Glycolysis and the Krebs cycle use what to make ATP?

Direct Synthesis

Photons

Discrete particles of light A fixed quantity of light energy

CAM plants are most adapted to what kind of environment?

Dry

What problem do farmers face when growing C3 plants?

Dry weather can reduce the rate of photosynthesis and decrease crop productivity. On a hot, dry day, plants close their stomata (the pores in the leaf surface) to reduce water loss. However, this also prevents CO2 from entering the leaf. As a result, CO2 levels can get very low in the leaf and sugar production consequently ceases.

What stage of cellular respiration uses oxygen to directly extract chemical energy from organic compounds?

Electron Transport

It is ______ ______ from NADH to oxygen that releases the energy your cells use to make most of their ATP.

Electron transport

What is the third stage of cellular respiration?

Electron transport

NADH transfers electrons and hydrogen to oxygen through which process?

Electron transport chain

Electron transport

Electrons captured from food by NADH "fall" down electron transport chains to oxygen. The proteins and other molecules that make up electron transport chains reside within mitochondria.

How does isolated chlorophyll behave?

Emit light as well as heat after absorbing photons.

ATP provides the _________ to link amino acids.

Energy

Conservation of Energy

Energy cannot be created nor destroyed. However, it can be converted from one form to another.

When hydrogen and its bonding electrons change partners, from sugar to oxygen...?

Energy is released

Potential Energy

Energy that an object has because of its location or arrangement.

Glycolysis generates ATP when

Enzymes transfer phosphate groups directly from fuel molecules to ADP.

At a cellular level, human muscle cells, like yeast cells, behave as

Facultative Anaerobes

Yeast is an example of a

Facultative anaerobe

The anaerobic harvest of food energy is called

Fermentation

The Calvin cycle depends on light in what way?

Indirectly - it depends on the supply of ATP and NADPH produced by the light reactions

Glycolysis and the Krebs Cycle generate a small amount of ATP directly. They generate much more ATP __________...?

Indirectly, via redox reactions that transfer electrons from fuel molecules to NAD+.

Where does electron transport occur?

Inner mitochondrial membrane

Work is performed whenever an object

Is moved against an opposing force.

Why is oxygen reduced during cellular respiration?

It accepts electrons lost from glucose (which is oxidized)

What does glycolysis do?

It breaks the six-carbon glucose in half, forming three-carbon molecules. These molecules then donate high energy electrons to NAD+, the electron carrier. Glycolysis also makes some ATP directly when enzymes transfer phosphate groups from fuel molecules to ADP. What remains of the fractured glucose at the end of glycolysis are two molecules of pyruvic acid.

How can an object at rest have energy?

It can have potential energy because of its location or structure.

What is visible light to us (small fraction of the spectrum)?

It consists of the wavelengths that our eyes see as different colors

What is the overall effect of all of this electron traffic during cellular respiration?

It creates a downhill trip for electrons from glucose to oxygen via NADH and electron transport chains. It is the freeing of chemical energy during electron transport that our cells use to make most of their ATP.

Cellular Respiration

It harvests energy that is stored in sugars and other organic molecules. It uses oxygen to help convert energy extracted from organic fuel to another form of chemical energy called ATP.

What is misleading about the following statement? "Plants do photosynthesis and animals do cellular respiration."

It implies that cellular respiration does not occur in plants, but it does.

Where is ATP synthase located?

It is built into the inner mitochondrial membrane, the same membrane where electron transport chains are located.

Lactic Acid movement in muscle cells to the rest of the body

It is transported in the blood from the muscles to the liver, where liver cells convert the lactic Acid back to pyruvic acid. This requires oxygen, so fermentation in muscles results in an "oxygen-debt."

What does the Calvin Cycle contribute to the light reactions?

NADP+ and ADP + P

What provides the high-energy electrons for the reduction of carbon dioxide to sugar?

NADPH

NADPH

Nicotinamide adenine dinucleotide phosphate Chemical cousin of NADH and is an electron carrier

Breathing

Not the same as cellular respiration Exchanges oxygen and carbon dioxide between blood and the outside air

For each CO2 molecule it consumes, how many O2 molecules does a plant release to the atmosphere?

One

What happens when a pigment molecule absorbs a photon?

One of the pigment's electrons gains energy - the electron has been raised from a ground state to an excited state.

CAM Plants

Open their stomata at night, incorporating CO2 into organic acids

NAD+ (nicotinamide adenine dinucleotide)

Organic molecule that serves as an electron carrier by being oxidized to NAD+ and reduced to NADH

Obligate Aerobes

Organisms that are dependent on oxygen and cellular respiration to stay alive.

Obligate Anaerobes

Organisms that are poisoned by oxygen Examples are certain bacteria that live in stagnant ponds or deep in the soil.

Heterotrophs

Organisms that cannot make organic molecules from inorganic ones. Therefore, they depend on autotrophs for their organic fuel and material for growth and repair. In Greek: "other-feeders"

Producers

Organisms that make their own food and are the source of all food in any ecosystem

Producers

Organisms that make their own food through photosynthesis The organic material that they produce nourishes them and also supplies food for other organisms

What is another name for redox reactions?

Oxidation-reduction reactions

What molecules are oxidized and reduced during cellular respiration?

Oxidized: Glucose Reduced: Oxygen

Glycolysis does not require

Oxygen

Many prokaryotes died due to the exposure to

Oxygen

What makes electron grabbing possible during cellular respiration?

Oxygen. By pulling electrons down the transport chain from fuel molecules, oxygen functions somewhat like gravity pulling downhill.

Photosystem I

P700, makes NADPH, does not take place first, transfers electrons It produces NADPH by transferring light-excited electrons from chlorophyll to NADP+. An electron transport chain connecting the two photosystems releases energy that the chloroplast uses to make ATP.

All green parts of a plant have chloroplasts and can carry out

Photosynthesis

Natural selection has refined...?

Photosynthetic adaptations that enable certain plants to continue producing food even in arid conditions

Plants usually make more organic molecules than they need. This...?

Photosynthetic surplus provides organic material for the plant to grow and is also the source of food for humans and other consumers.

When a photon strikes one pigment molecule, the energy jumps from

Pigment to pigment until it arrives at the reaction center of the photosystem

By pumping H+ ions, electron transport chains store

Potential energy by making the ions more concentrated on one side of the membrane than the other.

C4 Plants

Precede the Calvin Cycle by first fixing CO2 into a four-carbon compound. Saves water without shutting down photosynthesis.

Photolysis

Process by which light energy breaks down a water molecule

Anaerobic

Process that does not require oxygen

Sunlight is a type of energy called

Radiation or electromagnetic energy

In chemical work...?

Reactants are utilized to form products

What do chloroplasts do with the materials?

Rearranges the atoms of these organic ingredients to produce sugars and other organic molecules.

Is oxygen reduced or oxidized in cellular respiration?

Reduced

The chemical energy that cellular respiration harvests from sugars and other organic fuels is put to work...?

Regenerating a cell's supply of ATP

Is ATP a renewable or nonrenewable resource?

Renewable

Anaerobic respiration

Respiration in the absence of oxygen. This produces lactic acid.

Do old trees or seedlings require more CO2?

Seedlings

Redox process in photosynthesis

Since hydrogen is moved along with electrons, the redox process takes the form of hydrogen transfer from water to carbon dioxide. This requires the chloroplast to split water molecules into hydrogen and oxygen.

The biosphere is

Solar powered

Examples of fermentation in food

Soybeans to soy sauce, cucumbers into pickles, and cabbage into sauerkraut

What is the job of the Calvin Cycle?

Spends the ATP and NADPH produced by the light reactions to produce sugar

What provides the energy for sugar synthesis?

The ATP generated by the light reactions

In all plants, what is ultimately responsible for sugar synthesis?

The Calvin Cycle

C3 Plants

The Calvin Cycle uses CO2 directly from the air Named "C3" because the first organic compound produced is the three-carbon compound 3-PGA. They are common and widely distributed Examples include soybeans, oats, wheat, and rice

In terms of spatial organization of photosynthesis within the chloroplast, what is the advantage of the light reactions producing NADPH and ATP on the stroma side of the thylakoid membrane?

The Calvin cycle, which consumes the NADPH and ATP, occurs in the stroma.

The oxidation of acetic acid by NAD+ extracts some chemical energy from the acetic acid. How can the cell harness that energy to make ATP?

The NADH can supply electrons to the electron transport chain, which generates a hydrogen ion gradient that drives ATP synthesis.

Reduction

The acceptance of electrons during a redox reaction (gives a negative charge)

Calorie

The amount of energy that raises the temperature of 1 gram (g) of water 1 degree Celsius.

Energy

The capacity to perform work

A glucose-fed yeast cell is moved from an aerobic environment to an anaerobic one. If the cell continues to generate ATP at the same rate, how will its rate of glucose consumption compare with its consumption in the aerobic environment?

The cell must consume glucose at a rate of about 19 times the consumption rate in the aerobic environment (2 ATPs by fermentation versus 38 ATPs by cellular respiration).

Cellular respiration requires the exchange of what two gases?

The cell takes in oxygen and releases carbon dioxide

Glycolysis

Splits glucose into two three-carbon molecules (pyruvate) and has a net gain of two molecules of ATP Enzymes are located in the cytosol

What does the word glycolysis mean?

Splitting of sugar

Mesophyll

Spongy green tissue in the interior of the leaf where most chloroplasts are found.

Grana

Stacks of thylakoids embedded in the stroma of a chloroplast.

Polysaccharides and Cellular Respiration

Starts at Glycolysis

Proteins and Amino Acids - Cellular Respiration

Starts at the Krebs Cycle

Light reactions do not produce

Sugar

Energy enters as

Sunlight

Wavelength

The distance between the crests of two adjacent waves

Walking at 3 miles per hour (mph), how long would you have to walk to burn off three slices of pepperoni pizza (181 kcal)? How far would you have to travel?

You would have to walk about 3.4 hours, traveling 10.3 miles.

During moderate exercise, ________.

Your muscle cells are operating under aerobic conditions because the oxygen supply to your cells can keep pace with your activity level

Aerobic process

A metabolic process that requires oxygen

Xanthophyll

A photosynthetic antenna pigment common in algae that is a structural variant of a carotenoid It is typically of a yellow coloration

How much of the air does carbon dioxide make up?

0.03% Helps to moderate world climates - retains heat from the sun that would otherwise radiate back to Earth

The Calvin Cycle

1. Carbon enters the cycle as CO2. An enzyme adds the CO2 to RuBP (ribulose biphosphate), a five-carbon sugar already present in the chloroplast. The product then breaks into a three-carbon compound called 3-PGA (3-phosphoglyceric acid). 2. ATP and NADPH from the light reactions provide energy and electrons. Enzymes use the ATP energy and high-energy electrons from NADPH to convert the 3-PGA to a three-carbon sugar, G3P (glyceraldehyde-3-phosphate). 3. Carbon exits the cycle as sugar. The cycle has converted three CO2 molecules to one molecule of the sugar G3P. This is the direct product of photosynthesis, but plant cells can use the G3P to make glucose and other organic compounds for growth and fuel. 4. The cycle regenerates its starting material. Although 6 G3P are produced in step 3, there is a net sugar output of only 1. That's because the cycle started with a total of 15 sugar carbons in the three RuBP molecules that accepted CO2 in step 1. Enzymes now regenerate the RuBP by rearranging the five G3P molecules that are left after one of those sugars exits the cycle.

Link between Glycolysis and the Krebs Cycle Steps

1. Each pyruvic acid (two per starting glucose) loses a carbon as CO2. The remaining fuel molecules, each with only two carbons left, are called acetic acid (same acid in vinegar). 2. Oxidation of the fuel generates NADH 3. The acetic acid is attached to an adapter molecule called Coenzyme A (CoA) to form acetyl-CoA. The CoA escorts the acetic acid into the first reaction of the Krebs Cycle.

Steps of the Krebs Cycle

1. Input includes fuel in the form of acetic acid from acetyl-CoA. It joins a four-carbon acceptor molecule to form a six-carbon product. For every acetic acid molecule that enters the cycle this way as fuel, 2. Two CO2 molecules eventually exit as waste product. Along the way, the Krebs Cycle harvests energy from the fuel. 3. Some of the energy is used to produce ATP directly. 4. Most of the energy is trapped by NADH. 5. FADH2 is another electron carrier that works similarly to NADH 6. All the carbon atoms that entered the cycle as fuel are accounted for as CO2 exhaust, and the four-carbon acceptor molecule is recycled. The Krebs Cycle turns twice for each glucose molecule that fuels a cell.

Steps of how electron transport drives ATP Synthase

1. NADH transfers electrons from food to electron transport chains 2. Electron transport chains use this energy supply to pump H+ ions across the inner membrane of the mitochondrion. The infoldings (cristae) of the inner membrane increase surface area, maximizing the number of electron transport chains that are built into the membrane. 3. The function of oxygen is to pull electrons down the transport chain 4. The H+ ions flow back through an ATP Synthase. This spins a part of the Synthase 5. The ATP Synthase uses the energy of the H+ gradient to generate ATP from ADP

The sun converts about ______ million metric tons of matter to energy each minute.

120

How many photosystems work together in light reactions?

2

Glycolysis produces

2 ATP

The Krebs Cycle produces

2 ATP

When did Cyanobacteria evolve?

2.5 to 3.4 billion years ago

Muscle cells have enough ATP to support anaerobic activity for about

5 seconds

Photosynthesis equation

6CO2 + 6H2O + light energy -> C6H12O6 + 6O2 + heat energy

What is the potential energy source that directly drives ATP production by ATP synthase?

A concentration gradient of hydrogen ions across the inner membrane of a mitochondrion

The chloroplast has what kind of membrane?

A double-membrane envelope

Chlorophyll

A green pigment found in the chloroplasts of plants, algae, and some bacteria

Entropy

A measure of disorder or randomness.

Combustion

A rapid reaction between oxygen and fuel that results in fire

Metabolic pathway

A series of linked reactions where a specific enzyme catalyzes each reaction

Excited State

A state in which an atom has a higher potential energy than it has in its ground state It is very unstable, and generally the electron loses the excess energy and falls back to its ground state almost immediately.

Describe glycolysis

A team of enzymes splits glucose, eventually forming two molecules of pyruvic acid. Along the way, energy is stored as ATP and NADH. To get glycolysis started, the cell has to invest some ATP. Enzymes attach phosphate groups to the fuel molecules during this energy investment phase. That investment is laid back with dividends during the energy harvest phase. Glycolysis generates some ATP directly, but it also donates high-energy electrons to NAD+, forming NADH.

Stroma

A thick fluid enclosed by the inner membrane of a chloroplast where sugars are made from carbon dioxide.

In transport work...?

A transport protein is used to transport a solute across a membrane

Kilocalorie

A unit of energy equal to 1,000 calories

In addition to conveying electrons from the water-splitting photosystem to the NADPH-producing photosystem, the electron transport chains of chloroplasts also provide the energy for the synthesis of

ATP

Another team of molecules built in the thylakoid membrane then uses the trapped energy by the Primary Electron Acceptor to make

ATP and NADPH

For chloroplasts to produce sugar from carbon dioxide in the dark, they would require an artificial supply of...?

ATP and NADPH

What do the light reactions contribute to the Calvin Cycle?

ATP and NADPH

Example of chemical work

ATP drives the chemical work of making a cell's giant molecules. An example is the linking of amino acids to make a protein.

Example of transport work

ATP enables brain cells to pump ions across their membranes. This prepares the brain cells to transmit signals.

ATP and cilia

ATP energizes proteins in cilia that line the human windpipe. The beating cilia remove mucus that has trapped dust, pollen, and other inhaled debris.

Electron Transport uses what to produce ATP?

ATP synthase

Explain how ATP powers cellular work.

ATP transfers a phosphate group to another molecule, increasing that molecule's energy content

ATP and motor proteins

ATP transfers phosphate groups to special motor proteins. The proteins change their shape, causing the muscle cells to contract.

Speed of the ATP Cycle

About 10 million ATP molecules are spent and regenerated per second per cell.

Electron Transport produces

About 34 ATP

For each glucose molecule ____ ATPs are made

About 38

Maximum amount of ATP per glucose molecule

About 38 ATP

How many reactions occur in cellular respiration?

About two dozen

Mechanical work, transport work, and chemical work all require...?

Target molecules to accept phosphate from ATP. Special enzymes catalyze these phosphate transfers that energize the working parts of cells.

Chlorophyll-b

Absorbs mainly blue and orange light Reflects/appears yellow-green It does not participate directly in the light reactions, but it broadens the range of light that a plant can use by conveying absorbed energy to chlorophyll-a, which then puts the energy to work in the light reactions.

Chlorophyll-a

Absorbs mainly blue-violet and red light It looks grass-green because it reflects green light Participates directly in the light reactions

In a series of redox reactions, each member of the chain can first

Accept and then donate electrons. The electrons give up a small amount of energy with each transfer.

At the uphill end, the first molecule of the electron transport chain

Accepts electrons from NADH

ATP can be restored by

Adding a phosphate group back to ADP

ADP

Adenosine diphosphate; molecule that ATP becomes when it gives up one of its three phosphate groups

Cellular respiration is what kind of process?

Aerobic

Metabolism

All of the chemical reactions that occur within an organism

Consumers

All of their food traces back to producers

What makes cutting trees down dangerous for the environment?

Along with getting rid of an organism that does photosynthesis, decomposition and conversion into commercial products that will be burned results in more CO2 being released into the air than young trees can take up.

Thylakoids

An elaborate system of disk-like membranous sacs suspended in the stroma.

How is ATP made from light reactions?

An electron transport chain pumps hydrogen ions across a membrane, the inner mitochondrial membrane for cellular respiration or the thylakoid membrane for photosynthesis. ATP synthases use the energy stored by the hydrogen gradient to make ATP.

A very rapid electron transfer generates...?

An explosive release of energy in the form of heat and light

Autotrophs

An organism that makes all of its own organic matter from inorganic nutrients. In Greek: "self-feeders"

Consumers

An organism that obtains energy and nutrients by feeding on plants or animals that have eaten plants.

Facultative Anaerobe

An organism with the metabolic versatility to harvest food energy by either respiration or fermentation.

The role of glycolysis in both fermentation and respiration - evolutionary link

Ancient bacteria probably used glycolysis to make ATP long before oxygen was present in Earth's atmosphere. The oldest known fossils date back to 3.5 billion years, but oxygen did not significantly accumulate in the atmosphere until 2.5 billion years ago. Since glycolysis is the most widespread metabolic pathway, it occurs in the cytosol and not the mitochondria, and does not require oxygen, it indicates evolution.

How does light also behave?

As discrete packets of energy called photons

Explain the greenhouse effect.

Atmospheric carbon dioxide allows sunlight through, which heats Earth's surface, but the carbon dioxide slows the escape of the heat back into space.

Why are heterotrophs called consumers?

Because they must acquire organic material by consuming it rather than making it

How does the Krebs Cycle finish extracting energy of sugar?

By breaking the acetic acid molecules (two per glucose) all the way down to CO2. The cycle uses some of this energy to make ATP by the direct method. However, the Krebs Cycle captures much more energy in the form of NADH and a second electron carrier, FADH2. Electron transport then converts NADH and FADH2 energy to ATP energy.

How do CAM plants conserve water?

By opening its stomata and admitting CO2 mainly at night. When CO2 enters the leaves, it is incorporated into a four-carbon compound, as in C4 plants. The four-carbon compound in a CAM plant banks CO2 at night and releases it to the Calvin Cycle during the day, which keeps photosynthesis operating during the day (even though the leaf admits no more CO2 because the stomata are closed).

How might the combustion of fossil fuels and wood be contributing to global warming?

By raising concentrations of atmospheric CO2 and increasing the greenhouse effect.

The atmospheric oxygen we breathe and use for cellular respiration is a

By-product of the water-splitting step of photosynthesis.

How do C4 plants continue to undergo photosynthesis?

C4 plants contain an enzyme that incorporates carbon from CO2 into a four-carbon compound instead of 3-PGA. This enzyme has an intense affinity for CO2 and can continue to mine it from the air spaces of the leaf even when the stomata are closed. The four-carbon compound produced proceeds to donate the CO2 to the Calvin Cycle in a nearby cell, which therefore keeps on making sugars even though the plant's stomata are closed.

Inputs of the Calvin Cycle

CO2, ATP, NADPH

Examples of CAM plants

Cacti, pineapples, succulent plants (such as ice plants and jade plants)

What stage of photosynthesis makes sugar from carbon dioxide?

Calvin cycle

Chloroplasts

Capture energy from sunlight and use it to produce food for the cell They trap light energy and use it to produce sugars and other energy-rich organic molecules.

What are some other molecules that can serve as fuel for cellular respiration?

Carbohydrates, fats, and proteins

What is reduced in photosynthesis?

Carbon dioxide

Ingredients of Photosynthesis

Carbon dioxide and water

Waste products of cellular respiration

Carbon dioxide and water

What are the chemical ingredients for photosynthesis?

Carbon dioxide and water

When substances are burned, what is released?

Carbon dioxide and water

Animals and plants can both perform

Cellular Respiration

What process mainly harvests chemical energy from food and converts it to ATP energy?

Cellular Respiration

Yeast, a microscopic fungus, is capable of both

Cellular respiration and fermentation

Photosynthesis takes the products of

Cellular respiration and rearranges its atoms to produce food and oxygen.

The role of oxygen in harvesting food energy

Cellular respiration combines oxygen and hydrogen to produce water and breaks up the "fall" of electrons from food to oxygen into steps. 1. NADH transfers electrons from food to an electron transport chain 2. Oxygen pulls the electrons down the chain 3. Cells use the stepwise release of energy to make ATP 4. The oxygen combines with the electrons and hydrogen from food to produce water

Cells have an ATP cycle where...?

Cellular work spends ATP, which is recycled from ADP and phosphate using energy from food

Chloroplasts are able to convert some of the solar energy they absorb into

Chemical energy

What is the source of energy for regenerating ATP from ADP?

Chemical energy harvested from sugar and other organic fuels via cellular respiration

In tracking photons in a chloroplast, light reactions convert solar energy to the

Chemical energy of ATP and NADPH

Redox reactions

Chemical reactions that transfer electrons from one substance to another

Main difference between the Light Reaction and Cellular Respiration in the making of ATP

Food provides the high-energy electrons in cellular respiration, while it is light-excited electrons that flow down the transport chain during photosynthesis.

Old growth forests

Forest that has never been cut and replanted; original forest Contain a lot of marketable lumber Conservationists argue that these forests are home to many species of plants and wildlife that can survive nowhere else and that we should save these remnants of our ancient forests for future generations.

Outputs of the Calvin Cycle

G3P, ADP, NADP+, inorganic phosphate (Pi)

Products of Photosynthesis

Glucose (C6H12O6) and oxygen (O2)

What is a common fuel molecule for cellular respiration?

Glucose (any molecule with C6H12O6 works)

Products of photosynthesis

Glucose and oxygen

Fats broken down into Glycerol and Fatty Acids - Cellular Respiration

Glycerol starts at Glycolysis and Fatty Acids start by being attached to Acetyl-CoA

What is the metabolic pathway that provides ATP during fermentation?

Glycolysis

What stage of cellular respiration occurs in the cytosol?

Glycolysis

What are the three main metabolic stages of cellular respiration?

Glycolysis, the Krebs Cycle, and electron transport

The Krebs Cycle is named after

Hans Krebs, the pioneer of biochemistry who worked out the steps of the cycle in the 1930s.

Energy exits as

Heat (thermal) energy

Formula of Cellular Respiration

Heat Energy + C6H12O6 + 6O2 ---> 6H2O + 6CO2 + ATP Energy glucose oxygen water carbon dioxide

When a person stops moving, energy has been converted to

Heat energy

Which form of energy is the most randomized and difficult to put to useful work?

Heat energy

What is moved along with the electrons?

Hydrogen

How does electron transport provide energy for ATP synthase indirectly?

Hydrogen ions pumped by electron transport rich back down the concentration gradient through an ATP Synthase. This rotation activates catalytic sites in the synthase that attach phosphate groups to ADP molecules to regenerate ATP.

What is important about how cellular respiration transfers hydrogen atoms from glucose to oxygen, forming water?

Hydrogen transfer is how oxygen enhances energy harvest during cellular respiration

How is your breathing related to your cellular respiration?

In breathing, your lungs exchange carbon dioxide and oxygen between your body and the atmosphere. In cellular respiration, your cells consume the oxygen in extracting energy from food and release carbon dioxide as a waste product.

Why does electron transfer to oxygen release energy?

In redox reactions, oxygen is an "electron grabber." An oxygen atom pulls on electrons harder than almost any other type of atom. When electrons move from glucose to oxygen, it is as though they were falling since potential energy is unlocked. Instead of gravity, it is the pull of oxygen on electrons that causes the "fall" and energy release during cellular respiration.

How does electromagnetic energy travel?

In rhythmic sine waves

Cellular respiration controls electron transfer very closely, so it unlocks chemical energy...?

In smaller amounts that cells can put to productive use

Compared to a solution of isolated chlorophyll, why do intact chloroplasts release less heat and fluorescence when illuminated?

In the chloroplasts, the light-excited electrons are trapped by a primary electron acceptor rather than immediately giving up all of their energy as heat and light.

Pyruvic acid, the fuel that remains after glycolysis, is not quite ready for the Krebs Cycle. How must it be "prepped" first?

It must be converted to a form the Krebs Cycle can use. The actual fuel consumed by the Krebs Cycle is a two-carbon compound called acetic acid. It must enter the Krebs Cycle in the form of acetyl-CoA, in which the acetic acid is bonded to a carrier molecule called coenzyme A (the CoA in acetyl-CoA).

What is the function of NADPH in the Calvin cycle?

It provides the high-energy electrons that are added to (and result in the reduction of) CO2 to form G3P sugar.

What does the chloroplast do with hydrogen and electrons?

It transfers the hydrogen along with electrons to carbon dioxide to form sugar

How does the Calvin cycle used ATP and NADPH?

It uses these two products of the light reactions to power the production of sugar from carbon dioxide. ATP provides energy and NADPH is a source of high-energy electrons to convert carbon dioxide to sugar.

Anything that moves has

Kinetic energy

Reduction of pyruvic acid produces a waste product called

Lactic Acid

What contributes to muscle soreness?

Lactic Acid as well as muscle tearing

_________ acid as to human muscle cells as ethyl _________ is to yeast.

Lactic; alcohol

Photosynthesis occurs mainly in green cells within the ______ of plants.

Leaves

What are the major sites of photosynthesis?

Leaves

In photosynthesis, how does the oxidized form of NADPH, NADP+, gain electrons?

Light drives electrons from water to NADP+

What are the two stages of photosynthesis?

Light reactions and Calvin cycle

The Theory of Light as waves explains most of

Light's properties

What do autotrophs require from the environment to synthesize sugar?

Light, carbon dioxide, and water (as well as soil minerals)

Most pigments release heat energy as their

Light-excited electrons fall back to their ground state

Krebs Cycle (Citric Acid Cycle)

Makes 2 ATP, FADH2 and NADH. CO2 is released as waste. Completes the breakdown of sugar all the way to carbon dioxide, the waste product of cellular respiration. The enzymes for the Krebs Cycle are dissolved in the fluid within the mitochondria.

What are the three main types of work that cells perform?

Mechanical work, transport work, and chemical work

What forms the apparatus where many of the reactions of photosynthesis occur?

Membranes in the chloroplast

Cellular respiration is a

Metabolic pathway

Cellular respiration is an example of

Metabolism

Production of ATP during cellular respiration occurs mainly in what organelles?

Mitochondria

Where does the Krebs cycle occur?

Mitochondrial matrix

Each link in an electron transport chain is a

Molecule, usually protein

Three major groups of plants

Mosses, ferns, and flowering plants

Pyruvic acid still holds

Most of the energy of glucose, and that energy is harvested in the Krebs Cycle

In mechanical work...?

Motor proteins are moved

ATP powers

Muscle cells

To harvest food energy during glycolysis, what must be present as an electron acceptor?

NAD+

How does the cell regenerate NAD+ in anaerobic conditions?

NADH disposes of electrons by adding them to pyruvic acid produced by glycolysis. This restores NAD+ and keeps glycolysis working as an ATP source.

What happens after NADH transfers electrons to the electron transport chain?

The electrons then cascade down the chain, from molecule to molecule. The molecule at the bottom of the chain finally drops the electrons to oxygen. The oxygen also picks up hydrogen to form water.

What does the energy stored by electron transport behave like? In what way?

The elevated reservoir of water behind a dam There is a tendency for the H+ ions to gush back to where they are less concentrated, much as there is a tendency for water to flow downhill. The membrane, analogous to the dam, temporarily restrains the H+ ions.

Kinetic energy

The energy of motion

Plants and other photosynthetic organisms convert

The energy of sunlight to the chemical energy of sugar and other organic compounds

Electromagnetic Spectrum

The full range of radiation from the very short wavelengths of gamma rays to the very long wavelengths of radio signals. From 380 to 750 nanometers in wavelength

The shorter the wavelength...?

The greater the energy

The molecules of electron transport chains are built into

The inner membranes of mitochondria

Reaction Center

The location of the first light driven chemical reaction of photosynthesis. It consists of a chlorophyll-a molecule that sits next to another molecule called a primary electron acceptor

Oxidation

The loss of electrons during a redox reaction (gives a positive change)

Examples of mechanical work

The movement of muscles and the movement of cilia

What happens to the oxygen when the water is split?

The oxygen escapes through the stomata and into the atmosphere as O2 Requires a lot of energy, which is provided by exposure to sunlight

Describe a photosystem in general

The pigment cluster of the photosystem functions as a light-gathering antenna that focuses energy onto the reaction center. At the reaction center of the photosystem, a chlorophyll molecule transfers its light-excited electron to a primary electron acceptor.

Why do plants appear green?

The pigments absorb mainly blue-violet and red-orange wavelengths, reflecting the green color to our eyes Chlorophyll and the other pigments built into the membranes of grana mainly absorb light in the blue-violet and red-orange part of the spectrum. The pigments do not absorb much green light, which is reflected to our eyes.

Chemical Energy

The potential to perform work is due to the arrangement of atoms within the fuel molecules.

Heat

The random motion of atoms and molecules

Why is water required as a reactant in photosynthesis?

The splitting of water provides electrons for converting carbon dioxide to sugar (via electron transfer by NADPH)

Why is the Calvin cycle called a cycle?

The starting material is regenerated with each turn of the cycle.

What is the stroma?

The thick fluid within the chloroplast

Light Reactions take place in

The thylakoid membrane

Where are the chlorophyll molecules that capture light energy built into?

The thylakoid membranes

Where is extensive deforestation occurring?

The tropics, the northwestern and southeastern United States, Canada, and Siberia.

How does the thylakoid membrane convert light energy to the chemical energy of NADPH and ATP?

The two photosystems and the electron transport chain that connects them transfer electrons from water to NADP+. The electron transport chain also functions as a hydrogen ion (H+) pump. ATP synthase molecules, much like the ones in mitochondria, use the energy of the H+ gradient to make ATP.

Energy coupling

The use of energy released from exergonic reactions to drive essential endergonic reactions The transfer of energy from processes that yield energy, such as the breakdown of organic fuels, to processes that consume energy, such as muscle contraction and other types of cellular work.

What effect would an absence of oxygen have on the electron transport chain?

There would be no production of ATP by ATP synthase. Without oxygen to "pull" electrons down the electron transport chain, the energy stored in NADH cannot be extracted and harnessed for ATP synthesis.

How do electrons move in photosynthesis?

They are boosted "uphill" and added to carbon dioxide to produce sugar.

Where are the enzymes for the Calvin cycle located?

They are dissolved in the stroma

If your muscles are working under anaerobic conditions,

They are spending ATP at a race that outpaces the delivery by the bloodstream of oxygen from your lungs to your muscles.

When the weather is hot and dry, how do C4 plants respond?

They close their stomata, but continue to produce sugar by photosynthesis

What do the thylakoids do with the light energy?

They convert the light energy to the chemical energy of ATP and NADPH

How does carbon monoxide and cyanide kill an organism?

They disrupt electron transport in mitochondria, which transfers essential electrons. Without its energy-harvesting mechanism, the mitochondrial membrane can no longer convert food energy to ATP energy. Therefore, cells stop working and the organism dies.

When ATP drives work in cells, how are phosphate groups utilized?

They energize other molecules in cells by transferring phosphate groups to those molecules

How do electron transport chains work?

They function as a simple chemical machine that uses the energy released by the "fall" of electrons to pump hydrogen ions (H+) across the inner mitochondrial membrane.

Why are plants called producers?

They produce organic molecules by photosynthesis

What do people in favor of saving old trees argue?

They remove a lot of CO2 from the atmosphere

After creatine phosphate is used up, how must muscle cells obtain energy?

Through the anaerobic process of fermentation

How does water enter the plant?

Through the roots

How does carbon dioxide enter the plant?

Through tiny pores on the surface of the leaves called stomata

What are the sites of the light reactions?

Thylakoids

Stomata

Tiny pores on the underside of a leaf through which oxygen can exit and carbon dioxide can enter

What is the function of NADH?

To carry electrons from glucose and other fuel molecules and deposit them at the top of an electron transport chain.

Primary Electron Acceptor

Traps the light-excited electron from the reaction-center chlorophyll.

What part of ATP provides energy for cellular work?

Triphosphate tail

Light Reactions of photosynthesis description

Two types of photosystems cooperate in a light-driven current of electrons from water to NADP+. Photons excite electrons from the chlorophyll of Photosystem 2 to a primary electron acceptor. Photosystem 2, the water-splitting photosystem, replaces its photo-excited electrons by extracting electrons from water. This is the step that releases oxygen during photosynthesis. Energized electrons from Photosystem 2 pass down an electron transport chain to the NADPH-producing photosystem, Photosystem I. The chloroplast uses the energy released by this electron "fall" to make ATP. From there, the NADPH-producing photosystem transfers its photo-excited electrons to NADP+, reducing it to NADPH. The electron transport chain replaces the electrons lost from the photosystem's chlorophyll.

Yeast fermentation

Uses glycolysis to make pyruvic acid which releases CO2 to become ethyl alcohol

Photosynthesis

Uses light energy from the sun to power a chemical process that makes organic molecules.

Greenhouse effect

Warming induced by CO2 It occurs because atmospheric CO2 traps heat and warms the air just as clear glass does in a greenhouse. It helps keep the average temperature on Earth 10 degrees Celsius warmer than it would be otherwise.

At the end of the transport chain, what is the final waste product of cellular respiration?

Water

What is oxidized in photosynthesis?

Water

How does water enter a plant?

Water is absorbed through the roots with specialized root cells and then travels via veins to the leaves

Reactants of photosynthesis

Water, carbon dioxide, sunlight

How does the cell regenerate NAD+?

When NADH drops its electrons down electron transport chains to oxygen Cannot occur under anaerobic conditions

How is NAD+ reduced to NADH?

When electrons from organic fuel are transported to NAD+, it is reduced to NADH

Why have carbon dioxide levels risen?

Worldwide industrialization, increased use of oil, gas, coal, and wood as fuels.

Carotenoids

Yellow-orange pigments, which absorb mainly blue-green light Some may pass energy to chlorophyll-a Others have a protective function: they absorb and dissipate excess light energy that would otherwise damage chlorophyll Similar carotenoids, like the ones from carrots, may protect our eyes from bright light

Describe the energy transformations that occur when you climb to the top of a stairway.

You convert the chemical energy of food to the kinetic energy of your upward climb. At the top of the stairs, some of the energy has been stored as potential energy because of your high elevation. The rest has been converted to heat.

Photosystem II

the FIRST photosystem in the thylakoid membrane. Accepts electrons from water P680 It uses light energy to extract electrons from water by splitting it into hydrogen and oxygen The oxygen goes towards replenishing the diminished amount due to the reduction of Photosystem I.