Lisa Michalek

You get energy from the food you eat. Directly or indirectly, almost all of the

energy in living systems needed for metabolism comes from the sun.

Energy from the sun enters living systems when plants, algae, and certain prokaryotes absorb sunlight.

Some of the energy in sunlight is captured and used to make macromolecule compounds.

These macromolecules store chemical energy and can serve as food for organisms.

Metabolism involves either using energy to build molecules or breaking down molecules in which energy is stored.

Photosynthesis is the process by which light energy is converted to chemical energy.

Organisms that use energy from sunlight or from chemical bonds in nonliving substances to make organic biomolecules are called autotrophs.

Most autotrophs (usually plants) are photosynthetic organisms.

Some autotrophs, including certain prokaryotes, use chemical energy from inorganic (nonliving) substances to make organic compounds.

Prokaryotes found near deep-sea volcanic vents live in perpetual darkness. Sunlight does not reach the bottom of the ocean.

These prokaryotes get energy from chemicals flowing out of the vents.

Prokaryotes found near deep-sea volcanic vents live in perpetual darkness.Sunlight does not reach the bottom of the ocean.

These prokaryotes get energy from chemicals flowing out of the vents.

The chemical energy in macromolecules can be transferred to other macromolecules or to organisms that consume food.

Organisms that must get energy from food instead of directly from sunlight or inorganic substances are called heterotrophs.Heterotrophs, including humans,

get energy from food through the process of cellular respiration.

Cellular respiration is a metabolic process similar to burning fuel.

While burning converts almost all of the energy in a fuel to heat, cellular respiration releases much of the energy in food to make ATP.

ATP provides cells with the energy they need to carry out the activities of life.

The word burn is often used to describe how cells get energy from food.The overall process is similar. However, the burning of food in living cells differs from the burning of a log in a campfire.

When a log burns, the energy stored in wood is released quickly as heat and light.

In cells, chemical energy stored in food molecules is released gradually in a series of enzyme assisted chemical reactions.

As shown in the above diagram, the product of one chemical reaction becomes a reactant in the next reaction.

When cells break down food molecules, some of the energy in the molecules is released as heat.

Much of the remaining energy is stored temporarily in molecules of ATP.

ATP delivers energy wherever energy is needed in a cell. The energy released from ATP can be used to power

other chemical reactions, such as those that build molecules.

Most chemical reactions require less energy than is released from ATP.

ATP (adenosine triphosphate) is a nucleotide with two extra energy-storing phosphate groups.

The three phosphate groups in ATP form a chain that branches from a five-carbon sugar (ribose). The phosphate tail is unstable

because the phosphate groups are negatively charged and repel each other.

The phosphate groups store energy like a compressed spring.

The energy is released when the bonds that hold the phosphate groups together are broken.

Breaking the outer phosphate bond requires an input of energy. However, much more energy is released, than is consumed by

the reaction. The removal of a phosphate

group from ATP produces ADP(adenosine diphosphate). This reaction releases

energy in a way that enables cells to use the energy.

Cells use this energy released by this reaction to power metabolism.

Plants, algae, and some bacteria capture about 1% of the energy in the sunlight that reaches the Earth and convert it to chemical energy through the process of photosynthesis.

Photosynthesis is the process that provides energyfor almost all life.

Photosynthesis occurs in the chloroplasts of algae and plant cells and in the cell membrane of certain prokaryotes.

Step 1 Energy is captured from sunlight.Step 2 Light energy is converted to

chemical energy, which is temporarily stored in ATP and the energy carrier molecule NADPH.

Step 3 The chemical energy stored in ATP and NADPH powers the formation of organic compounds, using carbon dioxide (CO2).

Can be summarized by the following equation:

6CO2 + 6H2O Light C6H12O6 + 6O2Carbon water Sugars OxygenDioxide Gas

8.1.A-What is ATP and what is its role in the cell? B-Explain, How does the structure of ATP make it an ideal source of energy for the cell? C-Explain how ADP and ATP are each like a battery. Which one is Partially charged and which one is

Fully charged? Why? 2.A-What is the ultimate source of energy for plants? B-How do heterotrophs obtain energy? How is this different from how autotrophs obtain energy? C-Infer, Why are decomposers such as mushrooms, considered heterotrophs and not autotrophs? 3. Recall that energy flows and that nutrients cycle how does the process of photosynthesis impact both the flow of energy and the cycling of nutrients? 8.2 A-Why are pigments such as chlorophyll needed for photosynthesis? B-How well would a plant grow under pure yellow light? Explain your answer. 2.A-What is the function of NADPH? B-How is light energy converted into chemical energy during photosynthesis? C-How would photosynthesis be affected if there were a shortage of NADP+ in the cells of plants? 3.a Describe the overall process of photosynthesis, including the reactants and products. B. (Figure 8-7) Into which set of reactions- light dependent or light Independent- does each reactant of photosynthesis enter? From which set of reactions is each product of photosynthesis generated? 4. Create your own labeled diagram of chlorophyll. (Figure8-5) Draw and label the thylakoids, grana, and stroma. Indicate on your drawing where the two sets of photosynthesis reactions take place. 5.Draw two leaves- one green and one orange. Using colored pencils, markers or pens, show which colors of visible might are absorbed and reflected by each leaf.

Can be summarized by the following equation:

6CO2 + 6H2O Light C6H12O6 + 6O2Carbon water Sugars OxygenDioxide Gas

The first two steps of photosynthesis are called light reactions, or light dependent reactions. Both need light to occur.

Light energy is used to make energy storingcompounds: ATP & NADPH.

The structures containing light-absorbing substances are called pigments.

Pigments absorb capture energy from sunlight. Chlorophyll, absorbs mostly Absorbs blue & red light Reflects green & yellow light.

Reflection of green and yellow light makes many plants, especially their leaves, look green.

Plant Chloroplast have two chlorophyll types,chlorophyll a & b.

Other colored pigments are called carotenoids. Fall leaf colors Fruit & Vegetable colors

Pigments involved in plant photosynthesis are located in the chloroplasts of leaf cells.

Clusters of pigments are embedded in the membranes of disk-shaped structures called thylakoids.

When light strikes a thylakoid in a chloroplast, energy is transferred to electrons in chlorophyll.

This energy transfer causes the electrons to jump to a higher energy level.

Electrons with extra energy are said to be excited! They jump from chlorophyll to other molecules

The excited electrons that leave chlorophyll molecules must be replaced by other electrons.

Plants get these replacement electrons from water molecules, H2O.

Splitting water apart and releasing O2 gas.

Excited electrons that leave chlorophyll molecules are used to produce new molecules, including ATP and NADPH, that temporarily store chemical energy.

The electron is passed through the electron transport chains in the thylakoid membrane.

As hydrogen ions pass through transport proteins, the protein acts like an enzyme and adds a phosphate group to a molecule of ADP, making ATP.

In addition to ATP, another set of proteins in the thylakoid membrane provides energy to make NADPH.NADPH- energy for the third step

photosynthesis.

Chlorophyll pigment molecules in the chloroplasts absorb light energy.

Electrons are excited by light and move through electron transport chains in thylakoid membranes.

These electrons are replaced by electrons from water molecules, which are split by an enzyme protein.

Oxygen atoms from water molecules combine to form oxygen gas.

The energy molecules of ATP and NADPH are formed.

In this final stage of photosynthesis, carbon atoms from carbon dioxide in the atmosphere are used to make organic compounds in which chemical energy is stored.

The transfer of carbon dioxide to organic compounds is called carbon dioxide fixation.

The reactions that fix carbon dioxide are sometimes called dark reactions, or light-independent reactions.

The most common method of carbon dioxide fixation is the Calvin Cycle.

The Calvin cycle is a series of enzyme-assisted chemical reactions that produces a three-carbon sugar.

A total of three carbon dioxide molecules must enter the Calvin cycle to produce each three-carbon sugar that will be used to make other organic compounds.

These organic compounds provide the organism with energy for growth and metabolism.

The energy used in the Calvin cycle is supplied by ATP and NADPH made during the second step of photosynthesis.

Used ProducedStep 1 Light, Water Oxygen, Hydrogen Ions

Step 2 Electrons, Hydrogen Ions

ATP, NADPH

Step 3 ATP, NADPH, Carbon Dioxide

Glucose and othermacromolecules

In carbon dioxide fixation, carbon dioxide (CO2) is joined together to form glucose, powered by the energy of ATP & NADPH.

CO2 is pieced together

ATP energy is used NADPH energy is

used The Carbohydrate

Monomer, Glucose is made from the pieces of CO2

Photosynthesis is directly affected by environmental factors. The most obvious factor is light.

In general, the rate of photosynthesis increase as light intensityincreases until all the pigments are being used.

At this saturation point, the reactions of the Calvin cycle cannot proceed any faster.

The overall rate of photosynthesis is limited by the slowest step, which occurs in the Calvin cycle.

The carbon dioxide concentration also affects the rate of photosynthesis. Once a certain concentration of carbon dioxide is present,

photosynthesis cannot proceed any faster. Photosynthesis is most efficient within a certain range of

temperatures. Photosynthesis involves many enzyme-assisted chemical reactions

and unfavorable temperatures may inactivate certain enzymes.

Moodle- 1)Factors that affect Photosynthesis 2) Virtually experiment with what affects photosynthesis

Distance from light Color of light

Most of the foods we eat contain usable energy.Much of the energy is stored in proteins,

carbohydrates, and fats. Cells transfer energy in organic compounds to

ATP through a process called cellular respiration.With Oxygen, cells can make much more ATP.

Cellular respiration is the process cells use to produce the energy in organic compounds.

Cellular respiration can be summarized by the following equation:

enzymes

C6H12O6 + 6O2 6CO2 + 6H2O + energyglucose oxygen carbon water ATP

gas dioxide

In the Cytoplasm Glucose Sugar is Broken in Half.

In Mitochondria The Enzyme

Acetyl-CoA helps start the Krebs cycle, making NADH & FADH energy molecules.

Carbon Dioxide released & 2 ATPare formed.

In the Mitochondria Water & a lot of ATP made (34 ATP).

Used ProducedStep 1Glycolysis

Glucose 2 ATP, 2NADH, Sugar Spit in Half (2 Pyruvate)

Step 2Krebs Cycle

Oxygen, Half (3C) Sugar & Acetyl CoA Enzyme

2 ATP, 8 NADH, CO2 is released.

Step 3Electron Transport Chain

Oxygen, NADH, Hydrogens from sugar,

34 ATP (Lots of ATP!), Water

Aerobic processes require oxygen (aerobic=air).

Anaerobic processes do notrequire oxygen (anaerobic=without air).

Aerobic AnaerobicRequires Oxygen No Oxygen Required

Produces Water & Carbon Dioxide

Produces Acids such as Lactic Acids (Sore Muscles)

Cytoplasm & Mitochondria Cytoplasm Only

Quiz Next Period! Study your notes!

The slides below were not included in the lessons.

When oxygen is present, pyruvate produced during glycolysis enters a mitochondrion and is converted to a two-carbon compound.

This reaction produces one carbon dioxide molecule, one NADH molecule, and one two-carbon acetyl group.

The acetyl group is attached to a molecule called coenzyme A (CoA), forming a compound called acetyl-CoA.

Cellular respiration occurs in two steps.Step 1 Called Glycolysis (Glycolysis=Sugar-

Break) Glucose is converted to pyruvate, producing a small amount of ATP and NADH.

Step 2 When oxygen is present, pyruvate and NADH are used to make large amounts of ATP (aerobic respiration). Aerobic respiration occurs in the mitochondria of all cells. When oxygen is not present, pyruvate is converted to either lactate or ethanol and carbon dioxide.

The primary fuel for cellular respiration is glucose, which is formed when carbohydrates such as starch and sucrose are broken down.

If too few carbohydrates are available to meet an organisms glucose needs, other molecules, such as fats, can be broken down to make ATP. One gram of fat contains more energy than two grams

of carbohydrates. Proteins and nucleic acids can also be used to

make ATP, but they are usually used for building important cell parts.

In the first step of cellular respiration, glucose is broken down in the cytoplasm during a process called glycolysis.

Glycolysis is an enzyme-assisted anaerobic process that breaks down one six-carbon molecule of glucose to two three-carbon pyruvate ions. Pyruvate is the ion of a three-carbon organic acid

called pyruvic acid. The pyruvate produced during glycolysis still

contains some of the energy that was stored in the glucose molecule.

As glucose is broken down, some of its hydrogen atoms are transferred to an electron acceptor called NAD+.

This forms an electron carrier called NADH. The electrons carried by NADH are eventually

donated to other organic compounds. This recycles NAD+, making it available to

accept more electrons.

Glycolysis uses two ATP molecules but produces four ATP molecules, yielding a net gain of two ATP molecules.

Glycolysis is followed by another set of reactions that use the energy temporarily stored in NADH to make more ATP.

After the Krebs cycle, NADH and FADH2now contain much of the energy that was previously stored in glucose and pyruvate.

When the Krebs cycle is completed, the four-carbon compound that began the cycle has been recycled, and acetyl-CoA can enter the cycle again.

In aerobic respiration, electrons donated by NADH and FADH2 pass through an electron transport chain.

In eukaryotic cells, the electron transport chain is located in the inner membranes of mitochondria.

The energy of these electrons is used to pump hydrogen ions out of the inner mitochondrial compartment.

Hydrogen ions accumulate in the outer compartment, producing a concentration gradient across the inner membrane.

Hydrogen ions diffuse back into the inner compartment through a carrier protein that adds a phosphate group to ADP, making ATP.

At the end of the electron transport chain, hydrogen ions and spent electrons combine with oxygen molecules, O2, forming water molecules, H2O.

What happens when there is not enough oxygen for aerobic respiration to occur? The electron transport chain does not function

because oxygen is not available to serve as the final electron acceptor.

Electrons are not transferred from NADH, and NAD+ therefore they cannot be recycled.

When Oxygen is not present, NAD+ is recycled in another way.

Under anaerobic conditions, electrons carried by NADH are transferred to pyruvate produced during glycolysis.

This process recycles NAD+ needed to continue making ATP through glycolysis.

The recycling of NAD+ using an organic hydrogen acceptor is called fermentation. Prokaryotes carry out more than a dozen kinds of fermentation

all using some form of organic hydrogen acceptor to recycle NAD+.

Two important forms of fermentation are lactic acid fermentation and alcoholic fermentation. Lactic acid fermentation by some prokaryotes and fungi is used

in the production of foods such as yogurt and some cheeses.

In some organisms, a three-carbon pyruvate is converted to a three-carbon lactate through lactic acid fermentation. Lactate is the ion of an organic acid called lactic acid.

During vigorous exercise, pyruvate in muscles is converted to lactate when muscle cells must operate without enough oxygen.

Fermentation enables glycolysis to continue producing ATP in muscles as long as the glucose supply lasts.

Blood removes excess lactate from muscles. Lactate can build up in muscle cells if it is not removed

quickly enough, sometimes causing muscle soreness.

In other organisms, the three-carbon pyruvate is broken down to ethanol, a two-carbon compound, through alcoholic fermentation.

Carbon dioxide is released during the process. First, pyruvate is converted to a two-carbon compound,

releasing carbon dioxide. Second, electrons are transferred from a molecule of

NADH to the two-carbon compound, producing ethanol.

As in lactic acid fermentation, NAD+ is recycled, and glycolysis can continue to produce ATP.

Alcoholic fermentation by yeast, a fungus, has been used in the preparation of many foods and beverages.

Wine and beer contain ethanol made during alcoholic fermentation by yeast.

Carbon dioxide released by the yeast causes the rising of bread dough and the carbonation of some alcoholic beverages, such as beer.

Ethanol is actually toxic to yeast. At a concentration of about 12 percent ethanol kills yeast. Therefore, naturally fermented wine contains about 12% ethanol.

The total amount of ATP that a cell is able to harvest from each glucose molecule that enters glycolysis depends on the presence or absence of oxygen.When Oxygen is present, aerobic respiration

occurs.When Oxygen is absent, fermentation occurs.