All living organisms must be able to obtain energy from the environment in which they live. Plants and other green organisms are able to trap the light.

• All living organisms must be able to obtain energy from the environment in which they live.

• Plants and other green organisms are able to trap the light energy in sunlight and store it in the bonds of certain molecules for later use.

Cell EnergyCell Energy

• Other organisms cannot use sunlight directly.

• They eat green plants. In that way, they obtain the energy stored in plants.

Cell EnergyCell Energy

• Some examples of cell processes that require energy.

1. Active transport

2. cell division

3. Movement by use of flagella or cilia

4. production, transport, and storage of proteins

Work and the need for energyWork and the need for energy

• There is a molecule in your cells that is a quick source of energy for any organelle in the cell that needs it.

• The name of this energy molecule is adenosine triphosphate or ATP for short.

• ATP is composed of an adenosine molecule with three phosphate groups attached.

Work and the need for energyWork and the need for energy

• The charged phosphate groups act like the positive poles of two magnets.

• Bonding three phosphate groups to form adenosine triphosphate requires considerable energy.

Forming and Breaking Down ATPForming and Breaking Down ATP

• When only one phosphate group bonds, a small amount of energy is required and the chemical bond does not store much energy. This molecule is called adenosine monophosphate (AMP).


• When a second phosphate group is added, more energy is required to force the two groups together. This molecule is called adenosine diphosphate, or ADP.

• An even greater amount of energy is required to force a third charged phosphate group close enough to the other two to form a bond.

• This molecule is called Adenosine triphosphate or ATP.

• When this bond is broken, energy is released.


• The energy of ATP becomes available to a cell when the molecule is broken down.

Adenosine

Adenosine

P P P

P

P

P P

Adenosine triphosphate (ATP)

Adenosine diphosphate (ADP)


ATP (Adenosine triphosphate)• Most important energy

storing compound in living things.

• ATP is produced from a low energy compound called ADP.

• ADP is for Adenosine diphosphate.

• The energy that is produced in these molecules is from the breaking of the bonds when ATP becomes ADP.

Trapping Energy from SunlightTrapping Energy from Sunlight• The process that uses the sun’s energy to make

simple sugars is called photosynthesis.

Photosynthesis

Photosynthesis is the process in which autotrophs convert sunlight into food energy (sugars and starches).

OR

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

OR

Carbon Dioxide + Water + Sunlight ---> Glucose + Oxygen

autotrophs --organisms which make their own food using

photosynthesis.

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

Photosynthesis in the Chloroplast• The process of

photosynthesis takes place in the chloroplast, specifically using chlorophyll, the green pigment involved in

photosynthesis.

• the parts of a chloroplast include the stroma, and thylakoids stacked in grana. The chlorophyll is built into the membranes of the thylakoids.

Photosynthesis (light & dark reaction)

• There are two reactions that make up photosynthesis, light reaction and dark reaction.

• Light reaction occurs in the thylakoid of a grana in a chloroplast.

Light that carry’s out Light Reaction.

• The color of light that triggers light reaction is not green.

• The color of light that is absorbed are violet, blue and red.

• The wavelength of these colors cause electrons to move and produce high energy molecules of ATP & NADPH & the release of oxygen

Light Reaction

Light Reaction (con’t)

• ATP is produce from a low energy molecule called ADP.

• NADPH is produce from a low energy molecule called NADP+.

• Oxygen is produce from the splitting of the water molecule.

Trapping Energy from Sunlight

Click image to view movie.

ATP and Dark Reaction

• The ATP along with NADPH that is produced in light reaction is used to carry out the 2nd reaction Dark Reaction. This reaction is also known as the Calvin Cycle or carbon fixation.

• The Dark Reaction occurs in the Stroma of the Chloroplast of a plant cell. (note that CO2 is also needed in this process).

stroma

Dark Reaction (con’t)

• Dark reaction is light-independent which means it does not require light.

• Just because its called dark reaction doesn’t mean it occurs only at night.

• Dark Reaction (aka Calvin Cycle) is the final stage of producing GLUCOSE the energy storing compound that is needed for other organisms.

Dark Reaction aftermath

• You may think this concludes photosynthesis, but the ATP & NADPH use to carryout dark reaction is now converted back to ADP & NADP+ in the light reaction which can later be repowered as high energy molecules.

• The Glucose (Sugar) molecules is now available for organisms to eat.

The Calvin Cycle

Cell Respiration• The process in which a cell breaks down sugar or other organic

compounds to release energy as ATP OR C6H12O6 + 6O2 6CO2 + 6H2O

+ ATP OR Glucose + Oxygen Carbon

Dioxide + Water + Energy

• The primary objective of cell respiration is producing ATP

Cell Respiration in the Mitochondrion

• Mitochondrion is known as the “powerhouse”or “power-pack” of a cell. Because, of its ability to produce energy known as ATP.

• Majority of Cell Respiration occurs in the Mitochondria.

• The 2 places that cell respiration occurs are the matrix ( fluid filled compartments) & the inner membrane called the cristae

Cell Respiration (Glycolysis)

• Cell Respiration has three parts, Glycolysis, Krebs Cycle, and Electron Transport Chain.

• Cell respiration begins with Glycolysis "sugar splitting.” conversion of glucose to pyruvic acid or (pyruvate: a 3 carbon molecule)

• Glycolysis occurs in the cytoplasm (cytosol) of a cell.

Electron Carriers used to make ATP

Glycolysis (con’t)• During glycolysis glucose is

split into 2 pyruvate and 2 NADH, and a net gain of 2 ATP molecules are produced.

• The 2 NADH (electron carrier) will later enter into the Electron Transport Chain to form ATP.

• The 2 pyruvate molecules will now enter into the Krebs Cycle

Krebs Cycle (Citric Acid Cycle)

• This reaction occurs in the matrix of the mitochondria

• The 2 pyruvate produce in glycolysis goes through a series of reactions releasing 2 ATP, 8 NADH, 2 FADH2 & CO2.

• The molecules of NADH, FADH2 (electron carriers) is now transported to the electron transport chain to produce more ATP.

• The cycle must go around 2 times, once for each pyruvate.

Flavin Adenine Dinucleotide (FAD)It picks up two Hydride ions along

with their bonding electron pairs to produce FADH2

Electron Transport Chain• This reaction occurs in the

inner mitochondrial membrane called cristae.

• Molecules of NADH and FADH2 are considered to be electron carriers that are used to form ATP from ADP.

• For every NADH, 3 ATP molecules are formed. (With one exception)

• For every FADH2, 2 ATP molecules are formed.

Electron Transport Chain (con’t)

• This reaction delivers about 90% of all ATP formed during cell respiration.

• Water is also formed with the addition of Oxygen during the Electron Transport Chain.

• NADH & FADH2 are now reduced to NAD+ and FAD.

Aerobic Respiration

• There are two types of cell respiration.

• One that requires Oxygen is called aerobic respiration. Some microorganisms that use oxygen in respiration are called aerobes.

• This is the type of respiration that we have been discussing in the notes.

Anaerobic Respiration

• Anaerobic respiration does not require oxygen. Anaerobes are microorganisms that are poisoned by oxygen.

• There are two types of anaerobic respiration, lactic acid fermentation and alcohol fermentation.

• Lactic acid fermentation occurs in microoganisms and muscle cells.

• We use bacteria to produce yogurt. The sour taste comes from the lactic acid released from anaerobic respiration

Lactic Acid Fermentation (con’t)

• Another form of lactic acid fermentation occurs when your body has exhausted its oxygen for aerobic respiration, it then converts to LAF

• You may recognize this reaction when you feel soreness. This soreness is the buildup of lactic acid in the muscle tissue

Alcohol Fermentation

• Another type of anaerobic respiration is alcohol fermentation. This form of respiration occurs in yeast.

• We use this form of respiration causing bread to rise(CO2 causes the bread to rise, the alcohol evaporates) and in the production of ethanol (ethyl alcohol) and alcohol products.

Which of the following chemical equations represents cellular respiration?

A.6CO2 + 6H2O C6H12O6 + 6O2 B.14H+ + Cr2O< > -2 + 6I - 2Cr+3 + 3I2 + 7H2O

C.C6H12O6 + 6O2 6CO2 + 6H2O D.C< > H16 + 11O2 7CO2 + 8H2O

Biology EOI Question 17 Answer

C - Cellular respiration breaks down glucose, C6H12O6, and releases carbondioxide, CO2, and water, H2O.

Only choices A and C have glucose in them. Choice A is the chemical equation forphotosynthesis, the reverse of respiration.

Choice B is a redox equation that has chromium in it that might be harmful tocells. Choice D is the chemical equation for combustion (the burning of ahydrocarbon).

The diagram above shows some of the stages in cellular respiration. Which of the following gives the stages in the correct order?

A.Electron transport system, Krebs cycle, glycolysis B.Glycolysis, electron transport system, Krebs cycle C.Krebs cycle, glycolysis, electron transport system D.Glycolysis, Krebs cycle, electron transport system


D - No other choice has the three stages in order.

33. This apparatus was used to collect the oxygen that was produced by Elodea. Which factor was most responsible for the production of oxygen by Elodea?

A.Sugar was present in the liquid. B.The liquid contained enough oxygen for the plant to absorb. C.The presence of light stimulated photosynthesis. D.The plant contained a large number of mitochondria.


C - Energy for photosynthesis comes from light.

Web Links

• http://www.cst.cmich.edu/users/baile1re/bio101fall/enzphot

A.

C

B

D

All living organisms must be able to obtain energy from the environment in which they live. Plants and other green organisms are able to trap the light.

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