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PHOTOSYNTHESIS AND GLYCOLYSIS

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I. Energy and Life

A. Autotrophs and Heterotrophs 

1. Plants and some other types of organisms are able to use light energy from the sun to produce food.

 2. Organisms such as plants, which make their own food, are called autotrophs.

 

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3. Other organisms, such as animals need to take in food are called heterotrophs.

 

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B. Chemical Energy and ATP 1.      Adenosine Triphosphate ATP is

food converted into what the cells can use as energy.

 

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II. Photosynthesis and overview

A. Investigating Photosynthesis 

1. In 1643, Van Helmont conducted an experiment and determined that trees gain most of their mass from water.

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2. In 1771, Jospeh Prietly found that plants release a substance that keeps a candle burring. A substance that we now know is oxygen.

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3. In 1779, Jan Ingenhousz found out that aquatic plants produce oxygen bubbles in the light but not the dark. He concluded that plants need sunlight to produce oxygen.

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B. Photosynthesis equation 1. 6CO2 + 6H2O ---light----- C6H12O6 + 6O2

Carbon dioxide water Glucose oxygen

 2. Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen.

 

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C. Light and pigments 

1. In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule in chloroplast.

 2. Plants gather the sun’s energy

with light absorbing molecules called pigments.

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3. The plants primary pigment is chlorophyll.

 4. There are two main types of chlorophyll a and b.

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D. The reactions of Photosynthesis 1.      In plants and other photosynthetic

Eukaryotes, photosynthesis takes place inside chloroplasts.

 2.      Portions in the thyakoid membrane

organize chlorophyll and other pigments into clusters known as photosystems.

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E. Light Dependent reactions 1.      Light dependent reactions require light. 2.      The light dependent reactions produce

oxygen gas and convert ADP and NADP into the energy carriers ATP and NADPH.

 3.      The Calvin cycle uses ATP and NADPH from

the light dependent reactions to produce high-energy sugars.

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F. Factors affecting photosynthesis 1.      Many factors affect the rate at

which photosynthesis occurs. 2.      Shortage of water can slow or

even stop photosynthesis. 

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3. Plants that live in dry climate have a waxy coating on their leaves to reduce water loss.

 4. Temperature above or below 0-35 C can slow down the rate of photosynthesis.

 5. The intensity of light also affects the rate at which photosynthesis occurs.

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6.Increased light activity increases photosynthesis.

 7. Decreased light activity decreases photosynthesis

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III. Cellular Respiration

A. Chemical energy and food 

1. How much energy is actually present in food? - Lots!

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2. One gram of glucose when burned can release 3811 calories of heat!

 3. A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.

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4. Cells don’t “burn” glucose; instead they gradually release the energy from glucose and other food compounds.

 5. Glycolysis releases only a small amount of energy.

 

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6. If oxygen is present, Glycolysis leads to two other pathways that release a great deal of energy.

 7. If oxygen is NOT present, Glycolysis goes to a different path.

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A.   Overview of cellular respiration 1.      Cellular respiration is the process

that releases energy by breaking down glucose and other food molecules in the presence of oxygen.

 2. 6O2 + C6H12O6 -------- 6CO2 + 6H2O +

energy Oxygen Glucose Carbon dioxide water

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C. Glycolysis 1.      Glycolysis is the process in which one

molecule of glucose is broken in half, producing two molecules of pyruvic acid. (Also 2 ATP’s.)

 2.      Pyruvic acid marks the end of

Glycolysis.

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3. The pyruvic acid can take three different paths.

 -         Respiration –presence of oxygen-         Fermentation –No oxygen-         Lactic acid- no oxygen 

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D. Anaerobic respiration (cellular respiration WITHOUT oxygen)

 1.    In an animal cell if the cell is under stress or if

there is insufficient amount of oxygen the body will convert the pyruvic acid into quick energy – lactic acid.

2. This is a quick fix for the body BUT lactic acid does have some down falls- pain.

 

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E. Fermentation (occurs in plants, without oxygen)

 1. Fermentation releases energy from food

molecules by producing ATP in the absence of oxygen.

 2.      Yeasts and a few other microorganisms

use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as waste.

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F. Krebs cycle – cellular respiration WITH oxygen.

 1.      During the Kreb cycle, pyruvic acid is

broken down into carbon dioxide in a series of energy extracting reactions.

 2.      The Kreb cycle is where most of the

ATP is made. 

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3. The Kreb cycle occurs inside the mitochondria.

 4. In the Kreb cycle the total ATP that is made is 36 or 38 ATP for 1 glucose molecule.

 5. Muscle cells have the capabilities of making 38 ATP. Why do you think?

 

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G. Energy and exercise

 1.      When quick energy is needed the body will use

what ATP is there and ready to go. If more ATP is needed then the body starts to produce lactic acid.

 

2. When long-term energy is needed the body will resort to stored energy. The body has the time to use the stored energy and convert it for energy.

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THE END