C ELLULAR R ESPIRATION AND P HOTOSYNTHESIS

*The respiratory system carries oxygen to the circulatory system. *The circulatory system in turn, carries oxygen to every cell in the human body.

A T THE CELL LEVEL Oxygen is able to diffuse into the cell while carbon dioxide diffuses out of the cell. Once inside the cell, oxygen moves into the mitochondria. -> the site of cellular respiration

with oxygen without oxygen Glycolysis

Heterotrophs and autotrophs go through the process of cellular respiration to release the energy stored in food. Before autotrophs go through the process of cellular respiration they have to go through the process of photosynthesis to make their own food. The energy that is released during cellular respiration is “packaged” in the form of ATP (adenosine triphosphate). An overview…

C ELLULAR RESPIRATION *During cellular respiration, glucose combines with oxygen to produce carbon dioxide and water (and ATP). C ₆H₁₂O₆ + 6O₂ 6CO₂ + 6H₂O + Energy (Glucose + Oxygen Carbon Dioxide +Water+ ATP) *For heterotrophs (like us!) the glucose comes from the food we eat.

The bond linking the last phosphate group is a high energy bond. When the third phosphate is removed and bonded to another compound, it transfers the energy to the other compound. ATP stands for adenosine tri-phosphate.

T HE PROCESS OF C ELLULAR R ESPIRATION

G LYCOLYSIS -> F IRST S TEP IN CELLULAR RESPIRATION *Glycolysis takes place in the cytoplasm. During glycolysis, 1 glucose molecule is broken down into 2 molecules of pyruvic acid. *4 ATP molecules are formed; however, glycolysis requires 2 ATP to break apart each molecule of glucose; therefore, the net energy produced during glycolysis is 2 ATP. * If oxygen is present, glycolysis leads to two other pathways; the Krebs cyle and the electron transport chain. -> this is an aerobic pathway.

A EROBIC VS. A NAEROBIC RESPIRATION Aerobic with oxygen Anaerobic without oxygen Aerobic respiration requires oxygen and anaerobic respiration is carried out without the presence of oxygen.

K REBS CYLE & E LECTRON T RANSPORT C HAIN The final two stages of cellular respiration take place in the mitochondria. The Krebs cycle occurs in the matrix of the mitochondria. The electron transport chain occurs in the inner membrane of the mitochondria.

During the Krebs cycle and the electron transport chain, pyruvate is further broken down and 34 more ATP are produced.

F ERMENTATION If oxygen is NOT present, fermentation occurs after glycolysis.-> this is an anaerobic pathway * No ATP is produced during fermentation; thus, all of the energy generated during anaerobic respiration is made during glycolysis.

F ERMENTATION CONT. Alcoholic Fermentation -> produces ethyl alcohol and carbon dioxide Example -> yeast Lactic Acid Fermentation -> produces lactic acid and carbon dioxide Examples -> muscle cells, certain bacteria

with oxygen without oxygen Glycolysis

R EVIEW OF C ELLULAR R ESPIRATION T RUE /F ALSE 1) Cellular respiration that is carried out without oxygen is aerobic. __________ 2) Glucose serves as a reactant during cellular respiration. __________ 3) Heterotrophs obtain glucose as a product of photosynthesis. ___________ 4) During cellular respiration, energy is produced in the form of ATP.___________ 5) The electron transport chain occurs during aerobic respiration. ___________

R EVIEW OF C ELLULAR R ESPIRATION T RUE /F ALSE 6) Glycolysis takes place in the mitochondria. _______ 7) The process that breaks a glucose molecule in half is fermentation. ________ 8) During aerobic respiration, the majority of ATP is made in the mitochondria. ________ 9) Anerobic respiration is more efficient than aerobic respiration at making ATP. _______ 10) Yeast cells undergo fermentation. ____

P HOTOSYNTHESIS

Where does all of the energy needed to sustain life come from? ____________________

The arrows below indicate the flow of ENERGY. The sun gives off energy in the form of light and heat. Plants are able to absorb sunlight. During photosynthesis, autotrophs (like plants) use the sunlight to produce their own food (glucose). Heterotrophs (like us!) cannot make their own food -> they must consume plants and other animals to obtain glucose.

A UTOTROPHS VS. H ETEROTROPHS Autotrophs are organisms that make their own food from inorganic substances. Heterotrophs are organisms that cannot synthesize their own food and must obtain in ready-made.

The following equation summarizes the process of photosynthesis. Carbon Dioxide + Water Glucose+ Oxygen Sunlight

S OME D ETAILS … The process of photosynthesis begins when light is absorbed by pigments in the plant cell. The most important photosynthetic pigment in plants is chlorophyll: this is what gives plants a green color

Chlorophyll is found in the chloroplasts -> an organelle found only in plant cells Mesophyll Cell

More specifically, chlorophyll is found within the thylakoids of chloroplasts.

S UMMARY OF P HOTOSYNTHESIS 1. Chlorophyll inside the chloroplasts absorbs photons of light. (a photon is a particle of light with a fixed amount of energy). 2. The energy is used, along with carbon dioxide, to blow water apart. 3. Glucose is produced. 4. Oxygen is released.

H OW DOES PHOTOSYNTHESIS RELATE TO CELLULAR RESPIRATION ?

* Photosynthesis and cellular respiration are complementary processes. Photosynthesis uses the energy of sunlight to produce sugars. The same sugars in turn serve as food (for both authotrophs and heterotrophs). Cellular respiration uses O ₂ and forms CO₂ from the same carbon atoms that had been taken in as CO₂ and converted into sugars during photosynthesis.

R EVIEW OF P HOTOSYNTHESIS T RUE /F ALSE 1) Heterotrophs can produce their own food. __________ 2) The chemical equation for photosynthesis is the opposite of the chemical equation for cellular respiration. __________ 3) Photosynthesis uses the energy from sunlight to produce water and carbon dioxide. _________ 4) Photosynthesis occurs in the mitochondria. __________ 5) It makes sense to talk to your plants. __________