CELLULAR RESPIRATION AND PHOTOSYNTHESIS

*The respiratory system carries oxygen to the circulatory system.

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

AT 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…

CELLULAR RESPIRATION*During cellular respiration, glucose

combines with oxygen to produce carbon dioxide and water (and ATP).

C₆H₁₂O₆ + 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.

THE PROCESS OF CELLULAR RESPIRATION

GLYCOLYSIS -> FIRST STEP 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.

AEROBIC VS. ANAEROBIC RESPIRATION

Aerobic with oxygen

Anaerobic without oxygen

Aerobic respiration requires oxygen and anaerobic respiration is carried out without the presence of oxygen.

KREBS CYLE & ELECTRON TRANSPORT CHAIN

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.

FERMENTATION

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.

FERMENTATION 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

REVIEW OF CELLULAR RESPIRATIONTRUE/FALSE

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. ___________

REVIEW OF CELLULAR RESPIRATIONTRUE/FALSE 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. ____

PHOTOSYNTHESIS

PHOTOSYNTHESIS

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.

AUTOTROPHS VS. HETEROTROPHS

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+ OxygenSunlight

SOME DETAILS…

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.

SUMMARY OF PHOTOSYNTHESIS

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.

HOW 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 O₂ and forms CO₂ from the same carbon atoms that had been taken in as CO₂ and converted into sugars during photosynthesis.

REVIEW OF PHOTOSYNTHESIS TRUE/FALSE

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. __________