Cellular Respiration Reading

Cellular Respiration

Why do we eat?

Because we're hungry? Not necessarily. Biologically speaking, we eat to obtainenergy. The food we eat is broken down, the glucose extracted (removed), and that energy is converted (changed) into ATP (adenosine triphosphate).

Cellular Respiration

What happens to the energy stored in glucose during photosynthesis? How do living things make use of this stored energy? The answer is cellular respiration. This process releases the energy in glucose to make ATP,the molecule that powers all the work of cells.

Stages of Cellular Respiration

Cellular respiration involves many chemical reactions. The reactions can be summed up in this equation:

C6H12O6 + 6O2 → 6CO2 + 6H2O + Chemical Energy (in ATP)

In order for cellular respiration to take place, an input of oxygen must be added to the cell. When oxygen is present, glucose (another input), can be broken down to maximize the amount of ATP created. This is called aerobic respiration. The outputs from the chemical transformation are carbon dioxide, water, and ATP.

The reactions of cellular respiration can be grouped into three stages: glycolysis (stage 1), the Krebs cycle, also called the citric acid cycle (stage 2), and electron transport (stage 3). The figurebelow gives an overview of these three stages. Glycolysis occurs in the cytosol of the cell and does not require oxygen, whereas the Krebs cycle and electron transport occur in the mitochondria and do require oxygen.

Structure of the Mitochondrion: Key to Aerobic Respiration

The structure of the mitochondrion is key to the process of aerobic (in the presence of oxygen) cellular respiration, especially the Krebs cycle and electron transport. A diagram of a mitochondrion is shown in figurebelow.

The structure of a mitochondrion is defined by an inner and outer membrane. This structure plays an important role in aerobic respiration.The space between the inner and outer membrane is called the intermembrane space. The space enclosed by the inner membrane is called the matrix. The second stage of cellular respiration, the Krebs cycle, takes place in the matrix. The third stage, electron transport, takes place on the inner membrane.

Summary

  • Cellular respiration takes the energy stored in glucose and transfers it to ATP.
  • Cellular respiration has three stages: glycolysis, the Krebs cycle, and electron transport.
  • The inner and outer membranes of the mitochondrion play important roles in aerobic respiration.

Assignment Directions: Read the article above and then answer the questions below.

Part One: Summarize the cellular respiration reading on a separate sheet of paper. Use the sentence starters below to keep you organized and on track. Remember in a summary, there is no opinion. Just state the facts from the article.

-The purpose of this article was ….

- The article informed me of…

-The importance of this article is…

-In conclusion, …

Part Two: What other words could you use here? Use a dictionary for help!

a) “The reactions can be summed up in this equation”

Other word(s) for summed: ______

b) “Glycolysis occurs in the cytosol of the cell and does not require oxygen…”

Other word(s) for require: ______

c) “Cellular respiration takes the energy stored in glucose and transfers it to ATP.”

Other word(s) for transfers: ______

Part Three: Answer these questions below using complete sentences.

1) In order for cellular respiration to take place, what should be added to the cell (inputs)?

2) What is transformed at the end of cellular respiration (outputs)?

3) What role does the mitochondrion (singular, plural is mitochondria) play in cellular respiration?

4) A scientist found an unknown cell in the lab. She looked at the cell under a microscope and found that the cell contained an unusually high number of mitochondria. What body organ do you think this cell came from? Why?

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