1. Cellular Respiration (An Overview)

2. Objectives SWBAT describe the process of cellular respiration.
SWBAT compare cellular respiration to photosynthesis.

3. Vocabulary Cellular respiration Aerobic Anaerobic Glycolysis
Krebs cycle
Mitochondria (review)
ATP and Electron Transport Chain from Sec. 4.1

4. Cellular Respiration
While plants make their own food, we animals have to eat other organisms (namely plants – directly or indirectly).
Animals and plants, through cellular respiration, make ATP by breaking down glucose.
Cellular respiration releases chemical energy from sugars and other carbon-based molecules to make ATP when oxygen is present.

5. Cellular Respiration
Cellular respiration is an aerobic process, which takes place in the mitochondria (your cells power plants).
Aerobic processes require oxygen to take place.
Mitochondria make most of your cell’s ATP.

6. Glycolysis The mitochondria cannot directly make ATP from food.
Foods are broken down into smaller molecules such as glucose.
Glycolysis is the process that breaks down glucose (thus the name).
Glycolysis occurs in the cell’s cytoplasm and does not need oxygen.
This means glycolysis is an anaerobic process.

7. Glycolysis
Glycolysis splits glucose into two three-carbon and makes 2 molecules of ATP.
The products of glycolysis are then broken down in the mitochondria to make ATP.

8. Glycolysis (an aside)
Glycolysis was among the first biochemical processes to evolve.
Early forms of life produced ATP from glycolysis.
Why? Because glycolysis takes place in the cytoplasm (this is before eukaryotes)
and does not require oxygen to take place.
Earth did not always have as much oxygen as it does today (in fact, 2.5 billion years ago, it would have had no free oxygen).

9. Endosymbiosis theory (an aside)
Mitochondria were once prokaryotes that were engulfed by other prokaryotes.
This process may have led to the evolution of eukaryotes and cellular respiration.
It would have taken place after photosynthesizers had added significant oxygen to Earth’s atmosphere.

10. Cellular Respiration
Cellular respiration is almost a mirror image of photosynthesis.
Photosynthesis chemical equation
Cellular respiration chemical equation

12. Cellular Respiration
Mitochondria and chloroplasts are similar in structure.
A mitochondrion is surrounded by a membrane.
It has 2 parts that are involved in cellular respiration: the matrix and the inner mitochondrial membrane.

13. Cellular Respiration
Part 1: the matrix where the Krebs cycle takes place.
Part 2: the inner mitochondrial membrane where the electron transport chain takes place.

14. Krebs Cycle (also known as citric acid cycle)
The Krebs cycle produces molecules that carry energy to the second part of cellular respiration – the electron transport chain.
takes place in mitochondrial matrix
breaks down three-carbon molecules from glycolysis
makes small amount of ATP
Releases carbon dioxide
Transfers energy-carrying molecules to electron transport chain.
6H O 2
6CO 6O
mitochondrion
matrix (area enclosed
by inner membrane)
inner membrane
ATP
energy
energy from glycolysis 1 4 3
and
Krebs cycle

15. energy from glycolysis
Krebs Cycle
6H O 2
6CO 6O
mitochondrion
matrix (area enclosed
by inner membrane)
inner membrane
ATP
energy
energy from glycolysis 1 4 3
and
In the Krebs cycle
Three-carbon molecules from glycolysis are broken down in a cycle of chemical reactions producing:
Small amount of ATP is made.
Other types of energy-carrying molecules are made.
Carbon dioxide is released as waste product.
Energy transfer to the second stage of cellular respiration.
Krebs cycle

16. Energy Transport Chain
The energy carrying molecules from the Krebs cycle along with oxygen are used to make lots of ATP.
takes place in inner membrane
energy transferred to electron transport chain
oxygen enters process
ATP produced (up to 38 molecules)
water is released as a waste product.
Electron Transport