Mitochondria and chloroplasts are important parts of eukaryotic cells. They help with how cells make and use energy. By learning how they work, we can see both how eukaryotic and prokaryotic cells differ, especially in how they get energy.

Mitochondria

1. Function: Mitochondria are often called the "powerhouses" of the cell. They turn nutrients into energy in a form called ATP.

2. How They Work:

   • First, Glycolysis happens in a part of the cell called the cytosol. Here, glucose (a type of sugar) is broken down into another substance called pyruvate, making 2 ATP from each glucose.
   • Next, the Krebs Cycle, also known as the Citric Acid Cycle, takes place in the mitochondria. This step makes 2 ATP and creates molecules called NADH and FADH₂, which help carry energy.
   • Finally, in the Electron Transport Chain (ETC), which happens in the inner part of the mitochondria, NADH and FADH₂ give up their electrons. This step creates a gradient that helps produce about 28-34 ATP.

3. Efficiency: When one glucose molecule is completely broken down, it can make about 30-32 ATP. This means that around 40% of the energy is used, while about 60% is lost as heat.

Chloroplasts

1. Function: Chloroplasts help with photosynthesis. They turn light energy from the sun into chemical energy stored in glucose.

2. How They Work:

   • The Light-dependent Reactions happen in structures called thylakoid membranes. They use sunlight to split water, which releases oxygen and makes ATP and NADPH.
   • The Calvin Cycle, which does not need light, occurs in the stroma. In this step, ATP and NADPH are used to turn carbon dioxide into glucose. This cycle can create 1 molecule of glucose by using 6 carbon dioxide molecules. It needs 18 ATP and 12 NADPH to do this.

3. Production: Under the best conditions, one chloroplast can make about 30-50 glucose molecules every hour, showing how effective they are for producing biomass.

Comparison with Prokaryotic Cells

• Prokaryotes, like bacteria, do not have mitochondria or chloroplasts. Instead, they make energy in the cytoplasm and through their cell membrane. For example, bacterial cells can create ATP through glycolysis and fermentation, but they only make 2 ATP per glucose, which is much less than eukaryotic cells can.

Conclusion

In summary, mitochondria and chloroplasts are key for making ATP through respiration and photosynthesis, respectively. This shows how complex eukaryotic cells are compared to prokaryotic cells. The way these organelles work is crucial for how energy is used in living things.