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Comparing the Energy Related Organelles
Episode 514th May 2021 • My AP Biology Thoughts • Hopewell Valley Student Publications Network
00:00:00 00:05:47

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My AP Biology Thoughts  

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Nidhi and I am your host for episode #51 called Unit 2 Cell Structure and Function: Comparing the Energy Related Organelles. Today we will be discussing the similarities and differences between the mitochondria and chloroplast. 

Segment 1: Introduction to the energy related organelles

  •  Both eukaryotes and prokaryote cells need energy to function. Eukaryotes rely on the mitochondria and chloroplast to provide their cell with energy. The Mitochondria and the chloroplast also both contain their own DNA and are able to grow and reproduce independently within the cell. Mitochondria are found in plant and animal cells while chloroplasts are found only in plant cells. The mitochondria work to convert oxygen and nutrients into ATP through a process known as cellular respiration. Without a mitochondrion, many animals would not exist because they would not be able to obtain enough energy. The mitochondria enable cells to produce 15 times more ATP than they could otherwise. The number of mitochondria in a cell depends on the metabolic requirements of that cell. They were first discovered in the 1800s but until the 1950s they were believed to transmit hereditary information. In contrast, the chloroplast produces energy through photosynthesis. It has a high concentration of chlorophyll, the molecule that captures light energy, and this gives many plants green color. Chloroplasts are essential for the growth and survival of plants and photosynthetic algae. Chloroplasts take light energy and convert it into energy stored in the form of sugar and other organic materials. Cells need both chloroplasts and mitochondria to undergo both photosynthesis and cell respiration. After photosynthesis, which occurs through the chloroplast, that produces oxygen and glucose, plants need to break down the glucose and they use cellular respiration to do this, which happens in the mitochondria. There Is one plant that does not have a chloroplast, Rafflesia, which obtains its nutrients from other plants. Since it gets all of its energy from parasitizing another plant, it no longer needs its chloroplasts, and has lost the genes coding for the development of the it.

Segment 2: More About the the Mitochondria and Chloroplasts 

  • There are many similarities and differences between the structures of the 2 organelles. Mitochondria have an inner and outer membrane, with an intermembrane space between them. The outer membrane contains proteins known as porins, which allow the movement of ions into and out of the mitochondrion. The space within the inner membrane of the mitochondria is known as the matrix, which contains the enzymes of the Krebs and fatty acid cycles, alongside DNA, RNA, ribosomes and calcium granules. The inner membrane contains a variety of enzymes. It contains ATP synthase which generates ATP in the matrix, and transport proteins that regulate the movement of molecules into and out of the matrix. The inner membrane is arranged into folds known as cristae in order to increase the surface area available for energy production. Chloroplasts are surrounded by a double membrane similar to the double membrane found within a mitochondrion. Within the chloroplast is a third membrane that forms stacked, disc-shaped structures called thylakoids. Embedded in the thylakoid membrane are molecules of chlorophyll. A stack of thylakoids is called a granum, and the space surrounding the granum is called the stroma. Just like the structure of the mitochondria was important to its ability to perform aerobic cellular respiration, the structure of the chloroplast allows the process of photosynthesis to take place.

Segment 3: Connection to the Course

  • The mitochondria and chloroplast can be connected to the greater theme of cell organelle functions and the endosymbiotic theory. The similar function of the mitochondria and chloroplast allows us to understand how a cell gets energy and functions as well as how the function of these 2 organelles impacts the other organelles in a cell. The endosymbiotic theory is based on the fact that both the mitochondria and chloroplast can produce their own energy being able to reproduce independently and contain their own DNA. This provides possible evidence that mitochondria and chloroplasts may have existed as prokaryotes before joining with other organelles to form eukaryotic cells.

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  • “Ice Flow” Kevin MacLeod (
  • Licensed under Creative Commons: By Attribution 4.0 License

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