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Mitichondria And Chloroplasts

 

            
             Mitochondria are found in nearly all eukaryotic cells. There may be only one, but usually there are hundreds to thousands per cell. The Mitochondria is like the powerhouse of the cell. It is directly correlated to the cell's activity. It is approximately 1-10um (micrometer) long and 1um wide. They are often oval but can change shape. They move freely in the cytoplasm of the cell. The mitochondria can divide and they contain their own ribosomes and DNA. The mitochondria are not part of the endomembrane system because it is not made by the endoplasmic reticulum (ER). The mitochondria are made of free ribosomes that are floating in the cytosol and those that are part of preexisting mitochondria. They have two membranes. The first membrane is smooth. It is it's outer most shell. It is highly permeable to small solutes, and blocks the passage of proteins and other macromolecules. The inner membrane is to be considered rough because it has folds and ribosomes on it. These folds are called cristae. This is the site for oxidative phosphorilation of ADP into ATP, which is where the cell gets its energy. These two membranes make two compartments to the organelle. First is the innermembrane space, which is located between the outer membrane and the inner membrane. It has a similar composition to that of the cytoplasm of the cell. The second is the matrix, which is inside the inner membrane. This contains enzymes that catalyze many of the steps in cellular respiration, which is another main process that provides the cell with energy. .
             The chloroplasts are found in eukaryotic algae, leaves and other green parts of plants. Their measurements are about 2um by 5um. They have a double membrane surrounding it. They have flattened membranous sacs inside the chloroplasts called thylakoids, stacks of these thylakoids are called grana. This is where the chlorophyll is found. This is the site for the step in photosynthesis where light is initially converted into chemical energy.


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