Mitochondrion

(Click image to enlarge in new window)

Objective: To find and learn about the Mitochondria!

If I’m to keep searching for these organelles, I’m going to need a lot of energy! Get the pun? Energy…and Mitochondria? Well if you don’t get it, keep reading and maybe that will help you identify and find the hidden mitochondria in the picture!

<Scroll to bottom for correct location…>
 
Mitochondria:

Introduction:

The mitochondria, singular mitochondrion, is the powerhouse of the cell, where energy is converted into ATP (adenosine tri-phosphate), a form cells can use to function. In other words cellular respiration takes place in the mitochondria, in which carbohydrates, lipids, and sugars are broken down to make ATP. An important thing about the mitochondria is that it is not in the endomembrane system (along with the chloroplast), for the following distinguishing traits: It has two membranes, makes its own membrane proteins using free ribosomes in the cytoplasm and its own ribosomes in the organelle (it doesn’t get proteins from the bound ribosomes), contains some of its own DNA, and is semiautonomous (can grow and reproduce by themselves in the cell). Although most of the proteins in the mitochondria are made by free ribosomes (directed by nuclear DNA), the rest of the proteins are made by the mitochondria’s own ribosomes (directed by its own DNA). These characteristics arose because when the mitochondria first evolved in the eukaryotic cell, a heterotrophic prokaryote entered the eukaryote, which resulted in having its own DNA, ribosomes, double membrane, and other characteristics.

Note how there are two membranes (the inner and outer membranes) that form two areas: the inter-membrane, and the matrix (shaded yellow).

Structure and Function:

The mitochondria is in almost all eukaryote cells, mainly for cellular respiration. It is around 1 – 10 micrometers, and in a living cell it moves around and replicates on its own (as mentioned before). One of its most important characteristics is the double membrane, which allows the mitochondria to make a hydrogen ion gradation necessary for cellular respiration. The outer membrane is smooth while the inner membrane is wrinkled in order to increase the surface area for ATP synthesis. The inner compartments that form when the inner membrane folds are called cristae. The area between the outer membrane and the inner membrane is called the inter-membrane space, and the area inside the inner membrane is called the mitochondrial matrix. The matrix has a lot of mitochondrial DNA, enzymes, and ribosomes. Some of these enzymes aid in cellular respiration, such as the ATP synthase complex. Basically, there is a high concentration of hydrogen ions in the intermembrane space, and a lower concentration in the membrane. As hydrogen ions go down the gradient and pass the ATP synthase, that movement is used to attach a phosphate to ADP to make ATP.

The ATP synthase is located on the inner membrane, and it makes energy when hydrogen ions from the inter-membrane space passes through it to the matrix.

Extra Stuff:

Here is a video provided by the NDSU Virtual Cell Animations Project:

Sumanas, Inc. also offers a detailed animation that covers cellular respiration.

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