Cristae: Definition, Types and Junctions of Cristae And Its Hazardous Disorders.

Cristae Definition

Cristae are sub-compartments of the innermost membrane of mitochondria that are necessary for mitochondrial action. Mitochondria are the organelles accountable for the creation of ATP, the cell’s energy molecule. They are sometimes referred to as the cell’s powerhouses.

Mitochondria have two membranes, one on the outside and one on the inside. Each membrane has its own shape and function. The outer membrane regulates the shape of the organelle and is required for mitochondrial contact with organelles and so on. The inner mitochondrial membrane is divided into two sections: 1) the inner border membrane, The foldable cristae, which feature protuberances and folds that breach the inner mitochondrial matrix, are found near to the external membrane.

Cylindrical linkages are known as cristae junctions, between the folded cristae membrane and the inner membrane.

Types of Cristae

Cristae Membrane

The major role of mitochondria consists of the oxidative phosphorylation of carbohydrates to produce ATP. Cristae membranes and connections play an important role in this process.

Folding or wrinkling, the cristae on the inner mitochondrial membrane, creates a vast surface area within the mitochondria. The amount of cristae in the mitochondria represents the cell’s ATP needs. Because heart muscle cells need more ATP, they have up to three times as many cristae as other cells. The electron transport chain, as well as oxidative phosphorylation enzymes like ATP synthase and succinate dehydrogenase, are found in the cristae membrane.

By transporting electrons through the inner mitochondrial membrane, the electron transport chain generates an electrochemical potential. The mitochondrial F1Fo-ATP synthase process uses this gradient to produce ATP from ADP and inorganic phosphate. The F0 portion of the enzyme is found in the cristae, whereas the F1 portion is found in the mitochondrial matrix.

The electron transport chain, which produces ATP, is positioned in the inner mitochondrial membrane, as shown in the picture below:

Cristae Junctions

Cristae connections are tubular formations with a diameter of between 12 and 40 nm that divide cristae from the rest of the inner border membrane. These connections allow enzymes such as F1F0-ATP synthase to concentrate preferentially on the cristae. Due to the presence of junctions, a number of enzymes participating in oxidative phosphorylation are selectively transported to the cristae and might even be retained in this region of the mitochondrial membranes. Furthermore, the F1F0-ATP synthase is crucial in defining the structure of the cristae.

Intermitochondrial communication is also facilitated by cristae junctions. Nearby mitochondria’s cristae align themselves parallel to one another and perpendicular to the mitochondria’s connections. This arrangement promotes electrochemical connection, enabling the mitochondria to work in unison. Cristae are essential elements of intercellular as well as intracellular mitochondrial pathways, due to the movement of ions and chemicals between cristae and membranes.

Examples of Cristae Disorders

Numerous medical diseases and cell apoptosis show unusual inner membrane architecture. For example, cristae morphology is disturbed in amyotrophic lateral sclerosis (ALS), Alzheimer’s disease, and Parkinson’s disease, for example, by inclusions inside mitochondria and abnormal inner membrane topologies.

Related Biology Terms

  • This refers to a collection of proteins on the inner mitochondrial membrane which take high-energy electrons produced via the citric acid cycle, commonly referred to as the respiratory chain. When electrons travel across the various stages of this chain, they shed power, which is subsequently used to generate a proton gradient across the inner mitochondrial membrane.
  • The enzyme F1Fo-ATP synthase is found on mitochondrial cristae and is accountable for adenosine triphosphate production (ATP).
  • Mitochondria are eukaryotic organelles that are located in the cytoplasm of cells and are enclosed in a double membrane. Their major job is to help with aerobic respiration and ATP production.

Question and Answer

1.On which of these mitochondrial structures are cristae found?

  1. The outer membrane
  2. The inner membrane
  3. The matrix
  4. All of the above

B is correct. Cristae are formed through invaginations of the inner mitochondrial membrane.

2. Which statement is true about cristae?

  1. The wrinkled form of cristae increases the surface area of the inner mitochondrial membrane.
  2. Cristae are located inside the nucleus.
  3. Cristae do not play a role in allowing mitochondria to communicate with other mitochondria in the cells.
  4. Cristae are part of the plasma membrane.

A is correct. Cristae are wrinkled to create more surface area inside the small mitochondria. Cristae are located on the inner membrane of mitochondria and mitochondria are located in the cell cytoplasm, not the nucleus. When mitochondria communicate with each other, the cristae of each mitochondrion align perpendicularly to the inter mitochondrial connections (the points where the two mitochondria are touching each other) in order to facilitate electrochemical coupling. Cristae are part of the inner membrane of the mitochondria, not the plasma membrane of the cell.

3. Which of the following statements is true?

  1. Cristae membrane surface area size is proportional to a cell’s capacity for ATP generation.
  2. Cristae membranes are deformed in diseases such as Parkinson’s and Alzheimer’s.
  3. The cylindrical connections between cristae membranes and the inner membrane boundary of mitochondria are called cristae junctions.
  4. All of the above.

D is correct. All of the above statements are true.

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