Difference Between Mitochondria and Plastids

Main Difference – Mitochondria vs Plastids

Mitochondria and plastids are two vital organelles found in eukaryotic cells. Mitochondria and plastids are membranous organelles with fluid-filled sacs inside them. The main difference between mitochondria and plastids is that mitochondria are involved in the energy production of the cell through cellular respiration whereas plastids have various functions such as food storage and photosynthesis.

Key Areas Covered

1. What are Mitochondria
    – Definition, Characteristics, Functions
2. What are Plastids
      – Definition, Characteristics, Functions
3. What are the similarities between Mitochondria and Plastids
      – Outline of Common Features
4. What is the difference between Mitochondria and Plastids
     – Comparison of Key Differences

Key Terms: Cellular Respiration, Chloroplasts, Chromoplasts, Cristae, Differences, Inner Mitochondrial Membrane, Leucoplasts, Mitochondria, Plastids, Similarities, Thylakoids, White Plastids

What are Mitochondria

Mitochondria are membranous organelles found in all eukaryotic cells. The metabolic energy in the form of ATP is produced in mitochondria in a process called cellular respiration. Mitochondria contain their own DNA inside the organelle. The number of mitochondria present in a particular cell depends on the cell type, tissue, and organism. Mitochondrial matrix is separated from the contents in the cytoplasm by inner and outer mitochondrial membranes. The inner mitochondrial membrane forms folds into the matrix called cristae. Cristae increase the surface area of the inner membrane. The citric acid cycle, which is the second step of the cellular respiration, occurs in the matrix of mitochondria. ATP is produced in the oxidative phosphorylation, which occurs at the inner membrane of mitochondria. A mitochondrion is shown in figure 1.

Difference Between Mitochondria and Plastids

Figure 1: A mitochondrion

What are Plastids

Plastids are membranous organelles found only in plant cells. Three types of plastids can be identified based on the type of pigment present in each plastid. They are leucoplasts, chromoplasts, and chloroplasts. Leucoplasts or white plastids are found in roots of sweet potatoes, internal leaves of cabbage, and stems of potatoes. They lack any kind of pigments. Leucoplasts serves as food storage in the form of starch. Chromoplasts are colored plastids, present in the petals of flowers, fruits, and roots of some plants. They contain carotenoid pigments with varying colors from red, orange to green. Chloroplasts are the green pigments found in stem and leaves of plants. They contain the green pigment, chlorophyll, which is responsible for photosynthesis. Light energy of the sunlight is captured by chlorophyll and simple sugars are produced from carbon dioxide and water. Chloroplast is composed of an inner and outer membrane, separating chloroplast’s stroma from the cytoplasm. It also comprises thylakoids, which are disk-like structures, forming grana. Leucoplasts in a plant cell is shown in figure 2.

Main Difference - Mitochondria vs Plastids

Figure 2: Leucoplast

Similarities Between Mitochondria and Plastids

Both mitochondria and plastids are double membranous organelles found in eukaryotic cells.

Both comprise fluid-filled sacs inside the organelles, maintaining a unique environment inside the organelles.

Definition

Mitochondria: Mitochondria are a type of organelles in which the biochemical processes of respiration and energy production occur.

Plastids: Plastids are double-membrane organelles found only in plants and algae in which production and storage of chemicals occur in the cell.

Pigments

Mitochondria: Mitochondria lack pigments.

Plastids: Many plastids contain pigments.

Occurrence

Mitochondria: Mitochondria is found in both plant and animal cells.

Plastids: Plastids are only found in plant cells and algae.

Inner Membrane

Mitochondria: Inner mitochondrial membrane contains folds known as cristae.

Plastids: No folds are found in the inner membrane of plastids.

Chambers

Mitochondria: Completely separated chambers are found inside the matrix.

Plastids: Plasmids lack completely separated chambers inside the matrix.

Function

Mitochondria: Mitochondria are mainly involved in the energy production through cellular respiration.

Plastids: Plastids are mainly involved in the food production and storage in the cell.

Types

Mitochondria: Mitochondrial structure may vary based on the needs of the cell.

Plastids: Leucoplasts, chromoplasts, and chloroplasts are the three types of plastids.

Organelle DNA

Mitochondria: Mitochondria have their own DNA inside the organelle.

Plastids: Only chloroplasts have their own DNA.

Conclusion

Mitochondria and plastids are two types of membranous organelles found in eukaryotes. Plastids can only be found in plants and algae. Mitochondria are the powerhouse of the cell, which produces metabolic energy in a process called cellular respiration. Plastids are mainly involved in the food production and storage inside the cell. Chloroplasts are the type of plastids, which carry out photosynthesis. The main difference between mitochondria and plastids is their functions.

Reference:

1.Cooper, Geoffrey M. “Mitochondria.” The Cell: A Molecular Approach. 2nd edition.U.S. National Library of Medicine, 01 Jan. 1970. Web. Available here. 23 June 2017.
2. Battista, Jeremy. “Plastids: Definition, Structure, Types & Functions.” Study.com. N.p., n.d. Web. Available here. 23 June 2017.

Image Courtesy:

1. “0315 Mitochondrion new” By OpenStax – (CC BY 4.0) via Commons Wikimedia
2. “010-Sol-tub-40xHF-Gewebe” By Dr. phil.nat Thomas Geier, Fachgebiet Botanik der Forschungsanstalt Geisenheim. – Präparation und Foto Thomas Geier, upload von Martin Bahmann (CC BY-SA 3.0) via Commons Wikimedia