Difference between Actin and Myosin Class 11 Pdf
Difference Between Actin and Myosin: Actin and myosin are present in muscle tissue. Both are responsible for the contraction of the muscle. Actin produces short, thin filaments, while myosin produces long, thick filaments. Both actin and myosin are present in eukaryotic cells, form the cytoskeleton, and participate in the movement of molecules.
Actin is the main constituent of the thin filaments in muscle cells and myosin makes up the thick filaments and is classified as a mechano-chemical enzyme or motor protein because it is capable of converting chemical energy into mechanical energy, useful for the mechanism of muscle contraction in the human body.
What is the Difference Between Actin and Myosin Filaments
| Actin | Myosin |
|---|---|
| Actin is family of globular Multifunctional Protein that forms Microfilaments in the cytoskeleton and the thin filaments in muscles fibrills. | Myosin are the superfamily of motor proteins best Known for there role in Muscles Contractions and Other motility processes occurs in Eukaryotes |
| Actin founds in essentially in all Eukaryotic Organisms | Myosin are also found in Eukaryotic organisms. |
| Actin exists in two forms G-Actin or Globular Actin and F-Actin or Fibrous Actin. | Myosin is divided in to 18 classes from Myosin I to Myosin XVIII. |
| They are thin and short in Size | They are thick and Longer In size |
| Actin filaments are approximately 7 nanometers in Diameter and upto several micrometers in length With Molecular mass 40 kDa. | The size of Myosin filaments is near about 1.6 Micrometer in lengths Approximately 300 A° in diameter with Molecular Mass 220 kDa |
| Molecular weight of Actin filament is Less as compare to myosin filaments. | Molecular weight of Myosin filaments are more than Actin filament. |
| Actin filament surface of action Is smooth | Myosin filaments surface of action is hard |
| It is located in cell membrane, Muscle Fibres Cell wall and Microfilaments | Myosin is located in Muscles Cells |
| Actin filaments are more abundant than Myosin filaments | Myosin filaments are less abundant than Actin filament. |
| Actin filaments Allows Sliding into the H zone during Muscle contraction | While Myosin filaments does not allow sliding during Muscle contraction. |
| Actin Proteins are globular Proteins. It carries tropomyosin and troponin | Myosin Proteins are motor Proteins and it carry meromyosin. |
| Actin filament do not form cross Bridges | Myosin filaments forms cross bridges |
| They are founds in A ans I bands | They are found in A bands of sarcomeres |
| They are free at one end | They are free at both ends. |
What is Actin?
- Actin is a form of protein that forms a thin contractile filament in muscle cells. It is essentially protein present in eukaryotic cells.
- Actin is an incredibly conservative protein.
- There are Two forms of actin filaments first one is monomeric class G-Actin or Globular Actin and second one is filamentous called F-Actin or Fibrous Actin. Under physical conditions, the monomer readily polymerizes to form filaments using the energy of ATP.
- Polymerization of actin filaments begins at both ends of the filament; the polymerization ratio is not the same at each end and results in inherent polarity in the filament.
- The ratio of tropomyosin and troponin stabilizes the actin filament. The nature and movement of the cell depend on the actin filaments.
- The central role of actin filaments is to form the active cytoskeleton of a cell. The cytoskeleton provides physical support and links the cell to its environment.
- Actin filaments are involved in the development of filopodia and lamellipodia that aid cell motility. Actin filaments aid in the transport of organelles to daughter cells during mitosis.
- The compound of thin filaments in the muscle cells produces forces that support the contraction of the muscles.
What is Myosin?
- Myosin is a superfamily of Motor proteins that bind actin, hydrolyze ATP, and most are located in muscle cells it forms the thick contractile filaments in muscle cells of eukaryotic organisms.
- Myosin plays important role Muscle contraction and wide range of other intracellular motility.
- Generally All myosin Filaments are made up of one or two heavy chains and many light chains of polypeptide.
- Myosin consists of head regions, neck region and tail regions. The head area is circular and comprises actin and ATP binding sites. The neck region comprises an α helix. The tails contain almost three hundred myosin molecules from the thick filament axis.
- The myosin heads of these molecules develop into thin filaments. The tail site comprises the binding sites for different molecules.
- There are 18 types of from myosin I, II, III, IV, to Myosin XVIII.
- Myosin I involved in vesicle transport. Myosin II is responsible for muscle contraction. Contraction of muscles is described as the sliding filament theory.