What is colony counter and how it works?

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.

Myosin and actin have different functions, locations and structures. Myosin acts on cell movement and intracellular material transport, while actin acts on cell movement and contraction, etc., and plays an important role in muscle movement. Myosin is in smooth muscle, while actin is in both smooth muscle and the thin filaments of striated muscle fibrils. Myosin is composed of one or two heavy chains and several light chains, while actin is composed of each actin molecule bound to adenosine triphosphate (ATP) or adenosine diphosphate (ADP) molecules.

Myosin is a constituent unit of myofibril thick filaments. In smooth muscle. It plays an important role in muscle movement. Its molecular shape is like a bean sprout, consisting of two heavy chains and light chains. Most of the two heavy chains are helical, forming a bean sprout-shaped rod, and the rest of the heavy chain is formed with the light chain, forming the valve of the bean sprout. After being activated, the enzyme, which is active and capable of decomposing phosphorylation, is activated. Its molecular weight is about 510,000. In the thick filament, the head of the molecule is toward the end of the thick filament, which is arranged linearly in the longitudinal direction.

Actin is a medium-sized protein composed of 375 amino acid residues and is encoded by a large, highly conserved gene. The molecular weight of a monomeric actin molecule is three, and its binding sites. One is a binding site for the actin, and the other two are binding sites for the actin. Actin is expressed in at least 6 isomeric forms, which are divided into three types: α, β, and γ. Actin in higher animal cells can be divided into three categories according to the different isoelectric points. α is distributed in various muscle cells, and β and γ are distributed in muscle cells and non-muscle cells. There are three types of α actin (skeletal muscle, cardiac muscle and smooth muscle), one β actin and two types of γ actin (γ smooth muscle and γ non-smooth muscle).

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. 

Importance of Actin and Myosin

Actin and myosin are essential proteins in the human body that play key roles in muscle contraction and other cellular functions. Their importance lies in supporting muscle movement, cell structure, transport, and communication. Here's a simplified overview of why they matter:

1. Muscle Contraction: Actin and myosin work together to contract muscles. Myosin pulls on actin filaments, shortening muscle fibers to produce movement.

2. Cellular Movement: Beyond muscles, they help cells divide (cytokinesis), move, and transport organelles, enabling essential cellular activities.

3. Maintaining Cell Shape: Actin forms the cell’s structural framework (cytoskeleton), helping maintain shape and stability.

4. Intracellular Transport: Myosin moves along actin filaments to transport cargo within cells, ensuring proper cell function.

5. Cell Signaling: They participate in signaling pathways, affecting cell growth, shape changes, and programmed cell death (apoptosis).

6. Muscle Disorders: Mutations in actin or myosin genes can cause disorders like muscular dystrophy, highlighting their importance in medical research.