what is structure and function of lysosomes
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function of lysosomes= Breaking down of tissues
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Lysosomes digest many complex molecules such as carbohydrates, lipids, proteins, and nucleic acids, which the cell then recycles for other uses. The pH of lysosomes is acidic (around pH 5) because their hydrolytic enzymes function best at this pH instead of at the neutral pH of the rest of the cell. Hydrolytic enzymes specifically break down large molecules through hydrolysis. During the process of hydrolysis, a molecule of water is added to a substance, causing it to cleave. Like the digestive system of the human body, which breaks down food using enzymes, the lysosome can be thought of as the “digestive system” of the cell because it breaks down molecules using enzymes.
Lysosomes digest several different kinds of molecules. They can digest food molecules that enter the cell into smaller pieces if an endocytic vesicle (a vesicle that brings particles into the cell) fuses with them. They can also perform autophagy, which is the destruction of improperly functioning organelles. In addition, lysosomes have a role in phagocytosis, which is when a cell engulfs a molecule in order to break it down; it is also known as “cell eating”. For example, the white blood cells called phagocytes ingest invading bacteria in order to break it down and destroy it, and the bacteria is enclosed by a vesicle that lysosomes fuse with. These lysosomes then break down the bacteria.
structure of lysosomes:
Lysosomes are generally very small, ranging in size from 0.1-0.5 µm, though they can reach up to 1.2 µm. They have a simple structure; they are spheres made up of a lipid bilayer that encloses fluid that contains a variety of hydrolytic enzymes. The lipids that make up the bilayer are phospholipids, which are molecules that have hydrophilic phosphate group heads, a glycerol molecule, and hydrophobic fatty acid tails. Due to these differences in properties, phospholipids naturally form double-layered membranes when placed in a solution containing water. The phosphate group heads move to the outside of the layer, while the fatty acid tails move to the inside of the layer to be away from water. Phospholipids make up many other membranes in the cell, such as the cell membrane which surrounds the entire cell, the nuclear membrane (or nuclear envelope) that surrounds the nucleus, the Golgi apparatus, and the endoplasmic reticulum.
Lysosomes are formed by budding off of the Golgi apparatus, and the hydrolytic enzymes within them are formed in the endoplasmic reticulum. The enzymes are tagged with the molecule mannose-6-phosphate, transported to the Golgi apparatus in vesicles, and then packaged into the lysosomes.
There are many different types of enzymes in lysosomes including proteases, amylases, nucleases, lipases, and acid phosphatases, among many others. Enzymes are usually named for the molecules that they break down; for example, proteases break down proteins, and nucleases break down nucleic acids. Amylases break down starches into sugars.
The following images are a simplified structure of the lysosome and a more detailed depiction of the phospholipid bilayer structure.
Lysosomes digest several different kinds of molecules. They can digest food molecules that enter the cell into smaller pieces if an endocytic vesicle (a vesicle that brings particles into the cell) fuses with them. They can also perform autophagy, which is the destruction of improperly functioning organelles. In addition, lysosomes have a role in phagocytosis, which is when a cell engulfs a molecule in order to break it down; it is also known as “cell eating”. For example, the white blood cells called phagocytes ingest invading bacteria in order to break it down and destroy it, and the bacteria is enclosed by a vesicle that lysosomes fuse with. These lysosomes then break down the bacteria.
structure of lysosomes:
Lysosomes are generally very small, ranging in size from 0.1-0.5 µm, though they can reach up to 1.2 µm. They have a simple structure; they are spheres made up of a lipid bilayer that encloses fluid that contains a variety of hydrolytic enzymes. The lipids that make up the bilayer are phospholipids, which are molecules that have hydrophilic phosphate group heads, a glycerol molecule, and hydrophobic fatty acid tails. Due to these differences in properties, phospholipids naturally form double-layered membranes when placed in a solution containing water. The phosphate group heads move to the outside of the layer, while the fatty acid tails move to the inside of the layer to be away from water. Phospholipids make up many other membranes in the cell, such as the cell membrane which surrounds the entire cell, the nuclear membrane (or nuclear envelope) that surrounds the nucleus, the Golgi apparatus, and the endoplasmic reticulum.
Lysosomes are formed by budding off of the Golgi apparatus, and the hydrolytic enzymes within them are formed in the endoplasmic reticulum. The enzymes are tagged with the molecule mannose-6-phosphate, transported to the Golgi apparatus in vesicles, and then packaged into the lysosomes.
There are many different types of enzymes in lysosomes including proteases, amylases, nucleases, lipases, and acid phosphatases, among many others. Enzymes are usually named for the molecules that they break down; for example, proteases break down proteins, and nucleases break down nucleic acids. Amylases break down starches into sugars.
The following images are a simplified structure of the lysosome and a more detailed depiction of the phospholipid bilayer structure.
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