| What are peroxisomes? | AKA microbodies, resemble lysosomes in terms of size and structure, but distinct in terms of origin proliferation mode, enzyme content and function. They are actively involved in diverse metabolic reaction such as oxidation and storage. Moreover they play a role in detoxication, and they are not present in bacteria. |
| Talk about the structure of peroxisomes. | Simple membrane bound vesicles that are common to plant and animal cells, diameter ranges between 0.1 and 1 microm, usually contain crystalline core of oxidative enzymes, proliferate by binary fission, and do not derive from TGN. Their proteins are synthesized by free ribosomes and derived into peroxisomes by their signal code. They may be interconnected by thin canaliculi independently from endomembrane system. |
| Talk about the peroxisome functions. | They are called peroxisomes since they are characterized by synthesis and degradation of hydrogen peroxide (H2O2) highly reactive and oxidizing agent. They contain 50 type of oxidizing enzymes, aa-oxidase, urate-oxidase... Enzymatic content is variable according to cell type.
They are also involved in synthesis of special types of lipids, plasmalogens abundant in brain cells, characterized by bonded fatty acid and glycerol by ether bond. |
| Talk about the most abundant enzyme in peroxisome. | Peroxisomal catalase involved in H2O2 degradation into water and oxygen, they use (utilize) H2O2 generated by other enzymes to oxidize a variety of substances (xenobiotics) which leads to detoxication, important in liver and kidneys. |
| Talk about the oxidizing of fatty acid in peroxisomes. | Having long hydrocarbon tail (glycolate oxidase) and alanine glyoxylate aminotransferase help in collaborating with mitochondria and chloroplast in photorespiration. |
| Talk about Light productivity role of peroxisomes. | Luciferase of firefly catalyzes transformation of luciferin into light. |
| Talk about glyoxysomes. | special form of peroxisomes involved in glyoxylatic cycle enzymes, other enzymes such as krebs cycle ones are also found, abundant in plant seeds usually rich in stored lipids. Germinating seedlings rely on lipids as a energy source since photosynthesis is no yet ready. They have to convert fatty acids into carbohydrates necessary for metabolism and ATP production in mitochondria as well as cell wall construction. |
| How are plant fatty acids oxidized? | Oxidized into acetyl_CoA reacts with oxaloacetate and form citric acid, which transforms into glucose by enzymatic reactions named glyoxylate cycle. These reaction occur in Glyoxysomes so they are indispensable for plant growth |
