Mitochondria and chloroplasts are mobile and move around the cell along tracks

Mitochondria and chloroplasts are mobile and move

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Mitochondria and chloroplasts are mobile and move around the cell along tracks of the cytoskeleton. Peroxisomes generate and degrade H 2 O 2 in performing various metabolic functions. Peroxisomes contain enzymes that transfer hydrogen from various substrates to oxygen. An intermediate product of this process is hydrogen peroxide (H 2 O 2 ), a poison. The peroxisome contains an enzyme that converts H 2 O 2 to water. Some peroxisomes break fatty acids down to smaller molecules that are transported to mitochondria as fuel for cellular respiration. Peroxisomes in the liver detoxify alcohol and other harmful compounds. Specialized peroxisomes, glyoxysomes, convert the fatty acids in seeds to sugars, which the seedling can use as a source of energy and carbon until it is capable of photosynthesis. Peroxisomes are bound by a single membrane. They form not from the endomembrane system, but by incorporation of proteins and lipids from the cytosol. They split in two when they reach a certain size. Concept 6.6 The cytoskeleton is a network of fibers that organizes structures and activities in the cell The cytoskeleton is a network of fibers extending throughout the cytoplasm. The cytoskeleton organizes the structures and activities of the cell. The cytoskeleton provides support, motility, and regulation. The cytoskeleton provides mechanical support and maintains cell shape. The cytoskeleton provides anchorage for many organelles and cytosolic enzymes. The cytoskeleton is dynamic and can be dismantled in one part and reassembled in another to change the shape of the cell. The cytoskeleton also plays a major role in cell motility, including changes in cell location and limited movements of parts of the cell. The cytoskeleton interacts with motor proteins to produce motility. Cytoskeleton elements and motor proteins work together with plasma membrane molecules to move the whole cell along fibers outside the cell. Motor proteins bring about movements of cilia and flagella by gripping cytoskeletal components such as microtubules and moving them past each other. The same mechanism causes muscle cells to contract. Inside the cell, vesicles can travel along “monorails” provided by the cytoskeleton. The cytoskeleton manipulates the plasma membrane to form food vacuoles during phagocytosis. Cytoplasmic streaming in plant cells is caused by the cytoskeleton. Recently, evidence suggests that the cytoskeleton may play a role in the regulation of biochemical activities in the cell. There are three main types of fibers making up the cytoskeleton: microtubules, microfilaments, and intermediate filaments. Microtubules, the thickest fibers, are hollow rods about 25 microns in diameter and 200 nm to 25 microns in length. Microtubule fibers are constructed of the globular protein tubulin.
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