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Organelles

Organelles. In Plant Cell. PLANT CELL STRUCTURE. Cell Wall. -a layer which only found in plant -a dead layer -the outermost layer of plant cell, make up by cellulose which forms very thin fibers -strong and rigid -gives shape to the cell

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Organelles

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  1. Organelles In Plant Cell

  2. PLANT CELL STRUCTURE

  3. Cell Wall -a layer which only found in plant -a dead layer -the outermost layer of plant cell, make up by cellulose which forms very thin fibers -strong and rigid -gives shape to the cell -protects and supports the enclosed substances (protoplasm) -resists entry of excess water into the cell -large empty spaces present between cellulose fibres -freely permeable

  4. Cell Membranes -component of every biological cell -selectively permeable cell membrane (or plasma membrane or plasmalemma) -Phospholipid bilayer was found, which is combine of two opposite layer of phospholipid, each molecule contain hydrophilic phosphate head and hydrophobic hydrocarbon chain -Cell surface membranes often contain receptor proteins and cell adhesion proteins. -One of the key roles of the membrane is to maintain the cell potential. - Some function of cell membrane: -Isolates cytoplasm from external environment -regulates flow or material into and out of the cell -allows interaction with other cells

  5. Cytoplasm -homogeneous, generally clear jelly-like material that fills cells. -consists of cytosol and the cellular organelles, except the nucleus. -made up of water, salts and organic molecules and many enzymes -plays an important role in a cell, serving as a "molecular soup" -plays a mechanical role, i.e. to maintain the shape, the consistency of the cell and to provide suspension to the organelles. -storage place for chemical substances indispensable to life. -Vital metabolic reactions take place here, for example anaerobic glycolysis and protein synthesis.

  6. Nucleus -contains most of the cell's genetic material -two primary functions: to control chemical reactions within the cytoplasm and to store information needed for cellular division. -Inside the nucleus is one or several nucleoli surrounded by a matrix called the nucleoplasm. The nucleoplasm is a liquid with a gel-like consistency (similar in this respect to the cytoplasm), in which many substances are dissolved. These substances include nucleotide triphospates, enzymes, proteins, and transcription factors. There also exists a network of fibers in the nucleoplasm known as the nuclear matrix. -Genetic material (DNA) is also present in the nucleus, the DNA is present as a DNA-protein complex called chromatin, present as a number of discrete units known as chromosomes.

  7. Vacuoles -serve a variety of different functions: -capturing food materials or unwanted structural debris surrounding the cell, sequestering materials that might be toxic to the cell, maintaining fluid balance (called turgor) within the cell, exporting unwanted substances from the cell, or even determining relative cell size. -typically filled with a liquid called ‘cell sap’, principally water. -Most mature plant cells have a central vacuole, takes up more than 80% of the cell interior. -surrounded by a single-layered membrane, called the tonoplast.

  8. In a plant cell, we can find a lot of organelles in cytoplasm: • Chloroplast • Mitochondria • Golgi apparatus • Endoplasmic Reticulum

  9. Chloroplast -Chloroplasts are organelles found in plant cells and eukaryotic algae -conduct photosynthesis. -similar to mitochondria but are found only in plants. -surrounded by a double membrane with an intermembrane space -have their own DNA and are involved in energy metabolism and both have reticulations, or many foldings, filling their inner spaces. -Chloroplasts convert light energy from the sun into ATP through a process called photosynthesis.

  10. Mitochondria -cristae surface houses needed for aerobic respiration and ATP formation, it folded to increases that capacity by increasing the surface area -one within the interior of the mitochondrion, called the matrix -between the inner and outer membranes, called the intermembrane space. -Mitochondria as "cellular power plants", their primary function is to convert organic materials into energy in the form of ATP. -standard bean-shaped organelle, ranging from 1 to 4 µm in length -living cells -contains two functionally distinct membranes: the outer mitochondrial membrane and the inner mitochondrial membrane.

  11. Mitochondria Chloroplast

  12. Golgiapparatus -primary function is to process proteins targeted to the plasma membrane as a central delivery system for the cell. -transport vesicles that leave the endoplasmic reticulum (ER), specifically rough ER, are transported to the Golgi apparatus, -modified, sorted and shipped towards their final destination, such as enzymes, being secreted. -is "postal office" of the cell. It handles all incoming lipids, proteins, etc., and controls their export as well. -The transport mechanism itself is not yet clear -As well as protein modification, Golgi apparatus is involved in the transport of lipids around the cell as well creating lysosomes -- organelles involved in digestion.

  13. Endoplasmic reticulum Smooth ER Rough ER -rough ER manufactures and transports proteins destined for membranes and secretion. -synthesizes membrane, organellar, and excreted proteins. Minutes after proteins are synthesized most of them leave to the Golgi apparatus within vesicles. -also modifies, folds, and controls the quality of proteins -The smooth ER has functions in several metabolic processes -takes part in the synthesis of various lipids ,fatty acids and steroids (e.g., hormones), -plays an important role in carbohydrate metabolism, detoxification of the cell, and calcium storage. -well developed in cells that produce steroid hormones and in liver cells.

  14. Which is Rough ER and Smooth ER? Rough ER Smooth ER

  15. Transportation between ER and Golgi Apparatus The transport vesicles from the ER fuse with the cis face of the Golgi apparatus (to the cisternae) and empty their protein content into the Golgi lumen. The proteins are then transported through the medial region towards the trans face and are modified on their way. The proteins are also labelled with a sequence of molecules according to their final destination. The transport mechanism itself is not yet clear; it could happen by cisternae progression (the movement of the apparatus itself, building new cisternae at the cis face and destroying them at the trans face) or by vesicular transport. It is also proposed that the cisternae are interconnected and the transport of cargo molecules within the Golgi is due to diffusion, while the localisation of Golgi-resident proteins is achieved by an unknown mechanism.

  16. Reference source: • http://www.yahoo.com.hk • http://en.wikipedia.org/wiki/Main_Page

  17. Group 5 - Poon Wing Man 6S (27)

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