Cell organelles


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Cell organelles

  1. 1. Cell Organelles<br />
  2. 2. The Nucleus<br />Most functions of a cell are controlled by the nucleus.<br />The nucleus is surrounded by a double membrane called the nuclear envelope or nuclear membrane.<br />The nuclear envelope is made of two lipid bilayers that separate the nucleus from the protoplasm.<br />
  3. 3. The Nucleus<br />Nuclear pores<br />Scattered over the surface of the envelope are many small channels called nuclear pores.<br />Substances that are made in the nucleus, including RNA, move into the cytoplasm by passing through these nuclear pores.<br />Ribosomes are partially <br /> assembled in a region called the nucleolus.<br />
  4. 4. The Nucleus<br />The hereditary information of a cell is coded in the cell’s DNA, most of which is stored in the nucleus.<br />Most of the time DNA is long thin strands but when it is about to divide it appears as tightly wound.<br />These DNA strands are called chromosomes.<br />The human body cells contain 46 chromosomes.<br />
  5. 5. Ribosomes<br />Eukaryotic cells have a system of internal membranes that play an essential role in the processing of proteins.<br />Cells make proteins on ribosomes.<br />A ribosome is a cell organelle composed of RNA and protein, the site of protein synthesis.<br />Each ribosome is made of dozens of different proteins as well as RNA.<br />
  6. 6. Production of Proteins<br />Proteins that are exported from a cell are made of ribosomes that lie on the surface of the endoplasmic reticulum. (ER)<br />The endoplasmic reticulum (ER) is an extensive system of internal membranes that move proteins and other substances through the cell.<br />
  7. 7. Production of Proteins<br />The part of the ER with attached ribosomes is called rough ER because it has a rough appearance when viewed in the electron microscope.<br />As each protein is made, it crosses the ER membrane and enters the ER.<br />
  8. 8. Production of Proteins<br />The rest of the ER is called smooth ER because it lacks ribosomes and thus appears smooth when viewed in an electron microscope.<br />The portion of the ER that <br /> contains completed protein<br /> pinches off to form a vesicle.<br />A vesicle is a small, membrane<br /> -bound sac that transports<br /> substances in cells.<br />
  9. 9. Packaging and Distribution of Proteins<br />Vesicles that contain newly made proteins move through the cytoplasm from the ER to an organelle called the Golgi Apparatus.<br />
  10. 10. Packaging and Distribution of Proteins<br />The Golgi Apparatusis a set of flattened, membrane-bound sacs that serve as the packaging and distribution centers of the cell.<br />
  11. 11. Packaging and Distribution of Proteins<br />Enzymes inside the Golgi Apparatus modify the proteins that are received in vesicles from the ER.<br />The modified proteins are than enclosed in new vesicles that bud from the surface of the Golgi Apparatus.<br />
  12. 12. Packaging and Distribution of Proteins<br />Other vesicles include lysosomes which are small spherical organelles that contain the cell’s digestive enzymes.<br />The ER, the Golgi Apparatus, and lysosomes work together in the production, packaging and distribution of proteins.<br />
  13. 13. Mitochondria<br />Nearly all eukaryotic cells contain many mitochondria.<br />A mitochondria is an organelle that harvests energy from organic compounds to make ATP, the main energy currency of cells.<br />Although some ATP is made in the cytosol, most of the cell’s ATP is made inside mitochondria.<br />mitochondria<br />
  14. 14. Mitochondria DNA<br />The nucleus is not the only organelle in the cell that contains nucleic acids.<br />Mitochondria also have DNA and ribosomes, and mitochondria make some of their own proteins.<br />Mitochondria DNA is separate from nuclear DNA and similar to the circular DNA of prokaryotic cells.<br />
  15. 15. Structure of Plant cells<br />The organelles described here are found in both plant cells and animal cells.<br />However, plant cells have three additional structures not found in animal cells.<br />Cell Walls<br />Chloroplasts<br />Central Vacuole<br />
  16. 16. Cell Wall & membrane<br />Cell Wall: cell membrane<br />The cell membrane of a plant is surrounded by a thick cell wall, composed of proteins and carbohydrates.<br />The cell wall <br />helps support and maintain the shape of the cell <br />protects the cell from damage<br /> and connects it with adjacent cells<br />
  17. 17. Chloroplasts<br />Plants cells contain one or more chloroplasts.<br />Chloroplasts are organelles that use energy from sunlight to make carbohydrates from carbon dioxide and water.<br />Carbon dioxide + water  carbohydrates<br />Chloroplasts, along with mitochondria, supply much of the energy needed to power the energy of plant cells.<br />
  18. 18. Central Vacuole<br />Much of a plant cell’s volume is taken up by a large membrane-bound space called the central vacuole.<br />The central vacuole stores water and may contain many substances, including ions, nutrients, and wastes.<br />When the central vacuole is full, it makes the plant rigid.<br />This rigidity enables a plant to stand upright.<br />