Cell Structure And Function

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Cell Structure And Function

  1. 1. CELL STRUCTURE AND FUNCTION
  2. 2. ORGANELLES <ul><li>Cytoplasm lies between the cell membrane and nucleus and contains the organelles </li></ul><ul><li>Cytosol is a gelatin like aqueous fluid that contains salts, minerals and organic molecules </li></ul>
  3. 3. Mitochondria <ul><li>Sites of chemical reactions that transfer energy from organic compounds to ATP </li></ul><ul><li>ATP- main energy source for cells </li></ul><ul><li>Cells with high energy requirements have more mitochondria ex: muscle and liver cells </li></ul><ul><li>Have 2 membranes </li></ul><ul><li>Smooth outer membrane serves as a boundary between the mitochondria and the cytosol </li></ul><ul><li>Inner membrane has many folds called Cristae – they enlarge the surface area for more chemical reactions </li></ul><ul><li>Have their own DNA ( for reproduction) </li></ul>
  4. 4. Ribosomes <ul><li>Most numerous </li></ul><ul><li>Not surrounded by a membrane </li></ul><ul><li>Made up of proteins and RNA </li></ul><ul><li>RNA is packaged into the ribosomes then transported to the cytosol </li></ul><ul><li>Some ribosomes are free </li></ul><ul><li>Some are attached to the endoplasmic reticulum </li></ul><ul><li>Protein is synthesized (produced) in the ribosomes </li></ul><ul><li>Proteins to be used in the cytosol – free ribosomes </li></ul><ul><li>Proteins to be exported or inserted in the cell membrane – ribosomes on the ER </li></ul>
  5. 5. Endoplasmic Reticulum <ul><li>System of membranous tubules and sacs </li></ul><ul><li>Intracellular Highway – molecules move from one part of the cell to another </li></ul><ul><li>2 types – rough and smooth </li></ul><ul><li>Rough covered by ribosomes – prominent in cells that make large amounts of proteins to be exported from the cell </li></ul><ul><li>Smooth – no ribosomes </li></ul><ul><li>Synthesis of steriods in gland cells </li></ul><ul><li>Regulation of calcium in muscle cells </li></ul><ul><li>Breakdown of toxic substances in liver cells </li></ul>
  6. 6. CILIA AND FLAGELLA <ul><li>Hairlike organelles that extend from the surface of the cell </li></ul><ul><li>Assist in movement </li></ul><ul><li>Cilia – short and present in large numbers </li></ul><ul><li>Flagella – long and less numerous </li></ul>
  7. 7. Nucleus <ul><li>Most prominent structure </li></ul><ul><li>Maintains its shape with a protein skeleton called the nuclear matrix </li></ul><ul><li>Double membrane – nuclear envelope </li></ul><ul><li>Inside the envelope – chromation (DNA & protein) </li></ul><ul><li>When the cell is about to divide it forms the chromosomes </li></ul><ul><li>Stores hereitary information in its DNA </li></ul><ul><li>RNA is copied from DNA </li></ul><ul><li>RNA travels from nucleus to the cytosol through small holes in the envelope – nuclear pores </li></ul><ul><li>Contains the nucleolus – the site where ribosomes are synthesized </li></ul>
  8. 8. Golgi Apparatus <ul><li>Processing, packaging and secreting organlle </li></ul><ul><li>System of membranes </li></ul><ul><li>Series of flattened sacs with convex shape </li></ul><ul><li>Works with the ER to modify proteins </li></ul>
  9. 9. LYSOSOMES <ul><li>Small spherical organelles </li></ul><ul><li>Enclose hydrolytic enzymes within single membranes </li></ul><ul><li>Digest proteins, carbohydrates, lipids, DNA and RNA </li></ul><ul><li>Digest old organelles, bacterias, viruses </li></ul><ul><li>Rare in plant cells </li></ul>
  10. 10. CYTOSKELETON <ul><li>Maintains the shape and size of cell </li></ul><ul><li>Network of long protein strands </li></ul><ul><li>Not surrounded by a membrane </li></ul><ul><li>Participates in the movement of organelles </li></ul><ul><li>2 major components – microfilaments and microtubules </li></ul><ul><li>Microfilaments – threads made of actin (protein) – smallest strands </li></ul><ul><li>Microtubules – largest strands that are hollow tubes – help the cell divide by forming spindle fibers that extend across the cell </li></ul>
  11. 11. CELL WALL <ul><li>Lies outside of the cell membrane </li></ul><ul><li>Helps support and protect the plant cell </li></ul><ul><li>Contains long chains of cellulose – hardens the entire structure </li></ul><ul><li>Pores in the cell wall allow ions to enter or exit the cell </li></ul>
  12. 12. VACUOLES <ul><li>Fluid filled organelles that store enzymes and metabolic wastes </li></ul><ul><li>Some vacuoles may make up 90% of the cell </li></ul>
  13. 13. Chloroplast <ul><li>Surrounded by 2 membranes and contain DNA </li></ul><ul><li>Some store starch or fats </li></ul><ul><li>Some contain pigments that absorb visible light – chlorophyll </li></ul><ul><li>Ex Chloroplasts – energy of sunlight is converted into chemical energy each chloroplast encloses a system of membranous sacs called thylakoids </li></ul>

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