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Protein Secretion

Protein Secretion. Rough Endoplasmic Reticulum (rough ER). System of flattened sacs and tubules Encrusted with ribosomes on the outer surface if their membranes Continuous with outer nuclear membrane Provides a large surface area for chemical reactions Pathway for transport of materials.

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Protein Secretion

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  1. Protein Secretion www.assignmentpoint.com

  2. Rough Endoplasmic Reticulum (rough ER) • System of flattened sacs and tubules • Encrusted with ribosomes on the outer surface if their membranes • Continuous with outer nuclear membrane • Provides a large surface area for chemical reactions • Pathway for transport of materials www.assignmentpoint.com

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  4. Golgi Apparatus • Group of flattened fluid-filled sacs • Vesicles containing newly synthesised protein pinched off from rough ER • Fuse with outermost sac of Golgi apparatus • Protein passed from sac to sac by means of vesicles • Golgi apparatus processes protein -e.g. adds a carbohydrate -form a glycoprotein www.assignmentpoint.com

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  6. Exocytosis • Vesicles containing finished product -mucus -digestive enzyme -hormone • Pinched off at end of Golgi apparatus • Vesicles move towards cell membrane and fuse with it • Contents of vesicle discharged to outside www.assignmentpoint.com

  7. Protein Secretion • Golgi bodies especially numerous and active in secretory cells -gastric gland cells in stomach walls -mucus -pepsin -pancreas -insulin www.assignmentpoint.com

  8. Elements in a protein • Carbon • Hydrogen • Oxgen • Nitrogen • (sulphur) www.assignmentpoint.com

  9. Structure of a protein www.assignmentpoint.com

  10. Quaternary structure of proteins • 3 different types -fibrous proteins -globular proteins -conjugated proteins www.assignmentpoint.com

  11. Fibrous proteins • Several spiral-shaped polypeptide molecules • Linked in parallel by disulphide bridges • Proteinhas a rope-like structure www.assignmentpoint.com

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  13. Globular proteins • Several polypeptide chains • folded roughly into a spherical shape like a tangled ball of string • Enzymes are globular proteins • Also vital component in cell and sub-cellular membranes www.assignmentpoint.com

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  15. Hormones • Chemical messengers • Globular protein • Exert a specific effect on tissues www.assignmentpoint.com

  16. Antibodies • Y-shaped globular proteins • Made by lymphocytes • Defend body against antigens www.assignmentpoint.com

  17. Conjugated proteins • Globular protein associated with a non-protein chemical • Glycoprotein -protein and carbohydrate -mucus www.assignmentpoint.com

  18. Haemoglobin • Oxygen-transporting pigment in blood • Conjugated protein -globular protein globin -haem (non-protein containing iron) www.assignmentpoint.com

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