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Protein Secretion Higher Biology Rough Endoplasmic Reticulum (rough ER) System of flattened sacs and tubules Encrusted with ribosomes on the outer surface.

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Presentation on theme: "Protein Secretion Higher Biology Rough Endoplasmic Reticulum (rough ER) System of flattened sacs and tubules Encrusted with ribosomes on the outer surface."— Presentation transcript:

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2 Protein Secretion Higher Biology

3 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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5 Golgi Apparatus Group of flattened fluid-filled sacs 1.Vesicles containing newly synthesised protein pinched off from rough ER 2.Fuse with outermost sac of Golgi apparatus 3.Protein passed from sac to sac by means of vesicles 4.Golgi apparatus processes protein -e.g. adds a carbohydrate -form a glycoprotein

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7 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

8 Protein Secretion Golgi bodies especially numerous and active in secretory cells -gastric gland cells in stomach walls -mucus -pepsin -pancreas -insulin

9 Elements in a protein Carbon Hydrogen Oxgen Nitrogen (sulphur)

10 Structure of a protein

11 Quaternary structure of proteins 3 different types -fibrous proteins -globular proteins -conjugated proteins

12 Fibrous proteins Several spiral-shaped polypeptide molecules Linked in parallel by disulphide bridges Protein has a rope-like structure

13 Fibrous protein Structural property Tissue rich in this protein Function of this protein ElastinStrong and elastic Wall of large arteries Flexible support CollagenStrong and inelastic -Bone -Tendon and ligament -Rigid support -attachment KeratinStrong and inelastic HairProtection Actin and myosin contractilemusclemovement

14 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

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16 Hormones Chemical messengers Globular protein Exert a specific effect on tissues

17 Antibodies Y-shaped globular proteins Made by lymphocytes Defend body against antigens

18 Conjugated proteins Globular protein associated with a non-protein chemical Glycoprotein -protein and carbohydrate -mucus

19 Haemoglobin Oxygen-transporting pigment in blood Conjugated protein -globular protein globin -haem (non-protein containing iron)

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