Structure of an epithelial cell 2
- Created by: Jasmin
- Created on: 19-10-13 16:17
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- Structure of an epithelial cell...
- ENDOPLASMIC RETICULUM: 3D - like membranes spreading through cytoplasm of cells
- Membranes enclose flattened sacs called cristae
- Rough Endoplasmic Reticulum (RER) has ribosomes present on outer surfaces of membrane
- Functions
- Provide large SA for synthesis of proteins and glycoproteins
- Provide pathway for transport of materials, esp proteins, throughout cell
- Functions
- Smooth Endoplasmic Reticulum (SER): lacks ribosomes on surface and is more tubular in appearance
- Functions
- Synthesise, store and transport lipids
- Synthesise, store and transport carbohydrates
- Functions
- GOLGI APPARATUS
- Stack of membranes that make up flattened sacs with small rounded hollow structures called vesicles
- Proteins, lipids produced by ER passed through GA
- Golgi modifies proteins adding non protein components e.g. carbohydrates to them
- Modified proteins, lipids transported in vesicles which are regularly pinched off from ends of Golgi cristemae
- Vesicles move to cell surface, where they fuse with membrane and release contents to the outside
- Functions
- Add carbohydrate to proteins to form glycoproteins
- Produce secretory enzymes
- Secrete carbohydrates
- Transport, modify and store lipids
- Form lysosomes
- LYSOSOMES: formed when vesicles produced by GA contain enzymes e.g. protease, lipase
- Fuctions
- Break down material ingested by phagocytic cells e.g. white blood cells
- Release enzymes to outside of cell to destroy material around the cell
- Digest worn out organelles so useful chemicals are made of can be reused
- Completely break down cells after have died (autolysis)
- Fuctions
- RIBOSOMES: small cytoplasmic granules found in all cells
- Important in protein synthesis
- 2 subunits - one large and one small each of which contains ribosomal RNA and protein
- 80S type - eukaryotic, 70S type - prokaryotic slightly smaller
- MICROVILLI: finger like projections that increase SA to allow more efficient absorption
- ENDOPLASMIC RETICULUM: 3D - like membranes spreading through cytoplasm of cells
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