Quiz 3 Biol-102 Fall17 1. Describe fluid mosaic model of cell membrane. 2. Defin
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Quiz 3 Biol-102 Fall17 1. Describe fluid mosaic model of cell membrane. 2. Define terms turgid, flaccid and plasmolyzed 3. Describe the role of cholesterol in maintaining cell membrane functional. 4. Why inside the dialysis bag become blue? 5. Betacyanin pigment is in beet root is stored in 6. Maximum leaching of betacyanin takes place at AJO C B) 5- C) 40 C s D) 80- 7, Draw red blood cells placed in water, 0.5% salt solution and 1.9% salt solution. 8. Absorption of water by plants is A) Diffusion B) active transport C) osmosis D) facilitated diffusion 9. How do cells recognize one another? 10. Define facilitated diffusion 11. Describe sodium potassium pump.Explanation / Answer
Fluid Mosaic Model:-
the cell membrane is made up of a bunch of different molecules that are distributed across the membrane. If you we observe cell membrane using a microscope, we see a pattern of different types of molecules put together, also known as a mosaic. These molecules are constantly moving in two dimensions, in a fluid fashion, similar to icebergs floating in the ocean. The movement of the mosaic of molecules makes it impossible to form a completely impenetrable barrier.
The phospholipids acts as a layer of ocean, in which peripheral protein are seen as icebergs.
2.
Turgid cell are those cells when placed in a hypotonic solution, water diffuses into the cell causing the cell to swell. The pressure developed on the cell wall is called turgor pressure.
Flaccid cell are those cells when placed in a hypertonic solution, water diffuses out of the cell causing the cell to shrink.
Plasmolysis is the process in plant cells where the plasma membrane pulls away from the cell wall due to the loss of water through osmosis.
3.
Cholesterol adds firmness and integrity to the plasma membrane and prevents it from becoming overly fluid, it also helps maintain its fluidity.
It prevents crystallization at high concentrations, cholesterol helps separate the phospholipids so that the fatty acid chains can't come together and cyrstallize.
Hence, cholesterol helps in preventing extremes conditions I.e too fluid, or too firm, in the consistency of the cell membrane.
4.
The iodine molecules come in to contact with the starch, turning them blue.
5.
It is found in the large central vacuole of the beetroot cells. The vacuole is enclosed by a single membrane called the tonoplast and the whole cell is enclosed by the cell membrane made up of phospholipids and proteins.
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