AS Biology AQA 3.1

Mind Map by mxriam-m, updated more than 1 year ago
Created by mxriam-m over 5 years ago


Mind-map on investigating the structure of cells

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AS Biology AQA 3.1
1 Microscopy: Microscopes are instruments that magnify the image of an object - using a convex glass (more effective in light microscope
1.1 Light microscope - light has a relitively long wavelength so can only distinguish between 2 objects that are 0.2um or further apart.
1.1.1 This limitation can be overcome by using a beam of electrons rather than light. e- have shorter wavelength the electron microscope can distingush two objects as close together as 0.1nm
2 MAGNIFICATION: material put under microscope is called the OBJECT and the material when viewed under the microscope is referred to as the IMAGE.
2.1 Mag =size of image / size of object
2.2 Size of object=size of image/magnification
3 Resolution (or resolving power). = Min distance apart 2 items can be in order 4 them 2 b distinguished as 2 separate items. Light microscope: items at least 2um apart can ve seen seperately.
3.1 Greater resoultion = GREATER CLARITY
4 Cell Fractionation: process where cells R broken up in2 diff organelles they contain & seperated out
4.1 The tissue must be in a cold buffer solution b/c: Cold - reduction of enzyme activity. Isotonic - prevention of organelles bursting b/c of osmotic gain or loss of water. Buffered - constant pH.
4.1.1 ISOTONIC: same water potential as original tissue.
4.2 Homogenation: Cells r broken up by a homogeniser (blender). This releases d organelles from d cell . Resultant fluid -homogenate filtrd 2 remove any complete cells & large debris.
4.3 Untracentrifugation: procedd by which fragments in d filtrd Homogenate seperated in machine called ultracentrifuge. spins tubes @ v high speed nd creates centrugal force. 4 Animal cells: Tube of filtrate placed in Ucentrifuge. spun at low speed. Then heaviest organelled -nuclei forced 2 bottom of tube. fluid at d top (supernatant) removed. D supernatant transferred 2 diff tube @ faster speed than b4. Nxt heaviest organelles - mitochondria forced 2 bottom of d tube. Process carries on etc, so tht nect heaviest organelle left @ bottom of tube.
4.3.1 1. Nuclei. 2. Mitochondria. 3. Lysosomes. 4.Ribosomes
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