Cells and movement in and out of them.

  • Created by: elyornais
  • Created on: 18-02-15 16:12
How would you work out magnification?
Size of image/ size of object
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How many nanometres in a millimeter?
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What is meant by resolution?
The minimum distance apart that two objects can be in order for them to appear as separate.
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What does resolution depend on?
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Before cell fractionation, why must the solution be cold?
To reduce enzyme activity that might break down organelles.
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Why must the solution be isotonic?
To prevent organelles bursting or shrinking as a result of loss or gain of water by osmosis.
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Why is the solution buffered?
To maintain the pH.
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Why are cells homogenised?
To release organelles from the cells.
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What do you get from spinning the filtrate at a low speed?
The heaviest organelles such as the nuclei.
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What happens when it is spun at a faster speed than the first time?
Mitochondria are found at the bottom of the tube.
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What organelle is found at the fastest speed?
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What are the two advantages of using an electron microscope?
Uses a very short wavelength so has a higher resolution and it has better magnification.
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Give two main limitations of the transmission electron microscope.
The whole system must be in a vacuum so living specimens cannot be observed. The specimen must be thin so we get flat 2D images.
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What is the function of the rough endoplasmic reticulum?
Provides a large surface area for the synthesis of proteins and glycoproteins.
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What is the job of the smooth ER?
Synthesise, store and transport lipids and carbohydrates.
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Give two functions of the golgi apparatus.
Secrete carbohydrates and transport, modify and store lipids.
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What do lysosomes do?
Break down material ingested by phagocytic cells and digest worn out organelles so that useful chemicals can be re-used.
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What are ribosomes important in?
Protein synthesis.
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What do lipids contain?
Carbon, hydrogen and oxygen.
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How are triglycerides formed?
Each fatty acid forms a bond with glycerol in a condensation reaction.
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What are phospholipids made from?
A hydrophillic head and a hydrophobic tail.
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How would you test for lipids?
Add ethanol to sample, shake, a cloudy white colour indicates the presence of a lipid.
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Why is the cell surface membrane known as the fluid mosaic model?
Fluid because the phospholipids can move and gives a flexible structure. Mosaic because the proteins that are embedded vary in shape, size and pattern.
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Why does the cholera toxin only affect the small intestine?
Because only the epithelial cells of the small intestine have the specific receptors that the bacteria binds to.
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What happens when the toxin enters the epithelial cells?
Ion channels open and chloride ions flood from the cells to the lumen of the intestine.
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What effect does this have on the water potential of the lumen of the intestine?
Decreases so water flows from the cells into the lumen by osmosis.,
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Card 2


How many nanometres in a millimeter?



Card 3


What is meant by resolution?


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Card 4


What does resolution depend on?


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Card 5


Before cell fractionation, why must the solution be cold?


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