Biology - DNA & RNA

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Author:
katienewman
ID:
112897
Filename:
Biology - DNA & RNA
Updated:
2011-10-28 18:19:00
Tags:
Biology
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Description:
Biology
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  1. DNA – Deoxyribonucleic acid
    • coiled and folded to fit into the nucleus
    • Proteins called histones hold folds
    • Double-helix in shape

    • Complementary base pairs
    • Adenine – Thymine
    • Guanine – Cytosine
    • At The Giants Causeway
  2. To Isolate DNA from a plant tissue
    • 1.3g sodium chloride to washing up liquid
    • 2.Add distilled water so solution is 100cm3
    • 3.Cut onion into small cubes
    • 4.Add onion to solution
    • Detergent - cell membranes break & release DNA
    • Salt - causes DNA to clump together
    • 5.Put in water bath at 60ºC for 15 mins
    • Denatures enzymes
    • 6.Cool in ice bath for 5 mins
    • Stops DNA breakdown
    • 7.Blend mix for 3 seconds
    • Breaks down cell walls & releases DNA
    • 8.Filter through coffee filter paper
    • Filtrate contains DNA & proteins
    • 9.Syringe 6cm3 filtrate into boiling test tube
    • 10. Add 4 drops protease enzyme
    • Breaks down protein around DNA
    • 11.Pour 9cm3 ice cold 95% ethanol slowly down side of test tube
    • Precipitates DNA out of water
    • 12.Twist a small glass rod in test tube
    • DNA attaches to rod & form a clear mesh
  3. Detailed Structure of DNA
    3 structures: nucleotides, base pairs & double helix
    • 1. Nucleotides
    • phosphate group, a sugar & a nitrogen-containing base
    • Join together with a bond between phosphate & sugar




    • Phosphate Group – PO4
    • Sugar - Deoxyribose
    • Nitrogenous base – One of Adenine, Guanine (Purine bases), Thymine & cytosine (pyramidine bases)


    • 2. Base Pairs
    • Adenine & thymine form 2 weak hydrogen bonds
    • Guanine & cytosine form 3 weak hydrogen bonds
    • Hydrogen bonds: weak bonds formed when slightly positive hydrogen is attracted by another slightly negative atom.


    • 3. Double Helix
    • Spiral chains of nuceotides
    • Outside strands – deoxyribose & phosphate
    • Rungs – Base pairs

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