Polynucleotides and DNA

Structure of DNA
1. Two Polynucleotide chains joined together by hydrogen bonds between bases
2. Complementary base-pairing means each base can only bond to a specific base
  1. Adenine and Thymine
  2. Guanine and Cytosine
3. Two hydrogen bonds between A and T, and three bonds for C and G
4. Two antiparallel polynucleotide strands twist to make double helix
DNA Purification Practical
1. 1) Break up cells in sample (eg onion) using a blender
2. 2) Make solution of detergent, salt and distilled water
3. 3) Add broken cells to solution and incubate in water bath at 60C for 15 mins
4. 4)When finished, place in ice bath to cool. When its cool, filter. Transfer sample to clean boiling tube
5. 5) Add protease enzymes to filtered mixture to break down proteins
6. 6) Slowly dribble cold ethanol down side to form layer on top of detergent mixture
7. 7) The DNA will form a white precipitate
Self-Replication
1. DNA copies itself before cell division so each new cell has the full amount of DNA
2. 1) The enzyme DNA Helicase breaks hydrogen bonds between the two polynucleotide strands. The helix unzips to form two single strands
3. 2) Each original single strand acts as a template for a new strand. Free floating nucleotides join to exposed bases on each strand by base pairing
4. 3) The nucleotides of the new strand are joined together by DNA polymerase to make the sugar phosphate backbone
5. 4) Hydrogen bods form between the bases on the original and new strand
6. 5) Each new DNA molecule contains one strand from the original DNA molecule and one new strand

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Polynucleotides and DNA

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	Erstellt von Dean Lundie vor mehr als 8 Jahre