DNA

• what is DNA made up of

  2 polynucleotide chains in a double-helix structure
• 2 DNA polynucleotide strands join together by what?

  hydrogen bonding between the bases
• each base can only join with what?

  one particular partner - this is complementary base pairing
• what does A always pair with

  thyminw
• what does cytosine always pair with

  guanine
• how many hydrogen bonds form between a AND t

  2 hydrogen bonds
• how many hydrogen bonds form between C and G?

  3 hydrogen bonds
• why are there always equal amounts of adenine and thymine in a DNA molecule

  adenine always pairs with thymine (A-T)
• What does antiparallel mean?

  running in opposite directions
• what forms the DNA helix?

  Two antiparallel polynucleotide strands twist to form the DNA double-helix
• when was DNA first observed?

  1800s
• what did the relative simplicity of DNA lead to?

  led many scientists to doubt that it carried the genetic code
• What had happened by 1953


  experiments had shown that DNA was the carrier of the genetic code
• what also happend in1953?

  the double-helix structure which helps DNA to carry out its function was determined by watson and crick