3.1.5 Nucleic Acids Flashcards
Describe how a phosphodiester bond is formed between two nucleotides within a DNA molecule
+ condensation reaction
between phosphate an
deoxyribose
+ catalysed by DNA polymerase
Describe how the separation of strands occurs
+ DNA helicase breaks hydrogen
bonds between base pairs/
polynucleotide chains
Describe the role of DNA polymerase in the semi-conservative replication of DNA
+ joins adjacent DNA nucleotides
+ catalyses condensation
reactions
+ catalyses formation of phosphodiester
What is the role of the single-stranded DNA fragments
+ template
+ determines the order nucleotides/bases
What is the role of DNA nucleotides
+ forms complementary pairs
Contrast the structures of ATP and a nucleotide found in DNA
- ATP has ribose and DNA nucleotide has deoxyribose
- ATP has 3 phosphate groups and DNA nucleotide has 1 phosphate group
- ATP - base always adenine and in DNA nucleotide base can vary
Explain why the enzymes work in opposite directions
+ DNA has anti parallel strands
+ Shape of the nucleotides is different/aligned differently
+ Enzymes have active sites with specific shape
+ Only binds to substrates with complementary shape
Explain why nucleotides can only be added in a 5’ to 3’ direction
+ DNA polymerase joins nucleotides
+ It is specific
+ Only complementary with 5’ end of strand
+ Strands of 5’ end and 3’ end are different