Structure Of Dna Flashcards
Name the type of bond between
-complementary base pairs
-adjacent nucleotides in a DNA strand
Complementary base pairs-hydrogen bonds
Adjacent nucleotides in DNA strand-phosphodiester bonds
Describe two differences between the structure of a tRNA molecule and the structure of an mRNA molecule
1tRNA is a clover leaf shape, mRNA is linear
2tRNA has hydrogen bonds, mRNA does not
In a eukaryotic cell, the structure of the mRNA used in translation is different from the structure of the pre-mRNA produced by transcription.
Describe and explain a difference in the structure of these mRNA molecules.
1mRNA fewer nucleotides 2 because of splicing
Describe the structure of DNA
1 polymer of nucleotides
2 each nucleotide formed from deoxyribose, a phosphate and an organic base
3 phosphodiester bonds between nucleotides
4 double helix
5 hydrogen bonds between adenine, thymine and cytosine, guanine
Give two features of DNA and explain how each one is important in the semi-conservative replication of DNA.
1 easily broken hydrogen bonds between bases allow strands to separate.
2 two strands so both can act as templates.
The enzymes DNA helicase and DNA polymerase are involved in DNA replication. Describe the function of these enzymes
DNA helicase-unwinding and breaking hydrogen bonds between chains.
DNA polymerase-joins adjacent nucleotides by forming phosphodiester bonds
DNA is a polymer of nucleotides. Each nucleotide contains an organic base.
Explain how the organic bases help to stabilise the structure of DNA.
1 Hydrogen bonds between the base pairs hold two strands together.
2 many hydrogen bonds provides strength.
Explain how a change in a sequence of DNA bases could result in a non-functional enzyme.
1 change in sequence of amino acids
2 change in hydrogen bonds leads to a change in tertiary structure.
3 substrate cannot bind
