AQA A-LEVEL BIOLOGY ESSAY: THE IMPORTANCE OF DNA AS AN INFORMATION CARRYING MOLECULE AND ITS USE IN GENETIC TECHNOLOGIES
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Module
AQA Alevel biology (7402)
Institution
Uppingham School
Top mark AQA A-Level biology essay on the importance of DNA as an information-carrying molecule and its importance in genetic technologies.
topics included are: DNA, Recombinant DNA technology, genetic diversity, mutations and cancer.
Useful for revision for this specific topic and to see a samp...
TIO DNA AS AN INFORMATION-CARRYING MOLECULE AND ITS USE IN
GENETIC TECHNOLOGIES
Deoxyribonucleic acid (DNA) is an important information-carrying molecule. In all
living cells, DNA holds genetic code to make proteins. A gene is a sequence of DNA
bases that codes for the polypeptide or function RNA. Protein synthesis is the
production of proteins from the information contained within a cell’s DNA. In
transcription, the DNA double helix is unzipped as DNA helicase breaks hydrogen
bonds between bases. One strand acts as a template for complementary mRNA
nucleotides. RNA polymerase lines up free RNA nucleotides alongside the exposed
bases of the template strand. Specific complementary base pairing means that the
mRNA strand ends up being a complementary copy of the template strand, this is
important to maintain genetic continuity and ensure that the correct protein is being
coded for. RNA polymerase assembles the pre-RNA stand by forming
phosphodiester bonds between adjacent nucleotides via a condensation reaction.
During translation, TRNA which is bound to specific amino acids binds via
anticodons which are complementary to codons on MRNA. Peptide bonds form
between amino acids to create a sequence. The process of transcription and
translation is Important because DNA codes for the unique sequence of amino acids,
which determines the location of hydrogen ionic and disulphide bonds in the tertiary
structure of a protein and therefore the role. This is because it enables enzymes to
have uniquely shaped active sites which are complementary to substrate An
example of this is rubisco which catalyses the formation of Glycerate-3- phosphate
by combining carbon dioxide with ribulose biphosphate. Without DNA coding for
specific amino acid sequences, the shape of the enzyme would be altered so
enzyme-substrate complexes can no longer form.
Recombinant DNA technology involves transferring a fragment of DNA from one
organism to another. The genetic code is universal (the same DNA base triplet’s
code for the same amino acids in all living things) genetic code is universal so DNA
from one organism can be inserted into another. E.g. human gene for insulin. The
transferred DNA can be used to produce a protein in the cells of the recipient
organism. The first step in in vivo cloning is to insert the DNA fragment into a
vector’s DNA. The vector DNA is isolated and then restriction endonucleases and
DNA ligase are used to stick the DNA fragment and vector DNA together.
Restriction endonucleases are enzymes that recognise specific palindromic
sequences and cut the DNA at these places t create complementary sticky ends
which is important because small tails of bases at each end of the fragment allow
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