Importance of DNA as an information-carrying molecule and its uses in gene technology

3.1.5 - structure of DNA and RNA 

• DNA – double helix with antiparallel strands and complementary base pairing 

• Carries genetic info in base sequences 

• Hydrogen bonds give stability but allow for easy unzipping during replication  

• Its stable, replicable structure allows inheritance (link to passing on favourable alleles in natural selection and evolution 

• OR universal code enables gene transfer across species in biotechnology 

3.1.5.2 - DNA replication 

• Semi-conservative replication using DNA helicase and DNA polymerase 

• DNA has complementary base pairing – ensures copying accuracy 

• Enables cell division and continuity between generations 

• Foundation for techniques like PCR, which mimics DNA replication, in vitro or in clonal expansion in the humoral response 

3.4.2 - protein synthesis 

• Transcription creates mRNA from DNA – process 

• Translation uses mRNA to assemble amino acids into those sequences to create the polypeptide chain 

• DNA controls structure and function of cells through protein production e.g. haemoglobin 

• Gene mutations here can lead to disease e.g. cystic fibrosis 

3.8.1 - gene expression 

• Gene expression can be controlled by epigenetic changes e.g. methylation and acetylation 

• DNA’s expression can change in response to the environment e.g. cell differentiation, cancer 

• Epigenetic markers can be manipulated in therapies or link to cancer development 

3.8.2 - recombinant DNA and gene technologies 

• Techniques e.g. sue of restriction enzymes, ligases, vectors e.g. plasmids, marker genes 

• PCR used to amplify DNA fragments 

• Can use DNA to create Genetically Modified Organisms e.g. insulin production and gene therapy 

• Allow diagnosis of genetic disorders and personalised medicine 

3.4.1 - DNA, genes and chromosomes 

• Genes = sequences of amino acids in the polypeptide chains and also functional RNA 

• Chromosomes carry DNA in eukaryotic cells; structure allows packaging and regulation 

• Key to inheritance – mutations in genes affect offspring – positive or negative