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Genetics: The code broken?

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Topic 4: Genetics: The code broken? A. The structure of a gene provides the code for a polypeptide Describe the processes involved in the transfer of information from DNA through RNA to the production of a sequence of amino acids in a polypeptide * Proteins are the building materials for organisms; they may also function as hormones or enzymes. Polypeptides are the building blocks for proteins * Gene - is a section of the DNA that codes for the production of a specific polypeptide Protein synthesis has two stages 1. Transcription * Occurs in the nucleus * The DNA unwinds to expose the base sequence on one strand (the template) * The sequence of the bases is transcripted (copied) by complimentary m-RNA nucleotides * The m-RNA only copies the coding part of the DNA sequence (exons), the 'non-coding' part (intron) is not copied by the m-RNA 2. Translation * The m-RNA molecule travels from the nucleus to the cytoplasm and attaches to a ribosome * T-RNA nucleotide in the cytoplasm reach the ribosome and one end of them translates the m-RNA code * Every three bases are read by an anticodon of the t-RNA nucleotide * On the other end of the t-RNA nucleotide is an amino acid * When the t-RNA anti-codon locks onto the m-RNA codon, the amino acid is held in place long enough for it to form a peptide bond with the next amino acid that is brought into place ...read more.


two alleles * Height can differ by less than a mm and this gradual increase from the very smallest for a certain age and gender, to the very tallest for a certain age and gender can be indicated by a bell curve Outline the use of highly variable genes for DNA fingerprinting of forensic samples, for paternity testing and for determining the pedigree of animals * DNA identification depends on the existence of hyper variable (highly variable) regions of DNA o Natural variations are found in everyone's DNA and are in the form of series of short sequence of base pairs (2-6 base pairs) which are repeated over and over again, these can be called short tandem repeats (STR), microsatalites or variable # tandem repeats o These STR's are then used in DNA fingerprinting * DNA profiling in forensic investigations is carried out by specialist scientists in authorised labs * In forensic investigations samples are taken from suspects and then STR's are matched between DNA from the crime scene and the suspects * Blood typing used to be the only method available for matching a child with its biological father in paternity cases, however, because someone who is blood type A or B could be heterozygous it is not very exact, DNA profiling is now used for more accurate results * DNA profiling can also be use to identify parentage in animals, this is important for breeders who sell animals priced to their bloodlines (horses etc.) ...read more.


Process information from secondary sources to access the reasons why the Human Genome Project could not be achieve by studying linkage maps Linkage maps do not * Identify which chromosomes carry which genes * Give an exact locus of every gene on every human chromosome * Give the base sequence on every chromosome * Give the function of every gene on every chromosome Outline the procedure to produce recombinant DNA * Recombinant DNA - is formed when DNA from one organism is inserted into another site Making recombinant DNA * Firstly a gene is cut out of the chromosome of one species using restriction enzymes * A circular piece of DNA (plasmid) present in bacterial cells is removed from the cells and cut out with the same enzyme * Restriction enzymes are used to cut the desired gene from its DNA (the passenger DNA) * The same restriction enzyme is used to cut the DNA of the plasmid (the vector) * DNA ligase is used to fuse the gene into the plasmid at the site of sticky ends * The DNA has now been 'recombined' and there are two sources of DNA fused together * The plasmid is then placed back into the bacterial culture and it reproduces to make hundreds of copies of itself (gene cloning) Some uses of recombinant DNA technology * The production of human insulin used in the treatment of human diabetes * The production of HGH in the treatment of stunted growth * The introduction pest resistance in plants (BT cotton) * The production of vaccines ...read more.

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