gene technology

a genome is a full set of genes in each cell a genome can be sequenced

the sequencing projects read the genome of a variety of organisms Determining the genome of a simple organism allows you to know the sequence of bases that codes it

in more complex organisms the presence of introns means that knowledge of the genome cant be translated into the proteome the proteome is the full range of proteins that can be encoded by the genome

is allows genome-wide comparison between different species allowing the determination of evolutionary relationships Therefore we can find out about a common ancestor Genome sequencing is also beneficial to medical research as genome comparison between individuals can allow the development of PERSONALISED MEDICATION

it has determined the sequence of bases in a human genome

• screening for abnormal/mutated sequences • allowing identification of disorders before symptoms arise • Pre-implantation screening which is screening embryos for lethal alleles • identification of potential antigens to use in vaccines

ethical concerns such as the misuse and discrimination of genetic information/ data

sequencing methods are constantly developing and are becoming faster and more efficient to use Sequencing has now become computerised; once the human genome took 15 years to sequence but nowadays to can take up to as little as 26 hours

it involves the transfer of fragments of DNA from one organism (or species) to another

the genetic code, transcription and translation machinery are universal, so transferred DNA fragments can be translated within cells of the recipient organisms

it is the word used to refer to the recipient organisms of the foreign DNA by recombinant technology

• reverse transcriptase • restriction endonuclease • gene machine

reverse transcriptase makes DNA copies from mRNA They naturally occur in retroviruses retroviruses are viruses that main genetic information comes from RNA not DNA

• the cell that produces the proteins that scientists want is chosen and should have a large amount of mRNA for the protein • Reverse transcriptase can align and join the complementary DNA bases to the mRNA bases • this single-stranded DNA is called complementary DNA (cDNA) • you need to make the DNA double-stranded and this is done by DNA polymerase • the cDNA does not have introns

restrictive endonucleases are enzymes that “cut” DNA at restriction sites to form DNA fragments as it is an enzyme, the restrictive endonucleases are complementary to specific restriction sites

some cut through the same location in the double-stranded DNA to produce a blunt end this means that no bases are exposed or overhang some creates a staggered ends with exposed bases These are palindromic and are called “sticky ends” because they can join to complementary DNA bases pairs

the same but backwards

it is a computerised way to create DNA fragments which is faster and more efficient

• scientists identify the amino acid sequence of the protein of interest They then deduce the mRNA sequence from that and the DNA sequence from the mRNA sequence • The DNA sequence is entered into a computer, whciuh has to pass biosafety and biosecurity checks • the computer creates small sections of overlapping DNA strands called olinguncleotides • the oligonucleotides can then join to form the DNA sequence of the entire gene

to use in experiments, these DNA fragments have to be amplified - lots of them have to be made

in vitro cloning: PCR (polymerase chain reactions) in vivo cloning

• DNA fragments are heated to 95C so hydrogen bonds between base pairs break, producing 2 single DNA strands • the mixture is then cooled to 55C to allow primers to anneal to the DNA fragments by complementary base pairings • the mixture is heated to 72C as this is the optimum temperature for DNA polymerase. DNA polymerase attaches nucleotides together to form new double-stranded DNA fragments

primers are short sequences of DNA that allows the attachment of DNA polymerase

the mixture in this reaction contains: -DNA fragments • DNA polymerase (and helicase) • primers • magnesium ions (that act as a co-factor for DNA polymerase)