recombinant DNA technology (making DNA fragments)

what is the promoter region?

sits before a gene and controls gene expression, allowing transcription to occur

what is recombinant DNA technology?

(aspect of genetic engineering which involves) transferring a fragment of DNA from one organism to another (in order to give it desirable characteristics)

compare and contrast selective breeding and recombinant DNA technology (genetic engineering):

• both increase desirable allele frequency

• recombinant DNA technology involves directly transferring a fragment of DNA and allows cross species transfer

• recombinant DNA technology is faster as you do not need to wait for alleles to become more frequent

• in selective breeding other traits are also passed down

what is a transgenic organism?

organism containing transferred DNA

what is the significance of DNA being universal in recombinant DNA technology?

allows cross species DNA transfer

give 2 uses of recombinant DNA technology:

• to produce a genetically modified organism e.g. Bt corn has a gene which codes for insecticidal proteins

• to produce large quantities of a protein of interest e.g. insulin

give 3 ways of making DNA fragments:

• reverse transcriptase

• restriction endonucleases/enzymes

• gene machine

describe the process of using reverse transcriptase to form DNA fragments:

1. mRNA extracted from cells and used as a template

2. complementary DNA (cDNA) formed from DNA nucleotides and isolated from mRNA strand

3. cDNA acts as template to form desired gene using DNA polymerarse

describe the process of using restriction endonuclease enzymes to form DNA fragments:

1. DNA incubated with chosen restriction enzyme(s)

2. restriction enzymes identify recognition sequences in DNA and cut dsDNA if their recognition sequence is present

3. recognition sequences at either end of the desired DNA fragment allow restriction enzymes to cut desired gene out via hydrolysis

what is a restriction enzyme and what is its function?

• bacterial enzymes which cut DNA at specific 6 base codes

• lots of different types - each cut DNA at specific base sequences known as recognition sites

why do different restriction enzymes cut at different specific recognition sites?

shape of recognition sequences complementary to restriction enzyme’s active site

what are sticky ends? what can they be used for?

• small tails of unpaired bases at the end of a DNA fragmenet

• to anneal DNA fragment to another DNA fragment with sticky ends with complementary sequences

what is the purpose of a gene machine?

synthesises correct DNA code when programmed with the sequence of amino acids needed to make the protein

what is a oligonucleotide?

short strands of nucleotides

describe the process of using a gene machine to form DNA fragments:

• amino acid sequence used to identify mRNA codons and thus complementary DNA sequence

• fed into computer

• computer produces oligonucleotides which can be constructed into the desired gene

• the desired gene is formed without introns or non coding DNA sections

give 2 advantages of using a gene machine to synthesise a protein:

• faster

• more reliable