Genomes and Gene Technologies OCR F215

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Basic Introductory Information...

DNA and Genomes can be sequenced:

DNA can be split into chunks using the shotgun approach.

Restriction enzymes can be used to cut out DNA fragments.

Electrophoresis can be used to seperate DNA by length.

Polymerase chain reaction can be used to make copies of the DNA fragment.

Sections of DNA can then be put into seperate bacterial artificial chromosomes: BACs. The BAC sections can be transferred to bacterial cells and clones will be produced when they divide. Clone libraries are formed.

Scientists can also add in parts they already know.

Comparitive Gene Mapping:

Allows comparisons of genes between species and individuals.

If a gene is found in lots of organisms it may be vital for life.

Evolutionary relationships can be shown.

Find alleles which cause disease and eliminate them.

Recombinant DNA:

Section of DNA often in a form of a plasmid which is formed by joining DNA sections from two different sources.

The Basic Outline of Genetic Engineering:

The required gene is obtained, mRNA is used as a template, copy of the gene required in put into a vector which is normally a plasmid, the vector carries the gene to the recipient cell, it may get into the cell by electroporation, the recipient cell expresses the gene through protein synthesis.

Firstly DNA must be extracted...

How is the DNA Extracted?

Restriction enzymes are used for cutting DNA.

Different enzymes can be used.

It catalyses a hydrolysis reaction that breaks the phosphate sugar backbones of DNA.

The cut edge is called a sticky end.

Seperate DNA fragments are stuck together using DNA ligase and this catalyses a condensation reaction whereby the phosphate sugar backbones are stuck back together.

Sticky ends must be complementory and therefore they must have been cut using the same restriction enzymes.

Recombinant DNA is formed.

DNA Fragments must then be seperated by lengths...


DNA + flourescent tag = can be seen under UV light.

DNA + gel + buffer solution = conducts electricity.

electrical current passed through.

DNA negatively charged due to phosphate backbone.

More to positive electrode = anode.

Small DNA fragments move faster and further,

Seen under UV light or southern blotting can be used, nylon sheet and paper over top, DNA is transferred and can be analysed.

DNA Fragments can then be copied...

Polymerase Chain Reaction (PCR)

DNA is a double strand.

Nucleotides and DNA polymerase are added.

The temperature is raised to 95 to break the hydrogen bonds to give 2 single strands of DNA.

Primers are then added which have 3 or 4 bases and they





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