DNA & B IOTECHNOLOGY

Biotechnology Recombinant DNA Gene splicing Restriction enzymes Sticky ends Ligase & DNA-ase DNA sequencing Gene probes DNA profiling Short tandem repeats Gel electrophoresis Capillary electrophoresis Keywords

W HAT IS BIOTECHNOLOGY ? Biotechnology is using living things to create products or to do tasks for human beings. It is the practice of using plants, animals and micro-organisms and their biological processes to some benefit eg. in medicine, agriculture and industry Researchers use DNA, genes, yeast, bacteria and cells

W HY USE BIOTECHNOLOGY ? For ourselves Biotechnological research has been used to assist human health in many areas: antibiotics vaccines genetic disorders DNA profiling & forensics For the environment Biotechnology is a tool used: to help control pests for conservation of plant & animal species leach metals from the soil for cleaner mining clean up heavy metal contamination

R ECOMBINANT DNA & GENE SPLICING

Recombinant DNA is a method of cutting and pasting a foreign piece of DNA into the DNA of a cell. It brings together genetic material from multiple sources, creating new sequences of DNA. Enables the genome to be manipulated very precisely

R ECOMBINANT DNA Recombinant DNA is used for the production of specific proteins The first chemical produced by this mehtod was human insulin The human gene is placed into a bacterium which can then use the genetic information to produce the human hormone. The hormone is refined from the culture of bacteria.

R ECOMBINANT DNA & GENE SPLICING Steps to gene splicing: 1. Restriction enzymes  Cut the DNA at a specific location  Leaves the DNA strand with ‘sticky ends’ 2. Sticky ends  Unattached (unpaired) nucleotides  Match up with the DNA to be inserted 3. Ligation  Ligase enzymes help form the hydrogen bonds between nucleotides  DNA-ase helps form the bonds between the side strands (backbone) Fluorescent green protein transgenic mouse

R ECOMBINANT DNA & GENE SPLICING

The gene responsible for cystic fibrosis has been identified and it is hoped that, using recombinant DNA technology, it will be possible to transfer a normal copy of the gene into affected cells. Young man with cystic fibrosis taking medication using a nebuliser. Wellcome Library

DNA SEQUENCING & GENE PROBES

DNA SEQUENCING AND DNA PROFILING DNA sequencing is used to work out the exact order of the base pairs in a section of DNA. Knowing the base sequence can be helpful in locating and identifying specific genes. Gene probes can then be made and used to locate these genes

G ENE PROBES The search for a particular gene uses a single-stranded piece of DNA called a gene probe. Probes are constructed with a radioactive or fluorescent tag so that they can be detected after attaching to the DNA. We know the base sequences in a number of disease-causing genes. Gene probes can detect if these genes are present in individuals being tested.

DNA PROFILING & GEL ELECTROPHORESIS

DNA SEQUENCING & DNA PROFILING DNA profiling is used to identify individuals Gel electrophoresis is used in DNA profiling.

S HORT TANDEM REPEATS Short tandem repeats (STRs) are sequences of non-coding DNA. They are sections of DNA that make each individual unique Closely related individuals will share many of the same STRs STRs are used in DNA profiling to identify individuals

G EL E LECTROPHORESIS Gel electrophoresis separates fragments of DNA using an electric current. DNA has a slight negative charge. It will migrate towards the positive end of the gel. Smaller fragments move faster through the gel than larger fragments. At the end of the ‘run’ a pattern of bands will be produced. Each band represents a fragment size of DNA from the sample. Different samples will have different patterns.

F RAGMENT LENGTHS AND GEL ELECTROPHORESIS

Blotting is a method of ‘photographing’ the resulting sequence of DNA fragments once they have gone through the process of gel electrophoresis. In the example below, what is the genotype of the father? Rule out all the mother’s alleles. The ones left are from the father. DNA BLOT ANALYSIS

DNA PROFILING - SUMMARY Steps in DNA profiling 1. Collect samples of material containing cells 2. Extract DNA from samples 3. Place solution of DNA into gel electrophoresis 4. Run gel 5. Process gel to see location of DNA bands 6. Photograph the gel (DNA or Southern blot)

SampleAmelogeninD3S1358vWAFGAD8S1179D21S11D18S51 VictimXY14, 1518, , 1628, , 15 SuspectXY14, 1515, 1821, 2213, , 15 Blood Stain from Crime Scene XY14, 1515, 1821, 2213,143014, 15 C APILLARY ELECTROPHORESIS STR profiles are more easily stored and compared in the form of numbers and letters rather than pictures of lines. Capillary electrophoresis is a way of collecting numerical data that is plotted on a line graph. The peaks on the graph represent the different STRs

Capillary electrophoresis graph

U SES OF DNA PROFILING Identification Criminals Victims – crimes, disasters Family members Species – quarantine, smuggling Genetic differences between populations Information is kept in data banks