Biotechnology Preimplantation Genetic Diagnosis Cloning Transgenic animals DNA Fingerprinting
Biotechnology • What is it? • Why do we study it and how can it be used? • How do we study it? …technology involved.. • What are the ethical issues involved?
What is a genome? The complete set of genetic material (DNA) in an organism. Genomics The study of genomes To sequence a genome… Scientists identify every DNA base pair that makes up the genome.
DID YOU KNOW?!!? • In 2003, a draft of the human genome was sequenced…. • Humans have about 25,000 genes • Less than 2% of human DNA actually codes for proteins • Wait…. What?! What does the other 98% code for? • YUP. The rest consists of introns (the regions of DNA that do not code for amino acids or proteins). JUNK DNA! • Humans have many of the same genes as other species • The genome of any 2 people is 99% IDENTICAL!
How can this information help us? • Diagnosing and preventing disease • Treating disease • Indentifying individuals
Diagnosing and Preventing Disease • Certain technologies can be used to determine when a gene is active. • Patterns of this gene activity could indicate disease. • When do we do this? • Pre-natal testing
Preimplantation diagnosis: prenatal screening • 1. Prenatal diagnosis discerns whether an embryo is at risk for various identifiable genetic diseases or traits. • Prenatal diagnosis is made using amniotic fluid, fetal cells, chorionic villus sampling, ultrasound, and pre-implantation genetic diagnosis(PGD) of embryos • Pre-implantation genetic testing must be done in conjunction with in-vitro fertilization.
FYI…. • The first human gene to be mapped and analyzed for its expression was the cystic fibrosis (CF) gene. • The CF gene has been mapped, sequenced and its function has been determined.
1. Gene Therapy • Human gene therapy is the introduction of normal alleles into the somatic cells of patients who lack them. • The gene is inserted by means of a virus.
2. Pharmacogenomics New field Scientists are making drugs that could supply proteins that are not made depending on a person’s genetic profile.
Although the DNA of all humans is very similar (99%!!!), each person has some sequence that is completely unique. Unless they have an identical twin! These unique sequences can be used to make a pattern of DNA bands called a DNA fingerprint.
On the basis of this test, suspect #2 can clearly be ruled out. None of his bands match the bands found in the semen. • Is suspect #1 guilty? • We can never be 100% certain. The best we can do is to estimate the probability that another person, picked at random, could provide the same DNA fingerprint. • Let’s take a look…
DNA Forensics: Paternity M = mother, C= child, F1= possible father, F2= possible father Whose the father?
2. Cut DNA using a variety of restriction enzymes and place the fragments in a gel made of agarose.
DNA fragments cut with RE 3. Separate the DNA through gel electrophoresis. DNA migrates form negative to positive pole. (note that smaller fragments migrate faster than larger fragments).
Fig. 20-9a TECHNIQUE Powersource Mixture ofDNA mol-ecules ofdifferentsizes Anode Cathode – + Gel 1 Powersource – + Longermolecules 2 Shortermolecules
4. X- ray the DNA/ radioactive probes and create an autoradiograph.
Fig. 20-9b RESULTS
restriction enzymes • Sometimes it is necessary to cut segments of DNA molecules. • This is done with the use of restriction enzymes. • Restriction enzymes work by recognizing short nucleotide sequences in DNA molecules and cutting at specific points within these sequences.
EcoR1 is a restriction enzyme that cuts between a G and A in the sequence GAATTC.
Segments of DNA cut with the same restriction enzymes can be annealed with DNA ligase( “molecular glue”).
OK… so we use technology to cut DNA, identify diseases, identify people… no big deal- right? So what’s all the fuss about “Bioethics”? What else is technology used for??
Scientists can manipulate genes Genetic Engineering- the direct manipulation of genes for practical purposes. Recombinant DNA- DNA in which genes from two different sources are linked. Genetically modified organism: organisms with recombinant DNA.
But WHY manipulate genes?? • Food crops • Livestock • Medicine • Basic research
Genetically modified foods • Genetically-modified foods: food plants that have been genetically altered by the addition of foreign genes to enhance a desired trait. Plants can be genetically modified for: • Pest resistance • Herbicide tolerance • Disease resistance • Cold tolerance • Drought/salinity tolerance • Increased nutrition.
Non-transgenic corn is heavily damaged by insect feeding, but the transgenic corn has little or no damage.
Livestock can be genetically engineered to… • Grow faster • Have more muscle • Have less fat • Produce more nutritious milk