C13- Genetic Technology

Pp. 336 - 365Pp. 336 - 365

ContentsContents

• 13.1 Applied Genetics• 13.2 Recombinant DNA Technology • 13.3 The Human Genome

                                                                                                                                                                                                                                                    

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Applied GeneticsApplied Genetics

• Selective Breeding- choosing organisms with the most desired traits to serve as parents of the next generation.

Applied GeneticsApplied Genetics

• Inbreeding- mating closely related individuals; results in homozygous offspring

• Animal breed• Plant cultivar

Applied GeneticsApplied Genetics

• Hybrids increase productivity and disease resistance in crops

• Usually larger and stronger than purebred parents

Hybrid sorghum

Determining GenotypesDetermining Genotypes

• Test Crosses- unknown genotype X known genotype

• Offspring ratios indicate genotype of unknown parent

• Homozygous dominant if 100% heterozygote

• Heterozygous if 1:1 ratio• P. 340

13.2 Recombinant DNA Technology13.2 Recombinant DNA Technology

• Genetic Engineering faster & more reliable method to increase the frequency of allele

• Involves cutting DNA from one organism & inserting it in another

• Recombinant DNA Technology

Recombinant DNA TechnologyRecombinant DNA Technology

• Transgenic organism has foreign DNA

• Tobacco plant with firefly DNA

Recombinant DNA TechnologyRecombinant DNA Technology

• Three step process

Recombinant DNA TechnologyRecombinant DNA Technology

• Step 1- isolate foreign DNA fragment to be inserted• Step 2- attach DNA fragment to a carrier• Step 3- transfer into host organism

Restriction Enzyme Cleaves DNARestriction Enzyme Cleaves DNA

• • Restriction enzymes bacterial proteins with ability to cut DNA sequence at specific nucleotide sequence

• Palindromes-same sequence in opposite orders

• Hundreds of restriction enzymes

• Fragments have sticky ends

Vectors Transfer DNAVectors Transfer DNA

• Carrier that transports foreign DNA into host

• Here a retrovirus serves as vector for engineered bone cells.

• Can be biological or mechanical

• Bacterial plasmid is a small ring of DNA

• Micropipette or DNA coated bullet from a gene gun

• ML 13.1, p. 343

Gene CloningGene Cloning

• Clones are genetically identical copies

• Each identical recombinant DNA molecule is called a gene clone.

• Recombinant DNA can be inserted in yeast, plant cells and animal cells.

Animal CloningAnimal Cloning

• Dolly the sheep first cloned animal, 1997

• Dewey, first cloned deer, 2003

Polymerase Chain ReactionPolymerase Chain Reaction

• PCR method to replicate DNA outside an organism

• Thermocycler uses heat to separate DNA strands

• Enzyme used to repeatedly replicate DNA

• Used in crime investigations and diagnosis of infectious disease

Sequencing DNASequencing DNA

• Sequencing DNA allows scientists to identify mutations

• Four tubes A, C, T & G tagged with different colors

• Strands separated by size using gel electrophoresis

Applications of DNA TechnologyApplications of DNA Technology

• Industrial• Produce chemical

compounds– Indigo for dye– Cheese production– Laundry detergent– Pulp & paper products– Sewage treatment

Applications of DNA TechnologyApplications of DNA Technology

• Medical • Production of proteins

– Human growth hormone– Insulin– Antibodies– Enzymes

Applications of DNA TechnologyApplications of DNA Technology

• Agriculture• Crop development• Insect resistance• Genetically modified

crops• Vitamin fortified food• Allergy reduction

13.3 The Human Genome13.3 The Human Genome

• In 2003 scientists in the Human Genome Project obtained the DNA sequence of 3 billion base pairs making up the human genome.

• It is nearly the same (99.9%) in all people.

13.3 The Human Genome13.3 The Human Genome

• Only about 2% of the human genome contains genes which are the instructions for making proteins.

• Humans have about 30,000 genes; the functions of more than half of them are unknown.

13.3 The Human Genome13.3 The Human Genome

• Almost half of human proteins share similarities with other organisms, underscoring the unity of life.

• Much is still unknown!

The Human GenomeThe Human Genome

• Genetic map that gives the relative location of genes on a chromosome is called a linkage map.

• Crossover occurs during prophase I of meiosis.

• Genes that crossover frequently must be farther apart.

The Human GenomeThe Human Genome

• Biotechnology increases the efficiency of mapping with new methods such as polymerase chain reaction (PCR) to make millions of copies of DNA fragments

The Human GenomeThe Human Genome

• Sequencing the human genome:

• 1) cleaving DNA into fragments

• 2) cloning fragments• 3) sequences aligned• All automated

ApplicationsApplications

• Diagnosis of genetic disorders

• Can be diagnosed before birth using amniotic fluid

• Isolating DNA• Using PCR to analyze

ApplicationsApplications

• Gene Therapy• Insertion of normal

genes into human cells to correct genetic disorders

• SCID, cystic fibrosis, sickle cell anemia, hemophilia

ApplicationsApplications

• New Methods of Crime Detection

• DNA fingerprints from non-coding DNA segments unique to individual

• Can be used even with ancient DNA such as mummies or historical figures