Biology 102 Biotechnology

Lecture outline What is biotechnology? Goals of biotechnology How does genetic recombination occur in nature? How does genetic engineering occur in the lab? Application of biotechnology Focus on GMOs (modified crops and animals)

What is biotechnology? Any commercial use or alteration of organisms, cells and biological molecules to achieve specific, practical goals. Examples (in long use) Selective breeding Use of yeast to make wine Current techniques Genetic engineering: modification of genetic material to achieve specific goals

Goals of Biotechnology To understand more about the processes of inheritance and gene expression To provide better understanding & treatment of various diseases, particularly genetic disorders To generate economic benefits, including improved plants and animals for agriculture and efficient production of valuable biological molecules Example: Vitamin A fortified engineered rice (Chapter-opening case study)

Methods of Biotechnology: Examples “Older” techniques Selective breeding Use of yeast to make wine Current techniques Genetic engineering: modification of genetic material to achieve specific goals

How does DNA Recombination occur in nature? Sexual reproduction Bacterial recombination Transfer by viruses

Recombination in Bacteria Bacterium Plasmid transferred to new host (b) (c) DNA fragments transferred to new host Chromosome Plasmid (a) In addition to their large circular chromosome, bacteria commonly possess small rings of DNA called plasmids, which often carry additional useful genes. Bacterial transformation occurs when living bacteria take up (b) these plasmids or (c) fragments of chromosomes. Plasmid replicates in cytoplasm 1 µm DNA fragment incorporated into chromosome Plasmids allow bacteria to grow in novel environments

Transfer of genes by viruses A virus infecting a eukaryotic cell uses its own genetic material and the host’s cellular machinery to copy the virus. When copies are released from the cell, they can infect new host cells. Segments of the host DNA may be incorporated into the viral genome and transferred to hosts of other species.

Genetic engineering in the lab Create a “DNA” library Fragments from entire genome end up in different bacterial colonies Most fragments will not end up being useful Some may have the gene(s) you want Getting the gene you want is like finding a needle in a haystack! First step: Cutting up the DNA Gives you workable fragments that can be incorporated into bacteria

Cutting DNA with restriction enzymes Restriction enzymes cut DNA in specific locations Example: The restriction enzyme EcoRI recognizes the sequence GAATTC Cuts the sequence in half anywhere encountered Different restriction enzymes cut in different places

Creating a DNA library Note that plasmid vector and desired DNA are cut with same restriction enzyme, so complementary base pairing occurs Create different bacterial colonies with different fragments

Finding the genes of interest Restriction length polymorphisms Tell you whether two individuals are the same or different for a particular fragment in your library IF individuals differ for sequence recognized by the restriction enzyme, then they will be cut differently Search for these polymorphisms for people known to differ for different traits

Gel electrophoresis

DNA fingerprinting

Finding genes of interest (cont.) Use a DNA probe: short sequence of single-strand DNA that is part of the sequence of interest Useful only if you already know the sequence you are looking for! Can use genes from one organism to find similar genes in another organism

Finding genes of interest (cont.) Identify genes on basis of gene product (i.e. the protein they make) Can transcribe and translate the gene inside the host bacterium

Applications of biotechnology DNA fingerprinting (identification) Transgenic crops and animals (GMOs) Production of therapeutic proteins Models of human genetic diseases created in other organisms Genetic testing Gene therapy Treatment for SCID