Frontiers of Genetics Chapter 13

Importance of bacteria in biotechnology Bacteria is a very important organism used in DNA technology Specifically Escherichia coli Bacteria can easily exchange genes

How can bacteria exchange genes? Through tunnel like connections Viruses carry bacterial genes Bacteria take up DNA from surrounding environment

Recombinant DNA Technology Some Bacteria are used to mass produce specific desirable genes and proteins

Cutting and Pasting DNA

Restriction enzymes cut DNA molecules at specific locations Fragments of DNA spliced together from two different sources produces a recombinant DNA molecule

Cloning of a human gene for a hypothetical protein V

Applications of recombinant DNA technology Bacteria engineered to clean up toxic waste Mass-production of useful chemicals Mass production of proteins and hormones for medical uses Develop vaccines against disease-causing microbes Develop genetically modified multicellular organisms

Genetic Markers Specific stretches of DNA that vary among individuals Genetic Markers can be present in: Alleles for diseases or other traits Non-coding regions of DNA (introns) Genetic markers can help to pick out the differences between two DNA fingerprints (particular banding pattern produced by individual’s restriction fragments)

Electrophoresis Animations http://learn.genetics.utah.edu/content/labs/gel/ http://www.sumanasinc.com/webcontent/animations/content/gelelectrophoresis.html http://www.youtube.com/watch?v=eJe9ltcMRww&feature=related

2. Genetic markers- particular stretches of DNA that are variable among individuals (easy way to tell if an individual is a carrier of a disease) 3. DNA fingerprints- an individual’s unique banding pattern

Control mechanisms switching genes on and off Regulation of Genes in Prokaryotes 1. Operon- cluster of genes and their controlled sequences 2. Promoter- control sequence on an operon where RNA polymerase attaches to the DNA

E. coli bacteria, natural inhabitants of your intestine, break down the sugar lactose. The genes that code for lactose-processing enzymes are located next to control sequences. Altogether, this stretch of DNA is called the lac operon.

3. Operator- a control sequence that acts like a switch, determining whether or not RNA polymerase can attach to the promoter 4. Repressor- a protein that functions by binding to the operator and blocking the attachment of RNA polymerase to the promoter; turns off transcription

The lac operon is inactive in the absence of lactose (top) because a repressor blocks attachment of RNA polymerase to the promoter. With lactose present (bottom), the repressor is inactivated, and transcription of lactose-processing genes proceeds.

Regulation of Genes in Eukaryotes 1. Transcription factors- proteins that regulate transcription by binding to those promoters or to RNA polymerases; are activated and deactivated by chemical signals in the cell 2. Gene expression- the transcription and translation of genes into proteins

From Egg to Organism 1. Cellular differentiation- when cells become increasingly specialized in structure and function

Though all the genes of the genome are present in every type of cell, only a small, specific fraction of these genes are actually expressed in each type of cell. The yellow color indicates a gene that is "turned on" (expressed).

Stem Cells 1. Cells that remain undifferentiated; they have the potential to differentiate into various types of cells; may be able to help people with disabling diseases

Present at a very early stage of human development, stem cells have the potential to develop into any type of human cell.

Homeotic Genes 1. Master control genes that direct development of body parts in specific locations in many organisms http://www.youtube.com/watch?v=AXjvG-FJX60 - Great transformations

The highlighted portions of the fruit fly and mouse chromosomes carry very similar homeotic genes. The color coding identifies the parts of the embryo and adult animals that are affected by these genes.