BIOL 401 Final: Exam IV Study - Lecture 17

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BIOL 401
Steven P Tammariello

Exam IV Study – Lecture 17 This lecture focused on animal models and how we use them to study genetics. We started with discussing C. Elegans. These nematodes are frequently used because they are small, have a short lifespan, and easy to rear. Their entire cellular development has been mapped and their cells are transparent, so we’re able to study their development and genome quite well. It’s also important to note that hermaphrodites have 959 cells, and males have 1031 cells. Their haploid number is 6, and they have a 97 million base pair genome. Additionally we’ve found that their hibernation state can aid in cancer research (WHY?). Another fact is that since they eat E. coli, we can use the bacteria as a vector to upregulate or downregulate genes. Another model we discussed was the zebrafish. These are often studied in development because they have transparent embryos, which make it easy to study cell migration and differentiation. Zebra fish gemones contain 1.7 billion base pairs with a 39-fold coverage, which means they have the same base sequenced at least 39 times. We know of about 5 million SNPs in the zebrafish genome. Remember, SNPs are differences in a single nucleotide, which can act as biological markers for diseases and affect gene function. Something Dr. T related back to the zebrafish was the Tol2 transposon system. This is a method used to knock out certain genes and replace them with a desired just. It essentially is the same thing as transposons. For example, if we had a mutant zebrafish but wanted to make it wild type again, we could use the Tol2 transposon system to knock out the mutant gene and replace it with the wild-type gene. Another system that was discussion in this section is the biosensor system. This is a method often utilized to detect chemical and hormone levels in water. A promoter, such as estrogen, is added to the zebrafish, making it a transgenic organism (discussed further later). Once the label has been added the fish will fluoresce when exposed to water containing estrogen or other hormones. Transgenic organisms are not a very efficient way to manipulate a genome, at least not in animal cells. Plant cells can tolerate becoming a transgenic organism, specifically via microinjection, since they have a cell wall that adds stabilization and prevents them from exploding. Animals cells don’t have a cell wall, so it’s more common for them to die while trying to get the DNA into the cell. There are several methods to transfer the transgenic DNA into the chromosome. These include the modification of cells so they can uptake DNA from outside the cell, use a virus with the desired DNA and program it to attach to a specific cell, microinjection, which is the least effective method due to cells often exploding, stem cell-mediated gene transfer, and a projectile gun, which shoo
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