Genetics

Q1. In an era in which genome and transcriptome sequences are increasingly easy and inexpensive to obtain, are more model organisms needed? Which organisms might be included among the model organisms and why or why not?

 Yes, model organisms are needed to study more about universal properties of eukaryotic organisms and apply those to humans. This is the major reason why researchers depend on the model organisms. Some of the model organisms like Danio rerio, Neurospora crassa, Schizosaccharomyces pombe,, Aspergillus nidulans, Oryza sativa Canis familiaris etc. might be included , because they contributes a lot of information like cell growth, development, chromosomal development, vertebrate growth in humans and some of them contributes in plant development.

Q2. There are a number of model organisms that, for lack of space and expertise, are not extensively discussed in this book. Some of these are listed in Table 2-2 of your text book, but there are many others as well. Using the on-line resources and the genome databases, research at least one of these organisms, and compile at least one biological question that could not be readily studied using this model organism. Also fill in the categories in Table 2-1 of the text book for this organism.

 Danio rerio - Zebra fish-

• Since it is not mammal, it is not closely related like mouse to study human diseases.

• Reverse genetics does not work in zebra fish.

Species: Danio rerio

Common name: zebra danio / zebra fish

Genome size: 25 chromosomes and 1.5 × 10 billion base pairs

Initial attractiveness as a research organism: Their embryos helped a lot to study about vertebrates. Easy to maintain in the lab and observe since they are transparent.

Method to make transgenics: Cre mediated site specific recombination, injection with mRNA that encodes the protein of interest

Particular advantages: shortest generation time; large number of off springs; embryos are transparent to study quickly; egg production can be stimulated by controlling darkness of periods. It is strongly favored in studying embryology.

Limitations: Reverse Genetics; physiology of zebra fish is not identical to humans; genome duplication

Genome Database: ZFIN (www.zfin.org)

Q3. When it was realized that transposable elements were found in many eukaryotic species and not only corn, it was also recognized that different categories of transposable element might move by different mechanisms and might have different sequence or structural features. However, DNA sequencing