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Chapter 21 Blog: Genomes, Proteomes, And Bioinformatics (Kathryn)

Page history last edited by Kathryn Addabbo 13 years, 4 months ago

A. Daily Blog


Chapter 21 differentiates between the genomes and proteomes of prokaryotes and eukaryotes while discussing bioinformatics. Like the cells, prokaryotes and eukaryotes have very different genomes. Prokaryotes lack centromeres and telomeres, but possess structures called plasmids, circular pieces of DNA which are separate from the chromosomes. Plasmids are essentially vectors used in genetic engineering. They can be broken apart and recombined to include a certain gene so that the cell gains the effects of that gene. Prokaryotic genomes usually have a single origin of replication, unlike eukaryotes, who have multiple origins. 


Eukaryotic genomes are much more complex, although they lack plasmids, they possess centromeres, telomeres, and have a larger overall size. There are several components found in DNA; only 2% of human DNA can be considered "coding". The other 98% is noncoding, although this does not mean that it is useless. Repetitive sequences make up 59%, while introns make up 24% and unique noncoding sections (function is unknown) make up 15% of the genome. The functions of these sections are widely unknown, but it is guessed that they are beneficial to the cell in some way. Some of these elements are created by transposable elements, which are DNA segments that periodically change location. They are termed "jumping genes" because of this. Sometimes this can be beneficial to the species, but when they land in the middle of an important functional gene, it can be turned off, causing havoc in the cell. This can cause gene duplication in some chromosomes. This can lead to the formation of gene families among different species. 


Proteomes are essentially the product of genomes. They are the proteins a cell can produce with its genetic material. The proteome can be larger than the genome because of a process termed alternative splicing; several different mRNAs can be created due to cutting and pasting at different points (endless possibilities). These proteins can be categorized into seven functional groups: metabolic enzymes, structural, motor, cell-signaling, transport, gene expression and protective proteins. 


Bioinformatics is defined as the use of a variety of tools to record, store, and analyze biological information. This consists widely of model organisms' genomes. Five questions can be answered when looking at this set of data: does the sequence contain a gene, does it contain a mutation that might cause a disease, where are functional sequences (promoters/regulatory sites/splice sites) located, what is the amino acid sequence of the polypeptide encoded by that gene, and is there an evolutionary relationship between two or more genetic sequences? These questions help scientists find what they are looking for within the data. All of this is input by scientists all around the world, it is essentially one file in which everything is kept so scientists all over the world can have access to it. The easiest way to locate a gene is the BLAST method, where homologous sequences are located within a gene using the database. It was developed in 1990, and is a quicker and easier way for scientists to find what they are looking for.


B. Useful Materials


This picture shows a basic image of how misaligned crossovers occur. The chromosomes are not evenly aligned during metaphase and then when crossing over occurs, an unequal transfer in DNA results. This causes one chromosome to have a gene duplication while the other has a gene deletion. As you can see, this is found when looking at exon 3.


This picture displays how overtime, a gene can change in many ways. Globin is the example here, and over time, it branches into different types: myoglobin, alpha and beta hemoglobins. But farther along the line, we can see that mutations occur. These mutations can be labeled as pseudogenes: they result in a nonfunctional area of the genome.


Transposons for cancer gene discovery: Sleeping Beauty and beyond.

This article talks about how "Sleeping Beauty" genes have been experimented on and documented countless times in association with cancer. This study covers the potential use of these genes to treat somatic mutagenesis. 


Comments (1)

Derek Weber said

at 12:03 am on Apr 1, 2011

Like to see images that aren't from our book or the ppt.

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