Showing posts with label gene. Show all posts
Showing posts with label gene. Show all posts

Monday, 5 May 2014

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How to download a list of the gene length of all genes from the UCSC genome browser?

Some basic information like length can be obtained in the GTF file (you can get the latest ENCODE GTF from the UCSC genome browser). Other information are also available and obtainable from the UCSC genome browser → table browser. Select the group and tracks that you want from the corresponding dropdown boxes. You can export the data as a text file or forward it to the galaxy interface for analysis.
If you are familiar with some programming then you can pull out the lengths (it is not explicitly given in the output or in the GTF). Also, the gene length may be different from the mRNA length because of the presence of introns in the former. The third field in the GTF file denotes the feature (gene, transcript, exon, etc); you can parse the GTF for picking up only desired features, lets say the mRNAs. The fourth and fifth fields denote start and end positions respectively; all you have to do is end−start to obtain the length.
A small scriptlet such as this would work in linux/cygwin terminal (I wont go in detail because this is not the scope of this forum):
awk -F "\t" '$3=="transcript"{print $9, $5-$4}' file.gtf > output.txt
The $9 refers to the ninth field which holds information about that feature including the gene name, gene id etc.
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Monday, 23 December 2013

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How does a mutation in BRCA1 gene that leads to an impairment of double-strand DNA repair affect cell’s response to cancer?

BRCA1 gene belongs to a class of genes known as tumor suppressor genes protein from the BRCA1 gene helps prevent cells from growing and dividing too rapidly

This gene produce a protein that is directly involved in repairing damaged DNA. In the nucleus of many types of normal cells, the BRCA1 protein interacts with several other proteins, including the proteins produced from the RAD51 and BARD1 genes, to mend breaks in DNA. These breaks can be caused by natural and medical radiation or other environmental exposures, and also occur when chromosomes exchange genetic material in preparation for cell division. By helping repair DNA, BRCA1 plays a role in maintaining the stability of a cell's genetic information.


So if a mutation in BRCA1 occurs the breaks in DNA can't be fixed and response to cancer affected
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Monday, 25 November 2013

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How can gene trees be used to estimate rates of gene flow among geographic populations of a species? What assumptions would have to be made?

GeneTree is a program used for comparing gene and species trees using reconciled trees. So this can compute the cost of embedding a gene tree within a species tree, visually display the location and number of gene duplication and losses, and search for optimal species trees.
Exploration of the relationship between gene trees and their containing species trees leads to consideration of how to reconstruct species trees from gene trees and of the concept of phylogeny as a cloud of gene histories.
This anomaly can arise from horizontal transfer such as hybridization, lineage sorting, and gene duplication and extinction.
Lineage sorting could also be termed as deep coalescence, the failure of ancestral copies to coalesce into a common ancestral copy until deeper than previous speciation events.
These events depend on various factors; for instance, deep coalescence is more likely if the branches of the species tree are short (in generations) and wide (in population size).
A similar dependence on process is found in historical biogeography and host-parasite relationships.
Each of the processes of discord could yield a different parsimony criterion for reconstructing the species tree from a set of gene trees: with horizontal transfer, choose the species tree that minimizes the number of transfer events; with deep coalescence, choose the tree minimizing the number of extra gene lineages that had to coexist along species lineages; with gene duplication, choose the tree minimizing duplication and/or extinction events.
Maximum likelihood methods for reconstructing the species tree are also possible because coalescence theory provides the probability that a particular gene tree would occur given a species tree











You can download free version of Genetree

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