Naučne zanimljivosti

[Lord Protector]

mape evolucije

 

 

Edited April 12, 2015 by slow

[Lord Protector]

 

 

Edited April 12, 2015 by slow

[Skyhighatrist]

Evo prilog sa astronomije:
If Moon were just one pixel

[Lord Protector]

[Lord Protector]

[Lord Protector]

[Lord Protector]

[Lord Protector]

 

[bigvlada]

 

 

 

 

[Lord Protector]

 

Wolf pack & strategy: The first 3 are the older or sick & they set the pace of the group. The following are the 5 strongest. In the center follow the remaining members of the pack, & at the end of the group the other 5 stronger. Last, alone, follows the alpha wolf. It controls everything from the rear. That position can control the whole group, decide the direction to follow & anticipate the attacks of opponents. The pack follows the rhythm of the elders & the head of command that imposes the spirit of mutual help not leaving anyone behind.

[Prokleto Djubre]

 

Wolf pack & strategy: The first 3 are the older or sick & they set the pace of the group. The following are the 5 strongest. In the center follow the remaining members of the pack, & at the end of the group the other 5 stronger. Last, alone, follows the alpha wolf. It controls everything from the rear. That position can control the whole group, decide the direction to follow & anticipate the attacks of opponents. The pack follows the rhythm of the elders & the head of command that imposes the spirit of mutual help not leaving anyone behind.

 

Moracu ja da budem onaj smarac :D

Ova slika ne govori nista i potpuno je pogresno objasnjenje. Fizicki najjaci vuk ide napred da bi pravio prtinu u snegu, a ideja alfa vuka je potpuno pobijena. Sama takva ideja je nastala bukvalno od jednog visegodisnjeg posmatranja u zooloskom vrtu i sam autor se ogradio od nje u kasnijim godinama. Problem je bio sto su zivotinje u zoo vrtu dovedene sa raznih strana i onda su napravile nekakvu hijerarhiju do kakve nikad u prirodi ne moze doci. Vodje copora su keva i cale, a deca kako stasavaju ili se odvajaju i prave svoje copore ili nastavljaju da slusaju roditelje dok su tu. Nazalost, ne mogu sad da nadjem bas dobar clanak koji je koristio bas ovu sliku da to objasni, ali evo ima ovde nesto:

 

http://io9.gizmodo.com/why-everything-you-know-about-wolf-packs-is-wrong-502754629

 

i ista prica na malo vedriji nacin:

 

http://www.cracked.com/article_22767_5-ridiculous-myths-about-animals-you-probably-believe.html

 

Ovaj mit je specijalno izdrzljiv iako je opovrgnut jos '70ih i puno stete je uradio kod vlasnika pasa, koji stalno brinu o tome da li su dovoljno "alfa" prema svom psu. Mnogo ruznih navika potice od toga sto ljudi zamisljaju svog psa kao nekoga kome treba vodja copora i insistiraju na psihologiji koja nema nikakvo uporiste u realnosti. Ako nikad ne smes da izgubis u igri natezanja igracke od svog psa velika je sansa da on to ne vidi kao da si alfa, nego da si bahati smrad koji ne ume da se igra :D

[Lord Protector]

 

How Do Different Species Differ?

 

The genomes of different organisms may be vastly different and amazingly similar. The human genome consists of about 3 billion bases, while the fly genome has a scant 140 million bases. However, an analysis of the genomic sequences for two vastly different organisms (fruit flies and humans) has revealed that many genes in humans and flies are similar. Moreover, as many  as 99% of all human genes are conserved across all mammals! Some human genes show strong similarity across not only mammals and flies but also across worms, plants, and (worse yet) deadly bacteria. A species, then, is a collection of individuals whose genomes are “compatible,” in the sense of mating.

Roughly only 0.1% of the 3 billion nucleotide human genome (or 3 million bases) are different between any two individuals. Still, this leaves room for roughly 4^3,000,000 different genomes, and is for all intents and purposes an endless diversity.

 

 

Genome Rearrangements

 

Waardenburg’s syndrome is a genetic disorder resulting in hearing loss and pigmentary abnormalities, such as two differently colored eyes. The disease was named after the Dutch ophthalmologist who first noticed that people with two differently colored eyes frequently had hearing problems as well. In the early 1990s, biologists narrowed the search for the gene implicated in Waardenburg’s syndrome to human chromosome 2, but its exact location remained unknown for some time. There was another clue that shed light on the gene associated with Waardenburg’s syndrome, that drew attention to chromosome 2: for a long time, breeders scrutinized mice for mutants, and one of these, designated splotch, had pigmentary abnormalities like patches of white spots, similar to those in humans with Waardenburg’s syndrome. Through breeding, the splotch gene was mapped to one of the mouse chromosomes. As gene mapping proceeded it became clear that there are groups of genes in mice that appear in the same order as they do in humans: these genes are likely to be present in the same order in a common ancestor of humans and mice—the ancient mammalian genome. In some ways, the human genome is just the mouse genome cut into about 300 large genomic fragments, called synteny blocks, that have been pasted together in a different order. Both sequences are just two different shufflings of the ancient mammalian genome. For example, chromosome 2 in humans is built from fragments that are similar to mouse DNA residing on chromosomes 1, 2, 3, 5, 6, 7, 10, 11, 12, 14, and 17. It is no surprise, then, that finding a gene in mice often leads to clues about the location of the related gene in humans. Every genome rearrangement results in a change of gene ordering, and a series of these rearrangements can alter the genomic architecture of a species. Analyzing the rearrangement history of mammalian genomes is a challenging problem, even though a recent analysis of human and mouse genomes implies that fewer than 250 genomic rearrangements have occurred since the divergence of humans and mice approximately 80 million years ago.

Every study of genome rearrangements involves solving the combinatorial puzzle of finding a series of rearrangements that transform one genome into another.

 

AN INTRODUCTION TO BIOINFORMATICS ALGORITHMS, MIT PRESS

NEIL C. JONES AND PAVEL A. PEVZNER

 

Kao u starom domaćem horor filmu Izbavitelj iz 1976. ljudi-pacovi  :o

 

 

 

 

 

Edited July 6, 2016 by slow

[Lord Protector]

 

Figure 5.1 (nacrtan deo hromozoma sa pet gena koji permutuju) presents a rearrangement scenario in which the mouse X chromosome is transformed into the human X chromosome. The elementary rearrangement event in this scenario is the flipping of a genomic segment, called a reversal, or an inversion. One can consider other types of evolutionary events but in this book we only consider reversals, the most common evolutionary events. Biologists are interested in the most parsimonious evolutionary scenario, that is, the scenario involving the smallest number of reversals. While there is no guarantee that this scenario represents an actual evolutionary sequence, it gives us a lower bound on the number of rearrangements that have occurred and indicates the similarity between two species.² Even for the small number of synteny blocks shown, it is not so easy to verify that the three evolutionary events in figure 5.1 represent a shortest series of reversals transforming the mouse gene order into the human gene order on the X chromosome.

 

2. In fact, a sequence of reversals that transforms the X chromosome of mouse into the X chromosome of man does not even represent an evolutionary sequence, since humans are not descended from the present-day mouse. However, biologists believe that the architecture of the X chromosome in the human-mouse ancestor is about the same as the architecture of the human X chromosome.

 

 Evolucija liči na mešanje (permutaciju) špila karata. DNK je špil, deljenje špila u jednoj partiji hromozomi, pojedine karte geni. Mutacije nastaju kada se vara na kartama  ^_^

 

 

In their simplest form, rearrangement events can be modeled by a series of reversals that transform one genome into another. The order of genes (rather, of synteny blocks) in a genome can be represented by a permutation.³

 

3. A permutation of a sequence of n numbers is just a reordering of that sequence. We will always use permutations of consecutive integers: for example, 2 1 3 4 5 is a permutation of 1 2 3 4 5.

Edited July 6, 2016 by slow

[Lord Protector]

Prikaz DNK kockanja u Nature

 

 

 

An Analogy for Gene Distribution

 

In this case, the card game is an analogy. Think of the deck of cards as a genome, with each card representing a single gene and each hand representing a chromosome; thus, in this example, we're looking at an organism with 52 genes distributed among four chromosomes. The pattern of dealing in this analogy is representative of mitosis—here, each deal (cell division) involves a precise, repetitive set of mechanical operations that ensures that the same cards (genes) get distributed to each player (daughter cell). The rules guarantee that the same hands (sets of genetic information) will be preserved in each successive round of the game (generation of cells).

 

http://www.nature.com/scitable/topicpage/synteny-inferring-ancestral-genomes-44022

 

 

Permutacija blokova gena čovek-pacov:

 

Edited July 6, 2016 by slow

[Lord Protector]

 

AutoGRAPH is an integrated web server for multi-species comparative genomic analysis. It is designed for constructing and visualizing synteny maps between two or three species, determination and display of macrosynteny and microsynteny relationships among species, and for highlighting evolutionary breakpoints.

Edited July 6, 2016 by slow