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Postuar nga NS-6 datė 30 Janar 2005 - 12:40:

struktura e ADN:pozicionet 3 dhe 5 te struktures se sheqerit dhe ADN

Cod. A30012005

Qellimi im per kete teme ky eshte qe cdokush te perfitoje dicka nga gjerat qe shkruaj. Dua vetem te them qe nese ka ndonje qe mund te shtoje ose te heqe ose te kritikoje ta shkruaj keshtu qe ta dine te gjithe...

Thashe qe pozicionet e karbonit 3 dhe 5 jane shume te rendesishem.Pse?Ne pozicionin 3 eshte pika ku lidhet njeri nukleotid ndersa pozicioni 5 eshte pika ku eshte i lidhur grupi fosfat qe lidhet me nukleotidin e ri.Praktikisht formohet nje lidhje ku grupi -OH i nukleotidit te dyte(te themi keshtu) leshon hidrogjenin dhe me oksigjenin lidhet me grupin fosfat te nukleotidit te pare i cili normalisht ka leshuar 2 grupe fosfat si grupe inorganik dhe lidhet me kete oksigjen.Pak a shume eshte menyra si shperbehet ATP ne ADP ose AMP +2Pi.(per ndihme referojuni figures se nukleotidit me siper)

Bashkimi i dy zinxhireve te ADN formon nje strukture ne forme helike qe ka edhe ajo karakteristikat e veta:ne saje te llojit te ADN qe ndryshon ne baze te sa nukleotideve qe formojne nje rrotullim te plote kemi ADN te tipit A,B dhe Z me duket. Forma A egziston vetem ne laboratore kurse per formen Z nuk ka dijeni akoma a egziston apo jo. Forma B (ajo e qelizave tona)ne nje rrotullim i plote ka rreth 10.5 baza dhe nje gjatesi rreth 0.34nm ndermjet 2 nukleotidesh.Pastaj ka edhe shume forma te tjera qe mund te marre ADN.Ka raste qe mund te gjehet edhe si zinxhir i vetem sic eshte ne rastin e viruseve me ADN ku eshte nje klase qe e ka gjenomen deri ne nje fare pike si helike po ne fund e ka nje pjese qe nuk eshte helike por filement tek...
Tek historia e ADN thashe qe u perdor nje karakteristike e ADN dhe e proteinave per te gjetur se kush prej tyre ishin percues te karakteristikave...

...As i mentioned before the position 3 and 5 in the nucleotide structure are very important.Why?The position 3 is the point where one nucleotide binds meanwhile position 5 is the point where the phosphate group binds with the new nucleotide.So a linkeage is formed,where the -OH group of the second nucleotide (let's say so) dissociates the hydrogen proton and gets connected with the phosphate group of the first nucleotide that normally has lost 2 phosphate groups as inorganic groups in order to make the connection with the oxygen. It's nearly the same thing that happens to the ATP (adenosine triphosphate) that dissociate in AMP and 2Pi (for reference during the explanation see the figure above)

The joint of the 2 DNA chains form a helix like structure that has its own characteristics:
It may vary according to the number of nucleotides that form a 360 degree rotation and so we get different types of DNA: A,B(the one present in our cells) and Z. The Z form is not yet found whether it exists or not. The A form is present only in laboratory conditions. The B form,has 10.5 bases per rotation with a total length of 0.34nm between 2 nucleotides.there are other forms DNA can take. It may exist as a single chain (there's a type of virus class that whose genoma is like the normal DNA structure but in the end it is like it has lost a piece and that DNA part is a single chain)

In the DNA history I mentioned that in order to find which one were responsable for the genetic traits (DNA or proteins),a nice method was used...

Sorry for the mistakes i do during the traslation


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