{"id":31114,"date":"2018-11-30T01:01:07","date_gmt":"2018-11-29T22:01:07","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=31114"},"modified":"2018-11-29T23:32:54","modified_gmt":"2018-11-29T20:32:54","slug":"yasami-ureten-mekanizmanin-yeni-kanitlari","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2018\/11\/30\/yasami-ureten-mekanizmanin-yeni-kanitlari","title":{"rendered":"Ya\u015fam\u0131 \u00fcreten mekanizman\u0131n yeni kan\u0131tlar\u0131"},"content":{"rendered":"

Cesur bir deney D\u00fcnyadaki ya\u015fam\u0131n temelinde d\u00f6n\u00fc\u015f\u00fcmsel sistemin yerini do\u011fruluyor. Bu deneyin ba\u015far\u0131s\u0131z olma durumu vard\u0131. Ancak bu deney, genlerimiz d\u0131\u015f\u0131nda ya\u015fam\u0131 m\u00fcmk\u00fcn k\u0131lan mekanizmalar olan d\u00f6n\u00fc\u015f\u00fcmsel sistemin ilk evrimini destekleyen \u00e7ok b\u00fcy\u00fck kan\u0131tlar sundu. \u00c7al\u0131\u015fma ribozomu merkezleyen sistemin bug\u00fcn sanki D\u00fcnyadaki ya\u015fam\u0131n temelinin 4 milyar y\u0131l \u00f6ncesiymi\u015f gibi geli\u015fti\u011fini g\u00f6sterdi.<\/p><\/blockquote>\n

Deney \u00f6ylesine c\u00fcretk\u00e2rd\u0131 ki Marcus Bray, deneyin ba\u015far\u0131s\u0131z olaca\u011f\u0131ndan bile korktu.<\/strong>
\nMarcus Bray, genetik kodu ya\u015fama d\u00f6n\u00fc\u015ft\u00fcren h\u00fccrelerin i\u00e7indeki sistemde, yakla\u015f\u0131k 1.000 temel yap\u0131y\u0131, d\u00f6n\u00fc\u015f\u00fcmsel sistemin ya\u015fam\u0131n\u0131 s\u00fcrd\u00fcr\u00fcp s\u00fcrd\u00fcrmedi\u011fini ve i\u015fleyip i\u015flemedi\u011fini g\u00f6rmek amac\u0131yla ilkel olanlarla de\u011fi\u015ftirdi. Bu, m\u00fcmk\u00fcn g\u00f6r\u00fcnmemesine ra\u011fmen i\u015fe yarad\u0131. Proteinlerin b\u00fcy\u00fck kurucusunun, 4 milyar y\u0131l \u00f6nce evrimle\u015fti\u011fi zorlu ko\u015fullarda aktif oldu\u011funa dair Bray\u2019in g\u00fc\u00e7l\u00fc kan\u0131tlar\u0131 vard\u0131.<\/p>\n

Deneyin ba\u015far\u0131lmas\u0131 D\u00fcnyadaki ya\u015fam\u0131n temelinde d\u00f6n\u00fc\u015f\u00fcmsel sistemin yerini yeniden do\u011frulad\u0131.
\n<\/strong>Her ya\u015fayan \u015fey var olur \u00e7\u00fcnk\u00fc d\u00f6n\u00fc\u015f\u00fcmsel sistem RNA taraf\u0131ndan ona aktar\u0131lan DNA\u2019dan mesajlar\u0131 al\u0131r ve proteine d\u00f6n\u00fc\u015ft\u00fcr\u00fcr. Sistem, \u00e7ok say\u0131da RNA molek\u00fcl\u00fcnden ve proteinden olu\u015fan ve bildi\u011fimiz kadar\u0131yla ya\u015famda var olan ribozom ad\u0131 verilen h\u00fccresel mekanizmalara odaklan\u0131r.<\/p>\n

Georgia Teknoloji Enstit\u00fcs\u00fc Kimya ve Biyokimya B\u00f6l\u00fcm\u00fc \u00d6\u011fretim \u00dcyesi Loren Williams, \u201cRibozomu olmayan bir canl\u0131 olmad\u0131\u011f\u0131n\u0131\u201d, \u201cRibozomun neredeyse en eski, biyolojinin en yayg\u0131n par\u00e7as\u0131 oldu\u011funu ve k\u00f6kenlerinin D\u00fcnya olu\u015ftuktan ve so\u011fuduktan sonraki d\u00f6neme kadar gitti\u011fini\u201d s\u00f6yledi.<\/p>\n

Magnezyumunuzu yiyin<\/strong>
\nBray\u2019in s\u00f6k\u00fcp \u00e7\u0131kard\u0131\u011f\u0131 ve de\u011fi\u015ftirdi\u011fi bu temel yap\u0131lar metal iyonlar\u0131d\u0131r (bu durumda pozitif y\u00fckl\u00fc atomlar).<\/p>\n

Bug\u00fcn\u00fcn ribozomlar\u0131nda ve b\u00fct\u00fcn d\u00f6n\u00fc\u015f\u00fcmsel sistemde bunlar, magnezyum iyonlar\u0131d\u0131r ve Bray\u2019in deneyinde bunlar\u0131n hepsi ilkel D\u00fcnyada \u00e7ok fazla bulunan demir ve manganez iyonlar\u0131yla de\u011fi\u015ftirildi. Bu \u00e7al\u0131\u015fmada ba\u015f ara\u015ft\u0131rmac\u0131 William ve Jennifer Glass\u2019\u0131n da deneyin ba\u015far\u0131labilir olaca\u011f\u0131 konusunda \u015f\u00fcpheleri vard\u0131.<\/p>\n

Daha \u00f6nce daha basit molek\u00fcllerle benzer bir \u00e7al\u0131\u015fma y\u00fcr\u00fcten Williams \u201c\u0130\u015fe yaramayacak fakat bunu da deneyebiliriz diye d\u00fc\u015f\u00fcnd\u00fcm\u201d dedi. \u201cD\u00f6n\u00fc\u015f\u00fcmsel sistemde t\u00fcm magnezyumu de\u011fi\u015ftirmenin i\u015fe yaramas\u0131 ak\u0131llara durgunluk verdi.\u201d<\/p>\n

\u00c7\u00fcnk\u00fc bug\u00fcn canl\u0131 sistemlerde magnezyum, ribozomlar\u0131 bir arada tutarak \u015fekillendirmeye yard\u0131m eder. Ayr\u0131ca d\u00f6n\u00fc\u015f\u00fcmsel sistemin 20 ek enzimi i\u00e7in magnezyuma da ihtiya\u00e7 duyulur. Besinsel magnezyumunun (Mg) \u00e7ok \u00f6nemli olmas\u0131n\u0131n bir nedeni de budur.<\/p>\n

Williams \u201cMagnezyumun ribozom ve d\u00f6n\u00fc\u015f\u00fcmsel sistemde yapt\u0131\u011f\u0131 farkl\u0131 \u015feylerin say\u0131s\u0131 muazzam\u201d dedi. \u201cD\u00f6n\u00fc\u015f\u00fcmde katalitik aktivitelerin \u00e7ok fazla t\u00fcr\u00fc var ve magnezyum hemen hemen hepsinde de bulunur.\u201d<\/p>\n

Lav p\u00fcsk\u00fcrten D\u00fcnya<\/strong>
\n\u0130lk ya\u015fam evrimle\u015fti\u011finde D\u00fcnya kabu\u011fundaki \u00e7atlaklar h\u00e2l\u00e2 lav p\u00fcsk\u00fcrt\u00fcyordu ve meteor \u00e7arpmalar\u0131 yayg\u0131nd\u0131. Solunabilir oksijen yoktu ve gezegen demir ve manganezle doluyordu.<\/p>\n

Bu durum bask\u0131n iyonlar olarak d\u00f6n\u00fc\u015f\u00fcmsel sistemde kullan\u0131lmalar\u0131n\u0131 \u00e7ekici h\u00e2le getirmi\u015f olabilir. Bug\u00fcn oldu\u011fundan muhtemelen daha az olmas\u0131na ra\u011fmen magnezyum da vard\u0131.<\/p>\n

Ara\u015ft\u0131rmac\u0131lar d\u00f6n\u00fc\u015f\u00fcmsel sistemin, temel yap\u0131lar\u0131 olarak bu maddelerle \u00e7al\u0131\u015facak \u015fekilde ilk defa evrimle\u015fip evrimle\u015fmedi\u011fini \u00f6\u011frenmek istediler. Bu nedenle, William ve Glass\u2019\u0131n laboratuvar\u0131nda ara\u015ft\u0131rma g\u00f6revlisi olan Bray, ya\u015fam\u0131n ilk olarak evrimle\u015fti\u011fi d\u00f6nemdeki \u015fartlar\u0131 yaratmak i\u00e7in magnezyum iyonlar\u0131n\u0131 de\u011fi\u015ftirdi.<\/p>\n

Bray \u201c\u0130\u015fe yarayaca\u011f\u0131na inanmam\u0131z i\u00e7in \u00f6nemli bir nedenimiz yoktu. \u0130\u015fe yarad\u0131\u011f\u0131nda ise hepimiz i\u00e7in b\u00fcy\u00fck bir s\u00fcrpriz oldu\u201d dedi. D\u00f6n\u00fc\u015f\u00fcmsel sistemin, ilk D\u00fcnya ko\u015fullar\u0131nda geli\u015fti\u011fini desteklemi\u015f oldu. Ba\u015fyazarlardan Timothy Lenz, ara\u015ft\u0131rmac\u0131lar Glass ve Williams 9 Kas\u0131m 2018\u2019de Ulusal Bilim Akademisi Bildirileri (Proceedings of the National Academy of Sciences)<\/em> dergisinde sonu\u00e7lar\u0131n\u0131 yay\u0131mlad\u0131lar. Ara\u015ft\u0131rma, NASA Eksobiyoloji Program\u0131 taraf\u0131ndan finanse edildi. Glass, Georgia D\u00fcnya ve Atmosfer Bilimleri Teknoloji Okulu\u2019nda \u00f6\u011fretim \u00fcyesi.<\/p>\n

\u2018Ders kitaplar\u0131 yeniden yaz\u0131labilir\u2019<\/strong>
\n\u015ea\u015f\u0131rt\u0131c\u0131 bir \u015fekilde, atom de\u011fi\u015ftirme ribozomlar\u0131n \u015feklini \u00e7ok az de\u011fi\u015ftirdi.<\/p>\n

Williams \u201cBunun i\u015fe yaramas\u0131 tamamen \u015fa\u015f\u0131rt\u0131c\u0131. \u00c7\u00fcnk\u00fc biyoloji \u00e7ok spesifik \u015feylerin kullan\u0131m\u0131n\u0131 m\u00fcmk\u00fcn k\u0131lar. Bir atomu de\u011fi\u015ftirin ve o, t\u00fcm proteini yok edebilir\u201d dedi. \u201cYap\u0131y\u0131 inceledi\u011fimizde b\u00fct\u00fcn \u00fc\u00e7 maddenin yap\u0131da temelde ayn\u0131 \u015feyi yapt\u0131\u011f\u0131n\u0131 g\u00f6rd\u00fck.\u201d<\/p>\n

D\u00f6n\u00fc\u015f\u00fcmsel sistemin performans\u0131n\u0131 magnezyum yerine demir ile test ettiklerinde, normalde (magnezyumla) oldu\u011fu kadar y\u00fczde 50 ile y\u00fczde 80 aras\u0131nda etkiliydi. Bray \u201cManganez, demirden bile daha iyi \u00e7al\u0131\u015ft\u0131\u201d dedi.<\/p>\n

Bray \u201cT\u00fcm ribozom ara\u015ft\u0131rma alan\u0131 magnezyum i\u00e7erdi\u011finden bence bunlar, ders kitaplar\u0131n\u0131n yeniden yaz\u0131lmas\u0131na neden olabilir\u201d dedi. \u201c\u015eimdi yapt\u0131\u011f\u0131m\u0131z \u015feyle, art\u0131k sadece magnezyumun \u00e7al\u0131\u015fmas\u0131 s\u00f6z konusu de\u011fil.\u201d<\/p>\n

En eski gaz \u00e7ad\u0131r\u0131<\/strong>
\nBray, t\u0131pk\u0131 4 milyar y\u0131l \u00f6nce D\u00fcnya gibi oksijenin bulunmad\u0131\u011f\u0131 yapay atmosferli \u00f6zel bir odan\u0131n i\u00e7inde bulunan magnezyum, demir veya manganezin varl\u0131\u011f\u0131nda ribozom \u00fcretti.<\/p>\n

Magnezyumun de\u011fi\u015ftirilmesinin ribozomdaki atomlar\u0131n \u00e7ok daha \u00f6tesine ge\u00e7ti\u011fini g\u00f6rd\u00fc.<\/p>\n

\u201cRibozomun etraf\u0131n\u0131 sarmak da b\u00fcy\u00fck bir magnezyum atomu bulutudur. Buna atmosfer veya kabuk denir ve onu tamamen sarar. Bu da d\u00e2hil her \u015feyi de\u011fi\u015ftirdim ve t\u00fcm sistem yine de \u00e7al\u0131\u015ft\u0131.\u201d<\/p>\n

\u00c7ok uzun bir s\u00fcre boyunca d\u00f6n\u00fc\u015f\u00fcmsel sistemin magnezyum varl\u0131\u011f\u0131nda evrimle\u015fmesi ona uyum avantaj\u0131 vermi\u015f olabilir. D\u00fcnyadaki oksijen seviyesi artt\u0131\u011f\u0131nda, serbest manganez ve demiri ba\u011flayarak ve biyolojide daha az eri\u015filebilir h\u00e2le getirerek magnezyum, muhtemelen bug\u00fcn d\u00f6n\u00fc\u015f\u00fcmsel sistemdeki binlerce rol\u00fcn\u00fc kolayl\u0131kla \u00fcstlenebilirdi.<\/p>\n

Kaynak:<\/strong> “Stripping the linchpins from the life-making machine reaffirms its seminal evolution”<\/a>, Sciencedaily<\/em>, 12 Kas\u0131m 2018.<\/p>\n","protected":false},"excerpt":{"rendered":"

Cesur bir deney D\u00fcnyadaki ya\u015fam\u0131n temelinde d\u00f6n\u00fc\u015f\u00fcmsel sistemin yerini do\u011fruluyor. Bu deneyin ba\u015far\u0131s\u0131z olma durumu vard\u0131. Ancak bu deney, genlerimiz d\u0131\u015f\u0131nda ya\u015fam\u0131 m\u00fcmk\u00fcn k\u0131lan mekanizmalar olan d\u00f6n\u00fc\u015f\u00fcmsel sistemin ilk evrimini destekleyen \u00e7ok b\u00fcy\u00fck kan\u0131tlar sundu. \u00c7al\u0131\u015fma ribozomu merkezleyen sistemin bug\u00fcn sanki D\u00fcnyadaki ya\u015fam\u0131n temelinin 4 milyar y\u0131l \u00f6ncesiymi\u015f gibi geli\u015fti\u011fini g\u00f6sterdi. Deney \u00f6ylesine c\u00fcretk\u00e2rd\u0131 ki […]<\/p>\n","protected":false},"author":868,"featured_media":31115,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[19,21],"tags":[272,2054,2055,595,2874],"class_list":["post-31114","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bilim-gundemi","category-biyoloji","tag-dna","tag-ribozom","tag-rna","tag-yasam","tag-yasamin-baslangici"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t