{"id":6746,"date":"2015-12-01T07:20:58","date_gmt":"2015-12-01T00:20:58","guid":{"rendered":"http:\/\/antoansinhhoc.vn\/?p=1024"},"modified":"2015-12-01T07:20:58","modified_gmt":"2015-12-01T00:20:58","slug":"cac-co-che-sua-loi-dna","status":"publish","type":"post","link":"https:\/\/nbca.gov.vn\/cac-co-che-sua-loi-dna\/","title":{"rendered":"C\u00e1c c\u01a1 ch\u1ebf s\u1eeda l\u1ed7i DNA"},"content":{"rendered":"<p>Nh\u01b0 ch\u00fang ta \u0111\u00e3 bi\u1ebft, Tomas Lindahl, Paul Modrich v\u00e0 Aziz Sancar, gi\u1ea3i Nobel H\u00f3a h\u1ecdc 2015, ph\u00e1t hi\u1ec7n nh\u1eefng \u0111i\u1ec1u c\u01a1 b\u1ea3n v\u00e0 c\u00f3 t\u00ednh \u0111\u1ed9t ph\u00e1 trong c\u01a1 ch\u1ebf enzyme s\u1eeda l\u1ed7i DNA.<\/p>\n<div>B\u00e0i vi\u1ebft sau \u0111\u00e2y nh\u1eb1m cung c\u1ea5p th\u00f4ng tin cho nh\u1eefng b\u1ea1n \u0111\u1ecdc mu\u1ed1n hi\u1ec3u th\u00eam c\u00e1c c\u01a1 ch\u1ebf s\u1eeda l\u1ed7i DNA.<\/div>\n<div><\/div>\n<div>DNA (Deoxyribonucleic acid) l\u00e0 ph\u00e2n t\u1eed m\u00e3 h\u00f3a c\u00e1c th\u00f4ng tin di truy\u1ec1n. DNA g\u1ed3m hai d\u00e3y nucleotide k\u00e9o d\u00e0i xo\u1eafn nhau.<\/div>\n<div><\/div>\n<div>M\u1ed7i nucleotide g\u1ed3m m\u1ed9t base (guanine G, adeline A, thymine T, cytosine C) ch\u1ee9a nitrogen + m\u1ed9t \u0111\u01b0\u1eddng + m\u1ed9t nh\u00f3m phosphate. Gi\u1eefa hai d\u00e3y xo\u1eafn nhau l\u00e0 c\u00e1c c\u1eb7p base gh\u00e9p \u0111\u00f4i v\u1edbi nhau.<\/div>\n<div><\/div>\n<div>Tr\u00ean h\u00ecnh 1 ta th\u1ea5y c\u00e1c base \u0111\u01b0\u1ee3c gh\u00e9p \u0111\u00f4i v\u1edbi nhau: C m\u00e0u \u0111\u1ecf gh\u00e9p \u0111\u00f4i v\u1edbi G m\u00e0u xanh l\u00e1 c\u00e2y v\u00e0 A m\u00e0u v\u00e0ng gh\u00e9p \u0111\u00f4i v\u1edbi T m\u00e0u xanh.<\/div>\n<div><\/div>\n<div>Trong t\u1ebf b\u00e0o, DNA \u0111\u01b0\u1ee3c t\u1ed5 ch\u1ee9c th\u00e0nh nh\u1eefng c\u1ea5u tr\u00fac d\u00e0i g\u1ecdi l\u00e0 nhi\u1ec5m s\u1eafc th\u1ec3. Nhi\u1ec5m s\u1eafc th\u1ec3 s\u1ebd \u0111\u01b0\u1ee3c sao b\u1ea3n khi t\u1ebf b\u00e0o ph\u00e2n chia, qu\u00e1 tr\u00ecnh n\u00e0y g\u1ecdi l\u00e0 qu\u00e1 tr\u00ecnh t\u00e1i t\u1ea1o DNA.<\/div>\n<div><\/div>\n<div>Nhi\u1ec5m s\u1eafc th\u1ec3 ch\u1ee9a DNA n\u1eb1m trong nh\u00e2n t\u1ebf b\u00e0o d\u1ec5 nh\u00ecn th\u1ea5y khi t\u1ebf b\u00e0o ph\u00e2n chia; DNA ch\u1ee9a gene (gene l\u00e0 m\u1ed9t ph\u1ea7n c\u1ee7a DNA). C\u00e1c nhi\u1ec5m s\u1eafc th\u1ec3 h\u1ee3p th\u00e0nh genome, t\u1ee9c ch\u1ea5t li\u1ec7u di truy\u1ec1n.<\/div>\n<div><\/div>\n<div>Khi c\u00e1c t\u1ebf b\u00e0o ph\u00e2n chia th\u00ec c\u00e1c ph\u00e2n t\u1eed DNA \u0111\u01b0\u1ee3c sao l\u1ea1i. S\u1ef1 nhi\u1ec5u lo\u1ea1n DNA trong qu\u00e1 tr\u00ecnh t\u00e1i t\u1ea1o c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn nhi\u1ec1u b\u1ec7nh di truy\u1ec1n, hi\u1ec7n t\u01b0\u1ee3ng l\u00e3o h\u00f3a v\u00e0 c\u00e1c b\u1ec7nh ung th\u01b0. C\u00e1c th\u00f4ng tin di truy\u1ec1n \u0111i\u1ec1u khi\u1ec3n h\u00ecnh d\u1ea1ng con ng\u01b0\u1eddi \u0111\u00e3 ch\u1ea3y qua th\u00e2n th\u1ec3 ch\u00fang ta nhi\u1ec1u tr\u0103m ng\u00e0n n\u0103m. Song th\u00f4ng tin \u0111\u00f3 d\u1ec5 b\u1ecb nhi\u1ec5u lo\u1ea1n b\u1edfi nhi\u1ec1u y\u1ebfu t\u1ed1. Tomas Lindahl, Aziz Sancar v\u00e0 Paul Modrich (Nobel H\u00f3a h\u1ecdc 2015) \u0111\u00e3 ph\u00e1t hi\u1ec7n v\u00e0 gi\u1ea3i th\u00edch t\u1ebf b\u00e0o \u0111\u00e3 s\u1eeda ch\u1eefa DNA v\u00e0 b\u1ea3o to\u00e0n th\u00f4ng tin di truy\u1ec1n nh\u01b0 th\u1ebf n\u00e0o. Ba \u00f4ng \u0111\u00e3 ti\u1ebfn \u0111\u1ebfn m\u00f4 t\u1ea3 qu\u00e1 tr\u00ecnh s\u1eeda ch\u1eefa \u0111\u00f3 \u1edf m\u1ee9c ph\u00e2n t\u1eed.<\/div>\n<div><\/div>\n<div>Th\u1ebf n\u00e0o l\u00e0 l\u1ed7i c\u1ee7a DNA<\/div>\n<div><\/div>\n<div>L\u1ed7i c\u1ee7a DNA x\u1ea3y ra khi quy lu\u1eadt gh\u00e9p \u0111\u00f4i c\u00e1c base (C-G) v\u00e0 (A-T) b\u1ecb vi ph\u1ea1m. C\u00f3 ba lo\u1ea1i l\u1ed7i v\u00e0 ba c\u01a1 ch\u1ebf s\u1eeda ch\u1eefa.<\/div>\n<div><\/div>\n<div>1\/ Lo\u1ea1i l\u1ed7i th\u1ee9 nh\u1ea5t<\/div>\n<div>L\u1ed7i n\u00e0y x\u1ea3y ra khi m\u1ed9t trong c\u00e1c base A, T, C, G v\u00ec m\u1ed9t l\u00fd do n\u00e0o \u0111\u00f3 bi\u1ebfn th\u00e0nh m\u1ed9t ch\u1ea5t kh\u00e1c. V\u00ed d\u1ee5:<\/div>\n<div><\/div>\n<div>Cytosine C th\u01b0\u1eddng \u0111\u00e1nh m\u1ea5t nh\u00f3m amino v\u00e0 bi\u1ebfn th\u00e0nh uracine U l\u00e0m sai h\u1ecfng th\u00f4ng tin di truy\u1ec1n. Cytosine C lu\u00f4n gh\u00e9p \u0111\u00f4i v\u1edbi guanine G, c\u00f2n uracine U kh\u00f4ng th\u1ec3 gh\u00e9p \u0111\u00f4i v\u1edbi G. N\u1ebfu l\u1ed7i n\u00e0y c\u1ee9 ti\u1ebfp t\u1ee5c th\u00ec xu\u1ea5t hi\u1ec7n \u0111\u1ed9t bi\u1ebfn (mutation) khi DNA \u0111\u01b0\u1ee3c nh\u00e2n l\u00ean (duplicated).<\/div>\n<div><\/div>\n<div>Mu\u1ed1n s\u1eeda l\u1ed7i n\u00e0y, ta c\u1ea7n c\u1eaft U v\u00e0 thay v\u00e0o \u0111\u00f3 C. \u0110\u00e2y c\u01a1 ch\u1ebf s\u1eeda l\u1ed7i c\u00f3 t\u00ean l\u00e0 c\u1eaft v\u00e0 s\u1eeda base (base excision repair).<\/div>\n<div><\/div>\n<div>T\u1eeb n\u0103m 1974, Lindahl \u0111\u00e3 ph\u00e1t hi\u1ec7n m\u1ed9t enzyme vi khu\u1ea9n c\u00f3 kh\u1ea3 n\u0103ng s\u1eeda ch\u1eefa l\u1ed7i n\u00e0y, \u0111\u00f3 l\u00e0 enzyme glycosylase. N\u0103m 1996, \u00f4ng th\u1ef1c hi\u1ec7n vi\u1ec7c s\u1eeda ch\u1eefa n\u00e0y in vitro.<\/div>\n<div><\/div>\n<div>Lindahl ch\u1ee9ng minh r\u1eb1ng DNA l\u00e0 nh\u1eefng ph\u00e2n t\u1eed kh\u00f4ng b\u1ec1n v\u1eefng n\u1ed9i t\u1ea1i. DNA c\u00f3 th\u1ec3 ph\u00e2n r\u00e3 ngay trong nh\u1eefng \u0111i\u1ec1u ki\u1ec7n sinh h\u1ecdc. Nh\u1edd \u00fd t\u01b0\u1edfng \u0111\u00f3 m\u00e0 Lindahl c\u00f3 th\u1ec3 \u0111\u1ecbnh d\u1ea1ng \u0111\u01b0\u1ee3c glycosylase v\u00e0 m\u00f4 t\u1ea3 t\u00e1c \u0111\u1ed9ng c\u1ee7a ch\u00fang trong c\u01a1 ch\u1ebf c\u1eaft v\u00e0 s\u1eeda base.<\/div>\n<div><\/div>\n<div>2\/ Lo\u1ea1i l\u1ed7i th\u1ee9 hai<\/div>\n<div>Lo\u1ea1i l\u1ed7i n\u00e0y x\u1ea3y ra khi trong m\u1ed9t d\u00e3y nucleotide (DNA c\u00f3 hai d\u00e3y nucleotide xo\u1eafn v\u00e0o nhau) c\u00f3 m\u1ed9t base l\u1ea1i gh\u00e9p n\u1ed1i v\u1edbi ch\u00ednh n\u00f3. V\u00ed d\u1ee5 T l\u1ea1i r\u1eddi A m\u00e0 t\u1ef1 gh\u00e9p n\u1ed1i v\u1edbi m\u00ecnh (d\u01b0\u1edbi t\u00e1c \u0111\u1ed9ng c\u1ee7a b\u1ee9c x\u1ea1 UV). \u0110i\u1ec1u n\u00e0y l\u00e0m nhi\u1ec5u lo\u1ea1n th\u00f4ng tin di truy\u1ec1n. C\u1ea7n c\u1eaft b\u1ecf \u0111o\u1ea1n nucleotide ch\u1ee9a sai h\u1ecfng \u0111\u00f3.<\/div>\n<div><\/div>\n<div>C\u01a1 ch\u1ebf s\u1eeda ch\u1eefa n\u00e0y c\u00f3 t\u00ean l\u00e0 c\u1eaft v\u00e0 s\u1eeda nucleotide (nucleotide excision repair).<\/div>\n<div><\/div>\n<div>Sancar \u0111\u00e3 nghi\u00ean c\u1ee9u v\u1ea5n \u0111\u1ec1 n\u00e0y. Ngo\u00e0i ra \u00f4ng c\u00f2n nghi\u00ean c\u1ee9u c\u01a1 ch\u1ebf photoreactivation (m\u1ed9t d\u1ea1ng s\u1eeda ch\u1eefa t\u1ebf b\u00e0o \u0111\u1ea7u ti\u00ean). N\u0103m 1973, Sancar b\u1eaft \u0111\u1ea7u nghi\u00ean c\u1ee9u m\u00f4n h\u00f3a sinh. \u00d4ng ph\u00e1t hi\u1ec7n khi m\u1ed9t vi khu\u1ea9n b\u1ecb ph\u01a1i nhi\u1ec5m b\u1ee9c x\u1ea1 UV th\u00ec sau \u0111\u00f3 s\u1ebd \u0111\u01b0\u1ee3c ph\u1ee5c h\u1ed3i do \u00e1nh s\u00e1ng xanh. Sancar mu\u1ed1n t\u00ecm hi\u1ec3u \u0111i\u1ec1u n\u00e0y t\u1eeb quan \u0111i\u1ec3m h\u00f3a h\u1ecdc.<\/div>\n<div><\/div>\n<div>Sancar nghi\u00ean c\u1ee9u b\u1eb1ng c\u00e1ch n\u00e0o t\u1ebf b\u00e0o s\u1eeda ch\u1eefa c\u00e1c h\u01b0 h\u1ecfng do UV.<\/div>\n<div><\/div>\n<div>\u00d4ng v\u00e0 c\u1ed9ng s\u1ef1 t\u00ecm ra hai c\u00e1ch ph\u1ee5c h\u1ed3i h\u01b0 h\u1ecfng: 1\/ nh\u1edd enzyme ph\u1ee5 thu\u1ed9c \u00e1nh s\u00e1ng (photolyase \u00e0 photoreactivation), 2\/ enzyme t\u1ed1i kh\u00f4ng ph\u1ee5 thu\u1ed9c \u00e1nh s\u00e1ng. C\u00e1c enzyme n\u00e0y c\u00f3 kh\u1ea3 n\u0103ng nh\u1eadn bi\u1ebft c\u00e1c h\u01b0 h\u1ecfng do UV v\u00e0 sau \u0111\u00f3 th\u1ef1c hi\u1ec7n hai v\u1ebft r\u1ea1ch \u0111\u1ec3 c\u1eaft \u0111o\u1ea1n (12 \u0111\u1ebfn 13 nucleotide) c\u00f3 ch\u1ee9a h\u01b0 h\u1ecfng.<\/div>\n<div><\/div>\n<div>3\/ Lo\u1ea1i l\u1ed7i th\u1ee9 ba<\/div>\n<div>Trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y m\u1edbi tr\u00f4ng d\u01b0\u1eddng nh\u01b0 kh\u00f4ng c\u00f3 v\u1ea5n \u0111\u1ec1 g\u00ec \u0111\u1ed1i v\u1edbi DNA nh\u01b0ng nh\u00ecn k\u1ef9 ta th\u1ea5y xu\u1ea5t hi\u1ec7n nh\u1eefng ch\u1ed7 gh\u00e9p \u0111\u00f4i kh\u00f4ng \u0111\u00fang.<\/div>\n<div><\/div>\n<div>V\u00ed d\u1ee5 tr\u00ean h\u00ecnh 4 ta th\u1ea5y c\u00f3 m\u1ed9t ch\u1ed7 T m\u00e0u xanh l\u1ea1i gh\u00e9p \u0111\u00f4i v\u1edbi C m\u00e0u \u0111\u1ecf (\u0111\u00e1ng l\u1ebd T ph\u1ea3i \u0111\u01b0\u1ee3c gh\u00e9p \u0111\u00f4i v\u1edbi A), v\u1eady l\u00e0 c\u00f3 vi ph\u1ea1m quy lu\u1eadt gh\u00e9p \u0111\u00f4i c\u1ee7a DNA. C\u1ea7n s\u1eeda ch\u1eefa l\u1ed7i n\u00e0y b\u1eb1ng c\u00e1ch thay \u0111o\u1ea1n ch\u1ee9a l\u1ed7i b\u1eb1ng m\u1ed9t \u0111o\u1ea1n sao cho c\u00e1c c\u1eb7p base \u0111\u01b0\u1ee3c gh\u00e9p \u0111\u00f4i \u0111\u00fang quy lu\u1eadt. C\u01a1 ch\u1ebf s\u1eeda ch\u1eefa n\u00e0y c\u00f3 t\u00ean l\u00e0 s\u1eeda ch\u1eefa gh\u00e9p \u0111\u00f4i nh\u1ea7m (mismatch repair).<\/div>\n<div><\/div>\n<div>\u0110\u00e2y l\u00e0 ph\u1ea1m vi nghi\u00ean c\u1ee9u c\u1ee7a Modrich. Tr\u01b0\u1edbc ti\u00ean \u00f4ng d\u00f9ng enzyme Dam methylase g\u1eafn methyl v\u00e0o m\u1ed9t \u0111o\u1ea1n c\u1ee7a DNA. \u0110o\u1ea1n n\u00e0y s\u1ebd d\u00f9ng l\u00e0m b\u1ea3n g\u1ed1c khi c\u1ea7n sao ch\u00e9p. Trong sao ch\u00e9p c\u00f3 th\u1ec3 x\u1ea3y ra sai h\u1ecfng v\u00ec gh\u00e9p \u0111\u00f4i nh\u1ea7m.<\/div>\n<div><\/div>\n<div>C\u00f3 hai enzyme l\u00e0 MutS, MutL nh\u1eadn d\u1ea1ng \u0111\u01b0\u1ee3c sai h\u1ecfng gh\u00e9p \u0111\u00f4i. C\u00f2n c\u00f3 enzyme MutH nh\u1eadn d\u1ea1ng \u0111\u01b0\u1ee3c \u0111o\u1ea1n DNA n\u00e0o kh\u00f4ng ch\u1ee9a methyl v\u00e0 vi\u1ec7c c\u1eaft b\u1ecf \u0111o\u1ea1n \u0111\u00f3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n. Ti\u1ebfp theo DNA polymerase s\u1ebd t\u00ecm c\u00e1ch l\u00e0m l\u1ea5p \u0111\u1ea7y \u0111o\u1ea1n b\u1ecb c\u1eaft v\u00e0 ti\u1ebfp \u0111\u1ebfn DNA ligase s\u1ebd h\u00e0n l\u1ea1i.<\/div>\n<div><\/div>\n<div>K\u1ebft lu\u1eadn<\/div>\n<div><\/div>\n<div>Nh\u1eefng sai h\u1ecfng DNA g\u00e2y n\u00ean b\u1edfi m\u1eb7t tr\u1eddi, h\u00fat thu\u1ed1c, c\u00e1c lo\u1ea1i ch\u1ea5t g\u00e2y ung th\u01b0,&#8230; v\u00e0 nhi\u1ec1u nguy\u00ean nh\u00e2n kh\u00f4ng ng\u1edd kh\u00e1c. B\u1ed9 gene c\u1ee7a ch\u00fang ta c\u00f3 th\u1ec3 b\u1ecb s\u1ee5p \u0111\u1ed5 n\u1ebfu kh\u00f4ng c\u00f3 c\u00e1c c\u01a1 ch\u1ebf s\u1eeda ch\u1eefa sai h\u1ecfng. N\u1ebfu m\u1ed9t trong ba c\u01a1 ch\u1ebf n\u00f3i tr\u00ean kh\u00f4ng l\u00e0m vi\u1ec7c th\u00f4ng tin di truy\u1ec1n thay \u0111\u1ed5i v\u00e0 ph\u00e1t sinh b\u1ec7nh v\u00e0 l\u00e0m t\u0103ng nguy c\u01a1 b\u1ecb ung th\u01b0.<\/div>\n<div><\/div>\n<div>C\u00f3 th\u1ec3 n\u00f3i th\u00e0nh t\u00edch n\u00e0y c\u1ee7a ng\u00e0nh h\u00f3a sinh qu\u1ea3 l\u00e0 th\u00e0nh t\u00edch c\u1ee7a m\u1ed9t th\u1ea7n y th\u00f4ng tu\u1ec7. Nh\u00e2n lo\u1ea1i c\u00f3 l\u1ebd ph\u1ea3i m\u00e3i nh\u1edb \u01a1n nh\u1eefng nh\u00e0 khoa h\u1ecdc Tomas Lindahl, Paul Modrich v\u00e0 Aziz Sancar v\u00ec \u0111\u00e3 \u0111\u1ed9t ph\u00e1 l\u0129nh v\u1ef1c s\u1eeda ch\u1eefa c\u00e1c l\u1ed7i c\u1ee7a DNA, m\u1edf \u0111\u01b0\u1eddng nghi\u00ean c\u1ee9u nh\u1eefng ph\u01b0\u01a1ng ph\u00e1p ch\u1eefa nh\u1eefng b\u1ec7nh nan y.<\/div>\n<div><\/div>\n","protected":false},"excerpt":{"rendered":"<p>Nh\u01b0 ch\u00fang ta \u0111\u00e3 bi\u1ebft, Tomas Lindahl, Paul Modrich v\u00e0 Aziz Sancar, gi\u1ea3i Nobel H\u00f3a h\u1ecdc 2015, ph\u00e1t hi\u1ec7n nh\u1eefng \u0111i\u1ec1u c\u01a1 b\u1ea3n v\u00e0 c\u00f3 t\u00ednh \u0111\u1ed9t ph\u00e1 trong c\u01a1 ch\u1ebf enzyme s\u1eeda l\u1ed7i DNA. B\u00e0i vi\u1ebft sau \u0111\u00e2y nh\u1eb1m cung c\u1ea5p th\u00f4ng tin cho nh\u1eefng b\u1ea1n \u0111\u1ecdc mu\u1ed1n hi\u1ec3u th\u00eam c\u00e1c c\u01a1 ch\u1ebf s\u1eeda [&#8230;]\n","protected":false},"author":1,"featured_media":6294,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[87],"tags":[],"acf":[],"_links":{"self":[{"href":"https:\/\/nbca.gov.vn\/wp-json\/wp\/v2\/posts\/6746"}],"collection":[{"href":"https:\/\/nbca.gov.vn\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nbca.gov.vn\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nbca.gov.vn\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nbca.gov.vn\/wp-json\/wp\/v2\/comments?post=6746"}],"version-history":[{"count":0,"href":"https:\/\/nbca.gov.vn\/wp-json\/wp\/v2\/posts\/6746\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nbca.gov.vn\/wp-json\/wp\/v2\/media\/6294"}],"wp:attachment":[{"href":"https:\/\/nbca.gov.vn\/wp-json\/wp\/v2\/media?parent=6746"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nbca.gov.vn\/wp-json\/wp\/v2\/categories?post=6746"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nbca.gov.vn\/wp-json\/wp\/v2\/tags?post=6746"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}