Name: central dogma: dna to protein
Uploaded: 2025-05-22T09:05:54.000Z
Duration: 1 min 20 s
Channel: JoVE

K12 Standards

Georgia Standards of Excellence

9-12

Biology

SB2.a

The Central Dogma

تنص العقيدة المركزية للبيولوجيا الجزيئية على أن المعلومات المشفرة في الحمض النووي يتم نقلها إلى الحمض النووي الريبي ، والذي يوجه بعد ذلك تخليق البروتينات بناء على هذه التعليمات.
أولا ، أثناء النسخ ، يتم استخدام الحمض النووي كقالب لتصنيع الحمض النووي الريبي المرسال أو الرنا المرسال.
يمثل mRNA نسخة من خيط الترميز للحمض النووي ، باستثناء أنه يتم استبدال الثايمين باليوراسيل.
بعد ذلك ، يتم ترجمة mRNA إلى سلسلة من الأحماض الأمينية بواسطة الريبوسوم.
هنا ، ترتبط مجموعات من ثلاثة نيوكليوتيدات على mRNA ، والمعروفة أيضا باسم الكودونات ، بالتسلسلات التكميلية أو مضادات الكودونات على جزيئات الحمض النووي الريبي أو الحمض النووي الريبي المنقول.
يرتبط كل tRNA بحمض أميني معين ، اعتمادا على الكودون المحدد.
على سبيل المثال ، يرتبط الكودون CCA بالحمض النووي الريبي المرسال المتصل بالبرولين ، بينما يرتبط AGC بالحمض النووي الريبي المرسال المتصل بالسيرين.
بهذه الطريقة ، يحدد الشفرة الجينية ترتيب الأحماض الأمينية في عديد الببتيد الناتج ، والذي تتم معالجته بشكل أكبر ليصبح بروتينا وظيفيا.

العقيدة المركزية

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تشرح العقيدة المركزية تدفق المعلومات الوراثية من نيوكليوتيدات الحمض النووي إلى تسلسل الأحماض الأمينية للبروتينات.

الحمض النووي الريبوزي (RNA) هو الحلقة المفقودة بين الحمض النووي والبروتينات

في أوائل القرن العشرين، اكتشف العلماء أن الحمض النووي يخزن جميع المعلومات اللازمة للوظائف الخلوية، وأن البروتينات تؤدي معظم هذه الوظائف. ومع ذلك، ظلت آليات تحويل المعلومات الوراثية إلى بروتينات وظيفية مجهولة لسنوات عديدة. في البداية، كان يعتقد أن الجين الواحد يتم تحويله مباشرة إلى البروتين المشفر الخاص به. هناك اكتشافان مهمان في الخلايا حقيقية النواة تحدى هذه النظرية. أولا، لا يحدث إنتاج البروتين في النواة. ثانيا، الحمض النووي غير موجود خارج النواة. أثارت هذه النتائج البحث عن جزيء وسيط يربط الحمض النووي بإنتاج البروتين. تم العثور على هذا الجزيء الوسيط ليكون RNA.

يتم تصنيع الحمض النووي الريبوزي (RNA) في النواة باستخدام الحمض النووي كقالب. يتشابه الحمض النووي الريبوزي (RNA) المُصنع حديثًا في تسلسله مع شريط الحمض النووي (DNA)، باستثناء استبدال الثايمين باليوراسيل. في حقيقيات النوى، تتم معالجة هذا النص الأولي بشكل أكبر، وإزالة مناطق البروتين غير المشفرة، وتغطية النهاية 5'، وإضافة 3' ذيل بولي-A ، لإنشاء mRNA ناضج، والذي يتم بعد ذلك تصديره إلى السيتوبلازم.

الكود الوراثي مكرر

يتم إنشاء البروتينات من 20 حمضًا أمينيًا في حقيقيات النوى. إن الجمع بين أربعة نيوكليوتيدات في مجموعات من ثلاثة يوفر 64 (43) كودونًا محتملاً. وهذا يعني أنه يمكن لأكثر من كودون واحد تشفير حمض أميني فردي. وبالتالي، يُقال إن الشفرة الوراثية مكررة أو متدهورة. في كثير من الأحيان، ولكن ليس دائمًا، تختلف الكودونات التي تحدد نفس الأحماض الأمينية فقط في النوكليوتيدات الثالثة من الثلاثي. على سبيل المثال، تمثل الكودونات GUU، وGUC، وGUA، وGUG جميعها الحمض الأميني فالين. ومع ذلك، AUG هو الكودون الوحيد الذي يمثل ميثيونين الحمض الأميني. الكودون AUG هو أيضًا الكودون الذي يبدأ منه تركيب البروتين، ولذلك يُسمى كودون البداية. التكرار في النظام يقلل من الآثار الضارة للطفرات. على سبيل المثال، التغيير في الموضع الثالث من الكودون قد لا يغير بالضرورة الحمض الأميني المشفر، وبالتالي لا يسبب أي تغيير في وظيفة البروتين.

الشفرة الوراثية عالمية

مع استثناءات قليلة، تستخدم معظم الكائنات بدائية النواة وحقيقية النواة نفس الشفرة الوراثية لتركيب البروتين. وقد مكنت عالمية الشفرة الوراثية من تحقيق تقدم في البحث العلمي في مجال الزراعة والطب. على سبيل المثال، يمكن الآن تصنيع الأنسولين البشري على نطاق واسع في البكتيريا باستخدام تكنولوجيا الحمض النووي المؤتلف. تتضمن تقنية الحمض النووي المؤتلف استخدام مواد وراثية من أنواع مختلفة. يتم ربط الجينات التي تشفر الأنسولين البشري بالحمض النووي البكتيري وإدخالها في الخلية البكتيرية. تقوم الخلية البكتيرية بعد ذلك بالنسخ والترجمة لإنتاج بروتين الأنسولين البشري، والذي يمكنه علاج مرض السكري لدى المرضى.
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تشرح العقيدة المركزية تدفق المعلومات الجينية من نيوكليوتيدات الحمض النووي إلى تسلسل الأحماض الأمينية للبروتينات.
الحمض النووي الريبي هو الحلقة المفقودة بين ...

Education

JoVE Core

Anatomy and Physiology

التشريح وعلم وظائف الأعضاء

Unit 1

الوحدة الأولى

Essential Cellular Processes

العمليات الخلوية الأساسية

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المصطلحات والمفاهيم الأساسية

central dogma: dna to protein

The central dogma explains how genetic information flows in cells from DNA to RNA to protein. It is a core idea in molecular biology and helps show how genes influence cell function.

DNA stores the instructions. During transcription, a cell copies a gene into RNA, which is a related nucleic acid. That RNA message can then be used in translation to build a protein.

Proteins carry out many jobs in cells and help determine traits. The central dogma links the genetic code in DNA to the molecules that do most of the work in living systems.

Central Dogma: DNA to Protein

the central dogma

The central dogma explains how genetic information flows in cells from DNA to RNA to protein. It is a core idea in molecular biology and helps show how genes influence cell function. DNA stores the instructions. During transcription, a cell copies a gene into RNA, which is a related nucleic acid. That RNA message can then be used in translation to build a protein. Proteins carry out many jobs in cells and help determine traits. The central dogma links the genetic code in DNA to the molecules...

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key terms and concepts

Explore the central dogma and how genetic information moves from DNA to RNA to protein. Learn how transcription and translation connect genes to proteins.

Central Dogma: DNA to Protein | JoVE K12

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Central Dogma: DNA to Protein

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