Name: how cells control gene expression
Uploaded: 2023-06-23T15:38:45.000Z
Duration: 1 min 23 s
Channel: JoVE

K12 Standards

Georgia Standards of Excellence

9-12

Biology

SB2.a

regulation-of-expression-at-multiple-steps

Regulation of Expression at Multiple Steps

تنظم الخلايا بدقة التعبير الجيني أثناء النسخ ومعالجة الرنا المرسال والترجمة.
يمكن التوسط في تنظيم النسخ بواسطة البروتينات التي تربط التسلسلات التنظيمية على الحمض النووي لتثبيط أو بدء نسخ جين معين.
يتم تعديل السلائف mRNAs الناتجة عن النسخ عن طريق إضافة غطاء 5 أولي وذيل بولي A مكون من 3 أوب. تخضع mRNAs للتضفير ، حيث تتم إزالة المناطق غير المشفرة ويتم ربط المناطق المشفرة لإنتاج mRNAs ناضجة. تنظم أنماط التضفير التفاضلي والبروتينات المرتبطة بالحمض النووي الريبي التعبير الجيني في هذه المرحلة.
يتم نقل فقط تلك الرنا المرسال التي ترتبط بالبروتينات المرتبطة بالحمض النووي الريبي لتكوين جزيئات البروتين النووي الريبي بشكل انتقائي إلى السيتوبلازم للترجمة.
يمكن أن يكون التنظيم الانتقالي محددا ، حيث يتم التحكم في تثبيط ترجمة مجموعة فرعية معينة من mRNA من خلال التفاعلات مع البروتينات ، والحمض النووي الريبي الصغير ، والتداخل القصير أو siRNAs.
في المقابل ، ينشط التنظيم الانتقالي العام أو يثبط بروتينات آلية الترجمة للتأثير على جميع النصوص.

تنظيم التعبير الجيني

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يتم تنظيم التعبير الجيني في الخلايا عبر مراحل مختلفة: (أ) النسخ، (ب) معالجة الحمض النووي الريبي (RNA)، (ج) توجيه الرنا، و(د) الترجمة.
تم تنظيم عملية النسخ بواسطة البروتينات التنظيمية مثل عوامل النسخ الجيني، العوامل المنشطة، أو العوامل المثبطة، حيث تتحكم هذه العوامل في تعبير الجين عن طريق تحفيز أو تثبيط عملية النسخ. بمجرد إنتاج جزيء الحمض النووي الريبي الأولي أو ما قبل الرنا المرسال (pre-mRNA)، فإنه يخضع لتعديلات ما بعد النسخ، بما في ذلك إضافة غطاء عند النهاية 5'، وقطع الوحدات غير المشفرة (تقنيع الرنا)، وإضافة ذيل بولي-أ، مما يؤدي إلى تكوين جزيء رنا ناضج.

يتم منع تحلل جزيئات الرنا الناضجة من خلال ارتباطها ببروتينات ربط الرنا (RBPs)، مما يؤدي إلى تكوين جسيمات ريبونوكليوتيدية تسهّل عملية نقلها إلى السيتوبلازم حيث تُترجم إلى بروتينات. أما جزيئات الرنا التي لا ترتبط ببروتينات RBP، فإنها لا تنتقل من النواة وبالتالي لا يتم ترجمتها إلى بروتينات. من ناحية أخرى، إذا ارتبطت جزيئات الرنا الناضجة بجزيئات ميكرو-رنا متممة، فإنها تتعرض للتحلل، مما يعيق عملية تخليق البروتين.
ومع ذلك، بمجرد ترجمة الرنا إلى بروتين، يخضع البروتين الناتج حديثًا لتعديلات تؤثر على نشاطه. على سبيل المثال، قد تؤدي إضافة مجموعات وظيفية مثل الميثيل أو الفوسفات أو الأسيتيل إلى تنشيط أو تثبيط البروتين. وعلى العكس، فإن ارتباط البروتين بجزيئات اليوبيكويتين يُعد إشارة لتحليله. وبالتالي، فإن نظام اليوبيكويتين يساهم في تنظيم استقرار البروتين ووظيفته.

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يتم تنظيم التعبير الجيني في الخلايا في مراحل مختلفة: (أنا) النسخ ، (ثانيا) معالجة الحمض النووي الريبي ، (ثالثا) توطين الحمض النووي الريبي ، و (رابعا) الترجمة. ...

Education

JoVE Core

Anatomy and Physiology

التشريح وعلم وظائف الأعضاء

Unit 1

الوحدة الأولى

Essential Cellular Processes

العمليات الخلوية الأساسية

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

how cells control gene expression

Cells control gene expression at several stages, from making RNA to building protein. These checkpoints include transcription, RNA processing, RNA localization, and translation. Together, they help decide when a gene is used and whether a protein is made.

Transcription is controlled by regulatory proteins. Transcription factors, activators, and repressors can start or slow the transcription of genes. After transcription, the cell makes a precursor RNA, also called pre-mRNA.

Pre-mRNA must be processed before it can be used. It receives a 5' cap, its introns are removed by splicing, and a 3' poly-A tail is added. These changes produce mature mRNA.

Only some mature mRNAs leave the nucleus. When mRNA binds RNA-binding proteins, or RBPs, it forms a ribonucleoprotein particle that helps protect it from degradation and allows selective transport out of the nucleus for protein synthesis. mRNAs that do not bind RBPs stay in the nucleus and are not translated into protein.

Gene expression can also be turned down after mRNA is made. If a mature mRNA binds a complementary microRNA, the mRNA is degraded and protein synthesis is blocked. After translation, the new protein can still be changed by modification.

Protein modification can change activity and stability. Adding methyl, phosphate, or acetyl groups may activate or inactivate a protein. Adding multiple ubiquitin proteins marks a substrate protein for degradation, which helps control protein stability and function.

How Cells Control Gene Expression

the central dogma

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...

replication in eukaryotes

Eukaryotic DNA Copying at the Replication Fork

Eukaryotic DNA copying happens at replication forks, where the two DNA strands separate and new strands are built. This process lets a cell make an exact copy of its genetic material before it divides. The transcript explains that eukaryotic replication follows the same basic steps seen in other DNA replication systems, but it takes place in cells with a nucleus. The replication machinery works on each separated strand as a template, so the new DNA matches the original sequence. This topic is...

types of rna

RNA Types in Gene Expression

RNA types play different roles in gene expression. RNA, or ribonucleic acid, helps carry and use genetic information in cells. The main types discussed here are messenger RNA, ribosomal RNA, and transfer RNA. Messenger RNA, or mRNA, carries the genetic code from DNA to the ribosome. The ribosome is the site where proteins are made. Ribosomal RNA, or rRNA, is a key part of the ribosome itself. Transfer RNA, or tRNA, brings the correct amino acids to the ribosome during protein building. These...

transcription

Transcription and RNA Synthesis

Transcription is the process of making RNA from a DNA template. It is a key step in gene expression, because cells use the DNA sequence to build an RNA copy that can carry the message forward. During transcription, RNA polymerase binds to DNA and reads one strand as the template. The enzyme links RNA nucleotides together in the correct order to form a growing RNA molecule. This copying step does not make DNA; it produces RNA. The transcript focuses on the central idea of transcription as DNA...

translation

Translation: mRNA to Protein

Translation is the step in gene expression where ribosomes use messenger RNA, or mRNA, to build a protein. The mRNA sequence carries the instructions copied from DNA. During translation, those instructions are read in order so the cell can make a specific chain of amino acids. This process depends on the ribosome and transfer RNA, or tRNA. The ribosome reads the mRNA, and tRNA brings the matching amino acids. As the chain grows, the amino acids are linked together to form a polypeptide, which...

regulation of expression at multiple steps

Cells control gene expression at several stages, from making RNA to building protein. These checkpoints include transcription, RNA processing, RNA localization, and translation. Together, they help decide when a gene is used and whether a protein is made. Transcription is controlled by regulatory proteins. Transcription factors, activators, and repressors can start or slow the transcription of genes. After transcription, the cell makes a precursor RNA, also called pre-mRNA. Pre-mRNA must be...

what is the cell cycle?

Cell Cycle Stages in Cell Growth

The cell cycle is the process that controls cell growth and division. It explains how one cell makes two new cells. This process helps cells grow and reproduce.

interphase

Interphase and Cell Growth

Interphase is the part of the cell cycle when a cell grows and prepares to divide. It is a major stage of the cell cycle, and it comes before cell division begins. During interphase, the cell carries out its normal functions. It also copies its DNA so each new cell can receive a full set of genetic material. The cell may also build up the materials it needs for division. Interphase is not a single step. It includes phases such as G1, S, and G2, which help the cell grow, copy DNA, and get...

mitosis and cytokinesis

Cell Division: Mitosis and Cytokinesis

Cell division depends on mitosis and cytokinesis. Mitosis is the stage when the cell’s nucleus divides and the copied chromosomes are separated into two sets. Cytokinesis is the step that follows and splits the cell into two daughter cells. These two processes work together to make sure each new cell receives genetic material and its own cytoplasm. Mitosis keeps the chromosome sets organized, while cytokinesis finishes the division of the whole cell. Together, they create two separate cells...

the cell cycle control system

Cell Cycle Checkpoints and Cyclin Control

The cell cycle is controlled by checkpoints that help a cell move from one phase to the next and begin mitosis. This control system uses internal regulatory molecules and outside signals to send stop or advance instructions. It makes sure each step is finished before the cell moves forward. Cyclins and cyclin-dependent kinases, or Cdks, are the main regulators of the cell cycle. They act during the G1, G2, and M phases. These regulators work at specific checkpoints to keep cell division...

molecular factors affecting cell division

molecular-factors-affecting-cell-division

Cell Cycle Regulators That Control Division

Cell division is controlled by outside signals and by internal cell cycle regulators. Nearby cell death can encourage division, and human growth hormone (hGH) can also promote it. In contrast, too little hGH or crowded cells can slow or stop division. Inside the cell, regulator molecules help each stage finish correctly before the next stage begins. Some regulators act directly on the cycle, while others affect the activity or production of other regulatory proteins. These molecules can either...

what is meiosis?

Meiosis and the Formation of Gametes

Meiosis is the cell division process that forms gametes, or sex cells. It reduces the chromosome number so offspring can inherit the correct amount of genetic material. This process includes two successive divisions. First, one cell divides, and then the resulting cells divide again. These steps separate the genetic material in a controlled way. Meiosis helps explain how sexual reproduction passes traits from one generation to the next. It is a key topic in high school biology because it...

overview of cell signaling

Cell Signaling Pathways and Responses

Cell signaling pathways and responses help cells communicate and react to changes. Cells send signals to one another, and those signals can trigger a specific response in the target cell. A signal usually begins when a signaling molecule reaches a cell with the right receptor, which is a protein that receives the message. The receptor helps the cell recognize the signal and start the communication process. Inside the cell, the message can move through a signaling pathway. This pathway passes...

types of signaling molecules

Chemical Messengers in Cell Signaling

Chemical messengers help cells communicate during signaling. These signaling molecules carry information from one cell to another and guide how cells respond. Some signaling molecules are gases, while others are proteins or peptides. Small lipids can also act as signals. In addition, cells may use steroids, amino acids, and even ions as signaling molecules. Each type of signaling molecule has different properties and works in a different way. Together, these molecules let cells send specific...

g protein-coupled receptors

G Protein-coupled Receptor Signaling

G protein-coupled receptors are a major class of cell-surface receptors. They help cells detect signals outside the cell and pass that information inward. These receptors are important in many kinds of cell communication. When a signal binds to a G protein-coupled receptor, the receptor changes shape. That change activates a G protein inside the cell. The activated G protein can then start a signaling pathway. This signaling system includes the receptor, the G protein, and the downstream...

cellular differentiation

From Stem Cell to Specialized Cells

Cellular differentiation turns unspecialized cells into specialized cells with specific jobs. This process helps a complex organism, such as a human, develop from a single fertilized egg into a body with many cell types. Nerve cells, muscle cells, and epithelial cells are examples of the final cell types that appear during development. A zygote is the first cell after fertilization. It is a totipotent stem cell, which means it has very high differentiation potential and can form all cell types...

key terms and concepts

Learn how cells control gene expression through transcription, RNA processing, RNA transport, translation, and protein modification, including ubiquitination.

How Cells Control Gene Expression | JoVE K12

anatomy and physiology

JoVE Core Anatomy and Physiology showcases the anatomical and physiological details of the human body in comprehensive, clear, and engaging video animations. This collection of lessons focuses on the structures, components, functions, and requirements of the human body. It is complemented by scientist-in-action videos that demonstrate the application of this knowledge in real-world medical and research settings.

The Central Dogma

Replication in Eukaryotes

Types of RNA

Transcription

Translation

The gene expression in cells is regulated at different stages: (i) transcription, (ii) RNA processing, (iii) RNA localization, and (iv) translation. ...

Construct an explanation of how the structures of DNA and RNA lead to the expression of information within the cell via the processes of replication, transcription, and translation

What is Meiosis?

Meiosis I

Meiosis is the division of a diploid cell into haploid cells forming sperm and eggs in animals through differentiation. Meiosis I is the first stage of ...

Meiosis II

Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for ...

Crossing over

Nondisjunction

Genome Copying Errors

DNA replication is a well-evolved process that copies millions of base pairs with high fidelity during each cell division. Occasionally a wrong base or a ...

Overview of DNA Repair

In order to be passed through generations, genomic DNA must be undamaged and error-free. However, every day, DNA in a cell undergoes several thousand to a ...

Base Excision Repair

One of the common DNA damages is the chemical alteration of single bases by alkylation, oxidation, or deamination. The altered bases cause mispairing and ...

RNA Editing

RNA editing is a post-transcriptional modification where a precursor mRNA (pre-mRNA) nucleotide sequence is changed by base insertion, deletion, or ...

Mutations

Teratogenicity

The ability of a drug to produce structural deformations and functional abnormalities in the developing embryo or the fetus is called teratogenicity, and ...

Mechanisms of Retrovirus-induced Cancers

Retroviruses are RNA viruses that have been shown to cause cancers in diverse species, including chickens, mice, cats, and monkeys. The RNA genomes of ...

Construct an argument based on evidence to support the claim that inheritable genetic variations may result from:New genetic combinations through meiosis (crossing over, nondisjunction), Non-lethal errors occurring during replication (insertions, deletions, substitutions), Heritable mutations caused by environmental factors (radiation, chemicals, and viruses)

SB2.b

Transgenic Plants

Recombinant DNA technology called transgenesis is often used to add a foreign gene or remove a detrimental gene from an organism. Such genetically ...

Transgenic Organisms

Overview

Transgenic organisms are genetically engineered to carry transgenes&#x2014;genes from a different species&#x2014;as part of their genome. The ...

Testing For Genetically Modified Foods

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Genetic modification of foods has been a controversial issue due to debated ...

Genetic Engineering of Model Organisms

Transgenesis, or the use of genetic engineering to alter gene expression, is widely used in the field of developmental biology. Scientists use a number of ...

Ask questions to gather and communicate information about the use and ethical considerations of biotechnology in forensics, medicine, and agriculture

SB2.c

Obtain, evaluate, and communicate information to analyze how genetic information is expressed in cells

How Cells Control Gene Expression

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