Name: cell signaling pathways and responses
Uploaded: 2023-06-23T15:38:45.000Z
Duration: 1 min 23 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

High School

Life Science

Structure and Function

HS-LS1-2.

Overview of Cell Signaling

תאים משתמשים במגוון מנגנוני איתות כדי לתאם תהליכים תאיים ולתקשר עם תאים אחרים. מסלול איתות מופעל כאשר מולקולת איתות הנקראת ליגנד נקשרת לקולטן המטרה שלה.
איתות פרקריני מתרחש כאשר ליגנד מופרש מכוון לתאים השכנים. ואילו, איתות אוטוקריני מתרחש כאשר הליגנד מכוון לאותו תא ששחרר אותו.
במסלול איתות סמיך או תלוי מגע, ליגנד נשאר קשור לפני השטח של התא ומקיים אינטראקציה ישירה עם הקולטנים בתאים סמוכים. ליגנדות קטנות ומסיסות עשויות גם לזרום ישירות בין התאים דרך צמתי רווחים בקרום הפלזמה.
אורגניזמים רב-תאיים מתאמים את ההתנהגות התאית למרחקים ארוכים. באיתות אנדוקריני, הורמונים נוסעים לחלקי גוף שונים דרך זרם הדם.
איתות סינפטי בין תאי עצב הוא צורה מיוחדת של איתות לטווח ארוך. בצומת הסינפטי, מסוף האקסון של תא עצב מפריש ליגנדים הנקראים מוליכים עצביים כדי לתקשר עם תאי המטרה.
בנוסף, חישת מניין מתבצעת על ידי כמה קהילות חיידקים כדי להגיב יחד על ידי חישה ריכוז קריטי של ליגנדות איתות.

סקירה כללית של איתות סלולרי

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למרות הממברנה המגינה שמפרידה תא מהסביבה, תאים זקוקים ליכולת לזהות ולהגיב לשינויים סביבתיים. בנוסף, תאים לעיתים קרובות זקוקים לתקשר אחד עם השני. אורגניזמים חד-תאיים ורב-תאיים משתמשים במגוון מנגנוני איתות תאיים כדי לתקשר עם הסביבה.

תאים מגיבים לסוגים רבים של מידע, לרוב באמצעות חלבוני קולטן הממוקמים על הממברנה. לדוגמה, תאי עור מגיבים ומעבירים מידע על מגע, בעוד פוטורצפטורים ברשתית יכולים לזהות אור. רוב התאים, לעומת זאת, התפתחו כדי להגיב לאותות כימיים, כולל הורמונים, נוירוטרנסמיטורים וסוגים רבים אחרים של מולקולות איתות. תאים יכולים אפילו לתאם תגובות שונות המופעולת על ידי אותה מולקולת איתות.

בדרך כלל, איתות תאים כרוך בשלושה שלבים: (1) קליטה, (2) התמרה ו-(3) תגובה. ברוב קליטת האותות, מולקולה שאינה חדירה לממברנה, או ליגנד, גורמת לשינוי בקולטן הממברנה; עם זאת, חלק ממולקולות האיתות, כגון הורמונים, יכולות לחצות את הממברנה כדי להגיע לקולטנים הפנימיים שלהן. הקולטן של הממברנה יכול לשלוח את האות הזה לשליחים תוך-תאיים, ולהעביר את המסר לתגובה תאית. תגובה תוך תאית זו עשויה לכלול שינויים בשעתוק, תרגום, הפעלת חלבונים, ותגובות אחרות.

אורגניזמים חד-תאיים כגון חיידקים יכולים להשתמש בסוג של איתות תאי הנקרא חישת מניין כדי לזהות את הריכוז שלהם במושבה וליצור תגובות מתואמות. תאים אוקריוטיים יכולים לשחרר ליגנדים המכוונים לאותו תא שיצר את האיתות (איתות אוטוקריני) או תאים שכנים (איתות פארקריני). אותות יכולים אפילו להישלח למרחקים ארוכים, כמו במקרה של הורמונים מסוימים, וליצור תגובות בתאים מרוחקים, הנקראות איתות אנדוקריני. איתות תלוי-מגע מתאר מסלולים פיזיים שנוצרו בין תאים שכנים שדרכם יכולים לעבור אותות ציטופלזמה במהירות. תאי מערכת העצבים יכולים ליצור תגובות מהירות באמצעות התמחות של איתות תאי הנקראת איתות סינפטי.

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למרות קרום ההגנה המפריד בין התא לסביבה, תאים זקוקים ליכולת לזהות שינויים סביבתיים ולהגיב להם. ...

Education

JoVE Core

Anatomy and Physiology

אנטומיה ופיזיולוגיה

Unit 1

יחידה 1

Essential Cellular Processes

תהליכים תאיים חיוניים

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

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 the signal along until the cell produces a response. That response may change how the cell behaves or how it functions.

Cell signaling is an important part of cell biology because it lets cells coordinate activities and respond to their environment. Understanding these pathways helps explain how cells communicate and why receptor-based signaling matters.

Cell Signaling Pathways and Responses

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

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types of rna

RNA Types in Gene Expression

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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

regulation-of-expression-at-multiple-steps

How Cells Control Gene Expression

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Cell Cycle Stages in Cell Growth

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interphase

Interphase and Cell Growth

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mitosis and cytokinesis

Cell Division: Mitosis and Cytokinesis

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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 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 use signaling pathways, receptors, and responses to communicate and react to signals in this concise high school science overview.

Cell Signaling Pathways and Responses | JoVE K12

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HS-LS1-1.

Cell Signaling Pathways and Responses

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