Name: nuclear dna and cell control
Uploaded: 2019-03-11T09:21:03.000Z
Duration: 1 min 32 s
Channel: JoVE

K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Biology

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms- Structures and Processes

LS.Bio.1.3

The Nucleus

הגרעין, תכונה בולטת של תאים איקריוטים, הוא אברון עטוף בקרום המאחסן את המידע הגנטי, הדנ"א, אשר מאורגן באופן משתנה בהתאם לשלב במחזור החיים של התא. לדוגמה, תצמידי דנ"א וחלבונים, המכונים כרומטין, צפים בנוקלאופלזמה, חומר דמוי ג'ל, ומתרכזים בעיקר באזור הנקרא גרעינון. כאשר התא אינו מתפצל, סיבי כרומטין מסודרים באופן רופף ומזכירים חוטים סבוכים, מה שמאפשר גישה קלה יותר אל הדנ"א במהלך התעתוק.לעומת זאת, כאשר התא עומד להתפצל, סיבי כרומטין נדחסים לכרומוזומים. הגרעינון הוא גם המקום בו נוצרות תת-יחידות של ריבוזומים, מבנים הכרחיים בתהליך התרגום. מסביב לגרעין ישנה מעטפת גרעין המורכבת משני קרומים בעלת נקבוביות מרופדות בחלבונים כדי לשלוט על זרימת היונים, מולקולות, חלקי ריבוזומים, ורנ"א שליח בין הנוקלאופלזמה הפנימית והציטופלזמה.בעוד שלרוב התאים בגוף יש גרעין אחד, חלקם, כמו תאי דם אדומים, הם אובדי"גרעין. הם חסרי גרעין, ואילו אחרים, כגון תאי שרירי השלד, הם מרובי גרעין בעלי יותר מגרעין אחד בשל צרכים מבניים ותפקודיים.

פדרסון, ת'ורו. "הגרעין הוצג". קולד ספרינג הארבור פרספקטיבות בביולוגיה 3, מס '5 (מאי 2011). [<a href="https://doi.org/10.1101/cshperspect.a000521" target="__blank">מקור</a>]
גואו, טונגטונג ויודה פאנג. "ארגון פונקציונלי ודינמיקה של גרעין התא". Frontiers in Plant Science 5 (12 באוגוסט 2014). [<a href="https://doi.org/10.3389/fpls.2014.00378" target="__blank">מקור</a>]

הגרעין

<div style="direction:rtl">הגרעין הוא אברון הקשור לממברנה הפועל כמרכז בקרה בתא איקריוטי. הוא מכיל DNA כרומוזומלי, השולט בביטוי הגנים ומווסת במדויק את ייצור החלבונים בתוך התא. לעומת זאת, ה-DNA בתוך המיטוכונדריה והכלורופלסט מבצע רק פונקציות ספציפיות לאותם אברונים. <h4>סידור ה-DNA בתוך הגרעין</h4> ויסות ביטוי הגנים בתוך הגרעין תלוי בגורמים רבים, כולל מבנה ה-DNA. ה-DNA בגרעין עטוף סביב חלבונים הנקראים היסטונים, ויוצר קומפלקס DNA-חלבון הנקרא כרומטין. כאשר התאים אינם מתחלקים, כלומר, במהלך האינטרפאזה, הכרומטין מאורגן בצורה דיפוזית. דבר זה מאפשר גישה קלה ל-DNA במהלך השעתוק. כאשר התא האוקריוטי עומד להתחלק, הכרומטין מתעבה בחוזקה לכרומוזומים ליניאריים ברורים, אותם ניתן להפריד בקלות לתאי בת. <h4>גרעינון</h4> הגרעין הוא אברון נטול קרום הנוצר סביב הלוקוסים הכרומוזומליים של ה-RNA הריבוזומלי בתוך הגרעין. לכן, נ גרעינונים הם האתר לסינתזה של rRNA והרכבה של תת-יחידות ריבוזומליות. יחידות משנה אלה מיוצאות מאוחר יותר מהגרעין להרכבה לריבוזומים מתפקדים במלואם. <h4>מבנים תת-גרעיניים נוספים</h4> הגרעין מכיל גם גופים גרעיניים רבים אחרים, כגון גופי קחאל, כתמים (speckles) וחברבורות (paraspeckles). גופים גרעיניים אלו מסייעים למידור מרחבי של הסביבה הגרעינית וליצור אתרים נפרדים לתגובות ביולוגיות ספציפיות. חוץ מזה, המבנה חסר הממברנה שלהם מאפשר החלפה טובה יותר של תוכן עם הנוקלאופלזמה.</div>

הגרעין הוא אברון הקשור לקרום המשמש כמרכז בקרה בתא אאוקריוטי. הוא מכיל DNA כרומוזומלי, השולט בביטוי גנים ...

Education

JoVE Core

ביולוגיה

Cellular Processes

תהליכים תאיים

Cell Structure and Function

מבנה התא ותפקידו

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

nuclear dna and cell control

The nucleus is the control center of a eukaryotic cell. It is a membrane-bound organelle that contains chromosomal DNA. That DNA helps control gene expression and regulate protein production in the cell.

Not all cellular DNA has the same role. The DNA in mitochondria and chloroplasts supports functions that are specific to those organelles. Inside the nucleus, DNA structure also affects how genes are regulated.

Nuclear DNA is wrapped around proteins called histones. This forms chromatin, a DNA-protein complex. During interphase, when the cell is not dividing, chromatin stays loosely arranged. This open form makes the DNA easier to access during transcription.

When a eukaryotic cell prepares to divide, chromatin changes shape. It condenses into distinct, linear chromosomes. These chromosomes can then be separated into daughter cells.

The nucleus also contains the nucleolus. This is a membrane-less organelle that forms around the chromosomal loci for ribosomal RNA, or rRNA. The nucleolus is the site where rRNA is made and ribosomal subunits are assembled. These subunits leave the nucleus and later combine to form functional ribosomes.

Other nuclear bodies are found in the nucleus as well. These include Cajal bodies, speckles, and paraspeckles. They help organize the nuclear space and create separate sites for specific biological reactions. Their membrane-less structure also allows contents to move more easily with the nucleoplasm.

Nuclear DNA and Cell Control

what are cells?

Cell Membrane, DNA, and Organelles

Cells are the basic units of life, from a bacterium made of one cell to a human made of trillions. Even though organisms can differ greatly, their cells share key features that support life. A cell has a plasma membrane, which is a lipid bilayer that separates the cytoplasm from the outside environment. It also contains DNA, the genetic material that carries instructions for the cell. In prokaryotic cells, DNA is found in a region called the nucleoid. In eukaryotic cells, DNA is enclosed...

cell size

Why Cell Size Is Limited

Cell size is limited by surface area and diffusion. Cells vary widely in size, both between organisms and within the same organism. Bacterial cells are usually 1 to 10 micrometers wide, and the smallest bacteria can be 0.1 micrometers in diameter. That is about a thousand times smaller than most eukaryotic cells, which are typically 10 to 100 micrometers across. A cell takes in nutrients and water through diffusion across the plasma membrane or through channels in the membrane. The membrane...

eukaryotic compartmentalization

Cell Organelles and Microenvironments

Eukaryotic cells use membrane-bound organelles to keep cell processes organized. The nucleus and mitochondria are two key examples. Because biological membranes are selectively permeable, they create controlled spaces inside each organelle. These small microenvironments support specialized jobs and separate them from the surrounding cytosol. Different organelles maintain different internal conditions. In animal cells, lysosomes keep an acidic environment that helps their enzymes digest...

prokaryotic cells

Prokaryotic Cell Structures

Prokaryotic cells are small, single-celled organisms found in the domains Archaea and Bacteria. Bacteria include familiar species such as Salmonella and E. coli. Archaea include extremophiles, which are organisms that live in harsh environments like volcanic springs. Prokaryotic cells share several basic features with eukaryotic cells. They are surrounded by a plasma membrane, contain cytoplasm, and have ribosomes that make proteins. Their genetic material is a single, circular DNA molecule.

cytoplasm

Cytoplasm and the Cell’s Internal Framework

The cytoplasm is the cell’s internal space that holds organelles and the cytoskeleton. It is suspended in the cytosol, an aqueous fluid made of water, ions, salts, and many organic molecules. Together, these parts create the environment where key cell activities happen. The cytoplasm is also a major site for protein synthesis and folding. The water-based cytosol helps proteins fold correctly. Hydrophobic amino acid side chains tend to hide in the protein core, while hydrophilic amino acids...

endoplasmic reticulum

ER in Protein and Lipid Transport

The endoplasmic reticulum is a membrane network in eukaryotic cells. It is continuous with the outer membrane of the nucleus. This connection helps link nuclear and cytoplasmic processes and supports efficient movement inside the cell. mRNA can move from the nucleus to ribosomes, which helps protein synthesis happen efficiently. The ER is a major site for making, processing, and distributing biomolecules. The rough endoplasmic reticulum has ribosomes attached to its surface. These ribosomes...

ribosomes

How Ribosomes Build Proteins

Ribosomes build proteins by reading messenger RNA, or mRNA, and linking amino acids in the right order. Both prokaryotic and eukaryotic cells contain ribosomes. Cells that make large amounts of protein, such as secretory cells in the human pancreas, can have millions of them. Ribosomes are made of ribosomal RNA, or rRNA, and proteins. In eukaryotic cells, rRNA is transcribed from genes in the nucleolus, a part of the nucleus that specializes in making ribosomes. There, rRNA combines with...

golgi apparatus

Protein Sorting in the Golgi Apparatus

The Golgi apparatus sorts and modifies proteins after they leave the endoplasmic reticulum (ER). Properly folded and assembled proteins are packaged into vesicles, or small membrane sacs, and moved by microtubule-based motor proteins. These vesicles can fuse into vesicular tubular clusters before reaching the Golgi, which often looks like a ribbon-shaped organelle in eukaryotic cells. Vesicles enter the cis face of the Golgi, the side facing the ER. They pass through a set of pancake-shaped...

peroxisomes

Peroxisomes and Cellular Detoxification

Peroxisomes and mitochondria are two important oxygen-utilizing organelles in eukaryotic cells. Mitochondria carry out cellular respiration, which turns energy from food into ATP. Peroxisomes focus on breaking down substances such as fatty acids and other materials the cell needs to process. A peroxisome is a single membrane-bound organelle. It helps with lipid metabolism and chemical detoxification. Enzymes inside peroxisomes move hydrogen atoms from molecules to oxygen. This reaction...

microtubules

Microtubules in Cells and Cell Movement

Microtubules are cytoskeletal fibers that help cells keep their shape, move materials, and divide. They are the thickest of the three main cytoskeletal structures in eukaryotic cells, with a diameter of about 25 nm. Along with microfilaments and intermediate filaments, they form the internal support network of the cell. Microtubules are hollow tubes built from tubulin proteins. Each tubulin molecule is a heterodimer, which means it has two different parts: α-tubulin and β-tubulin. These dimers...

plant cell wall

Plant Cell Walls in Growth and Support

Plant cell walls help plant cells keep their shape, stay protected, and remain supported. As a cell matures, its wall can change based on the cell type. Parenchyma cells in leaves usually have only a thin primary cell wall. These walls are part of how different plant cells take on different jobs. Collenchyma and sclerenchyma cells are found mostly in the outer layers of stems and leaves. Collenchyma cells add strength by partially thickening the primary cell wall. Sclerenchyma cells provide...

plasmodesmata

Plasmodesmata and Plant Cell Communication

Plasmodesmata are the connections that let plant cells communicate directly. These tiny passageways link neighboring cells through the cell wall and help tissues work together in a multicellular plant. Cells in multicellular organisms must communicate to function as a unit. One way they do this is through intercellular junctions, which are contact points between adjacent cells. Fungal, plant, and animal cells all have intercellular junctions, but the types differ. In animal cells, the main...

the nucleus

The nucleus is the control center of a eukaryotic cell. It is a membrane-bound organelle that contains chromosomal DNA. That DNA helps control gene expression and regulate protein production in the cell. Not all cellular DNA has the same role. The DNA in mitochondria and chloroplasts supports functions that are specific to those organelles. Inside the nucleus, DNA structure also affects how genes are regulated. Nuclear DNA is wrapped around proteins called histones. This forms chromatin, a...

the extracellular matrix

How ECM Supports Animal Tissues

The extracellular matrix (ECM) supports animal tissues by surrounding cells with structural molecules. It helps maintain tissue organization and gives tissues their specific physical properties. The ECM includes a gel-like ground substance, fibrous components, and many molecules with different jobs. A major part of the ECM is made of glycosaminoglycans, or GAGs. These polysaccharides fill much of the extracellular space and can take up a large volume for their mass. That makes the matrix...

gap junctions

Connexins and Cell-to-Cell Signaling

Gap junctions help animal cells send signals and share small materials with nearby cells. They are made of special proteins that form pores between neighboring cells and connect their cytoplasm. Through these channels, cells can exchange ions and other small molecules. These communication channels are found in many invertebrate and vertebrate species. They support important processes such as cell differentiation and development. They are also linked to human diseases, including disorders of...

tissues

Body Tissues and Their Jobs

Body tissues are groups of cells with similar structure and function. When different tissues work together, they form an organ with a specialized job. Vertebrates have four main tissue types: epithelial, connective, muscle, and nervous tissue. Epithelial tissue is made of thin sheets of cells. It covers the skin and lines internal organs and body cavities. These cells are tightly packed, so they help protect against injury, infection, and water loss. Epithelial tissue may be simple, with one...

key terms and concepts

Explore how the nucleus stores DNA, controls gene expression, packages chromatin, forms chromosomes, and builds ribosomal subunits in high school cells.

Nuclear DNA and Cell Control | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

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Pennsylvania State Academic Standards

Life Science

Structure and Function

3.1.9-12.A

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Ohio’s Learning Standards and Model Curriculum

Cells

Cell structure and function

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HS+B.L1

HS+B.L1U1.4

Alabama Course of Study Science

From Molecules to Organisms: Structures and Processes

9-12.B.1.1

Florida Department of Education

SC.912.L.14

SC.912.L.14.2

SC.912.L.14.3

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New York State Science Learning Standards

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Cytoplasm

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Endoplasmic Reticulum

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Ribosomes

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Lysosomes

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Nuclear DNA and Cell Control

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