Name: nuclear dna, chromatin, and nucleoli
Uploaded: 2023-04-30T10:29:41.000Z
Duration: 1 min 25 s
Channel: JoVE

K12 Standards

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NC 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.1.5

The Nucleus

在真核细胞中，细胞核是一个由膜包被的细胞器，其中储存着细胞的遗传信息——DNA。
然而，细胞核内DNA的排列方式取决于细胞周期的阶段。
例如，当细胞不分裂时，被称为染色质纤维的DNA-蛋白质复合物会松散地悬浮在核质中，从而便于DNA复制和转录相关酶的接触与作用。
相反，当细胞即将分裂时，染色质纤维会压缩形成染色体。
核仁是细胞核内一个独特的区域，专门负责核糖体的组装——核糖体是一种核糖核蛋白复合物，负责蛋白质的翻译。
细胞核由双层膜结构——核膜所包围，核膜上排列着核孔复合体（NPCs）。
这些核孔复合体控制细胞核与细胞质之间的分子交换。
虽然体内大多数细胞只有一个细胞核，但有些细胞（如红细胞）是无核的，即缺乏细胞核；而另一些细胞（如骨骼肌细胞）则由于结构和功能的需要，具有多个细胞核。

细胞核

细胞核是一种膜结合的细胞器，并作为真核细胞的控制中心。它含有染色体 DNA，能够控制基因表达并精确调节细胞内蛋白质的产生。相比之下，线粒体和叶绿体内的 DNA 只能执行这些细胞器中特有的功能。

DNA 在细胞核内的排列

细胞核内基因表达的调节取决于许多因素，其中含有 DNA 的结构。细胞核中的 DNA 能够包裹在称为组蛋白的蛋白质周围，从而形成一种称为染色质的 DNA-蛋白质复合物。当细胞在分裂间期没有发生分裂时，染色质便会呈弥散状排列。这样可以在转录的过程中轻松的获取到 DNA。当真核生物中的细胞即将分裂时，染色质就会紧密地凝结成不同的线性染色体，从而使这些染色体能够很容易地分离到子细胞中。

核仁

核仁是一种无膜的细胞器，通常会在细胞核内核糖体 RNA 的染色体位点周围形成。因此，核仁是 rRNA 合成和核糖体亚基组装的场所。这些亚基随后会从细胞核中输出，并组装成功能齐全的核糖体。

其他的亚核结构

细胞核中还包含许多其他的核体，例如卡哈尔体、散斑和对位散斑。这些核体有助于在空间上分隔核环境，并为特定的生物反应创造了独特的场所。此外，它们的无膜结构使其能够允许与核质更好地交换内容物。

细胞核是一种由膜包被的细胞器，作为真核细胞的控制中心。它含有染色体DNA，可调控基因表达……

Education

教育

JoVE Core

Cell Biology

细胞生物学

Unit 1

第一单元

Cells, Genomes, and Evolution

细胞、基因组与进化

KEY TERMS AND CONCEPTS

关键术语与概念

nuclear dna, chromatin, and nucleoli

The nucleus is a membrane-bound organelle that stores chromosomal DNA and helps control what proteins a eukaryotic cell makes. It acts as the cell’s control center. DNA in mitochondria and chloroplasts is different because it mainly supports functions specific to those organelles.

Inside the nucleus, DNA is wrapped around proteins called histones. This DNA-protein complex is called chromatin. During interphase, when the cell is not dividing, chromatin stays loosely arranged so the DNA is easy to access for transcription. As a eukaryotic cell prepares to divide, the chromatin condenses into distinct, linear chromosomes that can be separated into daughter cells.

The nucleus also contains the nucleolus, which is a membrane-less organelle. It forms around chromosomal regions that contain ribosomal RNA, or rRNA. The nucleolus is the site of rRNA synthesis and the assembly of ribosomal subunits. These subunits later leave the nucleus and join together to form functional ribosomes.

Other nuclear bodies are present as well. Cajal bodies, speckles, and paraspeckles help organize the nuclear space into regions for specific biological reactions. Their membrane-less structure also allows materials to move more easily with the nucleoplasm, the fluid inside the nucleus.

Nuclear DNA, Chromatin, and Nucleoli

what are cells?

Cells as the Building Blocks of Life

Cells are the basic building blocks of life. A bacterium can be a single cell, while a human is made of trillions of cells. Even with this range, cells share key features that support life. A living cell has a plasma membrane. This is a bilayer of lipids that separates the cytoplasm inside the cell from the outside environment. A cell also carries genetic information in the form of DNA. In prokaryotic cells, DNA is found in a region called the nucleoid. In eukaryotic cells, DNA is enclosed...

the tree of life - bacteria, archaea, and eukaryotes

the-tree-of-life-bacteria-archaea-and-eukaryotes

Three Domains on the Tree of Life

The tree of life shows how living things are grouped into three domains: Bacteria, Archaea, and Eukaryotes. This classification helps explain the major branches of life and how they are related. Bacteria and Archaea are both single-celled organisms, but they are not the same. Eukaryotes include organisms with more complex cells, such as plants, animals, and fungi. Together, these three domains give a broad picture of life on Earth. Understanding the tree of life helps students compare cell...

prokaryotic cells

How Prokaryotes Survive Without a Nucleus

Prokaryotes are small unicellular organisms that live without a nucleus. They include the domains Archaea and Bacteria. Bacteria include common microbes such as Salmonella and E. coli, while Archaea include extremophiles that live in harsh places like volcanic springs. Prokaryotic cells still share several basic features with eukaryotic cells. They have a plasma membrane, cytoplasm, ribosomes, and genetic material in the form of single, circular DNA. Their cell parts float freely in the...

eukaryotic compartmentalization

How Organelles Keep Cells Working

Eukaryotic cells keep their organelles separate so each part can do a specific job. Organelles such as the nucleus and mitochondria are surrounded by membranes. These membranes are selectively permeable, which means they control what enters and leaves. That control creates small internal environments with conditions suited to each organelle. These controlled spaces help organelles work more efficiently. In animal cells, lysosomes keep an acidic environment that helps their enzymes digest...

eukaryotic evolution

How Eukaryotic Cells Became Complex

Eukaryotic cells became complex through a debated evolutionary path that likely involved endosymbiosis. The most accepted model is the endosymbiont theory, which explains how organelles such as mitochondria and chloroplasts may have entered an ancestral cell. Other ideas include the nucleus-first hypothesis, the mitochondria-first hypothesis, and the eukaryote-first hypothesis. The nucleus-first hypothesis says an ancestral prokaryote first formed a membrane around its DNA, creating the...

animal and plant cell structure

Plant vs Animal Cell Division and Specialization

Plant and animal cells differ in how they divide, organize into tissues, and specialize for different jobs. Both cell types divide by mitosis in non-gametic cells and by meiosis in gametic cells, but the details are not the same. These differences help explain how each cell type supports growth and reproduction. During cell division, animal cells use centrosomes to organize spindle fibers and separate chromosomes. Plant cells do not have centrosomes. Instead, they use a microtubule-organizing...

cytoplasm

Cytoplasm and the Cell’s Internal Support

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. This fluid helps keep the cell organized and supports many cellular activities. The cytoplasm is also where protein synthesis and protein folding take place. The watery cytosol helps proteins fold correctly. In a folded protein, hydrophobic amino acid side chains tend to stay buried in the core, while...

the nucleus

The nucleus is a membrane-bound organelle that stores chromosomal DNA and helps control what proteins a eukaryotic cell makes. It acts as the cell’s control center. DNA in mitochondria and chloroplasts is different because it mainly supports functions specific to those organelles. Inside the nucleus, DNA is wrapped around proteins called histones. This DNA-protein complex is called chromatin. During interphase, when the cell is not dividing, chromatin stays loosely arranged so the DNA is easy...

the dna helix

How DNA Structure Was Discovered

DNA is the genetic material that passes traits from one generation to the next in organisms and most viruses. It is made of two strands of nucleotides that twist into a spring-like double helix. The shape is not perfectly even. It also has repeating grooves called the major groove and the minor groove. The major groove forms where the sugar-phosphate backbones are farther apart. This wider space gives DNA-binding proteins, including transcription factors, better access to the bases. The minor...

the central dogma

DNA to Protein: RNA’s Role

DNA to protein flow depends on RNA as the link between genetic information and the amino acids that build proteins. Early scientists knew that DNA stores the information for cell functions and that proteins carry out most of those functions. For a long time, they did not know how the code in DNA became a working protein. At first, many people thought one gene was changed directly into its protein. Two findings in eukaryotic cells challenged that idea. Protein production does not happen in the...

mutations

Mutations in DNA and Inherited Disease

Mutations are changes in the DNA sequence. They can happen on their own during DNA copying, or they can be caused by environmental factors. Scientists describe mutations in several ways, including whether they change the amino acid sequence of a protein, how much DNA they affect, and whether they occur in somatic cells or germline cells. Some mutations are point mutations. A point mutation changes a single nucleotide in DNA. Other mutations are chromosomal alterations, which change the number...

genome size and the evolution of new genes

genome-size-and-the-evolution-of-new-genes

Genome Size and Gene Evolution

Genome size and gene evolution are linked through changes in DNA sequence and genome structure. Some genes can arise from parts of the genome that were not coding before, while others come from changes to existing genes. These shifts help explain how new genetic material can appear over time. A genome is the full set of DNA in an organism. Its size can change as DNA is added, removed, or rearranged. The transcript highlights that genome size is not fixed, and that these changes can shape the...

gene families

Shared Origins of Gene Families

Gene families are groups of related genes that share a common origin. They form when genes are copied and then change over time. These related genes can be found within the same genome. The video also connects gene families to homologous genes and orthologous genes. Homologous genes are genes with a shared evolutionary origin. Orthologous genes are homologous genes found in different species. Gene families help show how these relationships are used to study evolution and related gene functions.

gene evolution - fast or slow?

Gene Evolution Rates and Selection

Gene evolution can happen at different rates, and natural selection helps shape those changes. Some genes change slowly because important DNA changes are removed over time. Other genes can change more quickly when different mutations are kept in a population. The rate of evolution depends on how a gene is used and how strongly it is affected by selection. Genes with essential jobs often stay more similar across species. Genes under weaker pressure may show more variation and may evolve faster.<br...

types of genetic transfer between organisms

types-of-genetic-transfer-between-organisms

Vertical and Horizontal Gene Transfer

Genetic transfer between organisms happens in two main ways: vertical gene transfer and horizontal gene transfer. These two routes explain how hereditary material moves from one generation to the next or between organisms that are not parent and offspring. Vertical gene transfer passes genes from parent to offspring during reproduction. This is the usual way genetic information is inherited in living things. Horizontal gene transfer moves genetic material between organisms outside of...

key terms and concepts

Explore how nuclear DNA is packed as chromatin, condenses into chromosomes, and how the nucleolus makes rRNA and ribosomal subunits in eukaryotic cells.

Nuclear DNA, Chromatin, and Nucleoli | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Louisiana Student Standards for Science

High School

Life Sciences

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance And Variation Of Traits

HS-LS3-1

Virginia  Standards of Learning

HIgh School

BIO.2

BIO.2.d

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

From Molecules to Organisms: Structures and Processes

B-LS1-1.

Compounds Essential to Human Function

The human body is composed of cells that are fundamentally made up of several different molecules. These molecules are essential to carry out all ...

Macromolecules

Biomolecules
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Solution Preparation
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Identifying Macromolecules with Indicator Solutions
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pH Regulation in Cells

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Carbohydrate Metabolism

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lipid-derived-compounds-in-the-human-body

Lipid-derived Compounds in the Human Body

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Protein Organization

Globular Proteins

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Fibrous Proteins

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Protein Denaturation

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Role of Proteins in the Human Body

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Nucleic Acids and Nucleotides

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Nucleic Acid Structure

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ATP Energy Storage and Release

ATP and Macromolecule Synthesis

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LS.Bio.1.1

Introduction to Enzymes

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Enzymes and Activation Energy

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Introduction to Enzyme Kinetics

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Turnover Number and Catalytic Efficiency

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Catalytically Perfect Enzymes

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introduction-to-mechanisms-of-enzyme-catalysis

Introduction to Mechanisms of Enzyme Catalysis

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Ligand Binding and Linkage

Cooperative Allosteric Transitions

Ribozymes

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LS.Bio.1.2

What are Cells?

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Cell Size

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Eukaryotic Compartmentalization

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Prokaryotic Cells

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Cytoplasm

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Endoplasmic Reticulum

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Ribosomes

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Golgi Apparatus

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Lysosomes

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Peroxisomes

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Introduction to the Cytoskeleton

Overview of the Cytoskeleton
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Introduction to Actin

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Cell Structure

Background
Cells represent the most basic biological units of all organisms, whether it be simple, single-celled organisms like bacteria, or large, ...

overview-of-myosin-structure-and-function

Overview of Myosin Structure and Function

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Visualizing Onion and Cheek Cells
ExpandImmediately before the experiment, wash and peel onion bulbs for the class.
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Microtubules

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The Structure of Intermediate Filaments

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Types of Intermediate Filaments

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Gap Junctions

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The Extracellular Matrix

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Tissues

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Plant Cell Wall

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Plasmodesmata

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Use models to explain how the structure of organelles determines its function and supports overall cell processes.

LS.Bio.1.3

Cells are the smallest and basic units of life, whether it is a single cell that forms the entire organism, e.g., in a bacterium, or trillions of them, ...

The Tree of Life - Bacteria, Archaea, and Eukaryotes

Construct explanations to compare prokaryotic and eukaryotic cells in terms of structures and degree of complexity.

LS.Bio.1.4

Analyze how the relationship between structure and function supports life processes within organisms.

Nuclear DNA, Chromatin, and Nucleoli

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