Name: cell types and organelles
Uploaded: 2019-01-29T11:04:45.000Z
Duration: 2 min 56 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

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

Cell Structure

生命，从最大的生物到最微小的生物，都是由细胞构成的。细胞是生命的基本单位，为生命的存续提供了所需的物质。
尽管来自各种生物的细胞都含有相似的结构，例如 DNA 和蛋白质，但根据这些结构在细胞内的组织方式，可将细胞分为两种不同类型。原核细胞，即细菌和古菌的细胞，其结构较为简单。例如，虽然它们的基因组高度致密，但并未被膜结构包裹。真核细胞则构成动物、植物和真菌，其结构更为复杂。它们将内部结构分隔到不同的细胞器中，这些细胞器是由膜包被的结构，各自执行特定功能。与原核细胞不同，真核细胞的 DNA 被包裹在核膜内。其他细胞器还包括内质网、线粒体和溶酶体。
地球上最早的生命细胞出现在约 37 亿年前的化石记录中，被认为属于原核细胞。真核细胞首次出现于约 24 亿年前，当时一个类似阿米巴的细胞吞噬了一个细菌细胞，并形成了稳定的共生关系。随着时间推移，这种细胞内的共生关系逐渐演化，形成了叶绿体和线粒体等细胞器。
植物和动物也具有多样的代谢和结构需求，导致它们的细胞存在进一步差异。由于植物需要自行制造能量，植物细胞中含有参与光合作用的叶绿体。植物细胞还包含一个大型液泡，用于储存蛋白质、代谢物和水。最后，植物细胞还具有坚硬的细胞壁，这对生长和保水至关重要。
由于细胞非常微小，只能通过显微镜观察。观察细胞最简单的方法之一是使用明场显微镜。这种显微镜包含一个光源、用于聚焦光线的聚光镜、用于观察样本的目镜以及用于放大成像的物镜。然而，仅靠显微镜还不足以观察到不可见的结构。细胞内部的结构是透明的，因此必须使用染料对细胞进行染色。例如，沙黄（safranin）可用于将细胞核染成红色。
在本实验中，你将使用复式显微镜观察口腔细胞和植物细胞。

细胞结构

<h4>背景</h4>
细胞是所有生物体最基本的生物学单位，无论是像细菌这样简单的单细胞生物，还是像大象和巨型红杉树这样的多细胞生物。在19世纪中期th 世纪，细胞学说被提出以定义细胞，其内容为：
<ul>
	<li>所有生物体均由一个或多个细胞组成。</li>
	<li>细胞是所有生物体的功能单位。</li>
	<li>所有细胞都来源于已存在的细胞。</li>
</ul>
所有细胞都具有一些共同特征，例如具有质膜、细胞质、DNA 和核糖体。质膜是一种磷脂双分子层，包裹在细胞周围。这种薄而流动的结构将细胞内容物与外界环境隔离开来，调节细胞与环境之间的物质交换，并促进细胞与其他细胞的相互作用。在质膜内部，细胞被一种称为细胞质的凝胶状液体所充满，其中含有对细胞功能至关重要的有机分子、盐类及其他物质。因此，支持生命活动的生化反应（即代谢过程）均在细胞质内进行。细胞能够执行的代谢过程类型取决于其遗传信息。所有细胞均以 DNA 作为遗传物质，DNA 是构建细胞结构和产物的遗传蓝图。最后，所有细胞均利用核糖体来合成其蛋白质产物。
根据遗传物质的位置，细胞可分为两种类型：原核细胞，意为“在细胞核之前”，以及真核细胞，意为“真正的细胞核”。因此，尽管这两类生物都含有DNA，但像细菌这样的原核生物具有拟核，即“类似细胞核”的结构，而非真正的细胞核；而真核生物则具有由膜包被的真正细胞核来容纳其DNA。此外，与真核细胞相比，原核细胞相对较小，大小约为0.1–5.0微米（µm），而真核细胞的大小通常在10–100 µm之间。原核细胞的小尺寸使其能够快速、高效地在细胞内运输物质并进行代谢过程，同时也能迅速将废物或其他产物排出细胞。因此，真核细胞拥有称为细胞器的特化结构，如线粒体或高尔基体，以执行各种重要功能。
<h4>真核细胞</h4>
真核细胞是所有真核生物共有的衍生性状，意味着它起源于一次单一事件，并被所有真核生物继承。最早的真核细胞化石出现在约24亿年前，因其体积大于原核细胞而可被识别1。这种细胞类型的起源源于一次内共生事件，其中一个类似阿米巴的细胞吞噬了一种微球菌类细菌，并形成了稳定的共存关系2。被吞噬的细菌进化成了最早的能量生成细胞器——线粒体，即细胞中负责有氧代谢的细胞器。线粒体拥有独立的基因组，其大小与原核生物相似。它们包含两层膜，包裹着两个不同的区室。分解高能生物分子的部分反应发生于内区室，而外区室则进行将这些化合物释放的能量捕获并转化为三磷酸腺苷（ATP）分子的反应，ATP作为细胞的能量“货币”被利用。
细胞核和线粒体并非真核细胞中唯一的共有结构。其他普遍存在的真核细胞器还包括光面内质网和粗面内质网（ER）、高尔基体、溶酶体以及液泡。内质网字面意思是“细胞质内的网络”，顾名思义，它是细胞内（尤其是细胞核周围）一个庞大的膜性网络结构。粗面内质网的部分结构从核膜延伸而来，因其表面附着大量核糖体而呈现粗糙外观，从而与光面内质网相区别。粗面内质网是蛋白质合成的场所，例如嵌入质膜的蛋白质或细胞分泌的蛋白质。相比之下，光面内质网则负责合成脂质类产物，同时还含有可降解有害化学物质的酶。因此，肝细胞中含有丰富的光面内质网。此外，肌细胞也含有大量的光面内质网，因为该细胞器具有储存钙离子的功能，这对肌肉收缩至关重要。高尔基体负责对细胞产物进行分类、修饰并将其包装进囊泡中，这些囊泡随后与质膜融合，释放所含物质。在粗面内质网中合成的部分蛋白质为细胞内消化酶，这些酶在高尔基体中被包装成一种特殊的囊泡，称为溶酶体。溶酶体的主要功能是消化细胞吞噬的食物颗粒以及衰老的细胞组分。液泡是由细胞膜形成的囊状结构，在细胞中起储存作用。它们可用于储存水分以调节细胞的含水量，也可储存代谢产物甚至有毒分子，具体功能取决于细胞类型和生物体种类。
<h4>界特异性细胞器</h4>
真核细胞也演化出了不同的细胞器，这些细胞器在各个生物界中具有特异性。例如，植物界（Plantae）和动物界（Animalia）均为真核生物，但植物细胞与动物细胞的细胞器在关键方面存在差异，使其分别能够作为生产者和消费者完成生命活动。陆生植物需要长高并具有坚硬的茎以支撑叶片，而叶片用于光合作用。它们还需要能够保留由根部吸收的水分。其细胞结构反映了这些特定需求。与动物细胞不同，植物细胞含有叶绿体，用于进行光合作用，且通常含有绿色色素叶绿素。此外，植物细胞外还包裹着由纤维素构成的坚硬外层——细胞壁，以支持生长并帮助保水。由于需要储存大量水分以维持细胞内的水压，植物细胞的液泡比动物细胞更大。此外，植物细胞还具有另一类特化的储存性细胞器，称为质体，其中含有色素以及淀粉等光合作用产物。这些差异十分明显，可将植物细胞与动物细胞区分开来：由于具有坚硬的细胞壁，植物细胞通常呈规则的矩形；而动物细胞则呈圆形或不规则形状。
<h4>显微镜检查</h4>
某些细胞（例如蛙类卵母细胞）体积较大，肉眼可见，但大多数细胞若无视觉辅助则无法观察。因此，科学家采用显微技术来研究细胞结构，并区分不同类型的细胞。尽管显微镜能够放大人眼难以或无法看见的物体，但大多数组织本身缺乏色素。为此，人们开发出可根据分子组成选择性染色细胞的溶液。这使得研究人员能够区分细胞内的细胞器、植物茎中的不同组织类型以及动物体内的脂肪层，仅举几例。亚甲蓝染料可对死细胞的核酸进行染色，与带负电荷的DNA结合。沙黄溶液是另一种可将细胞核染成红色的生物染料。细胞仅需在染色液中短时间浸泡，染色后即可立即封片。常用的封片技术包括湿封片和油浸片。湿封片的制备方法是将样本置于载玻片上，并在盖玻片与载玻片之间加入液体。细胞样本通常悬浮于水或甘油等液体中。活体培养时更适合使用甘油，因为它可抑制细菌增殖3。在盖玻片上方加入浸油，可提高高倍镜下样本的观察效果。这是因为浸油与玻璃具有相同的折射率，使光线通过时如同通过玻璃一般。玻璃与空气界面比油或玻璃更易散射光线，因此当样本以“干片”方式封片（即不使用浸油）时，图像清晰度会受到影响。细胞经染色和封片处理后，即可在显微镜下进行观察。
从电子扫描技术使研究人员能够观察原子级别的物体，到荧光活细胞成像技术实现对单个细胞内分子运动的实时监测，显微技术种类繁多4。明场显微镜是最简单的显微技术，仅需一个卤素光源、一个用于聚焦光线的聚光镜、一个用于观察图像的目镜以及一个用于放大图像的物镜。无论使用何种显微技术，在操作前理解显微镜的各个组成部分都至关重要。通常用于明场成像的复式显微镜顶部配有目镜，目镜连接在镜头和物镜上。目镜的放大倍数为10倍，而物镜的放大倍数则设定在4倍至100倍的范围内。标准显微镜通常配备三至五个物镜。物镜朝向载物台，待观察的样本即放置于此。载物台通常配备机械装置和标本夹，用于固定玻片并可在观察时移动玻片。载物台上设有通光孔，供光线通过。光线由位于照明光源（即光源）上方的可调节聚光镜控制。为了调节所观察物体的焦距，显微镜设有粗调和微调焦旋钮。粗调焦旋钮的移动幅度大于微调焦旋钮，但两者位于同一轴线上。当载物台上的物体已接近物镜时，微调焦旋钮尤为有用。必须注意避免物镜接触载物台上的物体，以免划伤镜头。观察样本时，应始终先使用最低放大倍数的物镜进行观察，并清晰对焦后，再切换至更高放大倍数的物镜。
显微镜技术是医学领域多个方面的重要工具，包括科研、诊断和治疗。该技术在医学中应用纳米技术，作为一种替代更具侵入性手术的新型治疗方法5。外科医生也广泛使用显微镜，其中一些显微镜经过改装，可安装在医生头部，并通过脚踏板操作。这些显微镜的放大倍数甚至低于当今使用的普通光学显微镜，但有助于安全实施精细的手术操作，例如眼科和神经外科手术。
<h4>参考文献</h4>
<ol class="references">
	<li>Bengtson S, Rasmussen B, Ivarsson M, Muhling J, Broman C, Marone F, Stampanoni M, Bekker A. 24亿年前多孔玄武岩中的类真菌菌丝化石。Nature Ecology &amp;#38; Evolution. 2017年，第1卷，文章编号：0141。</li>
	<li>Vellai T, Vida G. 真核生物的起源：原核细胞与真核细胞之间的差异。Proc. R. Soc. Lond. B. 1999年，第266卷，1571-1577页。</li>
	<li>Gouet V, Roger G, Fonty C, Andre P. 甘油对瘤胃纤维素分解细菌和厌氧真菌的生长、黏附及纤维素分解活性的影响。Current Microbiology. 24，1992年，第4卷，197-201页。</li>
	<li>Cognet L, Leduc C, Lounis B. 活细胞单粒子追踪与动态超分辨率成像技术的进展。Curr Opin Chem Biol. 2014年，6月；20：78-85页。</li>
	<li>Asiyanbola B, Soboyejo W. 外科医生指南：纳米技术简介。J Surg Educ. 2008年，第65卷，第2期（155-61页）。</li>
</ol>

背景  
细胞是所有生物体最基本的生物学单位，无论是像细菌这样的简单单细胞生物，还是大型的……

Education

教育

JoVE Lab Manual

生物学

Fundamentals

基础知识

单元结构

cell types and organelles

Cells are the basic units of life, and their structures help explain how living things work. Cell theory says that every living organism is made of one or more cells, cells are the functional units of organisms, and new cells come from preexisting cells. Cells also share key features, including a plasma membrane, cytoplasm, DNA, and ribosomes.

The plasma membrane is a phospholipid bilayer that surrounds the cell. It separates the cell from its environment and controls what enters and leaves. Inside it, the cytoplasm is a gel-like fluid that contains organic molecules, salts, and other materials needed for cell activity. Many metabolic processes, or life-supporting chemical reactions, take place there.

Cells use DNA as their genetic material, which acts as the blueprint for cellular structures and products. Ribosomes make proteins. Cells are often grouped as prokaryotic or eukaryotic based on where their genetic material is found. Prokaryotes, such as bacteria, have nucleoids instead of a true nucleus, while eukaryotes have membrane-bound nuclei.

Prokaryotic cells are usually small, about 0.1 to 5.0 micrometers, while eukaryotic cells are often 10 to 100 micrometers. Their small size helps prokaryotes move materials quickly and remove waste efficiently. Eukaryotic cells use organelles, such as mitochondria and the Golgi apparatus, to carry out important functions.

Eukaryotic cells are thought to have a shared origin and appear in fossils about 2.4 billion years ago. The earliest eukaryotic cells were larger than prokaryotic cells and likely formed through an endosymbiotic event. In this event, an amoeba-like cell engulfed a micrococcal bacterium, and that bacterium later became the mitochondrion. Mitochondria perform aerobic metabolism and have their own genome.

Mitochondria have two membranes that enclose two compartments. Some reactions that break down high-energy biomolecules happen in the inner compartment. Other reactions in the outer compartment capture released energy and convert it into ATP, the cell’s energy currency. Eukaryotic cells also contain the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, and vacuoles.

The endoplasmic reticulum means “network inside the plasma,” and it forms a membrane network around the nucleus. Rough ER has ribosomes on its surface and makes proteins, including proteins for the plasma membrane and proteins that are secreted from the cell. Smooth ER makes lipid-based products and helps detoxify harmful chemicals, which is why liver cells contain much of it. Muscle cells also have a lot of smooth ER because it stores calcium needed for contraction.

The Golgi apparatus sorts, modifies, and packages cellular products into vesicles. Some proteins made in the rough ER are digestive enzymes. The Golgi packages these enzymes into lysosomes, which digest food particles taken into the cell and break down old cell parts. Vacuoles are membrane sacs used for storage, including water, metabolic products, or even poisonous molecules, depending on the cell.

Plant and animal cells are both eukaryotic, but they do not have the same organelles. Plant cells have chloroplasts for photosynthesis and often contain chlorophyll, the green pigment. They also have cell walls made of cellulose, which give support and help with water retention. Their larger vacuoles help maintain water pressure, and they also contain plastids that store pigments and products such as starch.

These differences make plant cells and animal cells easy to tell apart. Plant cells usually have a regular, rectangular shape because of their rigid cell walls. Animal cells are more rounded and irregular. Cell walls, chloroplasts, and large vacuoles are key features that distinguish plant cells from animal cells.

Many cells are too small to see without help, so scientists use microscopy to study them. Some cells, such as frog oocytes, are large enough to see with the naked eye, but most samples need magnification. Because many tissues lack color, stains are used to highlight cell parts and tissue types. Methylene blue stains nucleic acids in dead cells by binding to DNA, and safranin stains cell nuclei red.

After staining, cells can be mounted as a wet mount or with immersion oil. In a wet mount, the sample is placed on a slide with liquid between the slide and coverslip. Water or glycerol can be used as the liquid, and glycerol is better for live cultures because it prevents bacterial growth. Immersion oil improves high-magnification viewing because it has the same refractive index as glass and reduces light scattering.

Once stained and mounted, the sample is ready for the microscope. Microscopy methods range from electron scanning technology, which can view objects at atomic scale, to fluorescent live-cell imaging, which tracks molecules in real time. Bright-field microscopy is the simplest method and uses a halogen light source, condenser lens, ocular lens, and objective lens.

Compound microscopes have an eyepiece, a head with objectives, and a stage for the specimen. The eyepiece usually has 10X magnification, and objective lenses commonly range from 4X to 100X. The stage may have clips and mechanical parts to move the slide, and light passes through an aperture in the stage. Coarse and fine focus knobs control sharpness, and the slide should be viewed first at low magnification before moving higher.

Microscopy is important in medicine for research, diagnosis, and treatment. It also supports newer approaches such as nanotechnology in medicine, which can reduce the need for more invasive surgery. Surgeons use modified microscopes as well, including head-mounted models operated with foot pedals. These lower-magnification tools help doctors perform delicate procedures such as optical and neurosurgery safely.

Cell Types and Organelles

scientific method

Scientific Method Steps and Controls

The scientific method gives scientists a way to solve problems and explain natural events. Its development grew alongside new ideas in science during the European Renaissance. Thinkers such as Francis Bacon, Galileo, and Isaac Newton helped formalize the process. Although the method has changed over time, much of its basic framework is still used today. The process begins with observation and a clear question. A scientist first notices a natural phenomenon and then asks why it happens. This...

diffusion and osmosis

Cell Membrane Transport and Water Balance

Cell membrane transport and water balance help cells move materials in and out of the cytoplasm. Cell membranes are semipermeable, which means some molecules can pass through while others cannot. The phospholipid bilayer and its embedded proteins control this movement. Some of these proteins act as transport channels for ions and carbohydrates that could not cross on their own. Cells stay small in part because of the surface-area to volume ratio. As a cell grows, its surface area does not keep...

cell structure

Cells are the basic units of life, and their structures help explain how living things work. Cell theory says that every living organism is made of one or more cells, cells are the functional units of organisms, and new cells come from preexisting cells. Cells also share key features, including a plasma membrane, cytoplasm, DNA, and ribosomes. The plasma membrane is a phospholipid bilayer that surrounds the cell. It separates the cell from its environment and controls what enters and leaves.

macromolecules

Biomolecules and Their Tests

Biomolecules are the organic molecules that living things use for structure, energy, and heredity. They all have a carbon backbone and hydrogen atoms, and carbon can form four covalent bonds. That bonding flexibility lets carbon build chains, branches, rings, and other complex shapes. Biomolecules also commonly include oxygen, nitrogen, phosphorus, and sulfur. Small building blocks join together to make larger molecules. These units are called monomers. Two monomers can form a dimer through...

physiology of the circulatory system

Circulatory System: Blood Flow and Pressure

The circulatory system moves blood, oxygen, nutrients, and wastes through the body to support homeostasis. Homeostasis is the stable internal balance that organisms must maintain even when the outside environment changes. Physiology is the study of how body systems work, and the circulatory system is one of the key systems that helps keep internal conditions steady. Body systems are built from cells, tissues, organs, and organ systems. Humans have 11 major organ systems, and they work together...

fundamentals

Explore how prokaryotic and eukaryotic cells differ, what organelles do, and how microscopes reveal cell structures in plants and animals.

Cell Types and Organelles | JoVE K12

Pennsylvania State Academic Standards

Life Science

Structure and Function

3.1.9-12.A

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Cells

Cell structure and function

Virginia  Standards of Learning

HIgh School

BIO.3

BIO.3.a

LS.2

LS.2.a

LS.2.c

Arizona Science Standards

High School

HS+B.L1

HS+B.L1U1.4

Next Generation Science Standards

From Molecules to Organisms: Structures and Processes

HS-LS1-1

Florida Department of Education

SC.912.L.14

SC.912.L.14.3

SC.912.L.14.5

new-york-state-science-learning-standards

New York State Science Learning Standards

HS-LS1-1.

Inheritance and Variation of Traits

HS-LS1-4.

通过这段 1 分钟的教师指南，准备教授 细胞结构。涵盖 JoVE Lab Manual 上 Biology 实验的关键准备步骤。

Biology 中的 细胞结构 教师准备 - 7.7K+ 观看次数 | JoVE Lab Manual

在这段 5 分钟的学生实验流程视频中，逐步学习 细胞结构 的操作步骤。属于 JoVE Lab Manual 上的 Biology 系列。

Biology 中的 细胞结构 学生实验流程 - 25K+ 观看次数 | JoVE Lab Manual

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
Organisms contain a wide variety of organic molecules with numerous functions which depend on the chemical structures and properties of these ...

Solution Preparation
ExpandCAUTION: It is important to always use care when handling reagents. For example, iodine will stain clothes and skin so wear ...

Identifying Macromolecules with Indicator Solutions
ExpandHYPOTHESES: In this activity, the experimental hypothesis might be that the addition of an ...

pH Regulation in Cells

pH plays a critical role in maintaining normal cellular activities. It helps maintain the structure and function of various proteins, dictates the charge ...

Chemistry of the Cell

Overview of Functional Groups

Functional groups are a group of atoms with characteristic properties, which when linked to the carbon skeleton of a molecule, alter the properties of ...

Introduction to Carbohydrates

Carbohydrates, proteins, and fats are the primary macronutrients in the human diet. However, carbohydrates are the most favored source of energy in the ...

Carbohydrate Metabolism

Sugars as Energy Storage Molecules

What are Lipids?

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

Lipid-derived Compounds in the Human Body

Fats and lipids are crucial components in the human body. Some lipid-derived compounds, such as fat-soluble vitamins, eicosanoids, lipoproteins, and ...

Fats as Energy Storage Molecules

What are Proteins?

Protein Organization

Globular Proteins

In organisms, proteins are the most abundant macromolecules. They act as the building blocks of life and play various crucial roles in the body. Proteins ...

Fibrous Proteins

Fibrous proteins are either long and narrow proteins or assemble to form long and thin structures. They contain repetitive units and usually consist of ...

Protein Denaturation

The function of proteins depends on their native three-dimensional structure, which is dictated by the amino acid sequence of the specific protein. ...

Role of Proteins in the Human Body

Proteins are the building block of life. They are also&#160; the most abundant macromolecules with as many diverse roles in the body. They are part of ...

Nucleic Acids and Nucleotides

Nucleic acids are the most important macromolecules for the continuity of life. They carry the cell&#39;s genetic blueprint and have instructions for its ...

Nucleic Acid Structure

The pentose sugar in DNA is deoxyribose, while in RNA the pentose sugar is ribose. The difference between the sugars is the presence of the hydroxyl group ...

ATP Energy Storage and Release

ATP and Macromolecule Synthesis

Biological macromolecules are organic compounds, predominantly composed of carbon atoms. The carbon atoms are covalently bonded with hydrogen, oxygen, ...

Construct an explanation to illustrate relationships between structure and function of major macromolecules essential for life.

LS.Bio.1.1

Introduction to Enzymes

The use of enzymes by humans dates to 7000 BCE. Humans first used enzymes to ferment sugars and produce alcohol without knowing that this was an ...

Enzymes and Activation Energy

The activation energy (or free energy of activation), abbreviated as Ea, is the small amount of energy input necessary for all chemical reactions to ...

Introduction to Enzyme Kinetics

Enzyme kinetics studies the rates of biochemical reactions. Scientists monitor the reaction rates for a particular enzymatic reaction at various substrate ...

Turnover Number and Catalytic Efficiency

The turnover number of an enzyme is the maximum number of substrate molecules it can transform per unit time. Turnover numbers for most enzymes range from ...

Catalytically Perfect Enzymes

The theory of catalytically perfect enzymes was first proposed by W.J. Albery and J. R. Knowles in 1976. These enzymes catalyze biochemical reactions at ...

introduction-to-mechanisms-of-enzyme-catalysis

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple &#34;lock-and-key&#34; fashion. This model stated that the enzyme ...

Ligand Binding and Linkage

Cooperative Allosteric Transitions

Ribozymes

Carry out investigations to illustrate how enzymes act as catalysts for biochemical reactions and how environmental factors affect enzyme activity.

LS.Bio.1.2

What are Cells?

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, ...

Cell Size

Cell sizes vary widely among and within organisms. Bacterial cells range between 1-10 micrometers (&#x3BC;m)and are considerably smaller than most ...

Eukaryotic Compartmentalization

One of the distinguishing features of eukaryotic cells is that they contain membrane-bound organelles, such as the nucleus and mitochondria, that carry ...

Prokaryotic Cells

Prokaryotes are small unicellular organisms that include the domains&#x2014;Archaea and Bacteria. Bacteria include many common organisms, such as ...

Cytoplasm

The cytoplasm consists of organelles and a framework of protein scaffolds called the cytoskeleton suspended in an aqueous solution, the cytosol. The ...

The Nucleus

The nucleus is a membrane-bound organelle that acts as a control center in a eukaryotic cell. It contains chromosomal DNA, which controls gene expression ...

Endoplasmic Reticulum

Endoplasmic ReticulumThe endoplasmic reticulum (ER) is an extensive network of membranous sacs and tubules in eukaryotic cells, continuous with the outer ...

Ribosomes

Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that ...

Golgi Apparatus

As they leave the Endoplasmic Reticulum (ER), properly folded and assembled proteins are selectively packaged into vesicles. These vesicles are ...

Lysosomes

Lysosomes are membrane-enclosed spherical sacs derived from the Golgi apparatus. The most important function of the lysosome is degrading macromolecules ...

Peroxisomes

Peroxisomes and mitochondria are two important oxygen-utilizing organelles in eukaryotic cells. Mitochondria carry out cellular respiration&#x2014;the ...

Introduction to the Cytoskeleton

Overview of the Cytoskeleton
The cytoskeleton is a network of protein filaments present within the cell, having three distinct filaments ...

Introduction to Actin

Actin is a highly conserved cytoskeletal protein found abundantly in eukaryotic cells. It constitutes 10% weight of the total cellular protein in muscle ...

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

Myosins are a family of molecular motor proteins, first identified in the skeletal muscles, where they are responsible for muscle contraction. Along with ...

Visualizing Onion and Cheek Cells
ExpandImmediately before the experiment, wash and peel onion bulbs for the class.
Remove the entire brown outer skin and ...

Microtubules

Microtubules are the thickest cytoskeletal filaments with a diameter of 25 nm. In prokaryotic organisms, microtubules are commonly found in locomotory ...

The Structure of Intermediate Filaments

The intermediate filaments are one of three widely studied cytoskeletal filaments. They are so named as their diameter (10 nm) is in between that of ...

Types of Intermediate Filaments

The intermediate filaments are an essential component of the cytoskeleton. Presently six types of intermediate filament have been identified. Type I and ...

Gap Junctions

Multicellular organisms employ a variety of ways for cells to communicate with each other. Gap junctions are specialized proteins that form pores between ...

The Extracellular Matrix

In order to maintain tissue organization, many animal cells are surrounded by structural molecules that make up the extracellular matrix (ECM). Together, ...

Tissues

Cells with similar structure and function are grouped into tissues. A group of tissues with a specialized function is called an organ. There are four main ...

Plant Cell Wall

The plant cell wall gives plant cells shape, support, and protection. As a cell matures, its cell wall specializes according to the cell type. For ...

Plasmodesmata

The organs in a multicellular organism&#x2019;s body are made up of tissues formed by cells. To work together cohesively, cells must communicate. One way ...

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

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

The Tree of Life - Bacteria, Archaea, and Eukaryotes

Prokaryotes are small unicellular organisms that include the domains &#8212; Archaea and Bacteria. Bacteria include many common microorganisms, such as ...

Prokaryotic vs. Eukaryotic Cells

Prokaryotic and eukaryotic cells represent two fundamental types of cellular organization, differing significantly in structure, complexity, and function. ...

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

LS.Bio.1.4

The DNA Helix

Deoxyribonucleic acid, or DNA, is the genetic material responsible for passing traits from generation to generation in all organisms and most viruses. DNA ...

The Central Dogma

The central dogma explains the flow of genetic information from DNA nucleotides to the amino acid sequence of proteins.
RNA is the Missing Link Between ...

What is Gene Expression?

A gene is a stretch of DNA that serves as the blueprint for functional RNAs and proteins. Since DNA is comprised&#160; of nucleotides and proteins are ...

RNA Structure

The basic structure of RNA consists of a string of ribonucleotides attached by phosphodiester bonds. Although most RNA is single-stranded, it can form ...

Types of RNA

Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse ...

Transcription

Transcription is the synthesis of RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene sequence. ...

Bacterial RNA Polymerase

Construct an explanation to summarize how DNA and RNA direct the synthesis of proteins.

LS.Bio.1.5

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

Cell Types and Organelles

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