Name: cells as the basic unit of life
Uploaded: 2023-06-23T15:38:44.000Z
Duration: 1 min 15 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Life Sciences

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

From Molecules To Organisms: Structures And Processes

HS-LS1-1

What are Cells?

From single-celled bacteria to multicellular plants and animals, cells are the basic building blocks of every organism.
They can be classified into two broad categories&#8212; prokaryotic and eukaryotic.
Prokaryotic cells are relatively simple structures that lack membrane-bound organelles, barring a few exceptions. Their DNA is freely bundled in the center of a cell, a region called the nucleoid.
In contrast, eukaryotic cells have a membrane-bound nucleus. Their overall structure is more complex and compartmentalized with specific organelles, like the mitochondria and endoplasmic reticulum.
These organelles perform distinct functions but maintain internal communication that is essential for the cell&#39;s survival.
Moreover, different eukaryotic organisms, such as plants and animals, vary in their exact cellular makeup.
For example, a typical plant cell contains chloroplast, while animal cells do not.
Thus, understanding the structural complexity and functionality of these cells is essential for learning about the biological world.

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, e.g., in humans. No matter what organism a cell is a part of, they share specific characteristics.
Basic Characteristics of Cells
A living cell has a plasma membrane, a bilayer of lipids that separates the aqueous solution inside the cell called the cytoplasm from the outside environment.
Furthermore, a living cell possesses genetic information encoded in the form of DNA. DNA can be localized to a particular cell region, as in the nucleoid of a prokaryotic cell, or it can be contained inside another membrane, such as the nucleus of eukaryotes. The word &#8216;eukaryote&#39;&#160;means &#34;true nucleus.&#34;&#160;Hence, the word prokaryote implies that these cells existed before membrane-bound nuclei appeared in the history of life.
Other special characteristics of a living cell include the ability to replicate, respond to the extracellular environment, process energy, and regulate its own functions. These characteristics are essential for the survival and functioning of the cell independently as well as a part of organized structures like tissues.
Organelles Compartmentalize Eukaryotic Cells
Prokaryotic cells lack internal membranes. In contrast, eukaryotes have membrane-bound internal compartments called organelles. Each of these organelles fulfills a specific cellular function. For example, in plant cells, chloroplasts are specialized organelles that convert light energy to sugar. Similarly, animal cells contain lysosomes, membrane-enclosed compartments that contain enzymes to break up larger molecules.

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, ...

Education

JoVE Core

Anatomy and Physiology

Unit 1

Cells and their Components

KEY TERMS AND CONCEPTS

cells as the basic unit of life

Cells are the basic unit of life. They are the smallest structures that make up living things, and they carry out the jobs needed to stay alive. Many organisms are made of one cell, while others are made of many cells working together.

Cells share a few common features, but not all cells are the same. Some cells have a nucleus, which holds the genetic material, and other cells do not. Cells also differ in size, shape, and the specific work they do in an organism.

Understanding cells helps explain how living things are organized. It also gives students a foundation for studying tissues, organs, and body systems. Cells are the starting point for understanding life at the microscopic level.

Cells as the Basic Unit of Life

Cells are the basic unit of life. They are the smallest structures that make up living things, and they carry out the jobs needed to stay alive. Many organisms are made of one cell, while others are made of many cells working together. Cells share a few common features, but not all cells are the same. Some cells have a nucleus, which holds the genetic material, and other cells do not. Cells also differ in size, shape, and the specific work they do in an organism. Understanding cells helps...

cell diversity

How Cells Become Specialized

Cells are the basic units of life, and they can become specialized for different jobs in the body. The idea of the cell began in 1665, when Robert Hooke looked at dead cork tissue under a microscope and named the small boxlike spaces "cells" because they reminded him of monks' rooms. About ten years later, Antonie van Leeuwenhoek became the first person to see living, moving cells under a microscope. Over the next century, scientists developed the theory that cells are the fundamental unit of...

cytoplasm

Cytoplasm: The Cell’s Internal Fluid

Cytoplasm is the internal fluid of the cell. It fills the space inside the cell membrane and surrounds the cell’s structures. This fluid helps support the cell and gives organelles a place to stay suspended. It is an important part of cell structure because many cell activities happen within it. In many cells, the cytoplasm also helps move materials around the cell. Its fluid nature allows substances to travel where they are needed and helps keep the cell organized.

the nucleus

Nucleus Structure and Cell Control

The nucleus is the cell’s control center. It helps direct how a cell works and supports the cell’s genetic material. In many eukaryotic cells, the nucleus is the most obvious internal organelle. The nucleus is surrounded by a nuclear envelope. This envelope separates the nucleus from the rest of the cell. It also helps protect the DNA inside. Inside the nucleus, the genetic material is organized as chromatin. Chromatin contains DNA and proteins. When a cell prepares to divide, this material...

the nucleosome

DNA Packing with Histones

DNA packing with histones allows human DNA to fit inside the cell nucleus. Human DNA is almost two meters long, but the nucleus is only a few microns wide. To fit this amount of DNA into such a small space, it is organized into several levels of compaction. The most compact form of DNA is the chromosome, which can be seen under a microscope in a dividing cell. Inside a chromosome, DNA wraps twice around a histone octamer core. This core is made of eight histone proteins. The DNA and histone...

the nucleosome core particle

Histone Tails and DNA Packing

Nucleosomes help pack and protect DNA inside the cell. They are made when DNA wraps around a histone core. That core is an octamer, or eight-part protein complex, with two copies each of H2A, H2B, H3, and H4. Nucleosomes must do two jobs at once. They protect fragile DNA from physical damage and help DNA fit into a smaller space. They also must let polymerase enzymes reach histone-bound DNA during replication and transcription. To solve this, the DNA can partially unfold when needed, while...

chromatin packaging

How DNA Fits Inside the Nucleus

Chromatin is the DNA-protein material that helps human DNA fit inside the nucleus. A human somatic cell contains about 6 billion base pairs of DNA, and each base pair is 0.34 nm long. That means a diploid cell holds about 2 meters of DNA inside a nucleus that is only 10 to 20 microns wide. Histones make this packing possible. These specialized DNA-binding proteins help organize DNA into a compact chromatin structure. Chromatin is then folded into higher-order forms, and it reaches its highest...

the endoplasmic reticulum

Endoplasmic Reticulum: Cell Transport Network

The endoplasmic reticulum is a major membrane network inside the cell. It helps move materials and supports cell function. Its structure gives the cell a large internal surface for important processes. The endoplasmic reticulum has two main forms. Rough endoplasmic reticulum has ribosomes attached to its surface, while smooth endoplasmic reticulum does not. These forms help the cell handle different tasks. The rough endoplasmic reticulum is linked to protein production. The smooth endoplasmic...

golgi apparatus

Golgi Apparatus in Cell Transport

The Golgi apparatus is a cell structure that helps sort and move materials inside the cell. It works with membrane traffic, which is the movement of substances in small membrane-bound packages. The Golgi apparatus receives materials from other parts of the cell and processes them before they are sent to their next destination. It plays an important role in helping the cell organize what it makes and where those materials go. In many cells, the Golgi apparatus is part of a larger system of...

lysosomes

Lysosomes and Cell Recycling

Lysosomes are cell organelles that help break down worn-out materials and recycle useful parts. They contain digestive enzymes that work inside a membrane-bound compartment. This makes them important for keeping cells clean and organized. Lysosomes use hydrolytic enzymes to digest large molecules, cell debris, and other unwanted material. Their membrane helps protect the rest of the cell from these enzymes. When digestion is complete, the cell can reuse some of the released building blocks. <br...

mitochondria

Mitochondria in Cellular Energy Production

Mitochondria are cell structures linked to energy production. They help cells convert energy from nutrients into a usable form. In many cells, they are important for keeping energy supply steady. Mitochondria also have their own DNA. This sets them apart from many other parts of the cell. Their structure and genetic material help scientists study how they function in cells. Understanding mitochondria is important in biology because energy use affects how cells work. These structures play a...

mitochondrial membranes

Mitochondrial Membranes in Energy Production

Mitochondrial membranes help cells make energy. They form the outer boundary of the mitochondrion and also create the inner folds inside it. These membranes give the organelle its structure and support its role in energy production. The outer membrane surrounds the mitochondrion. The inner membrane is folded into many cristae, which increase surface area. This extra surface gives more space for the steps that help the cell produce usable energy. Together, the mitochondrial membranes separate...

peroxisomes

Peroxisome Functions in Cells

Peroxisomes are small organelles in cells that help manage chemical reactions. They are known for breaking down fatty acids and for handling harmful byproducts made during metabolism. These roles help keep the cell functioning normally. Peroxisomes also contain enzymes that use and break down hydrogen peroxide. Hydrogen peroxide is a reactive molecule, so cells must control it carefully. By processing it, peroxisomes support the cell's chemical balance. In cell biology, peroxisomes are...

ribosomes

Ribosomes and Protein Assembly

Ribosomes are the cell structures that build proteins. They read the instructions carried by messenger RNA, or mRNA, and join amino acids together in the correct order. This process is called translation. Ribosomes are made of ribosomal RNA and proteins. They work as the site where genetic information is turned into a protein. As the ribosome moves along the mRNA strand, it helps match each code in the message with the right amino acid. Protein assembly by ribosomes is a key step in how cells...

the proteasome structure

How Cells Tag Proteins for Breakdown

Cells use the ubiquitin-proteasome pathway to remove cytoplasmic proteins that are misfolded, damaged, or no longer needed. In this pathway, a protein is first tagged with ubiquitin, a small protein marker. This ubiquitination usually adds a chain of ubiquitin molecules to the 48th lysine residue on the target protein. The tag helps the proteasome tell a protein that should be removed from a healthy one. The proteasome is a large, ATP-driven protease called the 26S proteasome. It is found in...

the proteasome

How Cells Remove Damaged Proteins

Eukaryotic cells use the ubiquitin-proteasome pathway to remove damaged, misfolded, or unwanted cytoplasmic proteins. This selective cleanup helps protect the cell and keep protein levels under control. In this pathway, target proteins are tagged with ubiquitin, a small protein label. Three enzymes work together to attach ubiquitin to the target: E1, the ubiquitin-activating enzyme; E2, the ubiquitin-conjugating enzyme; and E3, the ubiquitin ligase. After tagging, the ubiquitinated proteins...

introduction to cytoskeleton

Cytoskeleton: Cell Support and Movement

The cytoskeleton gives cells shape, support, and the ability to move. It is a network of protein fibers inside the cell. These fibers help organize the cell and keep its parts in place. The cytoskeleton includes microfilaments, intermediate filaments, and microtubules. Microfilaments are made of actin. They help the cell change shape and move. Intermediate filaments provide strength. Microtubules are larger fibers that help with cell organization and transport. Together, these structures...

centrioles and centrosomes

Centrosomes in Cell Division

Centrosomes help organize cell division in animal cells. Most animal cells contain a pair of centrioles that together make a centrosome. Before division begins, the cell copies its centrosome so that two centrosomes sit side by side. During prophase, these centrosomes start moving toward opposite sides of the cell. As the centrosomes separate, microtubules grow outward from each one. These fibers and the centrosomes form the mitotic spindle. Near the end of prophase, also called prometaphase...

microtubules in cell motility

Microtubules and Cell Movement

Microtubules help cells move and change shape. They are part of the cell’s internal support system, called the cytoskeleton. In moving cells, microtubules work with other cell parts to guide motion. These structures are built from tubulin, a protein that joins together to form long, hollow tubes. Their shape makes them strong and flexible enough to support cell activity. In many cells, microtubules also help organize movement inside the cell. Cell motility means the ability of a cell to move.

mechanism of ciliary motion

How Cilia Create Movement

Cilia create movement by bending in a coordinated way. These tiny, hairlike structures help cells and fluids move in specific directions. The mechanism of ciliary motion explains how this repeated motion works. Cilia beat through a controlled motion that depends on their internal structure. Their movement is not random. It follows a set pattern that allows the cilia to push material across a surface or help a cell move. Understanding ciliary motion is important in cell biology. It shows how...

microvilli

Microvilli and Cell Surface Area

Microvilli are tiny finger-like projections on the surface of certain cells. They increase the surface area of the apical surface, which helps cells absorb or secrete substances more effectively. These structures are common in cells lining the small intestine, kidney tubules, and some cells in the respiratory and reproductive systems. Each microvillus has a core made of actin filaments. Actin is a structural protein that helps support cell shape. Other proteins, including villin and fimbrin,...

key terms and concepts

Learn how cells are the smallest units of life, how single-celled and multicellular organisms differ, and why cell structure matters in biology.

Cells as the Basic Unit of Life | 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.

Virginia  Standards of Learning

HIgh School

Life Science

LS.2

LS.2.b

Arizona Science Standards

HS+B.L1

HS+B.L1U1.7

Next Generation Science Standards

From Molecules to Organisms: Structures and Processes

new-york-state-science-learning-standards

New York State Science Learning Standards

Structure and Function

HS-LS1-1.

Georgia Standards of Excellence

9-12

Biology

SB1.a

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 ...

DNA Base Pairing

Erwin Chargaff&#x2019;s rules on DNA equivalence paved the way for the discovery of base pairing in DNA. Chargaff&#x2019;s rules state that in a ...

From DNA to Protein

The flow of genetic information in cells from DNA to mRNA to protein is described by the central dogma, which states that genes specify the sequence of ...

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 ...

Genomic DNA in Prokaryotes

The genome of most prokaryotic organisms consists of double-stranded DNA organized into one circular chromosome in a region of cytoplasm called the ...

Genomic DNA in Eukaryotes

Eukaryotes have large genomes compared to prokaryotes. To fit their genomes into a cell, eukaryotic DNA is packaged extraordinarily tightly inside the ...

Overview

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

DNA Packaging

Overview

Eukaryotes have large genomes compared to prokaryotes. In order to fit their genomes into a cell, eukaryotes must pack their DNA tightly inside ...

RNA Structure

Overview
The basic structure of RNA consists of a five-carbon sugar and one of four nitrogenous bases. Although most RNA is single-stranded, it can form ...

RNA Stability

Intact DNA strands can be found in fossils, while scientists sometimes struggle to keep RNA intact under laboratory conditions. The structural variations ...

Pre-mRNA Processing

In eukaryotic cells, transcripts made by RNA polymerase are modified and processed before exiting the nucleus. Unprocessed RNA is called precursor mRNA or ...

Types of RNA

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

DNA as a Genetic Template

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 ...

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. ...

Translation

Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes ...

Ribosomes

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

tRNA Activation

Initiation of Translation

Termination of Translation

Cell Diversity

The concept of a cell started with microscopic observations of dead cork tissue by Robert Hooke in 1665. Hooke coined the term &#34;cell&#34; based on the ...

Cells of the Epidermis

The epidermis is made of four or five layers of epithelial cells, depending on its location in the body. From deep to superficial, these layers are the ...

Bone Cells and Tissue

Bones contain a relatively small number of cells entrenched in a matrix of organic and inorganic components. Although bone cells compose only a small ...

Gross Anatomy of Skeletal Muscles

The connective tissues play a significant role in arranging the muscle fibers into a hierarchical structure that forms a complete muscle. Consider a ...

Structure of Cardiac Muscles

Cardiac muscle, or myocardium, is a specialized type of muscle found exclusively in the heart. Its unique structural and functional characteristics enable ...

structure-and-organization-of-smooth-muscles

Structure and Organization of Smooth Muscles

In the human body, smooth muscle tissue is found lining the visceral and tubular organs such as the liver, lungs, blood vessels, and respiratory tract.
...

Chromosome Replication

Before a cell can divide, it must accurately replicate all of its chromosomes, including the DNA and its associated histone and non-histone ...

Neurons: The Cell Body and the Dendrites

A typical nerve cell comprises three main components: the cell body, dendrites, and the axon. The cell body, also known as the soma or perikaryon, serves ...

Lampbrush Chromosomes

In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, R&#252;ckert observed LBCs in shark egg cells and coined the ...

Neurons: The Axon

The axon is a long, thin extended portion of the neuron that carries impulses from its cell body toward the effector cell.
Axoplasm, the axon&#39;s ...

Polytene Chromosomes

Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in ...

Nervous Tissue: Neuron Types

Neurons, the fundamental units of the nervous system, can be classified based on both their structural and functional characteristics.
Structurally, ...

Euchromatin

The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions ...

Nervous Tissue: Glial Cells

Glial cells or neuroglia are non-neuronal cells in the nervous system that outnumber neurons. These include astrocytes, oligodendrocytes, microglia, and ...

Heterochromatin

Lymphoid Cells and Tissues

Lymphoid cells and lymphoid tissues are the two major components of lymphoid organs.
Lymphoid cells consist of immune system cells such as B and T ...

chromatin-position-affects-gene-expression

Chromatin Position Affects Gene Expression

Chromatin is the massive complex of DNA and proteins packaged inside the nucleus. The complexity of chromatin folding and how it is packaged inside the ...

Two structural features of the DNA molecule provide a basis for the mechanisms of heredity: the four nucleotide bases and its double-stranded nature. The ...

Organization of Genes

Chromosome Structure

A functional eukaryotic chromosome must contain three elements: a centromere, telomeres, and numerous origins of replication.
The centromere is a DNA ...

Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins which carry out the essential functions of life through systems of specialized cells. Emphasis is on the conceptual understanding that DNA sequences determine the amino acid sequence and thus protein structure. Students can produce scientific writing, or presentations, and/or physical models that communicate constructed explanations.

Characteristics of Life

Biology is a natural science that studies life and living organisms, including their structure, function, development, interactions, evolution, ...

https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10647.jpg

Levels of Organization

Biological organization is the classification of biological structures, ranging from atoms at the bottom of the hierarchy to the Earth&#x27;s biosphere. ...

The Scientific Method

The scientific method is a detailed, empirical problem-solving process used by biologists and other scientists. This iterative approach involves ...

Taxonomy

Taxonomy is the science of defining and naming groups of biological organisms based on shared characteristics. It uses a hierarchy of increasingly ...

Phylogeny

Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon ...

Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms. Emphasis is on functions at the organism system level such as nutrient uptake, water delivery, or organism movement in response to neural stimuli. An example of an interacting system could be an artery depending on the proper function of elastic tissue and smooth muscle to regulate and deliver the proper amount of blood within the circulatory system.

HS-LS1-2

Overview of Metabolism

Living cells constantly carry out various chemical reactions which are necessary for their proper functioning. These reactions are interlinked to one ...

Regulation of Metabolism

Cellular needs and conditions vary from cell to cell and change within individual cells over time. For example, the required enzymes and energetic demands ...

Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis in living organisms. Examples of investigations could include heart rate responses to exercise, stomate responses to moisture and temperature, root development in response to water levels, or cell response to hypertonic and hypotonic environments.

HS-LS1-3

Cells as the Basic Unit of Life

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