Name: how cell division is controlled
Uploaded: 2021-04-07T12:12:01.000Z
Duration: 2 min 11 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Life Science

LS.2

LS.2.d

The Cell Cycle Control System

The cell cycle involves the duplication of the intracellular content, followed by the division into two daughter cells.
Replication of cellular content, especially the DNA, is highly critical, and any mistake during the process can lead to conditions such as cancer.&#160;
So how do cells prevent any errors during division?
The cell cycle control system features regulator proteins that halt the cycle at various checkpoints.
At every checkpoint, the regulator proteins prevent the initiation of each step until the earlier stages are completed and any errors have been corrected.
Generally, the control system has three crucial checkpoints found in the G1, G2, and M phases.
At the G1 checkpoint, the regulator protein checks if the cell has reached the critical size and the DNA is free from errors. It also checks whether enough nutrients and growth factors are present to begin DNA synthesis.
At this point, if the cell does not receive the necessary signal, it switches to a resting state called the G0 phase until all the conditions are met.
The cells that pass the G1 checkpoint transit through the synthesis, or S-phase, when the DNA gets replicated.
After this, the cell encounters a second checkpoint at the G2 phase, where the regulator proteins check any errors in the DNA and whether the cell has an appropriate size to enter Mitosis or M-phase.
During Mitosis, the control system verifies if the chromosomes are attached to the spindle and are accurately aligned so that the cycle proceeds for cell division. If at any point the regulator protein detects irreparable damage, cell death occurs. One type of critical regulator proteins are the cyclin-dependent protein kinases, or CDK. CDKs form complexes with cyclins, and their activity affects proteins directly involved in cell growth and DNA synthesis.

the cell cycle control system

The cell cycle is an organized set of events that leads the cell to divide into two daughter cells, each containing chromosomes identical to the parent cell. It is the cell cycle that leads to the formation of an entire organism from a single-cell zygote. Besides, cell division also functions in the renewal or repair of tissues in adult multicellular eukaryotes. For example, in the bone marrow, the stem cells divide to form new blood cells. Although essential for several functions, cell division in the absence of a control mechanism leads to cancer and many genetic diseases.
To ensure DNA replication occurs correctly and each daughter cell inherits the right number of chromosomes, the cell has surveillance mechanisms that make up the cell cycle control system. There are at least two known cell cycle control methods. One of these processes includes a cascade of protein phosphorylations that transitions a cell from one phase to the next. Also, there is a series of checkpoints that monitor the completion of essential events and, if necessary, delay progression to the next phase. At every checkpoint, the regulator proteins prevent the cell initiation from entering the next phase until the previous phase&#39;s errors are rectified.
The first form of regulation includes a highly regulated family of kinases. Kinase activation requires interaction with a second subunit expressed at fixed points of the cell cycle. This secondary component is termed as- a phase-specific &#34;cyclin&#34;&#160; that combines with its partner &#34;cyclin-dependent kinase&#34; (CDK), forming an active complex, each of which exhibits distinct substrate specificity. Regulatory phosphorylation and dephosphorylation fine-tune the function of cyclin-CDK complexes, ensuring a well-defined progression.
The second form of cell cycle regulation - checkpoint control, is more of a surveillance mechanism. Cell cycle checkpoints identify defects in crucial events such as DNA replication and chromosome segregation. For instance, DNA damage triggers a signaling cascade that activates several cell cycle inhibitors. These inhibitors bind critical cell cycle proteins to arrest the cycle until the risk of mutation has been eliminated.

The cell cycle is an organized set of events that leads the cell to divide into two daughter cells, each containing chromosomes identical to the parent ...

Education

JoVE Core

Molecular Biology

Unit 2

Cell Proliferation

KEY TERMS AND CONCEPTS

how cell division is controlled

The cell cycle is the organized process that controls cell division. It helps one cell divide into two daughter cells with chromosomes that match the parent cell. This process is essential for growth from a single-cell zygote and for tissue renewal in adult multicellular eukaryotes.

Cell division also supports repair and replacement in the body. In bone marrow, stem cells divide to make new blood cells. When cell division happens without control, it can lead to cancer and many genetic diseases.

Cells use surveillance systems to keep the cycle on track. These cell cycle control mechanisms help make sure DNA is copied correctly and that each daughter cell gets the right number of chromosomes. One control method uses a cascade of protein phosphorylations to move the cell from one phase to the next.

A key part of this regulation involves cyclins and cyclin-dependent kinases, or CDKs. Cyclins are phase-specific proteins that appear at fixed points in the cycle. When a cyclin binds its partner CDK, the complex becomes active and can act on specific targets. Phosphorylation and dephosphorylation help fine-tune these cyclin-CDK complexes.

The second control method is checkpoint control. Checkpoints are surveillance points that monitor important events, such as DNA replication and chromosome segregation. If a problem is found, regulator proteins delay the cell until the error is fixed. DNA damage can also trigger a signaling cascade that activates cell cycle inhibitors, which bind critical cell cycle proteins and stop the cycle until the risk of mutation has been reduced.

How Cell Division Is Controlled

what is the cell cycle?

Cell Growth and Division in the Cell Cycle

The cell cycle is the process that cells use to grow and divide. It helps living things make new cells for growth and repair. In many cases, it is also the way single cells reproduce. The cycle has two main parts: interphase and cell division. During interphase, the cell grows and prepares for division. During cell division, one cell splits into new cells. This sequence keeps cells in a repeating pattern of growth, copying, and splitting.

interphase

Interphase in the Cell Cycle

Interphase is the part of the cell cycle when a cell grows and prepares to divide. It is a major stage in the life of a cell, and it includes the phases G1, S, and G2. During G1, the cell grows and carries out its normal functions. In the S phase, the cell copies its DNA. During G2, the cell continues to grow and gets ready for mitosis, the stage when the cell divides. Interphase takes up most of the cell cycle. It gives the cell time to build materials, make a copy of its genetic...

The cell cycle is the organized process that controls cell division. It helps one cell divide into two daughter cells with chromosomes that match the parent cell. This process is essential for growth from a single-cell zygote and for tissue renewal in adult multicellular eukaryotes. Cell division also supports repair and replacement in the body. In bone marrow, stem cells divide to make new blood cells. When cell division happens without control, it can lead to cancer and many genetic diseases.

positive regulator molecules

Cyclins and Cdks in Cell Cycle Control

Cyclins and cyclin-dependent kinases help control how cells move through the cell cycle. These positive regulator molecules keep mitotic cell division on schedule so daughter cells can match the parent cell. When this control fails, errors in DNA replication or in the distribution of genetic material can create mutant cells that pass those changes to every new cell they form. Cell cycle checkpoints limit the spread of these abnormal cells. A checkpoint is a control point at a specific stage of...

inhibition of cdk activity

Cdk4/6 Blockers and Cell Cycle Control

Cdk4/6 blockers help control the cell cycle by stopping the signals that push cells from G1 into S phase. Cdks, or cyclin-dependent kinases, must bind cyclins to become active, and cyclin D often pairs with Cdk4/6 to form this active complex. The cyclin D-Cdk4/6 complex then phosphorylates the retinoblastoma protein, or Rb, which normally acts as a tumor suppressor. When Rb is inactivated, cells can move into the next stage of division. In normal cells, Cdk activity is carefully regulated so...

s-cdk initiates dna replication

Cdk Control of DNA Replication Timing

Cdk control of DNA replication timing helps cells copy DNA once each cycle. The cell cycle has four main stages: G1, S, G2, and M. In G1, the cell grows. In S phase, it copies its DNA. In G2, it prepares to divide. In M phase, mitosis divides the cell content into two daughter cells. In eukaryotes, DNA replication starts at many sites on the chromosomes called origins of replication. These origins switch between two states during the cell cycle. In G1, a multiprotein pre-replicative complex,...

m-cdk drives transition into mitosis

Cell Cycle Kinases Trigger Entry into Mitosis

Cell cycle kinases help control the move from G2 into M phase. Checkpoints act as safeguards and gatekeepers, so the cell cycle can continue in good conditions and slow down or stop when problems appear. This regulation is called the cell cycle control system. Cyclin-dependent kinases, or Cdks, work with cyclins to manage cell cycle transitions. A key example is M-Cdk, which is made of Cdk1 bound to M cyclin. M-Cdk helps drive the shift from G2 to M phase by preparing the cell for mitosis. M...

mitogens and the cell cycle

EGF Signaling and Cancer Cell Growth

Epidermal growth factor, or EGF, is a mitogen that helps control cell division. Its receptor, EGFR, sits in the cell membrane and sends a growth signal when EGF binds to it. EGFR is part of the ErbB family of tyrosine kinase receptors, and this signaling helps decide whether a cell will keep proliferating. In healthy tissue, the number of EGFR molecules on the cell surface is tightly regulated. This balance helps cell division match the tissue’s needs. In cancer cells, however, EGFR is often...

replicative cell senescence

Telomeres, Telomerase, and Tumor Control

Telomeres and telomerase help control how many times a cell can divide. Telomeres are short, repetitive DNA sequences at the ends of chromosomes. They are covered by proteins that form a protective cap. In many human body cells, this cap gets a little shorter after each round of cell division. This shortening is part of replicative senescence, the point at which a cell stops dividing permanently. Embryonic stem cells make telomerase, an enzyme that adds telomeric repeats and supports repeated...

abnormal proliferation

Ras and MYC in Uncontrolled Cell Growth

Ras and MYC can drive abnormal cell proliferation, which is uncontrolled cell growth. Under normal conditions, most adult cells stay non-proliferative unless they receive internal or external signals to replace lost cells. In abnormal proliferation, cell division continues even after those signals stop. This persistent growth can lead to tumors. The tumor forms from damaged cells that keep copying themselves. Those cells pass the damage to daughter cells and to later generations of daughter...

cells coordinate growth and proliferation

cells-coordinate-growth-and-proliferation

Cell Size Control in Growth and Muscle

Cell size control helps cells keep their shape, function, and fitness. Many dividing cells grow and then double their mass before they divide. This coordination depends on checkpoints between cell cycle phases, which help the cell stay in balance. When checkpoint control fails, cells may grow without proper control. That loss of coordination can lead to uncontrolled growth and reduced cellular function. In adult tissues, non-dividing cells also adjust size based on metabolic state. Adult...

key terms and concepts

Explore how the cell cycle is regulated by cyclins, CDKs, and checkpoints that help ensure accurate DNA copying and chromosome segregation.

How Cell Division Is Controlled | JoVE K12

molecular biology

JoVE Core Molecular Biology showcases the molecular processes of the cell through clear and concise animated video lessons. Additionally, in scientist-in-action videos, these concepts' application is demonstrated through real experiments in modern laboratories.

Next Generation Science Standards

High School

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

From Molecules to Organisms: Structures and Processes

HS-LS1-4

new-york-state-science-learning-standards

New York State Science Learning Standards

Inheritance and Variation of Traits

HS-LS1-4.

Cell Structure

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

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, ...

Animal and Plant Cell Structure

Animal and plant cells not only differ in their structure, function, and mode of nutrition but also in how they reproduce, specialize, and organize into ...

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 ...

An Introduction to Cell Division

Cell division is the process by which a parent cell divides and gives rise to two or more daughter cells. It is a means of reproduction for single-cell ...

The student will investigate and understand that all living things are composed of one or more cells that support life processes, as described by the cell theory. Key ideas include the development of the cell theory demonstrates the nature of science;

LS.2.a

Cytoplasm

The Nucleus

The Nucleosome

Human DNA is almost two meters long. However, it is compressed inside a tiny nucleus measuring only a few microns in diameter. To make this degree of ...

The Nucleosome Core Particle

Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of ...

Chromatin Packaging

Each human somatic cell contains 6 billion base pairs of DNA. Each base pair is 0.34 nm long, meaning each diploid cell contains a staggering 2 meters of ...

The Endoplasmic Reticulum

Golgi Apparatus

Lysosomes

Mitochondria

Mitochondrial Membranes

Peroxisomes

Ribosomes

Introduction to Cytoskeleton

Centrioles and Centrosomes

Most animal cells comprise a pair of centrioles together called a centrosome. The cell duplicates its centrosome and contains two centrosomes ...

Functions of Life

Human life is characterized by a variety of functions that are essential for survival and well-being. These functions include metabolism, movement, ...

Requirements for Human Life

The Earth and its atmosphere have provided humans with air, water, and food, but these are not the only requirements for survival. Humans also require a ...

The student will investigate and understand that all living things are composed of one or more cells that support life processes, as described by the cell theory. Key ideas include cell structure and organelles support life processes;

LS.2.b

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

Visualizing Onion and Human Cells
ExpandIn this experiment you will prepare different types of cells from a plant and animal, onion and human ...

Prokaryotic vs. Eukaryotic Cells

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

Plant Cells and Tissues

Plant tissues are collections of similar cells performing related functions. Different plant tissues will have their own specialized roles and can be ...

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 ...

The student will investigate and understand that all living things are composed of one or more cells that support life processes, as described by the cell theory. Key ideas include similarities and differences between plant and animal cells determine how they support life processes;

LS.2.c

Mitosis and Cytokinesis

In eukaryotes, the cell division cycle is divided into distinct, coordinated cellular processes that include cell growth, DNA replication/chromosome ...

What is the Cell Cycle?

The cell cycle refers to the sequence of events occurring throughout a typical cell&#8217;s life. In eukaryotic cells, the somatic cell cycle has two ...

Binary Fission

Fission is the division of a single entity into two or more parts, which regenerate into separate entities that resemble the original. Organisms in the ...

Live Cell Imaging of Mitosis

Mitosis is a form of cell division in which a cell&#8217;s genetic material is divided equally between two daughter cells. Mitosis can be broken down into ...

Cell Division

Cell division is fundamental to all living organisms and required for growth and development. As an essential means of reproduction for all living things, ...

Preparation of Onion Root Tips and Solutions
ExpandFor the cell cycle experiment using root tips, first, leave an onion suspended over a beaker of water ...

Observing the Cell Cycle in a Root Tip
ExpandHypotheses: The experimental hypothesis is that in root tips slices that have been treated with nocodazole, a ...

The student will investigate and understand that all living things are composed of one or more cells that support life processes, as described by the cell theory. Key ideas include cell division is the mechanism for growth and reproduction; and

What are Membranes?

A key characteristic of life is the ability to separate the external environment from the internal space. To do this, cells have evolved semi-permeable ...

Membrane Fluidity

Cell membranes are composed of phospholipids, proteins, and carbohydrates loosely attached to one another through chemical interactions. Molecules are ...

Fluid Mosaic Model

The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of ...

What is an Electrochemical Gradient?

Adenosine triphosphate, or ATP, is considered the primary energy source in cells. However, energy can also be stored in the electrochemical gradient of an ...

Diffusion

Diffusion is the passive movement of substances down their concentration gradients&#x2014;requiring no expenditure of cellular energy. Substances, such as ...

Osmosis

Approximately 60% to 95% of the weight of living organisms is attributed to water. Therefore, maintaining appropriate water balance within cells is of ...

Tonicity in Animals

The tonicity of a solution determines if a cell gains or loses water in that solution. The tonicity depends on the permeability of the cell membrane for ...

Tonicity in Plants

Tonicity describes the capacity of a cell to lose or gain water. It depends on the quantity of solute that does not penetrate the membrane. Tonicity ...

Introduction to Membrane Proteins

The cell membrane, or plasma membrane, is an ever-changing landscape. It is described as a fluid mosaic where various macromolecules are embedded in the ...

Facilitated Transport

The chemical and physical properties of plasma membranes cause them to be selectively permeable. Since plasma membranes have both hydrophobic and ...

Primary Active Transport

In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or ...

Secondary Active Transport

One example of how cells use the energy contained in electrochemical gradients is demonstrated by glucose transport into cells. The ion vital to this ...

Receptor-mediated Endocytosis

Overview

Receptor-mediated endocytosis is a process through which bulk amounts of specific molecules can be imported into a cell after binding to cell ...

Pinocytosis

Cells use energy-requiring bulk transport mechanisms to transfer large particles, or large amounts of small particles, into or out of the cell. The cells ...

Phagocytosis

Cells pull particles inward and engulf them in spherical vesicles in an energy-requiring process called endocytosis. Phagocytosis (&#x201C;cellular ...

Exocytosis

Exocytosis is used to release material from cells. Like other bulk transport mechanisms, exocytosis requires energy.

While endocytosis takes particles ...

The student will investigate and understand that all living things are composed of one or more cells that support life processes, as described by the cell theory. Key ideas include cellular transport (osmosis and diffusion) is important for life processes.

LS.2.e

How Cell Division Is Controlled

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