Name: cell cycle stages and checkpoints
Uploaded: 2023-04-30T12:01:48.000Z
Duration: 56 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Inheritance and Variation of Traits

3.1.9-12.D

What is the Cell Cycle?

The cell cycle refers to the sequence of events throughout a cell&#39;s typical life, including growth, DNA replication, sometimes more growth, and division.
For sexually reproducing organisms, life begins as a zygote, a fertilized egg. Over time, that original single cell grows and divides in a controlled manner to produce a multicellular complex individual.
Cells continue this process, especially to maintain and repair tissues during the progression of aging.
In contrast, single-celled organisms like bacteria rely on cell division to simply reproduce via binary fission.
Unfortunately, when cell division is left unchecked, cancer results, with a loss of control over genomic sequences that regulate the normal process.

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 stages: the interphase and the mitotic phase. During interphase, the cell grows, performs its basic metabolic functions, copies its DNA, and prepares for mitotic cell division. Then, during mitosis and cytokinesis, the cell divides its nuclear and cytoplasmic materials, respectively. This generates two daughter cells that are identical to the original parent cell. The cell cycle is essential for the growth of the organism, replacement of damaged cells, and regeneration of aged cells. Cancer is the result of uncontrolled cell division sparked by a gene mutation.
<h4>Cell Cycle Checkpoints</h4>
There are three major checkpoints in the eukaryotic cell cycle. At each checkpoint, the progression to the next cell cycle stage can be halted until conditions are more favorable. The G1 checkpoint is the first of these, where a cell&#8217;s size, energy, nutrients, DNA quality, and other external factors are evaluated. If the cell is deemed inadequate, it does not continue to the S phase of interphase. The G2 checkpoint is the second checkpoint. Here, the cell ensures that all of the DNA has been replicated and is not damaged before entering mitosis. If any DNA damage is detected that cannot be repaired; the cell may undergo apoptosis, or programmed cell death. The M or spindle checkpoint ensures that all the sister chromatids are correctly attached to the spindle microtubules at the metaphase plate before the cell enters anaphase.
<h4>Cancer: When the Cell Cycle Goes Awry</h4>
Cell cycle checkpoints ensure that healthy cells move through the cell cycle in a regulated way. However, cancer cells often bypass these checkpoints. Each successive round of unchecked cell division produces more damaged daughter cells. Additionally, cancer cells in the human body can divide many more times than normal cells, which can only undergo about 40-60 rounds of division. Cancer cells express telomerase, an enzyme that repairs the wear and tear at the ends of chromosomes that is typically caused by cell division.

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 ...

Education

JoVE Core

Cell Biology

Unit 1

Cell Proliferation

KEY TERMS AND CONCEPTS

cell cycle stages and checkpoints

The cell cycle is the set of events that a typical eukaryotic cell goes through during its life. In somatic cells, it has two main stages: interphase and the mitotic phase. Interphase is the time when the cell grows, carries out basic metabolic functions, copies its DNA, and gets ready to divide.

The mitotic phase comes next. During mitosis, the nucleus divides, and during cytokinesis, the cytoplasm divides. These steps produce two daughter cells that are identical to the original parent cell. The cell cycle supports organism growth, replacement of damaged cells, and regeneration of aged cells.

The cycle is controlled by checkpoints that help keep cell division regulated. The G1 checkpoint checks the cell’s size, energy, nutrients, DNA quality, and other external factors before the cell moves into S phase. The G2 checkpoint makes sure DNA has been fully copied and is not damaged before mitosis begins. The M, or spindle, checkpoint confirms that sister chromatids are attached correctly to the spindle microtubules at the metaphase plate before anaphase starts.

If damage cannot be repaired at the G2 checkpoint, the cell may undergo apoptosis, which is programmed cell death. When checkpoints fail, cancer can develop because cell division becomes uncontrolled after a gene mutation. Cancer cells can bypass these controls and divide many more times than normal cells, which usually divide about 40 to 60 times. They also express telomerase, an enzyme that helps repair the wear at the ends of chromosomes caused by repeated division.

Cell Cycle Stages and Checkpoints

The cell cycle is the set of events that a typical eukaryotic cell goes through during its life. In somatic cells, it has two main stages: interphase and the mitotic phase. Interphase is the time when the cell grows, carries out basic metabolic functions, copies its DNA, and gets ready to divide. The mitotic phase comes next. During mitosis, the nucleus divides, and during cytokinesis, the cytoplasm divides. These steps produce two daughter cells that are identical to the original parent cell.

interphase

Cell Growth Phases Before Mitosis

Interphase is the part of the cell cycle when a eukaryotic cell grows and gets ready for mitosis. In a typical human cell, the full cell cycle lasts about 24 hours. Interphase makes up about 95 percent of that time and includes three stages: G1, S, and G2. After mitosis and cytokinesis, cells enter G1, or gap 1. During this stage, cells grow continuously and prepare for DNA replication. They are metabolically active and copy important organelles and biochemical molecules, including proteins. <br...

the cell cycle control system

Cell Cycle Checkpoints and Regulation

The cell cycle is controlled by checkpoints and regulator proteins that help cells divide in an orderly way. These controls monitor whether a cell is ready to move from one stage to the next. They help prevent division from continuing when conditions are not right. The control system depends on proteins that can either encourage or block progress through the cycle. Some of these regulators act as signals that push the cell forward. Others act as brakes that slow the cycle when problems are...

positive regulator molecules

Positive Regulators in Cell Growth

Positive regulator molecules help cells move through the cell cycle. The cell cycle is the series of steps a cell uses to grow and divide. These molecules act as signals that support progress through each stage. Two important examples are cyclins and cyclin-dependent kinases, or CDKs. Cyclins are proteins that rise and fall during the cell cycle. CDKs are enzymes that work with cyclins to help control cell-cycle events. Together, these positive regulators help the cell advance when conditions...

inhibition of cdk activity

How CDK Inhibitors Slow Cell Division

Cyclin-dependent kinase (CDK) inhibitors slow cell division by blocking CDK activity. CDKs are enzymes that help control the cell cycle, which is the series of steps a cell follows to grow and divide. When CDKs are inhibited, the cycle can pause instead of moving forward. The video focuses on this control point in cell growth. CDK inhibition is important because it helps regulate when cells enter the next stage of the cycle. By stopping CDK activity, cells do not continue dividing at the wrong...

s-cdk initiates dna replication

S-Cdk Starts the DNA Copying Process

S-Cdk starts the DNA copying process by triggering DNA replication. S-Cdk is a cyclin-dependent kinase that helps move the cell into S phase, the part of the cell cycle when DNA is copied. This step matters because the cell must begin replication at the right time. S-Cdk adds phosphate groups to target proteins, which changes their activity and helps turn on the machinery needed for DNA synthesis. The result is that replication can begin in a controlled way. This process is an important part...

m-cdk drives transition into mitosis

M-Cdk Triggers the Start of Mitosis

M-Cdk triggers the start of mitosis by helping a cell move from interphase into division. It is a key cell-cycle regulator that turns on the mitotic program at the right time. The M-Cdk complex includes a cyclin and a cyclin-dependent kinase. When this complex becomes active, it sends signals that push the cell into mitosis. This step helps control when chromosomes begin to condense and the nuclear changes of division can begin. Understanding M-Cdk is important because it links cell-cycle...

mitogens and the cell cycle

Mitogen Signals in Cell Division

Mitogens are signals that help cells move through the cell cycle. The cell cycle is the set of stages a cell follows to grow and divide. In many cells, mitogens are needed before the cell can enter division. These signals work through pathways inside the cell. One important route is the MAP kinase signaling pathway, which helps pass the mitogen message from the cell surface to the cell’s interior. This signaling helps the cell respond and continue through the cycle. Mitogens are closely tied...

replicative cell senescence

Telomere Shortening and Cell Aging

Replicative cell senescence is a form of cell aging linked to repeated cell division. As cells divide, their telomeres shorten. Telomeres are protective DNA caps at the ends of chromosomes. When telomeres become too short, cells can no longer keep dividing in the same way. The cell enters senescence, a state in which it stays alive but stops dividing. This process helps explain how division limits can affect cell growth over time.

abnormal proliferation

Unchecked Cell Growth Patterns

Abnormal proliferation is a pattern of cell growth that does not follow normal control. In healthy tissue, cells divide only when they are needed. When that control is lost, cells can keep multiplying in an unusual way. This kind of cell growth can be seen in different settings. It may involve cells that divide too fast, too often, or when they should stop. The result is tissue that grows in a way that no longer matches the body’s normal balance. Understanding abnormal proliferation helps...

cells coordinate growth and proliferation

cells-coordinate-growth-and-proliferation

Cell Size Homeostasis and Checkpoints

Cells coordinate growth and proliferation to keep cell size under control. Growth increases cell mass, while proliferation creates new cells. Together, these processes help cells maintain size homeostasis, which means keeping a stable size over time. The cell cycle includes a checkpoint called the size checkpoint. At this point, the cell checks whether it has grown enough before it divides. This control helps connect growth with cell division, so cells do not become too small or too large. <br...

key terms and concepts

Learn how interphase, mitosis, cytokinesis, and cell cycle checkpoints control cell division, and how checkpoint failure can lead to cancer.

Cell Cycle Stages and Checkpoints | 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

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

From Molecules To Organisms: Structures And Processes

HS-LS1-4

Tennessee Academic Standards

Biology

From Molecules to Organisms: Structures and Processes

BIO1.LS1.6

Minnesota Academic Standards in Science

2.2.1 9L.2.2.1.2

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Arizona Science Standards

HS.L1

HS.L1U1.22

HS.L1U3.23

Alabama Course of Study Science

9-12.B.1.3

Next Generation Science Standards

Florida Department of Education

SC.912.L.16

SC.912.L.16.8

Interphase

The cell cycle occurs over approximately 24 hours (in a typical human cell) and in two distinct stages: interphase, which includes three phases of the ...

The Cell Cycle Control System

Positive Regulator Molecules

Inhibition of CDK Activity

Mitosis and Cytokinesis

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

Chromosome Duplication

Cohesins

Condensins

The Mitotic Spindle

Centrosome Duplication

Spindle Assembly

Attachment of Sister Chromatids

Forces Acting on Chromosomes

Separation of Sister Chromatids

The Spindle Assembly Checkpoint

Anaphase A and B

Anaphase Promoting Complex

The Contractile Ring

Determining the Plane of Cell Division

The Phragmoplast

Distribution of Cytoplasmic Content

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 ...

Cell Cycle Analysis

Cell cycle refers to the set of events through which a cell grows, replicates its genome, and ultimately divides into two daughter cells through 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 ...

Fertilization

During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ...

Cleavage and Blastulation

After a large-single-celled zygote is produced via fertilization, the process of cleavage occurs while zygotes travel through the uterine tube. Cleavage ...

Gastrulation

Gastrulation establishes the three primary tissues of an embryo: the ectoderm, mesoderm, and endoderm. This developmental process relies on a series of ...

Neurulation

Neurulation is the embryological process which forms the precursors of the central nervous system and occurs after gastrulation has established the three ...

Cell Migration

Cell migration, the process by which cells move from one location to another, is essential for the proper development and viability of organisms ...

an-introduction-to-developmental-genetics

An Introduction to Developmental Genetics

Development is the complex process through which a single-celled embryo transforms into a multicellular organism. Developmental processes are guided by ...

An Introduction to Organogenesis

Organogenesis is the process by which organs arise from one of three germ layers during the later stages of embryonic development. Researchers studying ...

Fate Mapping

Fate mapping is a technique used to understand how embryonic cells divide, differentiate, and migrate during development. In classic fate mapping ...

Students who demonstrate understanding can use a model to illustrate the role of cellular division (mitosis) and differentiation in producing and maintaining complex organisms.  Assessment Boundary: Assessment does not include specific gene control mechanisms or rote memorization of the steps of mitosis.

DNA Packaging

DNA as a Genetic Template

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

Structure of a Gene

A gene is the fundamental unit of heredity. Every individual has two copies of each gene, one inherited from each parent. Although most people contain the ...

Chromosome Structure

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

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 ...

The Nucleosome

DNA in a human cell is almost 2m long and it is packed inside a tiny nucleus that is only a few microns in diameter. The level of compaction of DNA inside ...

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 ...

Nucleosome Remodeling

Nucleosomes are the basic units of chromatin compaction. Each nucleosome consists of the DNA bound tightly around a histone core, which makes the DNA ...

Chromatin Packaging

Each human somatic cell contains 6 billion base-pairs of DNA. Each base-pair is 0.34 nm long, which means that each diploid cell contains a staggering 2 ...

Karyotyping

Proteins: From Genes to Degradation

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 ...

Mutations

Mutations are changes in the sequence of DNA. These changes can occur spontaneously or they can be induced by exposure to environmental factors. Mutations ...

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

Genome Size and the Evolution of New Genes

Gene Families

Students who demonstrate understanding can ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring. Assessment Boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.

3.1.9-12.P

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 ...

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 ...

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 ...

What is Meiosis?

Meiosis is the process by which diploid cells divide to produce haploid daughter cells. In humans, each diploid cell contains 46 chromosomes, half from ...

Meiosis I

Meiosis is a carefully orchestrated set of cell divisions, the goal of which&#x2014;in humans&#x2014;is to produce haploid sperm or eggs, each containing ...

Meiosis II

Meiosis II is the second and final stage of meiosis. It relies on the haploid cells produced during meiosis I, each of which contain only 23 ...

Crossing Over

Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where ...

Nondisjunction

During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed ...

Base-pairing and DNA Repair

The DNA Replication Fork

Lagging Strand Synthesis

The Replisome

Proofreading

Synthesis of new DNA molecules is carried out by the enzyme DNA polymerase, which adds nucleotides on the daughter strand complementary to the template ...

Replication in Prokaryotes

DNA replication has three main steps: initiation, elongation, and termination. Replication in prokaryotes begins when initiator proteins bind to the ...

Replication in Eukaryotes

In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high fidelity before ...

Telomeres and Telomerase

background-and-environment-affect-phenotype

Background and Environment Affect Phenotype

Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as ...

Gene Evolution - Fast or Slow?

types-of-genetic-transfer-between-organisms

Types of Genetic Transfer Between Organisms

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 ...

Students who demonstrate understanding can make and defend a claim based on evidence that inheritable genetic variations may result from (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors. Assessment Boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.

3.1.9-12.Q

What is Population Genetics?

A population is composed of members of the same species that simultaneously live and interact in the same area. When individuals in a population breed, ...

Students who demonstrate understanding can apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population. Assessment Boundary: Assessment does not include Hardy-Weinberg calculations.

3.1.9-12.R

Cell Cycle Stages and Checkpoints

Description

Transcript

Tags

More videos by Standards