Name: unchecked cell growth patterns
Uploaded: 2023-04-30T18:28:50.000Z
Duration: 2 min 23 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-LS1-4

Abnormal Proliferation

&#160;Cells have special genes called tumor suppressor genes that can neutralize the effect of harmful genetic alterations and prevent uncontrolled cell proliferation.
For example, p53 is a tumor suppressor gene that maintains a basal level of expression under normal cell conditions.
Mdm2 protein acts as a negative regulator of p53 activity. It binds to the functional domain of p53 protein, reducing its transcriptional activity.
Mdm2 also exhibits p53-specific ubiquitin ligase activity and catalyzes the attachment of ubiquitin to p53. The polyubiquitinated p53 proteins are then recognized and degraded by the proteasome, maintaining it at extremely low levels inside the cell.
However, when the cells encounter abnormal conditions such as cellular stress or excessive mitogenic stimulation, the p53 gene is induced to enforce its tumor suppression activity.
For instance, overexpression of transcription factor Myc in the nucleolus triggers the accumulation of a tumor suppressor protein called- Arf.
Arf directly binds to Mdm2, inhibiting its ubiquitin ligase activity and sequestering it in the nucleolus, thus releasing active p53 into the nucleoplasm.
Active p53 then binds to specific DNA sequences and induces the expression of its target genes that can trigger accelerated DNA repair, arrest cell cycle, or induce cell apoptosis, thus, preventing further propagation of damaged cells.
&#160;However, when genetic or epigenetic changes alter p53 activity, it results in the collapse of the cell&#8217;s protective mechanisms. Such cells start proliferating aggressively and form tumors.
Besides, overexpression of Mdm2 is also frequently observed in liposarcomas.&#160; Although such tumors retain the normal p53 gene, the increased levels of Mdm2 keep p53 in an inactive state, hence, restricting their tumor suppression activity.

abnormal proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell&#39;s growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter cells and all the future daughter cells. Such abnormal cell proliferation defines the characteristic of what we call cancer. The best example to explain this condition is the mutation in the Ras and MYC proteins.
Normal Ras proteins are GTPases that function in signal transduction from cell surface receptors to the cell&#8217;s interior. Ras proteins can be denoted as the binary switches that cycle between ON and OFF states during cellular growth. Usually, these switches are tightly regulated, but in Ras-related diseases such as cancer, the Ras gene mutation or their regulator renders Ras proteins persistently active. For instance, a single amino acid missense mutation in the K-Ras protein (a type of Ras protein) impairs its normal functioning. The mutant K-Ras cannot be inactivated, leading to continuous growth stimulation. K-Ras mutation occurs in 15%- 20% of human cancers, and is most commonly seen in colon cancer, lung cancer, pancreatic cancer, and leukemia.
Abnormal cell proliferation can also occur when mutation results in overexpression of MYC protein. The MYC oncogene belongs to a family of &#34;super-transcription factors&#34; and is deregulated in more than 50% of human cancers. The MYC affects a spectrum of cellular functions, including protein translation, cell cycle progression, ribosome biosynthesis, cell proliferation, differentiation, survival, and immune surveillance.

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. ...

Education

JoVE Core

Cell Biology

Unit 1

Cell Proliferation

KEY TERMS AND CONCEPTS

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 explain how cells behave when growth signals go wrong. It is an important concept in biology because it connects normal cell division with disease-related changes. Studying this process helps students see how tightly the body controls growth under normal conditions.

Unchecked Cell Growth Patterns

what is the cell cycle?

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 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 abnormal proliferation changes normal cell growth, why cells divide too often, and how loss of control affects tissue balance in biology.

Unchecked Cell Growth Patterns | 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.

Tennessee Academic Standards

Biology

From Molecules to Organisms: Structures and Processes

BIO1.LS1.6

Minnesota Academic Standards in Science

9-12

Life Science

3.1.1 9L.3.1.1.2

Arizona Science Standards

HS.L1

HS.L1U1.22

HS.L1U3.23

Florida Department of Education

SC.912.L.16

SC.912.L.16.8

Texas Essential Knowledge and Skills

BIO.6

BIO.6.C

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Overview

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structure-and-organization-of-smooth-muscles

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...

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Heterochromatin

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chromatin-position-affects-gene-expression

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Organization of Genes

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The centromere is a DNA ...

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HS-LS1-1

Characteristics of Life

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

Levels of Organization

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The Scientific Method

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Taxonomy

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Phylogeny

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HS-LS1-2

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Regulation of Metabolism

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Positive and Negative Feedback Loops

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Functions of Life

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Negative and Positive Feedback

Homeostatic Imbalance

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pH Homeostasis

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homeostatic-imbalances-in-body-temperature

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HS-LS1-3

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Interphase

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The Cell Cycle Control System

Positive Regulator Molecules

Use a model to illustrate the role of the cell cycle and differentiation in producing and maintaining complex organisms. Emphasis is on conceptual understanding that mitosis passes on genetically identical materials via replication, not on the details of each phase in mitosis.

Unchecked Cell Growth Patterns

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