Controls on Cell Division and Cell Cycle Regulators
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Questions and Answers

What is the primary role of cyclins in eukaryotic cells?

  • Replicating chromosomes during mitosis.
  • Stimulating cell growth and division.
  • Preventing cells from entering anaphase.
  • Regulating the timing of the cell cycle. (correct)

Internal regulators respond to events outside the cell, directing the cell cycle.

False (B)

Name one type of external regulator and describe its function.

Growth factors stimulate the growth and division of cells.

________ is a disorder in which cells lose the ability to control growth.

<p>cancer</p> Signup and view all the answers

Which of the following describes the function of internal regulators?

<p>They ensure that certain processes inside the cell have been completed before the cell cycle proceeds. (C)</p> Signup and view all the answers

Cancer cells respond normally to the signals that regulate cell growth.

<p>False (B)</p> Signup and view all the answers

Match the type of regulator with its function:

<p>Internal Regulators = Respond to events inside the cell External Regulators = Respond to events outside the cell Growth Factors = Stimulate cell growth and division</p> Signup and view all the answers

What can happen if cell growth in a multicellular organism is not carefully regulated?

<p>Uncontrolled cell growth may lead to the formation of tumors and damage to surrounding tissues. (B)</p> Signup and view all the answers

Which of the following is a key difference in cell division rates between different cell types in the human body?

<p>Most muscle and nerve cells do not divide once developed, while skin, digestive tract, and bone marrow cells divide rapidly. (B)</p> Signup and view all the answers

In a petri dish, cells will continue to grow indefinitely, regardless of contact with other cells or the availability of nutrients.

<p>False (B)</p> Signup and view all the answers

What happens to the rate of cell division when an injury, such as a cut in the skin, occurs?

<p>Cells at the edges of the injury are stimulated to divide rapidly.</p> Signup and view all the answers

The substance discovered by biologists in the early 1980s that, when injected into a nondividing cell, would cause a mitotic spindle to form is called a ______.

<p>cyclin</p> Signup and view all the answers

Match the following cell types with their typical rate of cell division:

<p>Muscle cells = Do not divide once developed Skin cells = Divide rapidly Nerve cells = Do not divide once developed Bone marrow cells = Divide rapidly</p> Signup and view all the answers

What is the effect of removing cells from the center of a petri dish containing a layer of cells?

<p>The cells bordering the open space will begin dividing until they have filled the empty space. (B)</p> Signup and view all the answers

The process of division slows down as the healing process nears completion after an injury.

<p>True (A)</p> Signup and view all the answers

Why is stem cell research considered a potential solution for spinal cord injuries?

<p>Stem cells have shown potential in animal studies to reverse the effects of spinal injuries. (B)</p> Signup and view all the answers

What prompted scientists to search for a substance that might regulate the cell cycle?

<p>They were looking for what would cause the cell to enter another phase of the cycle.</p> Signup and view all the answers

Adult stem cells are only found in bone marrow.

<p>False (B)</p> Signup and view all the answers

Name two potential medical applications of stem cells, besides treating spinal cord injuries.

<p>Growing new liver tissue, replacing heart valves, reversing the effects of diabetes</p> Signup and view all the answers

The production of blood cells by stem cells in bone marrow helps replace cells lost due to normal ______ and ______.

<p>wear, tear</p> Signup and view all the answers

Match each stem cell type with its description:

<p>Adult Stem Cells = Stem cells isolated from bone marrow and other tissues in the body. Embryonic Stem Cells = Stem cells isolated from early human embryos. Therapeutic application of Stem cells = Growing new liver tissue.</p> Signup and view all the answers

What is a common characteristic found in all cancers?

<p>Breakdown in the control of the cell cycle (C)</p> Signup and view all the answers

The p53 gene promotes cell division by ensuring chromosomes are replicated quickly, even if errors occur.

<p>False (B)</p> Signup and view all the answers

How might a defect in the p53 gene contribute to the development of cancer?

<p>loss of growth control, and an inability to respond to signals that regulate cell growth</p> Signup and view all the answers

Stem cells are ______ cells that can differentiate into a variety of cell types.

<p>unspecialized</p> Signup and view all the answers

Match the following concepts with their descriptions:

<p>Tumor = A mass of abnormal cells. Metastasis = The spread of cancer cells from the primary site to other parts of the body. p53 Gene = A gene that normally halts the cell cycle until all chromosomes have been properly replicated. Stem Cells = Unspecialized cells with the potential to differentiate into various cell types.</p> Signup and view all the answers

A scientist is developing a new anticancer drug. Which of the following would be the MOST promising target for the drug's action?

<p>Interfering with the growth signals of other cells. (B)</p> Signup and view all the answers

If cyclin were injected into a cell that was already in mitosis, what would MOST likely happen?

<p>Mitosis would proceed normally, as cyclin levels are already high during this phase. (C)</p> Signup and view all the answers

Describe the role of stem cells in embryonic development and their significance in regenerative medicine.

<p>Stem cells act as the source for all cells in developing body, they provide potential to repair damaged tissues and organs by differentiating into specialized cells</p> Signup and view all the answers

Flashcards

Adult Stem Cells

Undifferentiated cells found in adults that can differentiate into specific cell types.

Bone Marrow Stem Cells

Specialized cells in bone marrow that produce various blood cell types.

Regenerative Medicine

Restoring function to damaged tissues or organs using new cells.

Adult Stem Cell Potential

Stem cells can differentiate into nerve, muscle, and liver cells when isolated from bone marrow and other tissues in the body.

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Personalized Stem Cell Therapy

Using a person's own stem cells to grow replacement tissue.

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Cyclins

Proteins that regulate the timing of the cell cycle in eukaryotic cells.

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Cancer

The general term for a disease in which some body cells grow uncontrollably and spread to other parts of the body.

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Non-dividing Cells

Muscle and nerve cells that typically do not divide once developed.

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Rapidly Dividing Cells

Skin and digestive tract cells that divide rapidly throughout life to replace worn-out cells.

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Petri Dish

A dish containing nutrient broth used to grow cells in a laboratory, observing controlled growth in the cells inside.

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Contact Inhibition

The phenomenon where cells stop growing when they come into contact with other cells.

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Cell Division in Healing

Stimulation of cell division at the edges of an injury to produce new cells and initiate healing.

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Cell Cycle Regulators

Substances made of protein which stimulate cell division and cause a mitotic spindle to form.

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Internal regulators

Proteins that respond to events inside the cell and allow the cell cycle to proceed only when certain processes have happened inside the cell.

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External regulators

Proteins that respond to events outside the cell and direct cells to speed up or slow down the cell cycle.

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Growth factors

External regulators that stimulate the growth and division of cells, important during embryonic development and wound healing.

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Tumors

Masses of cells formed by cancer cells that can damage the surrounding tissues.

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Cyclin (original)

The protein discovered that seemed to regulate the cell cycle.

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Mitosis checkpoint proteins

Regulatory proteins that ensure a cell doesn't enter mitosis until all its chromosomes have been replicated

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Stem Cells

Cells that can divide without limit and differentiate into specialized cells.

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p53 Gene

A gene that halts the cell cycle until chromosomes are properly replicated; often defective in cancer cells.

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Unregulated Cell Growth

Loss of growth control and failure to respond to regulatory signals, leading to tumor formation.

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Cell Contact Response

They stop dividing upon contact with other cells.

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Loss of Response to Regulators

When cells dont respond to growth regulators, which can lead to tumors.

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Study Notes

  • Multicellular organisms carefully control cell growth and division.
  • Cells do not all move through the cell cycle at the same rate.
  • Muscle and nerve cells typically don't divide once developed.
  • Skin, digestive tract, and bone marrow cells grow and divide rapidly, completing cycles in a few hours to replace worn-out cells.

Controls on Cell Division

  • Scientists can observe the effects of controlled cell growth in the lab using nutrient broth in a petri dish.
  • Cells typically grow until they form a thin layer on the dish bottom and stop growing when they contact other cells.
  • If cells are removed in the center, cells at the edge of the space begin to divide until the space fills.
  • Similar processes happen within the body: injuries stimulate cell division for healing, then the rate slows as healing completes.

Cell Cycle Regulators

  • Scientists have long searched for substances that regulate the cell cycle, indicating when cells should divide, duplicate chromosomes, etc.
  • In the early 1980s, biologists discovered cyclins, proteins that regulate the cell cycle.
  • Experiments showed injecting cytoplasm from a cell in mitosis into another cell in interphase would cause that cell to enter mitosis.
  • Cyclins regulate the timing of the cell cycle in eukaryotic cells.
  • Internal regulators are proteins inside the cell that respond to internal events, allowing the cell cycle to proceed only when certain processes have occurred.
  • Examples of Internal regulators: Regulatory proteins ensure chromosomes are replicated before mitosis begins; another prevents anaphase until chromosomes are attached to the mitotic spindle.
  • External regulators are proteins that respond to events outside the cell.
  • External regulators direct cells to speed up or slow down the cell cycle. Growth factors, important external regulators, stimulate cell growth and division, especially during development and wound healing.
  • Molecules on neighboring cells can have the opposite effect, stopping cell cycles to prevent excessive growth.

Uncontrolled Cell Growth

  • Uncontrolled cell growth consequences in multicellular organisms are severe.
  • Cancer is a disorder where body cells lose the ability to control growth.
  • Cancer cells do not respond to growth signals, dividing uncontrollably and forming tumors that damage surrounding tissues.
  • Cancer cells may break loose and spread, disrupting normal activities and causing medical problems or death.
  • Cancer causes include smoking tobacco, radiation exposure, and even viral infections.
  • A commonality of all cancers: The control over the cell cycle has broken down.
  • Some cancer cells no longer respond to external growth regulators, while others fail to produce internal regulators.
  • Many cancer cells have a defect in the p53 gene, which normally halts the cell cycle until all chromosomes have been properly replicated.
  • Damaged p53 genes cause cells to lose needed information to respond to signals that would normally control their growth.

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Chapter 10.3 - Regulating the Cell Cycle PDF

Description

Multicellular organisms carefully control cell growth and division. Cells don't all move through the cell cycle at the same rate. Scientists observe controlled cell growth in the lab. Injuries stimulate cell division for healing, then the rate slows as healing completes.

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