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10.3 Regulating the Cell Cycle - Lesson Summary

Controls on Cell Division Dozens of proteins regulate the cell cycle.

Cyclins are proteins that regulate the timing of the cell cycle in eukaryotic cells.

Regulatory proteins are proteins that control the cell cycle both inside and outside of the cell.

• Internal regulators allow the cell cycle to proceed when certain events have occurred INSIDE a cell.

• Ex. make sure a cell does not divide until chromosomes have replicated

• Ex. Prevents cell from entering anaphase until chromosomes are attached to spindle

• External regulators are proteins that respond to events OUTSIDE the cell. Some of these are called growth factors which stimulate the cell cycle, very important during embryonic development and wound healing. Other external regulators cause the cell cycle to slow down or stop, preventing excessive growth and keeps body tissues from disrupting one another.

Apoptosis is programmed cell death that plays a key role in the development of tissues and organs.

Cancer: Uncontrolled Cell Growth Cancer is a disorder in which cells divide uncontrollably, forming a mass of cells called a tumor.

Cancers are caused by defects in genes that regulate cell growth.

Treatments for cancer include:

• Surgery, removal of cancerous tumors.

• Radiation, which interferes with the copying of DNA in multiplying cancer cells.

• Chemotherapy, which is the use of chemicals to kill cancer cells.

Controls on Cell Division

For Questions 1–6, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true.

STOP 1. Cells tend to continue dividing when they come into contact with other cells.

SLOWS DOWN 2. Cell division speeds up when the healing process nears completion.

CYCLINS 3. Proteins called growth factors regulate the timing of the cell cycle in eukaryotic cells.

TRUE 4. If chromosomes have not attached to spindle fibers during metaphase, an internal regulatory protein will prevent the cell from entering anaphase.

SPEED UP 5. Growth factors are external regulatory proteins that slow down the cell cycle.

TRUE 6. Once apoptosis is triggered, a cell proceeds to self-destruct.

Cancer: Uncontrolled Cell Growth

7. What is cancer?

DISORDER IN WHICH SOME THE BODY’S OWN CELLS LOSE THE ABILITY TO CONTROL GROWTH

8. What are the two basic types of tumors? Explain how they are different.

TUMORS – MAY BE MALIGNANT OR BENIGN

M- CANCEROUS – WILL INVADE AND DESTROY HEALTHY TISSUE AROUND IT OR IN OTHER PARTS OF THE BODY

B- NONCANCEROUS – IT DOES NOT SPREAD TO OTHER PARTS OF THE BODY

9. Why can cancer be life threatening?

RAPIDLY DIVIDING CANCER CELLS TAKE NUTRIENTS AWAY FROM HEALTHY TISSUES. THIS LEADS TO A DISRUPTION OF THE PROPER FUNCTIONING OF BODY ORGANS THAT CAUSES ILLNESS AND MAY LEAD TO DEATH.

10. Complete the cause-and-effect chart by giving an example of an effect caused by each type of regulatory protein.

|Factors Affecting the Cell Cycle |

|Cause |Effect |

|Cyclins |TELL A CELL WHEN TO BEGIN STEPS OF THE CELL CYCLE (EX. GROWTH, DNA SYNTHESIS, MITOSIS, CYTOKINESIS) |

|Internal regulatory proteins |STOP A CELL FROM GOING TO THE NEXT STAGE OF THE CELL CYCLE IF INTERNAL EVENTS HAVE NOT OCCURRED (EX. |

| |PREVENT A CELL FROM ENTERING MITOSIS UNTIL CHROMOSOMES HAVE REPLICATED - S PHASE) |

|External regulatory proteins |SPEED UP THE CELL CYCLE (EX. FOR EMBRYONIC GROWTH AND WOUND HEALING) OR SLOW DOWN THE CELL CYCLE (EX.|

| |SO THAT ONE BODY TISSUE’S GROWTH DOES NOT DISRUPT ANOTHER’S) |

11. What is the cause of cancer?

DEFECTS IN GENES THAT REGULATE CELL GROWTH AND DIVISION

12. How do radiation and chemotherapy affect cancer cells? RADIATION DISRUPTS THE CANCER CELL CYCLE BY INTERFERRING WITH THE COPYING OF DNA. CHEMO – chemicals that KILL CANCER CELLS.

13. Fill out the flowchart by completing each statement with the correct word or words.

Name Class Date

10.4 Cell Differentiation - Lesson Summary

From One Cell to Many Multicellular organisms produced via sexual reproduction begin life as a single cell.

Early cell divisions lead to the formation of an embryo.

Then, individual cells become specialized in both form and function through the process of differentiation.

Once cells of a certain type, such as nerve cells or muscle cells, have formed, the cells cannot develop into a different type of cell.

Stem Cells and Development During an organism’s development, some cells differentiate to become a wide variety of body cells.

A fertilized egg and the first few cells in an embryo are able to form any kind of cell and tissue. Such a cell is termed totipotent.

A blastocyst is an embryonic stage that consists of a hollow ball of cells. These cells are able to become any type of body cell. Such cells are termed pluripotent.

Unspecialized cells that can develop into differentiated cells are called stem cells. Stem cells are found in embryos and in adults.

• Embryonic stem cells are the pluripotent cells of an early embryo.

• Adult stem cells are multipotent, which means they can produce many, but not all, types of differentiated cells.

Frontiers in Stem Cell Research Scientists want to learn about the signals that tell a cell to become either specialized or multipotent.

Potential benefits of stem cell research include the repair or replacement of damaged cells and tissues.

Research with human stem cells is controversial because it involves ethical issues of life and death.

From One Cell to Many

For Questions 1–4, complete each statement by writing the correct word or words.

1. Humans, pets, and petunias all pass through an early stage of development called a(n) EMBRYO.

2. Cells become SPECIALIZED through the process of differentiation.

3. Scientists have mapped the outcome of every CELL DIVISION that leads to differentiation in the development of the microscopic worm C. elegans.

4. Most cells in the adult body are no longer capable of DIFFERENTIATION.

Stem Cells and Development

For Questions 5–7, write the letter of the correct answer on the line at the left.

C 5. Which is an example of a totipotent cell?

A. blastocyst

B. bone cell

C. fertilized egg

D. lymphocyte

D 6. Cells that are pluripotent are unable to develop into the tissue that

A. forms the skin.

B. lines the digestive tract.

C. produces blood cells.

D. surrounds an embryo.

A 7. Adult stem cells are best described as

A. multipotent.

B. pluripotent.

C. totipotent.

D. unable to differentiate.

8. Complete the concept map by identifying some of the types of cells that embryonic stem cells give rise to. Then explain how stem cells are like the stem of a plant.

MANY DIFFERENT TYPES OF CELLS CAN COME FROM STEM CELLS, LIKE THE BRANCHES EMERGING FROM A STEM

Vary – DIFFERENT TYPES OF CELLS (NERVE, FAT, MUSCLE, BLOOD…)

Frontiers in Stem Cell Research

For Questions 9–11, write the letter of the correct answer on the line at the left.

A 9. Which is not a new, potential benefit of stem cell research?

A. growing new skin cells to repair a cut

B. replacing heart cells damaged by heart attacks

C. repairing breaks between nerve cells in spinal injuries

D. preventing suffering and death caused by cellular damage

D 10. What is the main reason that embryonic stem cell research is considered ethically controversial?

A. growing new skin cells to repair a cut

B. replacing heart cells damaged by heart attacks

C. repairing breaks between nerve cells in spinal injuries

D. preventing suffering and death caused by cellular damage

B 11. What is one new technology that could make stem cell research less controversial?

A. implanting skin cells instead of stem cells in damaged tissue

B. developing the ability to switch on the genes that make an adult cell pluripotent

C. replacing stem cells with cancer cells

D. using the Internet to get more people to accept stem cell research

Stem Cells and Development

Unlike most cells during development, certain cells will maintain the ability to become different cells. Stem cells have the ability to differentiate into other types of cells.

Write the term from the word box that describes each part of the diagram.

Answer the questions.

1. Is the following sentence true or false? Totipotent cells can differentiate into any type of cell. TRUE

2. Adult stem cells in the brain can produce (A)

A. nerve cells.

B. muscle cells.

C. skin cells.

D. egg cells.

3. A blastocyst develops from a(n) fertilized egg or zygote.

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Name Class Date

Chapter 10 Review

Use the clues and words to help you write the vocabulary terms from the chapter in the blanks.

1. Division of the cell nucleus mitosis

2. Division of the cytoplasm of a cell cytokinesis

3. Condition in which cells grow uncontrollably cancer

Complete the linear concept maps using the terms below. All the terms will not be used.

4.

5.

Answer the questions.

6. The ratio of surface area to volume limits (D)

A. the amount of food a cell needs. C. the type of cell.

B. the number of times a cell can divide. D. the size of the cell.

7. Why are most cells small?SURFACE AREA TO-VOLUME RELATIONSHIP – IF A CELL GREW TOO BIG IT WOULD HAVE TROUBLE MOVING FOOD, NUTRIENTS, WASTES INTO OR OUT OF THE CELL, information overload

8. Which of the following is a form of asexual reproduction? (A)

A. binary fission C. fusion

B. fertilization D. meiosis

9. “As organisms develop, their cells differentiate into specialized cells.” In this sentence, differentiate means (C)

A. to see a difference. C. to develop for specific jobs.

B. to divide more quickly. D. to become less specific.

Use the diagrams below to answer questions 10 and 11.

10. What is the name for the process shown here? MITOSIS

11. Write the name of each phase on the line below the diagram.

A. ANAPHASE B. TELOPHASE C. PROPHASE D. METAPHASE

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blastocyst

Fat cell

Nerve cell

wbc

Cancer cells do not respond to signals that regulate cell GROWTH.

Embryonic Stem Cells

can become

Blastocyst White blood cell

Fat cell Smooth muscle cell

Inner cell mass Nerve cell

cancer mitosis interphase cytokinesis

cancer cell cycle cytokinesis

During the

a

cell grows, prepares for division, and divides.

causes

cells

to divide

uncontrollably.

Cancer cells form a mass of cells called a TUMOR.

Cancer cells may break loose and SPREAD throughout the body.

Cancer cells form tumors in other tissues by METASTASIS.

Smooth muscle cell

Inner cell mass

cell cycle

Cancer

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