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Unit 4: Cell Communication and Cell Cycle
Unit 4: Cell Communication and Cell Cycle
Biology in Focus Chapters 5.6 & 9 (plus examples from 32 & 33.5)
10 – 15 % of AP Bio Exam
Chapter 5.6 (starting on page 117)
This section has the basics of how cells generate and receive signals, coordinate mechanisms, and respond to environmental cues. This is one of the most important topics in biology because it applies to virtually every other process. I will give you some specific examples to look up in chapters 32 and 33 to take notes over, but as we go forward, you will see any number of examples in all types of systems.
Topic 4.1 Cell Communication
Learning Objectives: Describe the ways that cells can communicate with one another.
Explain how cells communicate with one another over short and long distances
Describe these types of local signaling: through cytoplasmic junctions, through direct contact, through secretion of messenger molecules, through synapses.
Cytoplasmic junctions: Direct transfer of small molecules or ions between neighboring cells
Direct contact: Signaling through physical interactions between cell surface molecules
Secretion of messenger molecules: Cells release signaling molecules into extra space to affect nearby cells.
Synapses: Nerve cells transmit signals across synapses using neurotransmitters binding to receptors on neighboring cells.
Describe the types of long-distance signaling: hormones and endocrine signaling.
Hormones: chemical messengers released by endocrine glands which create a cascade in a cell, typically can pass through without a problem
Endocrine: ligands are sent into the bloodstream to reach other cells in different tissues and parts of the body
Topic 4.2 Introduction to Signal Transduction
Learning Objectives: Describe the components of a signal transduction pathway.
Describe the role of components of a signal transduction pathway in producing a cellular response.
What is transduction? Use Figure 5.22 to describe the three steps involved in a signal transduction pathway.
reception, where the signal binds to a receptor; transduction, where the signal is relayed and amplified inside the cell and response, where the cell carries out a specific action
What is a ligand?
A cellular unit which signals actions in other cells or within one cell
Using Figures 5.23, 5.24, and the text, describe the structure and function of G-protein coupled receptors and ligand-gated ion channels.
Gcpr triggers the cell to start an action. Ligand-gated ion channels are triggered by ligands and are signaled to open an ion channel flow
Use Figure 5.25 and the text to describe the types of signal molecules that interact with intracellular receptors and to explain how these receptors work.
They work with signal molecules like hormones that can enter the cell. When the signal binds to the receptor, it tells the cell's dna to make changes, like turning genes on or off.
Why can it be beneficial to cellular response for the transduction of a signal to involve many intermediate steps?
It amplifies the signal and increases the control a cell has over its actions
What are protein kinases? Use Figure 5.26 to explain how these molecules can participate in a phosphorylation cascade.
Protein kinases are enzymes that add phosphate groups to proteins, changing their activity. In a phosphorylation cascade, one kinase activates another, making the signal stronger and leading to a bigger response in the cell.
What do protein phosphatases do?
Protein phosphatases are enzymes that remove phosphate groups from proteins, turning off or deactivating their activity, and to reset the signaling process.
What are second messengers?
It amplifies the signal the cell receives
Use Figure 5.27 and the text to explain how cAMP works as a second messenger.
cAMP amplifies the signal inside the cell and helps the cell carry out the appropriate response
Use the text and Figure 5.28 to describe how a signal can activate a gene.
A signal molecule binds to a receptor, which triggers a chain of events inside the cell. This activates proteins called transcription factors, which enable specific genes to make proteins that carry out the cell's response.
Topic 4.3 Signal Transduction
Learning Objectives: Describe the role of the environment in eliciting a cellular response.
Describe the different types of cellular responses elicited by a signal transduction pathway.
Topic 4.4 Changes in Signal Transduction Pathways
Learning Objective: Explain how a change in the structure of any signaling molecule affects the activity of the signaling pathway.
Make sure to read the Chapter summary
Use Figure 5.26 and the text to the right of the figure to describe a cytoplasmic response to a signal. Explain how this kind of cascade can lead to signal amplification (textbook example: each molecule of adenylyl cyclase can catalyze the synthesis of many molecules of cAMP.)
Signal amplification happens when one enzyme makes many second messengers, which then activate many proteins, causing a big response.
Chapter 32 - The Internal Environment of Animals: Organization and Regulation (start pg 690)
Compare and contrast the signaling methods, speed of transmission, duration of signals, and overall function of the nervous and endocrine systems. Starts on Pg 696 and table pg 692
The nervous system sends fast, short signals for quick control, while the endocrine system uses slower, longer signals to control things like growth and metabolism.
What are endocrine glands? How are they different from exocrine glands?
Endocrine glands are organs that release hormones directly into the bloodstream, while exocrine glands release their substances like enzymes or sweat through ducts to the outside of the body or into body cavities.
Topic 4.5 Feedback
Learning Objectives: Describe positive and/or negative feedback mechanisms.
Explain how negative feedback helps to maintain homeostasis.
Explain how positive feedback affects homeostasis.
Compare and contrast negative and positive feedback.
Negative feedback reduces or stops a process to maintain balance while positive feedback amplifies or increases a process, often leading to a specific outcome .
Use the text and Figure 32.7 to explain how a simple endocrine pathway works.
In a simple endocrine pathway, a stimulus triggers an endocrine gland to release a hormone, which then causes a response in a target organ, with feedback stopping hormone release once the response is achieved.
What does oxytocin do?
Oxytocin stimulates uterine contractions during childbirth and promotes milk release during breastfeeding.
Use the text and Figure 32.7 and 32.8 to explain how neuroendocrine pathways work.
In neuroendocrine pathways, nerve signals trigger hormone release, which then affects target organs, with feedback to regulate the process.
How do lipid soluble and lipid insoluble hormones differ in their mechanisms of bringing about a cellular response?
Lipid-soluble hormones pass through the cell membrane and bind to receptors inside the cell, while lipid-insoluble hormones bind to receptors on the cell surface, triggering a signaling cascade inside the cell.
Use Figure 32.9 and the text to describe the different effects of epinephrine in different tissues.
Epinephrine stimulates glucose release in the liver, increases heart rate, and causes different blood vessel responses, depending on the tissue, to prepare the body for "fight or flight."
What is homeostasis? Use Figure 32.11 to describe how a thermostat uses a heater to maintain “homeostasis” in room temperature. Use the terms set point, stimulus, sensor, and response in your description.
Homeostasis is the process of maintaining a stable internal environment. In a thermostat system, the set point is the desired room temperature.
What is the difference between a set point and a normal range? Also, how might set points change over the course of an organism’s life?
A set point is a specific value, like body temperature, that the body tries to maintain, while a normal range is the acceptable variation around that set point. Set points can change over an organism’s life due to factors like age, development, or environmental conditions.
Use the text and figures 32.12, 32.13, and 32.14 to describe thermoregulation, endothermy, and ectothermy. Describe adaptations and feedback loops in thermoregulation.
Thermoregulation involves maintaining body temperature through adaptations like shivering and sweating in endotherms, or behavioral changes like basking in ectotherms, with feedback loops that adjust body temperature to the set point, such as sweating to cool down or shivering to warm up.
Read the Chapter summary pg 715.
Chapter 33.5 - Animal Nutrition - Feedback circuits regulate digestion, energy allocation, and appetite
How is metabolic rate related to activity?
Metabolic rate increases with activity as the body requires more energy to fuel muscles and other processes during physical exertion.
How do animals regulate energy storage?
Animals regulate energy storage by converting excess food into fat for long-term storage and using hormones like insulin and glucagon to balance energy storage and release based on current needs.
Describe how insulin and glucagon interact in the regulation of blood sugar levels. Refer to figure 33.19.
Insulin lowers blood sugar by promoting glucose uptake and storage, while glucagon raises blood sugar by breaking down glycogen, maintaining balance through feedback.
Topic 4.6 Cell Cycle
Learning Objectives: Describe the events that occur in the cell cycle.
Explain how mitosis results in the transmission of chromosomes from one generation to the next.
Chapter 9 - The Cell Cycle
This chapter is about how cell division is the basis of the continuity of life. The cell division process is an important part of the cell cycle, the life of a cell from the time it is first formed during division of a parent cell until its own division into two daughter cells. You will learn the mechanics of cell division in eukaryotes and bacteria and then about the molecular control system that regulates the cell cycle, as well as what happens when the control system malfunctions. Mitosis and the cell cycle are involved with asexual reproduction: a parent cell divides into two identical daughter cells with the same genetic makeup as the parent cell (this is different from meiosis (unit 5) which is sexual reproduction resulting in offspring which are different from their parents.)
Explain three reasons why cell division is important.
Cell division is important for growth, tissue repair, and reproduction, allowing organisms to develop, replace damaged cells, and produce offspring.
Define genome, chromosome, and chromatin.
A genome is the complete set of genetic material in an organism, a chromosome is a tightly coiled structure of DNA found in the nucleus, and chromatin is the uncoiled, thread-like form of DNA and proteins that make up chromosomes.
Define somatic cell and gamete. Note that this chapter is about the reproduction of somatic cells.
A somatic cell is any body cell that is not involved in reproduction, while a gamete is a reproductive cell (sperm or egg) that carries half the genetic information for offspring.
Define sister chromatid and centromere. As you do, study figures 9.3, 9.4, and 9.5 to develop strong visual images of these terms.
A sister chromatid is one of two identical copies of a chromosome, connected by a centromere, which is the region where the two chromatids are attached and play a key role in cell division.
Distinguish between interphase, mitosis and cytokinesis. Refer to figure 9.6 the Cell Cycle.
Interphase is the phase where the cell grows and prepares for division, including DNA replication; mitosis is the process where the cell's nucleus divides into two identical nuclei; and cytokinesis is the final step, where the cytoplasm divides, forming two daughter cells.
List and describe the phases of the cell cycle (G1, S, G2, M). What is G0? In which phase does DNA replication occur? What phases are within Interphase?
The cell cycle consists of G1 (growth), S (DNA replication), G2 (preparation for division), and M (mitosis), with Interphase including G1, S, and G2, while G0 is a resting phase where cells are not dividing.
Describe a mitotic spindle.
What is it?
What does it do?
What is an aster?
What is a kinetochore?
How does the mitotic spindle develop?
The mitotic spindle is a structure made of microtubules that helps separate chromosomes during mitosis. An aster is a star-shaped pattern of microtubules around the centrosomes, and a kinetochore is a protein on the chromosome where spindle fibers attach. The spindle forms as the centrosomes move apart and extend microtubules to attach to the chromosomes..
Study the diagrams and the text in figure 9.7. According to the College Board, you won’t be tested on the names of the phases of mitosis, but it is difficult to discuss mitosis and meiosis without referring to them. Your main goal is to write a brief explanation of how doubled chromosomes are split apart and then distributed to the daughter cells. You need to know how many chromosomes are in each stage and when they are separated (and how they are separated).
Describe cytokinesis. How is it different in plant and animal cells?
Cytokinesis is the division of the cytoplasm into two daughter cells, with animal cells split and plant cells forming a cell plate.
Describe binary fission and explain how mitosis might have evolved from this bacterial process.
Binary fission is a form of asexual reproduction in bacteria where the cell splits into two identical daughter cells after replicating its DNA. Mitosis likely evolved from binary fission as more complex mechanisms for DNA separation and division developed in eukaryotic cells.
How is the cell cycle different in different cells of the human body?
The cell cycle varies in different human cells: some cells, like skin cells, divide frequently, while others, like nerve cells, rarely divide or remain in a resting phase (G0), and some, like muscle cells, may only divide in response to injury or specific signals.
Topic 4.5 Regulation of Cell Cycle
Learning Objectives: Describe the role of checkpoints in regulating the cell cycle.
Describe the effects of disruptions to the cell cycle on the cell or organism.
What is the evidence for control of the cell cycle through cytoplasmic signals? (starts on page 198)
Evidence for the control of the cell cycle through cytoplasmic signals comes from experiments where the cytoplasm of cells in different cell cycle stages is transferred into cells at different stages
How is the cell cycle controlled?
The cell cycle is controlled by checkpoints and regulatory molecules
What are checkpoints?
Checkpoints are control points in the cell cycle where the cell assesses whether key processes (like DNA replication or chromosome alignment) have been completed correctly before moving on to the next phase.
Use the text and Figures 9.15 and 9.16 to explain how the cell cycle clock works. Include the role of cyclins.
Describe some of the external signals and conditions that regulate cell division. Include PDGF, density dependent inhibition, and anchorage dependence.
What is the difference between normal cells and cancer cells? Be sure to read all the way to the end of this section to get a complete answer.
Cancer cells differ from normal cells in that they grow uncontrollably, bypassing regulatory checkpoints, avoiding cell death, and often spreading to other parts of the body.
Compare & contrast benign tumors with malignant ones.
Benign tumors are non-cancerous, grow slowly, and do not spread to other parts of the body, while malignant tumors are cancerous, grow rapidly, invade surrounding tissues, and can spread to distant areas (metastasize).
What is metastasis?
Metastasis is the spread of cancer cells from the original (primary) tumor to other parts of the body, where they form new (secondary) tumors.
Why is cancer thought of as a disease of the cell cycle? How do some cancer treatments relate to events in the cell cycle?
Cancer is considered a disease of the cell cycle because it involves uncontrolled cell division due to mutations that disrupt the normal regulation of the cycle.
Read the Chapter Review starting
Unit 4: Cell Communication and Cell Cycle
Unit 4: Cell Communication and Cell Cycle
Biology in Focus Chapters 5.6 & 9 (plus examples from 32 & 33.5)
10 – 15 % of AP Bio Exam
Chapter 5.6 (starting on page 117)
This section has the basics of how cells generate and receive signals, coordinate mechanisms, and respond to environmental cues. This is one of the most important topics in biology because it applies to virtually every other process. I will give you some specific examples to look up in chapters 32 and 33 to take notes over, but as we go forward, you will see any number of examples in all types of systems.
Topic 4.1 Cell Communication
Learning Objectives: Describe the ways that cells can communicate with one another.
Explain how cells communicate with one another over short and long distances
Describe these types of local signaling: through cytoplasmic junctions, through direct contact, through secretion of messenger molecules, through synapses.
Cytoplasmic junctions: Direct transfer of small molecules or ions between neighboring cells
Direct contact: Signaling through physical interactions between cell surface molecules
Secretion of messenger molecules: Cells release signaling molecules into extra space to affect nearby cells.
Synapses: Nerve cells transmit signals across synapses using neurotransmitters binding to receptors on neighboring cells.
Describe the types of long-distance signaling: hormones and endocrine signaling.
Hormones: chemical messengers released by endocrine glands which create a cascade in a cell, typically can pass through without a problem
Endocrine: ligands are sent into the bloodstream to reach other cells in different tissues and parts of the body
Topic 4.2 Introduction to Signal Transduction
Learning Objectives: Describe the components of a signal transduction pathway.
Describe the role of components of a signal transduction pathway in producing a cellular response.
What is transduction? Use Figure 5.22 to describe the three steps involved in a signal transduction pathway.
reception, where the signal binds to a receptor; transduction, where the signal is relayed and amplified inside the cell and response, where the cell carries out a specific action
What is a ligand?
A cellular unit which signals actions in other cells or within one cell
Using Figures 5.23, 5.24, and the text, describe the structure and function of G-protein coupled receptors and ligand-gated ion channels.
Gcpr triggers the cell to start an action. Ligand-gated ion channels are triggered by ligands and are signaled to open an ion channel flow
Use Figure 5.25 and the text to describe the types of signal molecules that interact with intracellular receptors and to explain how these receptors work.
They work with signal molecules like hormones that can enter the cell. When the signal binds to the receptor, it tells the cell's dna to make changes, like turning genes on or off.
Why can it be beneficial to cellular response for the transduction of a signal to involve many intermediate steps?
It amplifies the signal and increases the control a cell has over its actions
What are protein kinases? Use Figure 5.26 to explain how these molecules can participate in a phosphorylation cascade.
Protein kinases are enzymes that add phosphate groups to proteins, changing their activity. In a phosphorylation cascade, one kinase activates another, making the signal stronger and leading to a bigger response in the cell.
What do protein phosphatases do?
Protein phosphatases are enzymes that remove phosphate groups from proteins, turning off or deactivating their activity, and to reset the signaling process.
What are second messengers?
It amplifies the signal the cell receives
Use Figure 5.27 and the text to explain how cAMP works as a second messenger.
cAMP amplifies the signal inside the cell and helps the cell carry out the appropriate response
Use the text and Figure 5.28 to describe how a signal can activate a gene.
A signal molecule binds to a receptor, which triggers a chain of events inside the cell. This activates proteins called transcription factors, which enable specific genes to make proteins that carry out the cell's response.
Topic 4.3 Signal Transduction
Learning Objectives: Describe the role of the environment in eliciting a cellular response.
Describe the different types of cellular responses elicited by a signal transduction pathway.
Topic 4.4 Changes in Signal Transduction Pathways
Learning Objective: Explain how a change in the structure of any signaling molecule affects the activity of the signaling pathway.
Make sure to read the Chapter summary
Use Figure 5.26 and the text to the right of the figure to describe a cytoplasmic response to a signal. Explain how this kind of cascade can lead to signal amplification (textbook example: each molecule of adenylyl cyclase can catalyze the synthesis of many molecules of cAMP.)
Signal amplification happens when one enzyme makes many second messengers, which then activate many proteins, causing a big response.
Chapter 32 - The Internal Environment of Animals: Organization and Regulation (start pg 690)
Compare and contrast the signaling methods, speed of transmission, duration of signals, and overall function of the nervous and endocrine systems. Starts on Pg 696 and table pg 692
The nervous system sends fast, short signals for quick control, while the endocrine system uses slower, longer signals to control things like growth and metabolism.
What are endocrine glands? How are they different from exocrine glands?
Endocrine glands are organs that release hormones directly into the bloodstream, while exocrine glands release their substances like enzymes or sweat through ducts to the outside of the body or into body cavities.
Topic 4.5 Feedback
Learning Objectives: Describe positive and/or negative feedback mechanisms.
Explain how negative feedback helps to maintain homeostasis.
Explain how positive feedback affects homeostasis.
Compare and contrast negative and positive feedback.
Negative feedback reduces or stops a process to maintain balance while positive feedback amplifies or increases a process, often leading to a specific outcome .
Use the text and Figure 32.7 to explain how a simple endocrine pathway works.
In a simple endocrine pathway, a stimulus triggers an endocrine gland to release a hormone, which then causes a response in a target organ, with feedback stopping hormone release once the response is achieved.
What does oxytocin do?
Oxytocin stimulates uterine contractions during childbirth and promotes milk release during breastfeeding.
Use the text and Figure 32.7 and 32.8 to explain how neuroendocrine pathways work.
In neuroendocrine pathways, nerve signals trigger hormone release, which then affects target organs, with feedback to regulate the process.
How do lipid soluble and lipid insoluble hormones differ in their mechanisms of bringing about a cellular response?
Lipid-soluble hormones pass through the cell membrane and bind to receptors inside the cell, while lipid-insoluble hormones bind to receptors on the cell surface, triggering a signaling cascade inside the cell.
Use Figure 32.9 and the text to describe the different effects of epinephrine in different tissues.
Epinephrine stimulates glucose release in the liver, increases heart rate, and causes different blood vessel responses, depending on the tissue, to prepare the body for "fight or flight."
What is homeostasis? Use Figure 32.11 to describe how a thermostat uses a heater to maintain “homeostasis” in room temperature. Use the terms set point, stimulus, sensor, and response in your description.
Homeostasis is the process of maintaining a stable internal environment. In a thermostat system, the set point is the desired room temperature.
What is the difference between a set point and a normal range? Also, how might set points change over the course of an organism’s life?
A set point is a specific value, like body temperature, that the body tries to maintain, while a normal range is the acceptable variation around that set point. Set points can change over an organism’s life due to factors like age, development, or environmental conditions.
Use the text and figures 32.12, 32.13, and 32.14 to describe thermoregulation, endothermy, and ectothermy. Describe adaptations and feedback loops in thermoregulation.
Thermoregulation involves maintaining body temperature through adaptations like shivering and sweating in endotherms, or behavioral changes like basking in ectotherms, with feedback loops that adjust body temperature to the set point, such as sweating to cool down or shivering to warm up.
Read the Chapter summary pg 715.
Chapter 33.5 - Animal Nutrition - Feedback circuits regulate digestion, energy allocation, and appetite
How is metabolic rate related to activity?
Metabolic rate increases with activity as the body requires more energy to fuel muscles and other processes during physical exertion.
How do animals regulate energy storage?
Animals regulate energy storage by converting excess food into fat for long-term storage and using hormones like insulin and glucagon to balance energy storage and release based on current needs.
Describe how insulin and glucagon interact in the regulation of blood sugar levels. Refer to figure 33.19.
Insulin lowers blood sugar by promoting glucose uptake and storage, while glucagon raises blood sugar by breaking down glycogen, maintaining balance through feedback.
Topic 4.6 Cell Cycle
Learning Objectives: Describe the events that occur in the cell cycle.
Explain how mitosis results in the transmission of chromosomes from one generation to the next.
Chapter 9 - The Cell Cycle
This chapter is about how cell division is the basis of the continuity of life. The cell division process is an important part of the cell cycle, the life of a cell from the time it is first formed during division of a parent cell until its own division into two daughter cells. You will learn the mechanics of cell division in eukaryotes and bacteria and then about the molecular control system that regulates the cell cycle, as well as what happens when the control system malfunctions. Mitosis and the cell cycle are involved with asexual reproduction: a parent cell divides into two identical daughter cells with the same genetic makeup as the parent cell (this is different from meiosis (unit 5) which is sexual reproduction resulting in offspring which are different from their parents.)
Explain three reasons why cell division is important.
Cell division is important for growth, tissue repair, and reproduction, allowing organisms to develop, replace damaged cells, and produce offspring.
Define genome, chromosome, and chromatin.
A genome is the complete set of genetic material in an organism, a chromosome is a tightly coiled structure of DNA found in the nucleus, and chromatin is the uncoiled, thread-like form of DNA and proteins that make up chromosomes.
Define somatic cell and gamete. Note that this chapter is about the reproduction of somatic cells.
A somatic cell is any body cell that is not involved in reproduction, while a gamete is a reproductive cell (sperm or egg) that carries half the genetic information for offspring.
Define sister chromatid and centromere. As you do, study figures 9.3, 9.4, and 9.5 to develop strong visual images of these terms.
A sister chromatid is one of two identical copies of a chromosome, connected by a centromere, which is the region where the two chromatids are attached and play a key role in cell division.
Distinguish between interphase, mitosis and cytokinesis. Refer to figure 9.6 the Cell Cycle.
Interphase is the phase where the cell grows and prepares for division, including DNA replication; mitosis is the process where the cell's nucleus divides into two identical nuclei; and cytokinesis is the final step, where the cytoplasm divides, forming two daughter cells.
List and describe the phases of the cell cycle (G1, S, G2, M). What is G0? In which phase does DNA replication occur? What phases are within Interphase?
The cell cycle consists of G1 (growth), S (DNA replication), G2 (preparation for division), and M (mitosis), with Interphase including G1, S, and G2, while G0 is a resting phase where cells are not dividing.
Describe a mitotic spindle.
What is it?
What does it do?
What is an aster?
What is a kinetochore?
How does the mitotic spindle develop?
The mitotic spindle is a structure made of microtubules that helps separate chromosomes during mitosis. An aster is a star-shaped pattern of microtubules around the centrosomes, and a kinetochore is a protein on the chromosome where spindle fibers attach. The spindle forms as the centrosomes move apart and extend microtubules to attach to the chromosomes..
Study the diagrams and the text in figure 9.7. According to the College Board, you won’t be tested on the names of the phases of mitosis, but it is difficult to discuss mitosis and meiosis without referring to them. Your main goal is to write a brief explanation of how doubled chromosomes are split apart and then distributed to the daughter cells. You need to know how many chromosomes are in each stage and when they are separated (and how they are separated).
Describe cytokinesis. How is it different in plant and animal cells?
Cytokinesis is the division of the cytoplasm into two daughter cells, with animal cells split and plant cells forming a cell plate.
Describe binary fission and explain how mitosis might have evolved from this bacterial process.
Binary fission is a form of asexual reproduction in bacteria where the cell splits into two identical daughter cells after replicating its DNA. Mitosis likely evolved from binary fission as more complex mechanisms for DNA separation and division developed in eukaryotic cells.
How is the cell cycle different in different cells of the human body?
The cell cycle varies in different human cells: some cells, like skin cells, divide frequently, while others, like nerve cells, rarely divide or remain in a resting phase (G0), and some, like muscle cells, may only divide in response to injury or specific signals.
Topic 4.5 Regulation of Cell Cycle
Learning Objectives: Describe the role of checkpoints in regulating the cell cycle.
Describe the effects of disruptions to the cell cycle on the cell or organism.
What is the evidence for control of the cell cycle through cytoplasmic signals? (starts on page 198)
Evidence for the control of the cell cycle through cytoplasmic signals comes from experiments where the cytoplasm of cells in different cell cycle stages is transferred into cells at different stages
How is the cell cycle controlled?
The cell cycle is controlled by checkpoints and regulatory molecules
What are checkpoints?
Checkpoints are control points in the cell cycle where the cell assesses whether key processes (like DNA replication or chromosome alignment) have been completed correctly before moving on to the next phase.
Use the text and Figures 9.15 and 9.16 to explain how the cell cycle clock works. Include the role of cyclins.
Describe some of the external signals and conditions that regulate cell division. Include PDGF, density dependent inhibition, and anchorage dependence.
What is the difference between normal cells and cancer cells? Be sure to read all the way to the end of this section to get a complete answer.
Cancer cells differ from normal cells in that they grow uncontrollably, bypassing regulatory checkpoints, avoiding cell death, and often spreading to other parts of the body.
Compare & contrast benign tumors with malignant ones.
Benign tumors are non-cancerous, grow slowly, and do not spread to other parts of the body, while malignant tumors are cancerous, grow rapidly, invade surrounding tissues, and can spread to distant areas (metastasize).
What is metastasis?
Metastasis is the spread of cancer cells from the original (primary) tumor to other parts of the body, where they form new (secondary) tumors.
Why is cancer thought of as a disease of the cell cycle? How do some cancer treatments relate to events in the cell cycle?
Cancer is considered a disease of the cell cycle because it involves uncontrolled cell division due to mutations that disrupt the normal regulation of the cycle.
Read the Chapter Review starting
