chap 10 Flashcards
1
Q
What are the two main reasons cells divide?
A
- DNA Demand: As a cell grows, it places more demands on its DNA. 2. Nutrient and Waste Management: Larger cells have more difficulty moving nutrients and wastes across the cell membrane.
2
Q
What happens to chromosomes before cell division?
A
Each chromosome is copied and consists of two identical ‘sister’ chromatids.
3
Q
What are the four phases of the eukaryotic cell cycle?
A
- G1 Phase (Growth Phase 1): Cell grows and prepares for DNA replication. 2. S Phase (Synthesis Phase): DNA is synthesized and replicated. 3. G2 Phase (Growth Phase 2): Cell continues to grow and prepares for mitosis. 4. M Phase (Mitosis/Cytokinesis): Cell divides into two daughter cells.
4
Q
How does cell division differ between prokaryotes and eukaryotes?
A
- Prokaryotes: DNA replicates, and the cell membrane pinches to separate the cell contents. - Eukaryotes: Cell division involves a more complex process, including mitosis and cytokinesis.
5
Q
What are the four phases of mitosis?
A
- Prophase: Chromatin condenses into chromosomes, nuclear envelope breaks down, and spindle fibers form. 2. Metaphase: Chromosomes line up at the cell’s center. 3. Anaphase: Sister chromatids separate and move to opposite ends of the cell. 4. Telophase: Chromosomes gather at opposite ends, lose their shape, and nuclear membranes form.
6
Q
What is cytokinesis, and how does it differ in plants and animals?
A
- Cytokinesis: The cytoplasm divides, resulting in two daughter cells. - In Animals: The cell membrane pinches inward. - In Plants: A cell plate forms midway between the divided nuclei.
7
Q
What are stem cells, and what are their potential uses?
A
- Stem Cells: Undifferentiated cells with the potential to regenerate and differentiate into various cell types. - Potential Uses: Treating stroke, Alzheimer’s, Parkinson’s, spinal cord injury, diabetes, cancer, and more. They are also used in regenerative and personalized medicine.
8
Q
What are the three types of stem cells?
A
- Embryonic Stem Cells: Pluripotent, can become any cell type. 2. Adult Stem Cells: Multipotent, can only become certain cell types. 3. Induced Pluripotent Stem Cells (iPSCs): Adult cells reprogrammed to an embryonic-like state.
9
Q
What is apoptosis, and why is it important?
A
- Apoptosis: Programmed cell death essential for maintaining healthy tissues. - Importance: Prevents uncontrolled cell growth, which can lead to diseases like cancer.
10
Q
What role does the p53 gene play in cancer?
A
- The p53 gene regulates cell division and promotes apoptosis in damaged cells. - When mutated or non-functional, it can contribute to uncontrolled cell growth and cancer.
11
Q
What are internal and external regulators of the cell cycle?
A
- Internal Regulators: Proteins that respond to events inside the cell, ensuring proper sequence and timing of the cell cycle. - External Regulators: Proteins that respond to signals outside the cell, such as growth factors, which can speed up or slow down the cell cycle.
12
Q
What are cyclins, and what is their role in the cell cycle?
A
- Cyclins: Proteins that bind to cyclin-dependent kinases (CDKs) to activate them. - Role: They drive the cell cycle forward by phosphorylating target proteins at specific checkpoints.
13
Q
What are the key checkpoints in the cell cycle?
A
- G1 Checkpoint: Ensures the cell is ready for DNA synthesis. 2. G2 Checkpoint: Ensures DNA is correctly replicated. 3. M Checkpoint: Ensures chromosomes are properly attached to the spindle.
14
Q
What is the significance of the surface area-to-volume ratio in cells?
A
- It determines the efficiency of material exchange (nutrients, oxygen, waste) across the cell membrane. - A higher ratio is crucial for proper cell function and survival.
15
Q
What is contact inhibition, and how does it relate to cancer?
A
- Contact Inhibition: A process where cells stop dividing when they come into contact with other cells. - Relation to Cancer: Loss of contact inhibition leads to uncontrolled cell division, a hallmark of cancer.
16
Q
What is the role of spindle fibers during mitosis?
A
Spindle fibers help separate sister chromatids by attaching to chromosomes and pulling them to opposite ends of the cell during anaphase.
17
Q
What is the difference between chromatin and chromosomes?
A
- Chromatin: Uncoiled DNA and proteins present during interphase. - Chromosomes: Condensed and coiled chromatin visible during cell division.
18
Q
What happens during the S phase of the cell cycle?
A
DNA is synthesized and replicated, ensuring each daughter cell receives an identical copy of the genetic material.
19
Q
What is the significance of the G1 phase in the cell cycle?
A
The G1 phase is a growth phase where the cell increases in size, produces organelles, and prepares for DNA replication.
20
Q
What is the role of cyclin-dependent kinases (CDKs) in the cell cycle?
A
CDKs, when activated by cyclins, phosphorylate target proteins to drive the cell cycle forward at specific checkpoints.
21
Q
What is the difference between totipotent, pluripotent, and multipotent stem cells?
A
- Totipotent: Can form any cell type, including extraembryonic tissues (e.g., fertilized egg). 2. Pluripotent: Can form any cell type in the body (e.g., embryonic stem cells). 3. Multipotent: Can form only specific cell types (e.g., adult stem cells).
22
Q
What is the purpose of apoptosis in multicellular organisms?
A
Apoptosis eliminates damaged, infected, or unnecessary cells, maintaining tissue homeostasis and preventing diseases like cancer.
23
Q
What are growth factors, and how do they influence the cell cycle?
A
- Growth Factors: External proteins that stimulate cell growth and division. - Influence: They bind to cell receptors, signaling the cell to progress through the cell cycle.
24
Q
What is the role of the p53 gene in preventing cancer?
A
The p53 gene monitors DNA integrity. If damage is detected, it can pause the cell cycle for repair or trigger apoptosis to prevent the proliferation of damaged cells.
25
What are the two main pathways of apoptosis?
1. Intrinsic Pathway: Triggered by internal cell stress (e.g., DNA damage). 2. Extrinsic Pathway: Triggered by external signals (e.g., immune system signals).
26
What is the difference between benign and malignant tumors?
1. Benign Tumors: Non-cancerous, localized, and do not spread to other tissues. 2. Malignant Tumors: Cancerous, invasive, and can metastasize to other parts of the body.
27
What is the significance of the G2 checkpoint in the cell cycle?
The G2 checkpoint ensures that DNA replication is complete and accurate before the cell enters mitosis.
28
What is the role of the nuclear envelope during mitosis?
The nuclear envelope breaks down during prophase to allow spindle fibers to access chromosomes and reforms during telophase around the separated chromosomes.
29
What is the difference between embryonic stem cells and induced pluripotent stem cells (iPSCs)?
1. Embryonic Stem Cells: Derived from early embryos and are naturally pluripotent. 2. iPSCs: Adult cells reprogrammed to an embryonic-like state through genetic modification.
30
What is the significance of the M checkpoint in the cell cycle?
The M checkpoint ensures that all chromosomes are properly attached to spindle fibers before anaphase begins, preventing errors in chromosome segregation.
31
What is the role of the cell plate in plant cell division?
The cell plate forms during cytokinesis in plant cells, eventually developing into a new cell wall that separates the two daughter cells.
32
What is the relationship between the cell cycle and cancer?
Cancer results from uncontrolled cell division due to mutations in genes that regulate the cell cycle, such as p53 or cyclins, leading to tumor formation.
33
What is the difference between regeneration and differentiation in stem cells?
1. Regeneration: Stem cells divide to replace damaged or lost cells. 2. Differentiation: Stem cells specialize into specific cell types with unique functions.
34
What is the role of RNA molecules in regulating the cell cycle?
RNA molecules, such as microRNAs (miRNAs), can regulate gene expression by binding to mRNA, influencing the production of proteins involved in cell cycle control.
35
What is the significance of the surface area-to-volume ratio in cell division?
- As cells grow, their volume increases faster than their surface area, making it harder to exchange materials efficiently. Cell division restores a favorable surface area-to-volume ratio.
36
37
What is the role of the nuclear membrane during mitosis?
The nuclear membrane breaks down during prophase to allow spindle fibers to access chromosomes and reforms during telophase around the separated chromosomes.
38
What is the significance of contact inhibition in normal cells?
Contact inhibition prevents cells from dividing when they come into contact with other cells, ensuring controlled growth. Loss of contact inhibition is a hallmark of cancer.
39
What is the difference between intrinsic and extrinsic apoptosis pathways?
* Intrinsic Pathway: Triggered by internal signals like DNA damage.
* Extrinsic Pathway: Triggered by external signals like immune system molecules.
40
What is the role of cyclins in the cell cycle?
Cyclins bind to cyclin-dependent kinases (CDKs) to activate them, driving the cell cycle forward at specific checkpoints.
41
What is the G0 phase, and when do cells enter it?
The G0 phase is a resting state where cells exit the cell cycle and stop dividing. Cells enter G0 when they are not actively preparing to divide (e.g., nerve or muscle cells).
42
What is the significance of DNA replication errors in cancer development?
Errors in DNA replication can lead to mutations in genes that regulate the cell cycle (e.g., p53), resulting in uncontrolled cell division and cancer.
43
What is the role of growth factors in cell division?
Growth factors are external proteins that bind to cell receptors, signaling the cell to progress through the cell cycle and divide.
44
What is the difference between benign and malignant tumors?
* Benign Tumors: Non-cancerous, localized, and do not spread.
* Malignant Tumors: Cancerous, invasive, and can metastasize to other tissues.
45
What is the role of spindle fibers in mitosis?
Spindle fibers attach to chromosomes and pull sister chromatids apart during anaphase, ensuring each daughter cell receives an identical set of chromosomes.
46
What is the significance of stem cells in regenerative medicine?
Stem cells can differentiate into various cell types, making them valuable for repairing or replacing damaged tissues in conditions like spinal cord injury, Parkinson's disease, and diabetes.
47
What is the role of checkpoints in the cell cycle?
Checkpoints ensure that the cell cycle proceeds correctly by monitoring key events like DNA replication and chromosome attachment. If errors are detected, the cell cycle is paused or apoptosis is triggered.
48
What is the difference between embryonic stem cells and adult stem cells?
* Embryonic Stem Cells: Pluripotent, can become any cell type in the body.
* Adult Stem Cells: Multipotent, can only become specific cell types related to their tissue of origin.
49
What is the role of p53 in the cell cycle?
The p53 protein monitors DNA integrity. If damage is detected, it can pause the cell cycle for repair or trigger apoptosis to prevent the proliferation of damaged cells.
50
What is the significance of chromatids in mitosis?
Chromatids are identical copies of a chromosome formed during DNA replication. They are separated during anaphase to ensure each daughter cell receives an identical set of chromosomes.
51
What is the role of cytokinesis in cell division?
Cytokinesis divides the cytoplasm and organelles, completing the formation of two daughter cells after mitosis.
52
What is the difference between prokaryotic and eukaryotic cell division?
* Prokaryotes: Binary fission, where DNA replicates and the cell splits into two.
* Eukaryotes: Mitosis (nuclear division) followed by cytokinesis (cytoplasmic division).
53
What is the role of RNA molecules in cell cycle regulation?
RNA molecules, such as microRNAs (miRNAs), regulate gene expression by binding to mRNA, influencing the production of proteins involved in cell cycle control.
54
What is the significance of stem cell differentiation in development?
Stem cell differentiation allows a single fertilized egg to develop into a multicellular organism with specialized cell types and tissues.
55
What is the role of cleavage in cell division?
Cleavage refers to the division of the cytoplasm during cytokinesis, particularly in animal cells, where the cell membrane pinches inward.
56
What is the significance of chromosome condensation during mitosis?
Chromosome condensation ensures that DNA is tightly packed and organized, making it easier to separate during anaphase without tangling or breaking.
57
What is the role of proteins in regulating the cell cycle?
Proteins like cyclins, CDKs, and p53 regulate the cell cycle by controlling checkpoints, ensuring proper DNA replication, and triggering apoptosis if necessary.
58
What is the difference between regenerative medicine and personalized medicine?
* Regenerative Medicine: Focuses on repairing or replacing damaged tissues using stem cells.
* Personalized Medicine: Tailors treatments to an individual’s genetic makeup, often using stem cells for targeted therapies.
59
What is the role of spindle checkpoints in mitosis?
Spindle checkpoints ensure that all chromosomes are properly attached to spindle fibers before anaphase begins, preventing errors in chromosome segregation.
60
What is the significance of stem cell potency?
Stem cell potency refers to the ability of stem cells to differentiate into different cell types:
* Totipotent: Can form any cell type, including extraembryonic tissues.
* Pluripotent: Can form any cell type in the body.
* Multipotent: Can form only specific cell types.
61
What is the role of nutrient exchange in cell growth and division?
Efficient nutrient exchange is critical for cell growth and division. As cells grow, their surface area-to-volume ratio decreases, making it harder to exchange materials, which is why cells divide to maintain efficiency.
