AOS1 Cell Cycle and Cell Growth, Death and Differentiation Flashcards

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1
Q

What is binary fission?

A

Binary fission is the process by which prokaryotic cells divide to reproduce asexually.

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2
Q

In which type of cells does binary fission occur?

A

Binary fission occurs in prokaryotic cells, such as bacteria and archaea.

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3
Q

What is the first step of binary fission?

A

The first step is the replication of the cell’s DNA.

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4
Q

How does DNA replication occur in prokaryotic cells during binary fission?

A

The circular DNA molecule is copied, starting at the origin of replication, resulting in two identical DNA molecules.

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4
Q

What happens after DNA replication in binary fission?

A

The two DNA molecules move to opposite ends of the cell.

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5
Q

What structure forms to divide the prokaryotic cell during binary fission?

A

A septum (a new cell wall) forms between the two DNA molecules.

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6
Q

What is the final step of binary fission?

A

The cell splits into two daughter cells, each with an identical copy of the original DNA.

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7
Q

How do the daughter cells compare to the parent cell after binary fission?

A

The daughter cells are genetically identical to the parent cell.

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8
Q

Why is binary fission considered an asexual reproduction method?

A

Because it involves only one parent cell and produces genetically identical offspring without the involvement of sexual gametes.

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9
Q

What is the role of the origin of replication in binary fission?

A

It is the specific location on the circular DNA where replication begins.

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10
Q

How does binary fission contribute to the rapid growth of bacterial populations?

A

It allows for quick and efficient reproduction, often resulting in exponential population growth under favorable conditions.

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11
Q

What factors can influence the rate of binary fission in prokaryotic cells?

A

Environmental conditions such as nutrient availability, temperature, and pH can affect the rate of binary fission.

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12
Q

How does binary fission ensure genetic consistency?

A

The DNA is replicated accurately, and each daughter cell receives an identical copy of the DNA, maintaining genetic consistency.

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13
Q

Can binary fission lead to genetic variation? If so, how?

A

While binary fission itself does not create genetic variation, mutations during DNA replication can introduce genetic changes.

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14
Q

What is the significance of the septum formation during binary fission?

A

The septum ensures that the cell divides into two separate entities, each with its own complete set of DNA.

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15
Q

How does the size of prokaryotic cells change during binary fission?

A

The cell grows to roughly double its original size before dividing into two smaller daughter cells.

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16
Q

Why is binary fission efficient for prokaryotic organisms?

A

It is a simple and quick process that allows for rapid population increase, essential for survival and adaptation in changing environments.

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17
Q

What role do cell membrane and cell wall play in binary fission?

A

The cell membrane and cell wall grow inward at the septum to separate the two new cells.

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18
Q

How often can binary fission occur under optimal conditions?

A

Some bacteria can undergo binary fission every 20 minutes under optimal conditions.

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19
Q

What is the primary benefit of binary fission for prokaryotic cells?

A

It enables rapid and efficient reproduction, allowing prokaryotic populations to quickly adapt to their environments.

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20
Q

What are the main phases of the eukaryotic cell cycle?

A

Interphase and the mitotic (M) phase.

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21
Q

What are the sub-phases of interphase?

A

G1 phase, S phase, and G2 phase.

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22
Q

What occurs during the G1 phase of interphase?

A

The cell grows and carries out normal functions, while also preparing for DNA replication.

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23
Q

What happens during the S phase of interphase?

A

DNA replication occurs, resulting in the duplication of chromosomes.

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24
Q

What takes place during the G2 phase of interphase?

A

The cell continues to grow and prepares for mitosis by producing the proteins and organelles needed for cell division.

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25
Q

What are the sub-phases of mitosis?

A

Prophase, metaphase, anaphase, and telophase.

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26
Q

What happens during prophase?

A

Chromatins condense into visible chromosomes, the nuclear envelope begins to disintegrate, and the mitotic spindle starts to form.

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27
Q

What occurs during metaphase?

A

Chromosomes align at the metaphase plate (the cell’s equatorial plane) (down the middle).

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28
Q

What occurs during anaphase?

A

Sister chromatids are pulled apart to opposite poles of the cell by the spindle fibers.

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29
Q

What takes place during telophase?

A

Chromosomes de-condense back into chromatin, the nuclear envelope re-forms around each set of chromosomes, and the spindle apparatus disassembles.

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30
Q

What is cytokinesis?

A

Cytokinesis is the process of dividing the cytoplasm to form two distinct daughter cells.

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31
Q

How does cytokinesis differ in animal cells and plant cells?

A

In animal cells, cytokinesis occurs through the formation of a cleavage furrow. In plant cells, a cell plate forms to divide the cells.

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32
Q

What is the cleavage furrow?

A

The cleavage furrow is an indentation that appears in the cell membrane during cytokinesis in animal cells, eventually leading to the cell splitting into two.

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33
Q

What is the cell plate, and how is it formed?

A

The cell plate is a structure that forms in plant cells during cytokinesis, created by vesicles from the Golgi apparatus coalescing at the center of the cell to form a new cell wall.

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34
Q

What is the significance of the mitotic spindle?

A

The mitotic spindle, made of microtubules, is crucial for separating chromosomes during mitosis.

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35
Q

How do centrioles function in animal cell mitosis?

A

Centrioles help organize the mitotic spindle and ensure proper distribution of chromosomes.

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36
Q

What role does the nuclear envelope play during mitosis?

A

The nuclear envelope breaks down in prophase and re-forms around the separated chromosomes in telophase.

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37
Q

What ensures that each daughter cell receives an identical set of chromosomes?

A

The precise alignment and separation of chromosomes during metaphase and anaphase.

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38
Q

Why is the eukaryotic cell cycle tightly regulated?

A

To ensure accurate DNA replication and division, preventing mutations and maintaining cellular health.

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39
Q

What is apoptosis?

A

Apoptosis is a regulated process of programmed cell death that occurs in multicellular organisms.

40
Q

Why is apoptosis important for organisms?

A

Apoptosis is crucial for maintaining cellular homeostasis, development, and removing damaged or potentially harmful cells.

41
Q

What triggers apoptosis?

A

Apoptosis can be triggered by internal signals (such as DNA damage) or external signals (such as growth factor withdrawal or death receptor activation).

42
Q

What are caspases?

A

Caspases are a family of protease enzymes that play a central role in the execution of apoptosis.

43
Q

How are caspases activated?

A

Caspases are activated in a cascade, starting with initiator caspases that then activate executioner caspases.

44
Q

What are the two main pathways of apoptosis?

A

The intrinsic (mitochondrial) pathway and the extrinsic (death receptor) pathway.

45
Q

What initiates the intrinsic pathway of apoptosis?

A

The intrinsic pathway is initiated by internal stress signals, such as DNA damage or oxidative stress, leading to mitochondrial outer membrane permeabilization.

46
Q

What role do mitochondria play in the intrinsic pathway of apoptosis?

A

Mitochondria release cytochrome c into the cytoplasm, which helps form the apoptosome and activate caspase-9.

47
Q

What initiates the extrinsic pathway of apoptosis?

A

The extrinsic pathway is initiated by the binding of extracellular death ligands to death receptors on the cell surface.

48
Q

What is the role of death receptors in the extrinsic pathway?

A

Death receptors transmit apoptotic signals from extracellular death ligands, leading to the activation of caspase-8.

49
Q

What are the key morphological features of apoptosis?

A

Cell shrinkage, chromatin condensation, membrane blebbing, and formation of apoptotic bodies.

50
Q

How are apoptotic bodies removed from the body?

A

Apoptotic bodies are phagocytosed (ingested) and broken down by macrophages (A type of white blood cell that kills microorganisms, and removes dead cells) or neighbouring cells.

51
Q

What is the difference between apoptosis and necrosis?

A

Apoptosis is a controlled, programmed process that avoids inflammation, while necrosis is an uncontrolled cell death resulting from injury, often causing inflammation.

52
Q

How is apoptosis regulated?

A

Apoptosis is regulated by a balance between pro-apoptotic and anti-apoptotic proteins, such as those in the Bcl-2 family.

53
Q

What is the role of the Bcl-2 family of proteins in apoptosis?

A

The Bcl-2 family includes both pro-apoptotic and anti-apoptotic proteins that regulate mitochondrial membrane permeability and cytochrome c release.

54
Q

How can dysregulation of apoptosis contribute to disease?

A

Insufficient apoptosis can lead to cancer, while excessive apoptosis can contribute to degenerative diseases.

55
Q

What is the apoptosome?

A

The apoptosome is a complex formed in the intrinsic pathway that activates caspase-9, leading to the activation of executioner caspases.

56
Q

What is the role of p53 in apoptosis?

A

p53 is a tumor suppressor protein that can induce apoptosis in response to DNA damage or other stress signals.

57
Q

How do cells ensure that apoptosis is a contained process?

A

Apoptotic cells break into small apoptotic bodies that are quickly phagocytosed, preventing the release of harmful substances into the surrounding tissue.

58
Q

How do therapeutic strategies target apoptosis in cancer treatment?

A

Some therapies aim to induce apoptosis in cancer cells by activating pro-apoptotic pathways or inhibiting anti-apoptotic proteins.

59
Q

What can result from disruption to the regulation of the cell cycle?

A

Disruption to the regulation of the cell cycle can lead to uncontrolled cell division, potentially resulting in cancer.

60
Q

How does malfunctioning apoptosis contribute to cancer?

A

Malfunctioning apoptosis can allow damaged or abnormal cells to survive and proliferate, contributing to tumor development and cancer progression.

61
Q

What are oncogenes?

A

Oncogenes are mutated or overexpressed genes that promote excessive cell division and contribute to cancer development.

62
Q

What are tumor suppressor genes?

A

Tumor suppressor genes are genes that normally help prevent uncontrolled cell growth and promote apoptosis. When these genes are inactivated, cancer can develop.

63
Q

What is the role of the p53 gene in cancer prevention?

A

The p53 gene encodes a protein that helps regulate the cell cycle and induce apoptosis in response to DNA damage. Mutations in p53 are common in many cancers.

64
Q

How does the evasion of apoptosis contribute to cancer?

A

Cancer cells often acquire the ability to evade apoptosis, allowing them to survive and proliferate despite signals that would normally trigger cell death.

65
Q

What are the hallmarks of cancer cells?

A

The hallmarks of cancer cells include sustained proliferative signaling, evasion of growth suppressors, resistance to cell death, enabling replicative immortality, inducing angiogenesis (new blood cells), and activating invasion and metastasis (secondary malignant growths).

66
Q

What is angiogenesis in the context of cancer?

A

Angiogenesis is the process by which cancer cells stimulate the growth of new blood vessels to supply nutrients and oxygen, supporting tumor growth.

67
Q

How do cancer cells differ from normal cells in terms of growth signals?

A

Cancer cells can grow without the external growth signals required by normal cells, often producing their own growth signals.

68
Q

What is the significance of telomerase in cancer cells?

A

Many cancer cells express high levels of telomerase, an enzyme that extends telomeres, allowing them to divide indefinitely and avoid cellular senescence (the cessation of cell division).

69
Q

How can mutations in cell cycle regulators lead to cancer?

A

Mutations in cell cycle regulators, such as cyclins and cyclin-dependent kinases (CDKs), can lead to uncontrolled cell division and cancer.

70
Q

What is the relationship between DNA repair mechanisms and cancer?

A

Defective DNA repair mechanisms can result in the accumulation of genetic mutations, increasing the risk of cancer.

71
Q

How do cancer cells resist cell death?

A

Cancer cells can resist cell death by overexpressing anti-apoptotic proteins and downregulating pro-apoptotic proteins.

72
Q

What role do mutations in the Ras gene play in cancer?

A

Mutations in the Ras gene (family of proteins that are expressed in every animal cell) can lead to constant activation of cell proliferation pathways, contributing to uncontrolled cell growth and cancer.

73
Q

How does chronic inflammation contribute to cancer?

A

Chronic inflammation can lead to DNA damage, promote cell proliferation, and create a tumor-promoting environment.

74
Q

What is the significance of the BRCA1 and BRCA2 genes in cancer?

A

Mutations in the BRCA1 and BRCA2 genes, which are involved in DNA repair, significantly increase the risk of breast and ovarian cancer.

75
Q

How do cancer cells modify their metabolism to support rapid growth?

A

Cancer cells often switch to aerobic glycolysis (the Warburg effect) to produce energy and biosynthetic precursors needed for rapid growth.

76
Q

How does the immune system typically respond to cancer cells?

A

The immune system can recognize and destroy cancer cells, but cancer cells often develop mechanisms to evade immune detection and attack.

77
Q

What therapeutic strategies target the cell cycle and apoptosis in cancer treatment?

A

Therapeutic strategies include drugs that inhibit specific cell cycle proteins, activate apoptosis pathways, and block survival signals in cancer cells.

77
Q

What are stem cells?

A

Stem cells are undifferentiated cells capable of self-renewal and differentiation into specialized cell types.

78
Q

What does it mean for a stem cell to be totipotent?

A

Totipotent stem cells can differentiate into all cell types, including embryonic and extra-embryonic tissues, such as the placenta.

79
Q

What is pluripotency in stem cells?

A

Pluripotent stem cells can differentiate into nearly all cell types that make up the body, but not extra-embryonic tissues.

80
Q

What is the difference between totipotent and pluripotent stem cells?

A

Totipotent stem cells can form all cell types including extra-embryonic tissues, while pluripotent stem cells can form all body cell types but not extra-embryonic tissues.

81
Q

What are multipotent stem cells?

A

Multipotent stem cells can differentiate into a limited range of cell types within a specific tissue or organ.

82
Q

What is self-renewal in the context of stem cells?

A

Self-renewal is the ability of stem cells to divide and produce more stem cells, maintaining the stem cell population.

83
Q

What is differentiation in stem cells?

A

Differentiation is the process by which a stem cell develops into a more specialized cell type with distinct functions.

84
Q

How do stem cells contribute to tissue repair and regeneration?

A

Stem cells can differentiate into various cell types needed to replace damaged or lost cells, aiding in tissue repair and regeneration.

85
Q

What are embryonic stem cells?

A

Embryonic stem cells are pluripotent stem cells derived from the inner cell mass of a blastocyst, capable of differentiating into nearly all cell types.

86
Q

What are adult stem cells?

A

Adult stem cells, or somatic stem cells, are multipotent stem cells found in specific tissues that can differentiate into cell types of that tissue.

87
Q

What are induced pluripotent stem cells (iPSCs)?

A

iPSCs are somatic cells reprogrammed to a pluripotent state, capable of differentiating into nearly all cell types.

88
Q

What is the significance of stem cell niche?

A

The stem cell niche is the microenvironment that provides signals to regulate stem cell behavior, including self-renewal and differentiation.

89
Q

What are some applications of stem cells in medicine?

A

Stem cells are used in regenerative medicine, tissue engineering, and treatments for diseases like leukemia, as well as for research in developmental biology.

90
Q

What ethical concerns are associated with stem cell research?

A

Ethical concerns primarily involve the use of embryonic stem cells, which requires the destruction of embryos.

91
Q

How do stem cells maintain genetic stability during self-renewal?

A

Stem cells employ mechanisms like accurate DNA replication and repair to maintain genetic stability during cell division.

92
Q

What is the role of stem cells in development?

A

Stem cells play a crucial role in development by differentiating into the various cell types that form tissues and organs.

93
Q

How do signaling pathways influence stem cell differentiation?

A

Signaling pathways, such as Wnt, Notch, and BMP, provide cues that regulate stem cell fate decisions and differentiation.

94
Q

What are mesenchymal stem cells (MSCs)?

A

MSCs are multipotent stem cells found in bone marrow and other tissues that can differentiate into bone, cartilage, and fat cells.

95
Q

What are hematopoietic stem cells (HSCs)?

A

HSCs are multipotent stem cells found in bone marrow that give rise to all blood cell types.

96
Q

Why is stem cell research important for understanding human diseases?

A

Stem cell research helps scientists understand the mechanisms of cell differentiation and tissue development, providing insights into diseases and potential therapies.