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BIOL 1090 > Morris, Chapter 11: Cell Division - Variation, Regulation and Cancer > Flashcards

Morris, Chapter 11: Cell Division - Variation, Regulation and Cancer Flashcards

11.1, 11.2, 11.3, 11.4, 11.5, 11.6

1
Q

What is one of the fundamental principles of biology related to cells?

A

Cells come from preexisting cells.

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2
Q

What is cell division?

A

The process by which a single cell produces two daughter cells.

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3
Q

How do multicellular organisms begin life?

A

As a single cell, with cell division producing the billions or trillions of cells in the organism.

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4
Q

Why is cell division important after an organism reaches adult size?

A

It replaces worn-out cells, such as blood cells, skin cells, and cells lining the digestive tract.

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5
Q

What happens at a wound site, like a scraped knee?

A

Cells at the site begin dividing to replace damaged cells and heal the wound.

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6
Q

Definition

Asexual Reproduction

A

The reproduction of organisms by mitotic cell division or fragmentation. Offspring are clones of the parent.

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7
Q

How do bacteria reproduce?

A

By dividing into two daughter cells, each receiving one copy of the parent cell’s genetic material.

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8
Q

Definition

Sexual reproduction.

A

The process of producing offspring that receive genetic material from two parents; in eukaryotes, the process occurs through meiosis and fertilization.

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9
Q

Definition

Gametes

A

A reproductive haploid cell; gametes fuse in pairs to form a diploid zygote. In many species, there are two types of gametes: eggs in females, sperm in males.

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10
Q

What happens during fertalization?

A

A male gamete (sperm) and a female gamete (egg) fuse to form a new organism with the same number of chromosomes as the parents.

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11
Q

What processes produces gametes?

A

A form of cell division that results in daughter cells with half the number of chromosomes as the parent cell.

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12
Q

What results from a loss of control of cell division?

A

Cancer

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13
Q

What do cells need to determine for proper division and regulation?

A
  • When to divide
  • When not to divide
  • How cancer develops dur to loss of control in these processes.
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14
Q

Chapter 11.1 Cell Division

What are the requirements for successful cell division?

A

The cell must be large enough to divide and provide sufficient nuclear and cytoplasmic components to each daughter cell.

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15
Q

Chapter 11.1 Cell Division

What happens before a cell divides?

A

Key cellular components are duplicated to ensure proper division.

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16
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

Binary Fission

Definition

A

The process by which prokaryotic cells (e.g., bacteria or archaeons) divide to form two daughter cells.

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17
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

What occurs during binary fission?

A

The cell replicates its DNA, increases in size, and divides into two daughter cells, each receiving one copy of the parental DNA.

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18
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

Which organisms have been studied extensively for binary fission?

A

Bacteria, especially Escherichia coli.

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19
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

Where is the circular genome of E. coli attached during binary fission?

A

To the inside of the plasma membrane.

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20
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

What is the orgin on replication?

A

The specific location on the circular DNA molecule where DNA replication begins.

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21
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

What happens to the DNA after replication in binary fission?

A

The two DNA molecules attach to the plasma membrane at different sites and move apart as the cell elongates.

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22
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

What happens when the cell reaches twice its original size during binary fission?

A

A constriction forms at the midpoint of the cell, and new membrane and cell wall are synthesized, dividing the cell into two daughter cells.

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23
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

What is the role of the FtsZ gene in binary fission?

A

It encodes a protein that forms a ring at the site of constriction where the new cell wall forms.

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24
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

Why is the FtsZ protein significant?

A

It is evolutionarily related to tubulin, a protein in eukaryotic cells that forms microtubules and plays a role in cell division, intracellular transport, and cell movement.

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25
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

Apart form bacteria, where else is the binary fission process observed?

A
  • Archaeons
  • Chloroplasts
  • Mitochondria
    All evolved from free-living prokaryotic cells.
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26
Q

Chapter 11.1 Cell Division - Prokaryotic cells divide by binary fission.

What ensures the coordination of components in binary fission?

A

Genes like FtsZ and other components.

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27
Q

Chapter 11.1 Cell Division

WHat are the basic steps of binary fission?

A

DNA replication, segregation of replicated DNA to daughter cells, and division of one cell into two.

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28
Q

Chapter 11.1 Cell Division - Eukaryotic cells divide by mitotic cell div

How is eukaryotic cell division more complex than prokaryotic cell division?

A

Eukaryotic cells divide the nucleus by mitosis and the cytoplasm by cytokinesis, and require additional steps like breaking down and re-forming the nuclear envelope.

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29
Q

Chapter 11.1 Cell Division

How does the genome of prokaryotes differ from that of eukaryotes?

A

Prokaryotic genomes are single, small, circular DNA molecules, while eukaryotic genomes are larger and organized into linear chromosomes.

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30
Q

Chapter 11.1 Cell Division

Where is prokaryotic DNA located and how is it separated during cell division?

A

Prokaryotic DNA is attached to the plasma membrane, and cell growth separates the replicated DNA into daughter cells

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31
Q

Chapter 11.1 Cell Division

Where is eukaryotic DNA located, and how is it separated during cell division?

A

Eukaryotic DNA is in the nucleus, and its separation involves the mitotic spindle and the breakdown and re-formation of the nuclear envelope.

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32
Q

Chapter 11.1 Cell Division

How do chromosomes of dividing eukaryotic cells separate into daughter cells?

A

They attach to the mitotic spindle, which pulls them apart during cell division.

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33
Q

Chapter 11.1 Cell Division

What is an example of a unicellular eukaryote that combines features of binary fission and mitosis?

A

Dinoflagellates

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34
Q

Chapter 11.1 Cell Division

How does cell division in dinoflagellates differ from most eukaryotes?

A

The nuclear envelope remains intact, and replicated DNA is attached to the nuclear envelope as the nucleus grows and divides.

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35
Q

Chapter 11.1 Cell Division

What does the intermediate form of cell division in unicellular eukaryotes suggest?

A

It suggests that mitosis evolved from binary fission.

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36
Q

Chapter 11.1 Cell Division

What are the two main stages of the cell cycle in eukaryotic cells?

A

M phase and interphase.

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37
Q

Chapter 11.1 Cell Division

What are the two events that occur during M phase?

A

(1) Mitosis: separation of chromosomes into two nuclei.
(2) Cytokinesis: division of the cell into two separate cells.

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38
Q

Chapter 11.1 Cell Division

How long does M phase typically last in mammalian cells?

A

About one hour.

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39
Q

Chapter 11.1 Cell Division

What happens during interphase?

A

THe cell prepares for division by replicating DNA and growing in size.

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40
Q

Chapter 11.1 Cell Division

What are the three phases of interphase?

A

G1 phase, S phase, and G2 phase.

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41
Q

Chapter 11.1 Cell Division

What occurs during S phase?

A

DNA replication, also known as DNA synthesis.

42
Q

Chapter 11.1 Cell Division

What happens during the G1 phase?

A

Preparation for S-phase DNA synthesis, including the production of regulatory proteins like kinases.

43
Q

Chapter 11.1 Cell Division

What occurs during the G2 phase?

A

The cell increases in size and protein content in preparation for mitosis and cytokinesis.

44
Q

Chapter 11.1 Cell Division

How long does the entire cell cycle take in most actively dividing human cells?

A

About 24 hours.

45
Q

Chapter 11.1 Cell Division

Which cells complete the cell cycle more quickly, and why?

A
  • Yeast: 90 minutes.
  • Frog embryonic cells: ~30 minutes, due to the absence of growth phases (G1 and G2).
46
Q

Chapter 11.1 Cell Division

What is the G0 phase, and how is it distinguished from other phases?

A

A phase where cells pause between M phase and S phase without preparing for DNA synthesis.

47
Q

Chapter 11.1 Cell Division

Can cells in the G0 phase still perform functions? Provide examples.

A

Yes, they perform specialized functions. For example, liver cells carry out metabolism and detoxification.

48
Q

Chapter 11.1 Cell Division

Which cells permanently enter the G0 phase?

A

Nerve cells and lens cells of the eye, making them nondividing.

49
Q

Chapter 11.1 Cell Division

Why can’t many brain cells lost to damage or disease be replaced?

A

Because they permanently enter the G0 phase and do not divide.

50
Q

Chapter 11.1 Cell Division

Why is there no G1 or G2 phase in early frog embryonic cell divisions?

A

Early divisions focus on dividing the cytoplasm into smaller cells, so no growth period is needed.

51
Q

Chapter 11.2 Mitotic Cell Division

What is the challenge faced by a dividing eukaryotic cell?

A

Ensuring daughter cells receive an equal and complete set of chromosomes.

52
Q

Chapter 11.2 Mitotic Cell Division

How long is the DNA in an average eukaryotic cell nucleus, and why must it be condensed?

A

1 to 2 meters; to fit into the nucleus and prevent tangling during cell division.

53
Q

Chapter 11.2 Mitotic Cell Division

What structures are formed by the organization of DNA with histones in eukaryotic cells?

A

Chromosomes

54
Q

Chapter 11.2 Mitotic Cell Division

What happens to chromosomes during interphase?

A

They are long, thin, and threadlike.

55
Q

Chapter 11.2 Mitotic Cell Division

What is a karyotype?

A

The portrait of the number and shapes of chromosomes characteristic of a species.

56
Q

Chapter 11.2 Mitotic Cell Division

How many chromosomes do humans, horses, and corn have in their cells?

A

Humans: 46, Horses: 64, Corn: 20.

57
Q

Chapter 11.2 Mitotic Cell Division

How are human chromosomes arranged in a normal karyotype?

A

23 pairs: 22 numbered pairs and 1 pair of sex chromosomes.

58
Q

Chapter 11.2 Mitotic Cell Division

What are homologous chromosomes?

A

Pairs of chromosomes carrying the same set of genes, one from each parent.

59
Q

Chapter 11.2 Mitotic Cell Division

What determines the sex of an individual in humans?

A

The sex chromosomes: XX for females, XY for males.

60
Q

Chapter 11.2 Mitotic Cell Division

Define haploid.

A

1 complete set of chromosomes.

61
Q

Chapter 11.2 Mitotic Cell Division

Define diploid.

A

2 complete set of chromosomes.

62
Q

Chapter 11.2 Mitotic Cell Division

Define Polyploid.

A

4 or more complete sets of chromosomes.

63
Q

Chapter 11.2 Mitotic Cell Division

When does chromosome duplication occur, and what are the resulting identical copies called?

A

During S phase; sister chromatids.

64
Q

Chapter 11.2 Mitotic Cell Division

What physically holds sister chromatids together?

A

The centromere.

65
Q

Chapter 11.2 Mitotic Cell Division

How are chromosomes counted in a cell?

A

By counting centromeres.

66
Q

Chapter 11.2 Mitotic Cell Division

What happens to sister chromatids during mitosis?

A

They separate and are distributed to opposite ends of the cell.

67
Q

Chapter 11.2 Mitotic Cell Division

How many chromosomes are present in the nucleus of a human cell at the beginning of mitosis?

A

46 chromosomes, each consisting of a pair of identical sister chromatids.

68
Q

Chapter 11.2 Mitotic Cell Division

What happens in prophase, the first stage of mitosis?

A
  • Chromosomes condense and become visible
  • The centrosomes duplicate, migrate to opposite poles, and radiate microtubules to form the mitotic spindle.
69
Q

Chapter 11.2 Mitotic Cell Division

What are the five stages of mitosis?

A
  1. Prophase
  2. Prometaphase
  3. Metaphase
  4. Anaphase
  5. Telophjase
70
Q

Chapter 11.2 Mitotic Cell Division

What happens to the chromosomes during prometaphase?

A
  • The nuclear envelope breaks down and microtubules of the mitotic spindle attach to chromosomes.
  • Sister chromatids begin aligning toward the cell center.
71
Q

Chapter 11.2 Mitotic Cell Division

What defines metaphase?

A
  • Chromosomes align completely at the center of the cell (metaphase plate) with spindle poles at opposite ends.
72
Q

Chapter 11.2 Mitotic Cell Division

What happens during anaphase?

A
  • Sister chromatids seperate and become individual chromosomes as the centromeres split.
  • THe chromosomes travel to opposite poles of the cell.
73
Q

Chapter 11.2 Mitotic Cell Division

What characterizes telophase, the final stage of mitosis?

A
  • The nuclear envelope reforms, chromosomes decondense, and the cell prepares to divide into two daughter cells with two nuclei.
74
Q

Chapter 11.2 Mitotic Cell Division

What is the role of the mitotic spindle in mitosis?

A

The mitotic spindle, made of microtubules, pulls chromosomes to opposite ends of the dividing cell.

75
Q

Chapter 11.2 Mitotic Cell Division

How do centrosomes function during mitosis in animal cells?

A

Centrosomes duplicate during S phase, migrate to opposite poles during prophase, and organize microtubules into the mitotic spindle.

76
Q

Chapter 11.2 Mitotic Cell Division

How do plant cells differ from animal cells in forming the mitotic spindle?

A

Plant cells form the mitotic spindle without centrosomes, unlike animal cells.

77
Q

Chapter 11.2 Mitotic Cell Division

What is the importance of centrosomes in defining cell polarity during mitosis?

A

Centrosomes migrate to opposite poles, defining the cell’s two ends and guiding chromosome movement for proper division.

78
Q

Chapter 11.2 Mitotic Cell Division

How do microtubules contribute to prometaphase?

A

Microtubules radiating from the centrosomes grow and shrink, exploring the area where the nucleus once was, and attach to chromosomes at their centromeres.

79
Q

Chapter 11.2 Mitotic Cell Division

What is dynamic instability in the context of microtubules?

A

Dynamic instability refers to the growing and shrinking behavior of microtubules, which is essential for their exploration and attachment to chromosomes during prometaphase.

80
Q

Chapter 11.2 Mitotic Cell Division

What is the role of kinetochores in prometaphase?

A

Kinetochores are protein complexes located at the centromere of each chromosome, where microtubules attach. Each kinetochore is associated with one of the sister chromatids.

81
Q

Chapter 11.2 Mitotic Cell Division

How does the attachment of microtubules to kinetochores affect chromosome segregation?

A

The symmetrical attachment of each chromosome to two microtubules (one from each pole) ensures proper chromosome segregation during cell division.

82
Q

Chapter 11.2 Mitotic Cell Division

What happens when each chromosome is attached to the mitotic spindle?

A

The microtubules of the mitotic spindle lengthen or shorten to move the chromosomes to the middle of the cell.

83
Q

Chapter 11.2 Mitotic Cell Division

How are chromosomes aligned during metaphase?

A

The chromosomes are aligned in a single plane that is roughly equidistant from both poles of the cell.

84
Q

Chapter 11.2 Mitotic Cell Division

Why is metaphase one of the most visually distinctive stages of mitosis?

A

Because the chromosomes are clearly aligned in the middle of the dividing cell, making it easily identifiable under the microscope.

85
Q

Chapter 11.2 Mitotic Cell Division

What is the role of the mitotic spindle during metaphase?

A

The mitotic spindle’s microtubules help move the chromosomes to the middle of the cell and keep them aligned during metaphase.

86
Q

Chapter 11.2 Mitotic Cell Division

What is the key feature of metaphase under the microscope?

A

Chromosomes are aligned in the middle of the cell in a single plane.

87
Q

Chapter 11.2 Mitotic Cell Division

What happens during anaphase in mitosis?

A
  • Sister chromatids separate as the centromere splits.
  • After separation, each chromatid is considered a full-fledged chromosome.
  • Spindle microtubules shorten, pulling the chromosomes to opposite poles.
  • The chromosomes are equally segregated between the two daughter cells.
  • Each daughter cell receives 46 chromosomes, the complete genetic material.
88
Q

Chapter 11.2 Mitotic Cell Division

What marks the beginning of telophase?

A

The arrival of a complete set of chromosomes at a pole marks the beginning of telophase.

89
Q

Chapter 11.2 Mitotic Cell Division

What happens during telophase?

A

The cell prepares for division into two new cells, and the microtubules of the mitotic spindle break down and disappear.

90
Q

Chapter 11.2 Mitotic Cell Division

What occurs after the microtubules of the mitotic spindle break down during telophase?

A

A nuclear envelope re-forms around each set of chromosomes, creating two new nuclei.

91
Q

Chapter 11.2 Mitotic Cell Division

How do the chromosomes change during telophase?

A

The chromosomes decondense and become less visible under the microscope.

92
Q

Chapter 11.2 Mitotic Cell Division

What is the significance of telophase in the process of mitosis?

A

Telophase marks the end of mitosis as the nuclei become distinct and the chromosomes decondense.

93
Q

Chapter 11.2 Mitotic Cell Division

What is cytokinesis and when does it occur in the cell cycle?

A

Cytokinesis is the process where the cytoplasm divides, resulting in two daughter cells. It usually begins as mitosis nears its end.

94
Q

Chapter 11.2 Mitotic Cell Division

In animal cells, what structure forms during cytokinesis to divide the cell?

A

A contractile ring made of actin filaments forms and contracts, pinching the cell into two.

95
Q

Chapter 11.2 Mitotic Cell Division

What is the role of the contractile ring in cytokinesis in animal cells?

A

The contractile ring, made of actin filaments, contracts like a drawstring, dividing the cytoplasm and creating two daughter cells.

96
Q

Chapter 11.2 Mitotic Cell Division

How does the contractile ring in animal cells contract during cytokinesis?

A

Motor proteins slide actin filaments in opposite directions, driving the contraction of the contractile ring.

97
Q

Chapter 11.2 Mitotic Cell Division

How is cytokinesis in animal cells similar to binary fission?

A

Both processes involve a constriction that divides the cytoplasm, but binary fission is driven by the FtsZ protein, not actin filaments.

98
Q

Chapter 11.2 Mitotic Cell Division

What happens after cytokinesis in animal cells?

A

After cytokinesis, two daughter cells are formed, each with its own nucleus, and they enter the next phase of the cell cycle.

99
Q

Chapter 11.2 Mitotic Cell Division

In plant cells, how does cytokinesis differ from animal cells?

A

In plant cells, cytokinesis involves the formation of a cell plate instead of a contractile ring due to the presence of a cell wall.

100
Q

Chapter 11.2 Mitotic Cell Division

What is the phragmoplast in plant cells?

A

The phragmoplast is a structure made of overlapping microtubules that guides vesicles containing cell wall components to the middle of the cell during cytokinesis.

101
Q

Chapter 11.2 Mitotic Cell Division

How is the new cell wall formed during cytokinesis in plant cells?

A

Vesicles containing cell wall components fuse to form a cell plate, which then fuses with the original cell wall, completing the division.

102
Q
A

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