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Bio 1113 > Chapter 12: Cellular Division > Flashcards

Chapter 12: Cellular Division Flashcards

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1
Q

What type of chromosomes are in eukaryotes?

A

Linear chromosomes. Cells often contain 2 copies of each chromosome (homologous chromosomes)

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2
Q

What are the 6 stages of the eukaryotic cell cycle?

A

G0, G1, S, G2, Mitosis, and Cytokinesis

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3
Q

What are chromosomes?

A

Long strands of DNA wrapped around proteins called histones

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4
Q

What are external factors that impact cell division?

A

Growth factors, density dependent inhibition, and anchorage dependence

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5
Q

What is the spindle apparatus (MTOC) made of?

A

Microtubules and other proteins

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6
Q

What does interphase consist of?

A

Gap 1 (G1), Synthesis (S), and Gap 2 (G2)

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7
Q

What does cytokinesis indicate?

A

Division of organelles and cytoplasm

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8
Q

What is securin?

A

A protein that secures separase

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9
Q

What phases of the eukaryotic cell cycle is the cell dividing in?

A

Mitosis and cytokinesis

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10
Q

What are homologous chromosomes? Where do they come from?

A

Two copies of each chromosome. One from mom and one from dad

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11
Q

What is separase?

A

An enzyme that cuts the sister chromatids apart to be pulled to opposite poles

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12
Q

What is anchorage dependence?

A

Normal cells need to be anchored to the extracellular matrix and each other

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13
Q

What type of chromosomes are in prokaryotes?

A

Single circular chromosome

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14
Q

What are condensins?

A

Targets of G2 checkpoint (MPF) that help DNA pack together in prophase

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15
Q

How much DNA is in the human body?

A

2 x 10^13 (67 trips to the sun and back)

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16
Q

What does fission indicate?

A

There is no nucleus

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17
Q

What do microtubules that aren’t attached to chromosomes do in anaphase?

A

They push against each other to move the cell apart

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18
Q

What is the G2 checkpoint?

A

M phase-promotion factor (MPF). Allows G2 to continue to mitosis. Last check before mitosis

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19
Q

What two signals can a cell receive at the G1 checkpoint?

A

A green light to continue to s phase or a red light to exit the cell cycle and enter G0

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20
Q

What phase are chromosomes easiest to see under a microscope?

A

Metaphase

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21
Q

What forms in prophase?

A

Spindle apparatus (MTOC - microtubule organizing center)

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22
Q

What are the three parts of chromosome structure?

A

Centromere, telomere, and kinetochore

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23
Q

What happens with density dependent inhibition in cancer cells?

A

It doesn’t do anything. Cancer cells don’t stop dividing

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24
Q

What targets of the G2 checkpoint (MPF) are needed for mitosis to proceed?

A

All of them

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25
Q

What is a telomere?

A

Chromosome structure that is the region of repetitive DNA sequences at the end of chromosomes

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26
Q

What happens in prometaphase?

A

The nuclear envelope disassembles (DNA no longer protected) and spindle fibers attach to kinetochores

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27
Q

What does condensing before division do for cells?

A

Makes it easier for the cell to split the chromosomes evenly between the two cells

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28
Q

Example of a growth factor

A

Platelet-derived growth factor (PDGF). When you cut your leg, it triggers cells to divide to heal the wound

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29
Q

How does cytokinesis occur in animals?

A

Cleavage furrow pinches off separated nuclei

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30
Q

How much DNA is in a single cell?

A

2 meters

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31
Q

When can chromosomes be seen?

A

When cells are getting ready for division only, but they are always there

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32
Q

What happens when a microtubule doesn’t attach?

A

The cell doesn’t pass the M phase checkpoint (APC - metaphase to anaphase)

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33
Q

What are the two things that can happen in asexual cellular division?

A

Mitosis and binary fission (bacteria)

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34
Q

What is the metaphase plate?

A

The location where chromosomes align in metaphase. It is not an actual physical structure

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35
Q

Example of a growth factor

A

Rb attached to E2F (transcription factor) preventing it from transcribing DNA. Growth factor added to Ras pathway to cdk-cyclin complex which phosphorylates the Rb protein with ATP to allow E2F to transcribe

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36
Q

How is cell cycle regulation controlled?

A

A system of signaling molecules which trigger and coordinate the events of the cell cycle

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37
Q

How are sister chromosomes pulled to opposite poles of the cell in anaphase?

A

Microtubules shorten due to being disassembled which causes the sister chromosomes to be pulled to opposite poles

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38
Q

What can happen in G0?

A

Some cells, like liver cells, can be called back into division

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39
Q

What factors can cause a cell to enter G0 from the G1 checkpoint?

A

Is the cell big enough, are conditions favorable, any DNA damage, etc.

40
Q

What type of animal is the G1 checkpoint most important in?

A

Mammals

41
Q

What are the targets of the G2 checkpoint (MPF)?

A

Condensins (help DNA pack together in prophase), proteins involved in mitotic spindle formation, lamins (proteins involved in nuclear envelope assembly/breakdown), and also shutting itself down and allowing the cell to continue to mitosis

42
Q

What are the two types of cellular division?

A

Asexual and sexual

43
Q

What do the tails of histones do?

A

They are important in gene expression. Can block genes or turn them on

44
Q

What happens in G1 of interphase?

A

Growth, protein synthesis, and organelle synthesis. The cellular contents (excluding chromosomes) are duplicated

45
Q

How many genes are in the human body? What percentage of DNA is this? What is the other percent?

A

20,000-25,000 genes that are 2% of DNA. Other 98% are critical non-coding regions

46
Q

What is the end product of mitosis?

A

2 identical daughter cells

47
Q

What happens when cytokinesis doesn’t follow mitosis? Is this possible?

A

A cell with multiple nuclei will be the end product. It is possible, however, rare

48
Q

What happens in metaphase and why does it occur?

A

Chromosomes align along the metaphase plate and it occurs because of tug of war between the two poles

49
Q

What is interphase?

A

When the cell is getting ready for division

50
Q

What is a kinetochore?

A

Chromosome structure that is a disc shaped protein that spindle fibers attach to. It attaches to the centromere

51
Q

What happens in G2 of interphase?

A

Growth, synthesis of microtubules, cell cycle checkpoints (the cell double checks the duplicated chromosomes for error, making any needed repairs)

52
Q

How do cyclin dependent kinases work?

A

They are present at constant concentrations but usually are inactive. They are activated by attaching to cyclins and their activity matches cyclins when they attach to them

53
Q

How many phases is mitosis divided into? What are they? Why is this sort of hazy?

A

5 phases. Prophase, prometaphase, metaphase, anaphase, and telophase. It is hazy because mitosis is a continuous process and there are no starting or stopping points.

54
Q

What happens in anaphase?

A

Sister chromatids are cut apart and pulled to opposite poles of the cell

55
Q

What does mitosis indicate?

A

Nuclear division

56
Q

What is the M phase checkpoint (anaphase promoting complex - APC)

A

A complex of 11-13 proteins that marks cell cycle proteins for degradation. Metaphase to anaphase checkpoint

57
Q

How does cytokinesis occur in plants?

A

A new cell wall is formed between two cells. Golgi-derived vesicles bring materials to the middle that fuse to form cell plate which becomes a cell wall between the two cells

58
Q

What is a genome?

A

The DNA of a cell. It is the same in all cells in a person but varies per person

59
Q

What happens in cytokinesis?

A

The cytoplasm divides

60
Q

What is a centromere?

A

Chromosome structure that is the condensed region of the chromosome that stays condensed. The kinetochore connects here

61
Q

How do cyclins work?

A

Levels fluctuate cyclically. They go up and down at certain points of interphase

62
Q

What happens to chromosomes in prophase?

A

They begin to condense and can be seen under a microscope

63
Q

What is bacterial binary fission and what does it produce?

A

A form of asexual reproduction carried out by bacteria that produces no genetic diversity but is very fast

64
Q

What happens in S of interphase?

A

DNA is duplicated (each of the 46 chromosomes duplicated)

65
Q

What usually follows mitosis?

A

Cytokinesis

66
Q

How does the cell ensure it is ready to proceed to the next step?

A

Multiple checkpoints

67
Q

How does the cell plate form in plant cell cytokinesis?

A

Golgi-derived vesicles bring materials to the middle to create it

68
Q

Where does the kinetochore connect?

A

Centromere

69
Q

What two main regulatory molecules are involved in cell cycle clocks?

A

Cyclins and cyclin-dependent kinases (cdks)

70
Q

How are sister chromatids cut apart in anaphase?

A

Cohesion that holds them together is cleaved by enzymes

71
Q

What percentage of time do cells spend in interphase?

A

90%

72
Q

How do cyclin dependent kinases get activated?

A

They attach to cyclins

73
Q

What is the G1 checkpoint?

A

The restriction point that comes before DNA replication

74
Q

What happens in telophase?

A

Nuclear envelopes reform around DNA (2 nuclei) and chromosomes unfold back into chromatin (reversal of prophase)

75
Q

Why is tight cell cycle regulation important?

A

It ensures normal growth and development

76
Q

What stage are most cells in the human body at?

A

G0

77
Q

What do telomeres do?

A

They are the ends of chromosomes that don’t code for anything. Division causes the ends to not be replicated so telomeres act as a buffer to ensure all the DNA gets replicated. They tell the cell to stop dividing when they are gone. They cause the cell to have a limited number of divisions

78
Q

What happens in sexual cellular division?

A

Meiosis

79
Q

What does the protein dimer consist of in the G2 checkpoint?

A

A cyclin and a cdk

80
Q

What happens when chromosomes are duplicated?

A

It creates sister chromatids (two arms that are identical copies making up a chromosome)

81
Q

When are chromosomes duplicated?

A

Before cell division

82
Q

What is density dependent inhibition?

A

Cells grow and divide until they touch their neighbors, then they stop

83
Q

What happens at the G1 checkpoint?

A

The cell has to commit to dividing or not

84
Q

What are the four reasons why cells divide?

A

Reproduction, growth and development, tissue renewal, and maintain a favorable surface area to volume ratio

85
Q

What are lamins?

A

Targets of G2 checkpoint (MPF) that are proteins involved in nuclear envelope assembly/breakdown

86
Q

How are sister chromatids held together?

A

At the centromere

87
Q

What are growth factors and what do they do?

A

Signals from other cells (social cues) that multicellular organisms rely on

88
Q

What is the spindle apparatus (MTOC) and when does it form?

A

It is the machine responsible for pulling apart the chromatids. It is formed during prophase

89
Q

What is chromatin?

A

DNA and protein (histone) complex

90
Q

How many base pairs of DNA are in the human body?

A

3 billion

91
Q

What are cyclins and cyclin dependent kinases?

A

Proteins that are the 2 main regulatory molecules

92
Q

When phase does cytokinesis occur in? Alongside of?

A

It occurs in its own phase. It usually occurs along with mitosis beginning in telophase

93
Q

When are sister chromatids pulled apart?

A

Mitosis

94
Q

What happens in G0?

A

It is the quiescent or resting state. Cells are not preparing to divide but are metabolically active

95
Q

What phase does cytokinesis begin in?

A

Telophase

96
Q

What does the cell start to do in telophase?

A

Divide

Bio 1113 (22 decks)

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