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Histo LEC > Cell Division > Flashcards

Cell Division Flashcards

1
Q

Before differentiation, most cells undergo repeated cycles of macromolecular synthesis (______) and division (______).

A

growth

mitosis

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2
Q

The regular sequence of events that result in new cells is termed the

A

cell cycle.

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3
Q

The cell cycle has four distinct phases:

A

Mitosis
G1 - Gap 1
S - Synthesis
G2 - Gap 2

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4
Q

(the time gap between mitosis and DNA replication)

A

G1

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5
Q

(the period of DNA synthesis)

A

S

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6
Q

(the gap between DNA duplication and the next mitosis

A

G2

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7
Q

considerably longer than the M phase

A

Interphase

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8
Q

the period during which the cell doubles in size and DNA content

A

Interphase

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9
Q

Stimuli for cell division

A

Mitogen

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10
Q

small bioactive protein or peptide that induces a cell to begin cell division, or enhances the rate of division (mitosis)

A

Mitogen

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11
Q

Longest and most variable phase of the cycle

A

G1

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12
Q

Period of active RNA and protein synthesis, including proteins controlling progress through the cell cycle

A

G1

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13
Q

Characterized by DNA replication, histone synthesis and the beginning of centrosome duplication.

A

S phase

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14
Q

phase Proteins required for mitosis accumulate

A

G2

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15
Q

Cell cycle activities may be temporarily or permanently suspended

After mitosis - Before G1

A

G0

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16
Q

Cells not capable of dividing

A

Neurons
Skeletal
Cardiac

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17
Q

Entry or progression through other phase of the cycle is also monitored at other specific_________, where certain conditions must be met before the cell continues cycling.

A

checkpoints

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18
Q

• Are cell nutrition, size, and environment favorable?
• Is all DNA intact?

A

Start (G1/S) checkpoint

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19
Q

Is DNA completely replicated?

enter mitosis

A

G2/M checkpoint

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20
Q

Is all DNA intact?
• Are all chromosomes attached to the mitotic spindle?

begin chromatid separation and prepare for cytokinesis

A

Metaphase/ Anaphase checkpoint

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21
Q

Each phase of the cell cycle has one or more________ where the quality of specific cell activities is checked.

Progression to the next phase of the cycle does not occur until all activities of the preceding phase are completed satisfactorily.

A

checkpoints

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22
Q

Three important checkpoints are shown here, including

A

The start or restriction checkpoint

G2/M checkpoint

The metaphase spindle checkpoint

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23
Q

Checkpoint just before the start of S

A

The start or restriction checkpoint

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24
Q

Checkpoint that ensures that DNA replication is complete

A

The G2/M checkpoint

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25
Checkpoint that ensures that all chromosomes will be segregated
The metaphase spindle checkpoint
26
Overall progression in the cycle is regulated by proteins called_______ and ____________
cyclins cyclin-dependent kinases (CDKs)
27
phosphorylate/activate enzymes and other proteins needed for phase specific functions
cyclins cyclin-dependent kinases (CDKs)
28
Control factors: ___________________which initiate and/or induce progression through the cell cycle.
cyclin-dependent kinases (CDKs)
29
Control factors: During G1 phase, cyclins ____ and ____ bind to their respective CDKs; these complexes enable the cell to enter and advance through the S phase.
cyclins D and E
30
Control factors: Cyclin ___ binds to its CDKs, thus enabling the cell to leave the S phase and enter the G2 phase, and also to manufacture cyclin B.
Cyclin A
31
Control factors: Cyclin ____ binds to its CDK, inducing the cell to leave the G2 phase and enter the M phase.
B
32
Length in time: G1 S G2 P M A T
G1 - 25hrs S - 8hrs G2 - 2.5-3hrs P - more or less 1hr M - less than 1hr A - less than 30mins T - minutes only
33
It follows the G2 phase and completes the cell cycle.
Mitosis
34
Division of the nucleus (________) and cytoplasm (_________) results in the production of two identical daughter cells.
karyokinesis cytokinesis
35
Stages of mitosis
PROPHASE METAPHASE ANAPHASE TELOPHASE
36
Begins when the chromosomes condense
PROPHASE
37
Nucleolus and nuclear envelope begin to disappear
PROPHASE
38
Centrosomes migrate to opposite poles of the cell, and from them spindle fibers and astral rays of the mitotic spindle polymerize
PROPHASE
39
At the centromere region of each chromosome, a large protein complex called the _______ serves as a site for attachment to microtubules
kinetochore PROPHASE
40
Chromosomes condense further and attach to the mitotic spindle at large electron-dense protein complexes called kinetochores at each centromere
METAPHASE
41
Cell is now more spherical and the chromosomes are moved to align at its_________
equatorial plane METAPHASE
42
Sister chromatids separate and move toward opposite spindle poles by a combination of microtubule motor proteins
ANAPHASE
43
The two sets of chromosomes are at the spindle poles and begin reverting to their decondensed state
TELOPHASE
44
Spindle depolymerizes and the nuclear envelope begins to reassemble around each set of daughter chromosomes
TELOPHASE
45
occurs at the end of telophase
Cytokinesis
46
Specialized process involving two unique and closely associated cell divisions that occurs only in the cells that will form sperm and egg cells
MEIOSIS
47
Meiosis: Specialized process involving two unique and closely associated cell divisions that occurs only in the cells that will form _____ and _____ cells
sperm and egg
48
Meiosis = is a process that converts____ nuclei to_____ nuclei.
diploid to haploid
49
cells - have 2 sets of chromosomes.
Diploid cells
50
cells - have 1 set of 24 chromosomes.
Haploid cells
51
Meiosis occurs in the sex organs producing:
Gametes Sperm eggs
52
= is the fusion of a sperm and egg cell.
Fertilization
53
The zygote has a _____ chromosome number, one set from each parent.
diploid
54
MEIOSIS I consisting of 5 phases:
Interphase I Prophase I Metaphase l Anaphase I Telophase I
55
MEIOSIS II consisting of 4 phases:
Prophase II Metaphase II Anaphase II Telophase Il
56
2 stages of meiosis
Meiosis I Meiosis II
57
• Cell build up energy • DNA Replication (to make duplicated chromosomes) • Cell doesn't change structurally
MEIOSIS I: INTERPHASE I
58
Chromosomes coil and become individual chromosomes, nucleolus and nuclear envelope disappear. Homologous chromosomes come together as pairs by synapsis forming a tetrad (each pair, with four chromatids) Non-sister chromatids exchange genetic material through the process of crossing over to ensure genetic variation. Centrioles move to opposite poles with spindle fibers between
MEIOSIS I: PROPHASE I
59
= is the production of new combinations of genes due to crossing over.
Genetic recombination MEIOSIS I: PROPHASE I
60
= is an exchange of genes between separate (non-sister) chromatids on homologous chromosomes.
Crossing over MEIOSIS I: PROPHASE I
61
Non-sister chromatids join at a______ (plural,______), the site of attachment.
chiasma (chiasmata) MEIOSIS I: PROPHASE I
62
Genetic material are exchanged between maternal and paternal (nonsister) chromatids
MEIOSIS I: PROPHASE I
63
• Centrioles has reached the poles. • Homologous pairs align at the cell equator. • The two chromosomes attach to one spindle fiber by means of the kinetochore of the centromere
MEIOSIS I: METAPHASE I
64
• Spindle fibers contract • Duplicated chromosomes move to opposite poles.
MEIOSIS I: ANAPHASE I
65
• Duplicated chromosomes have reached the poles. • Nuclear envelope and nucleolus re-form around chromosomes. • Each nucleus now has the haploid number of chromosomes. • Cell invaginates forming a cleavage furrow, which extends to for 2 separate haploid cells
MEIOSIS I: TELOPHASE I
66
• Chromosomes coil and become compact (if uncoiled after telophase I). • Nuclear envelope and nucleolus, if re-formed, disappears again. • Centrioles move to opposite poles, forming spindle fibers between them.
MEIOSIS II: PROPHASE II
67
• Individual duplicated chromosomes align on the equator. • One chromosome per spindle fiber attached by means of kinetochore of centromere. • Centrioles has reached the poles.
MEIOSIS II: METAPHASE II
68
• Spindle fibers contract. • Duplicated chromosomes split in half (centromere dividing in 2) • Daughter chromosomes move to opposite poles
MEIOSIS II: ANAPHASE II
69
• Daughter chromosomes has reached the poles. • Two cells invaginate and form 4 daughter haploid cells (gametes) • They uncoil and form chromatin. • Nuclear envelope and nucleolus forms around chromatin again
MEIOSIS II: TELOPHASE II
70
Mitosis produces two genetically
Identical diploid somatic daughter cells
71
Meiosis produces four genetically
unique haploid gametes
72
SIMILARITIES or mitosis and meiosis
both begin with diploid parent cells that have chromosomes duplicated during the previous interphase
73
Process of cell suicide
APOPTOSIS
74
Redundant or defective cells are rapidly eliminated in a manner that does not provoke a local inflammatory reaction in the tissue.
APOPTOSIS
75
Involves a cascade of events controlled by the _____ family of proteins regulating the release of death-promoting factors from mitochondria.
APOPTOSIS Bcl-2
76
Specific Bcl-2 proteins induce a process with the following features:
o Loss of mitochondrial function and caspase activation o Fragmentation of DNA o Shrinkage of nuclear and cell volumes o Cell membrane changes o Formation and phagocytic removal
77
Loss of mitochondrial function and caspase activation releasing cytochrome c into the cytoplasm where it activates proteolytic enzymes called____
caspases
78
Fragmentation of DNA •______ are activated, which cleave DNA between nucleosomes into small fragments.
endonucleases
79
Shrinkage of nuclear and cell volumes ________ of the cytoskeleton and chromatin causes the cell to shrink quickly
destruction

Histo LEC (26 decks)

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