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General Bio 1 for science majors > Chapter 12 > Flashcards

Chapter 12 Flashcards

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1
Q

What happens in interphase?

A

The cell grows, in preparation for cell division the chromosomes are duplicated, with the genetic material (DNA) being copied precisely.

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2
Q

What happens in mitosis?

A

The chromosome copies are separated from each other and moved to opposite ends of the cell.

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3
Q

What happens in cytokinesis?

A

The cell divides into two daughter cells, genetically identical to each other and to the parent cell.

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4
Q

What characteristic distinguishes living things from nonliving matter?

A

The ability of organisms to produce more of their own kind.

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5
Q

What is the continuity of life based on?

A

The reproduction of cells, or cell division.

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6
Q

How prevalent is cell division in living organisms?

A

Single called organisms give rise to new organisms through cell division, multicellular eukaryotes undergo embryonic development through cell division, and cell division continues to function in renewal and repair in fully grown multicellular eukaryotes.

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7
Q

What is a crucial function of cell division?

A

The distribution of identical genetic material to the two daughter cells. It is remarkably accurate in passing DNA from one generation to the next.

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8
Q

What is a genome?

A

All the DNA in a cell. A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells).

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9
Q

How are DNA molecules packaged?

A

Into chromosomes; the DNA molecule of a chromosome carrie’s several hundred to a few thousand genes.

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10
Q

What do eukaryotic chromosomes consist of?

A

Chromatin, a complex of DNA and protein that condenses during cell division. Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus.

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11
Q

What are somatic cells?

A

Nonreproductive cells that have two sets of chromosomes.

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12
Q

What are gametes?

A

Reproductive cells (sperm and eggs) that have half as many chromosomes as somatic cells.

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13
Q

What does each duplicated chromosome have?

A

Two sister chromatids (joined copies of the original chromosome) that are attached along their lengths by cohesion’s.

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14
Q

What is the centromere?

A

The narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached.

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15
Q

What happens to the two sister chromatids during cell division?

A

They separate and move into two nuclei. Once separate, the chromatids are called chromosomes.

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16
Q

What does eukaryotic cell division consist of?

A

Mitosis (the division of the genetic material in the nucleus), and cytokinesis (the division of the cytoplasm).

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17
Q

How are gametes produced?

A

By a variation of cell division called meiosis.

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18
Q

What is meiosis?

A

It yields no identical daughter cells that have half as many chromosomes as the parent cell.

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19
Q

Who developed dyes to observe chromosomes during mitosis and cytokinesis?

A

German anatomist Walter Fleming in 1882.

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20
Q

What are the phases of the cell cycle?

A

Mitosis (M) phase, interphase.

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21
Q

What is the mitotic phase (M)?

A

The phase that includes mitosis and cytokinesis.

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22
Q

What is interphase?

A

The phase of cell growth and copying of chromosomes in preparation for cell division.

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23
Q

What are the three stages of interphase?

A

G1 phase, S phase, and G2 phase.

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24
Q

What is the G1 phase?

A

The “first gap” after the previous M phase. It consists of metabolic activity and growth. Unduplicated chromosomes in the cell.

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25
What is the S phase?
The "synthesis" phase after the G1 phase. It consists of metabolic activity, growth, and DNA synthesis.
26
What is the G2 phase?
The phase after the S phase. Consists of metabolic activity, growth, and preparation for cell division. Contains duplicated chromosomes due to the previous S phase.
27
What are the five stages of mitosis?
Prophase, prometaphase, metaphase, anaphase, and telophase.
28
What are distinguishing features of prophase?
Early mitotic spindle, aster, centromeres in a roughly nucleus shaped area.
29
Distinguishing features of prometaphase?
Fragments of nuclear envelope, no kinetichore microtubules, kinetochore and kinetochore microtubules.
30
Distinguishing features of metaphase?
Centrosomes at one spindle pole, metaphase plate, spindles attached to the chromosomes lined up in the middle.
31
Distinguishing features of anaphase?
Mostly the same as metaphase, but half of the chromosomes are getting pulled to each pole by the spindles.
32
Distinguishing features of telophase?
Nuclear envelope reforming around each pole of chromosomes, a cleavage furrow, and nucleolus formation.
33
What is a mitotic spindle?
A structure of microtubules that controls chromosome movement during mitosis. In animal cells, assembly of spindle microtubules begins in the centrosome, a type of microtubules organizing center.
34
35
What is an aster?
A radial array of short microtubules and extends from each centrosome. The spindle includes the centrosomes, the spindle microtubules, and the asters.
36
What is a kinetochore?
A protein complex associated with centromeres. During prometaphase, some spindle microtubules (kinetochore microtubules) attach to the kinetochores.
37
What is the metaphase plate?
At metaphase, the chromosomes are all lined up at the "metaphase plate," an imaginary plane midway between the spindle's two poles.
38
What is separate?
In anaphase, the cohesion's are cleaved by this enzyme.
39
What happens after the cohesins are cleaved?
Sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell. The microtubules shorten by depolymerizing at their kinetochore ends.
40
What are results from a certain clever experiment?
The results suggest that motor proteins on kinetochores "walk" the chromosomes along the microtubules during anaphase.
41
What is the "Pac-man" mechanism?
The depolymerization of the microtubules at the kinetochore ends occurs after the motor proteins have passed.
42
What does other research show?
That chromosomes are "reeled in" by general motor proteins at the spindle poles. The general consensus is that both mechanisms are used. Microtubules depolymerize after they pass by the motor proteins at the poles.
43
What do nonkinetochore microtubules do at opposite poles?
Overlap and push against each other, elongating the cell. At the end of anaphase, duplicate groups of chromosomes have arrived at opposite ends of the elongated cell.
44
What is the difference of cytokinesis in plant and animal cells?
Animal cells have a cleavage furrow, which is a shallow groove in the cell surface near the old metaphase plate before the actual cytokinesis. Plant cells have cell walls, which are hard to bend and break, so a cell plate forms during cytokinesis.
45
What happens in plant cells during cytokinesis?
The vesicles form the cell plate in the middle of the cell, and a new cell wall forms in between them and creates two daughter cells.
46
How do prokaryotes divide?
Bacteria and archaea reproduce by a type of cell division called binary fission.
47
What is binary fission?
The chromosome replicates (beginning at the origin of replication) and the two daughter chromosomes actively move apart. The plasma membrane pinches inward, dividing the cell in two.
48
What are still active areas of research?
How bacterial chromosomes move and their location established.
49
What are the simple steps of binary fission?
Chromosome replication begins, one copy of the origin is now at each end of the cell, replication finishes, two daughter cells result.
50
What would be the evolutionary timeline for cell division?
Prokaryotes evolved before eukaryotes, and mitosis probably evolved from binary fission. Certain unicellular eukaryotes exhibit types of cell division that seem intermediate between binary fission and mitosis.
51
What happens when cells escape the usual regulation of the cell cycle?
Cancer cells. Unregulated division as well as unregulated frequency of the division.
52
What drives the cell cycle?
Appears to be by specific signaling molecules present in the cytoplasm. Some evidence for this hypothesis comes from experiments in which cultured mammalian cells at different phases of the cell cycle were fused to form a single cell with two nuclei. Signals in the cytoplasm of the fused cell caused both nuclei to enter the same phase of the cell cycle.
53
What is the cell cycle control system?
The sequential events of the cell cycle. The checkpoints are subjected to both internal and external regulation.
54
What are two types of regulatory proteins that are involved in the cell cycle?
Cyclins and cyclin dependent kinases (Cdks).
55
What are cyclins and Cdks?
Cyclins are named for their cyclically fluctuating concentrations in the cell. The activity of a Cdk rises and falls with the changes in concentration of its cyclin partner. Cdks must be attached to a cyclin to be active.
56
What is MPF?
Maturation promoting factor. It is a cyclin-Cdk complex that triggers a cell's passage past the G2 checkpoint into the M phase. Peaks of MPF activity correspond to the peaks of cyclin concentration. MPF acts both directly as a kinase and indirectly through activating other kinases.
57
What are three important checkpoints?
The ones in G1, G2, and the M phases.
58
What is the G1 checkpoint?
It seems to be the most important. If a cell receives a go ahead signal the G1 checkpoint it will usually complete the S, G2 and M phases and divide. If it does not pass the checkpoint, it will exit the cycle and switch into a no dividing state called the G0 phase.
59
What is an example of the internal signals used for the checkpoints?
Cells will not begin anaphase until all chromosomes are properly attached to the spindle at the metaphase plate. This mechanism ensures that daughter cells have the correct number of chromosomes.
60
What are growth factors?
External factors that are released by certain cells and stimulate other cells to divide.
61
What are external factors?
Can be chemical or physical, they influence cell division.
62
What is PDGF?
Platelet derived growth factor, it is made by blood cell fragments called platelets. PDGF is required for the division of cultured fibroblasts.
63
What is density dependent inhibition?
Crowded cells will stop dividing.
64
What is anchorage dependence?
For (most) animal cells to divide, they must be attached to a substratum.
65
What do density dependent inhibition and anchorage dependence regulate?
They check the growth of cells at an optimal density. Cancer cells exhibit neither type of regulation of their division.
66
What all is abnormal about cancer cells?
They do not heed the normal signs that regulate the cell cycle, they do not stop dividing when growth factors are depleted, they do not need growth factors to grow and divide: they may make their own growth factor and may convey a growth factor's signal without the presence of the growth factor.
67
What happens when cells acquire the ability to divide indefinitely?
They have undergone transformation.
68
What happens when cancer cells are not eliminated by the immune system?
They form tumors, which are masses of abnormal cells within otherwise normal tissue.
69
What is a benign tumor?
Abnormal cells that remain only at the original site. Most benign tumors do not cause serious problems depending on their locations.
70
What are malignant tumors?
They invade surrounding tissues and can undergo metastasis, where they may form additional tumors. Localized tumors may be treated with high energy radiation which damages the DNA in the cancer cells. The majority of cancer cells have lost the ability to repair DNA damage.
71
What is metastasis?
The spread of cancer cells to other parts of the body.
72
Why is chemotherapy used on cancer cells?
It targets the cell cycle. Researchers are producing a flood of information about cell signaling pathways and their relationship to cancer. Coupled with new molecular techniques, treatments for cancer are becoming more "personalized" to a particular patient's tumor.
73
What are side effects of chemotherapy?
The drugs also start affecting normal working cells that divide frequently.

General Bio 1 for science majors (11 decks)

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