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Chapter 12 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

The ability of organisms to produce more of their own kind best distinguishes living things from

A

nonliving matter

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2
Q

The continuity of life is based on the reproduction of cells, or

A

cell division

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3
Q

In unicellular organisms,

A

division of one cell reproduces the entire organism

asexual reproduction

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4
Q

Multicellular organisms depend on cell division for

A

growth and development, and repair

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5
Q

3 key roles of Mitosis

A
  1. asexual reproduction
  2. growth and development
  3. repair
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6
Q

Cell division is an integral part of the cell cycle,

A

the life of a cell from formation to its own division

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7
Q

Mitosis-

A

dividing of DNA in the nucleus

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8
Q

Most cell division results in

A

daughter cells with identical genetic information, DNA

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9
Q

The exception is meiosis,

A

a special type of division that can produce sperm and egg cells

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10
Q

Cytokinesis

A

dividing the cytoplasm

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11
Q

All the DNA in a cell constitutes the cell’s

A

genome

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12
Q

A genome can consist of

A

a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells)

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13
Q

DNA molecules in a cell are packaged into

A

chromosomes

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14
Q

Eukaryotic chromosomes consist of a chromatin,

A

a complex of DNA and protein that condenses during cell division

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15
Q

Every eukaryotic species has a characteristic number of

A

chromosomes in each cell nucleus.

Humans have 46

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16
Q

Somatic cells (nonreproductive cells)

A

have two sets of chromosomes

called diploid cells; 2n

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17
Q

Gametes (reproductive cells: sperm and eggs)

A

have half as many chromosomes as somatic cells

called haploid cells; n

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18
Q

Somatic Cells

A 
body cell
2 sets of chromosomes
diploid
2n
2n=46
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19
Q

Gametic Cells

A

egg/sperm (germ)
1 set of chromosomes
haploid
n

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20
Q

In preparation for cell division,

A

DNA is replicated and the chromosomes condense

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21
Q

Each duplicated chromosome has

A

two sister chromatids (joined copies of the original chromosome), which separate during cell division

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22
Q

The centromere is the

A

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

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23
Q

During cell division,

A

the two sister chromatids of each duplicated chromosome separate and move into two nuclei

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24
Q

Sister chromatids ONLY exist as

A

sisters

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25
Q

Once separate, the (sister?) chromatids are called

A

chromosomes

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26
Q

Eukaryotic cell division consists of

A

Mitosis
and
Cytokinesis

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27
Q

Mitosis

A

the division of the genetic material (DNA) in the nucleus

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28
Q

Cytokinesis

A

the division of the cytoplasm

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29
Q

Gametes are produced by a

A

variation of cell division called meiosis

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30
Q

Meiosis yields nonidentical daughter cells that have only

A

one set of chromosomes, half as many as the parent cell

Humans 2n=46 to n=23

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31
Q

The mitotic phase alternates with

A

interphase in the cell cycle

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32
Q

Interphase (about 90% of the cell cycle) can be divided into subphases

A 
G1 phase ("first gap")
S phase ("synthesis")
G2 phase ("second gap")
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33
Q

The cell grows during all three phases, but

A

chromosomes are duplicated only during the S phase

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34
Q

Mitosis is conventionally divided into five phases

A 
P- Prophase
P- Prometaphase
M- Metaphase
A- Anaphase
T- Telophase
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35
Q

Prophase

A

chromosomes become visible

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36
Q

Prometaphase

A

nuclear envelope disappears/ spindle fibers attach to kintochore (DNA)

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37
Q

Metaphase

A

line up

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38
Q

Anaphase

A

pull apart

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39
Q

Telophase

A

nuclear envelope reforms, goes back to chromatin

40
Q

Cytokinesis overlaps the

A

latter stages of mitosis

41
Q

The mitotic spindle is a structure made of

A

microtubules that controls chromosome movement during mitosis

42
Q

In animal cells, assembly of spindle microtubules begins in the

A

centrosome, the microtubule organizing center

43
Q

The centrosome replicates during interphase (G2 phase), forming

A

two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase

44
Q

An aster (a radial array of short microtubules)

A

extends from each centrosome

45
Q

The spindle includes the

A

centrosomes, the spindle microtubules, and the asters

46
Q

During prometaphase,

A

some spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosomes

47
Q

Kinetochores are

A

protein complexes associated with centromeres

48
Q

At metaphase,

A

the chromosomes are lined up at the metaphase plate, an imaginary structure at the midway point between the spindle’s two poles

49
Q

In anaphase,

A

sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell.

Proteins holding together sister chromatids are suddenly inactivated

50
Q

The microtubules shorten by

A

depolymerizing at their kinetochore ends.

Motor proteins on a kinetochore “walk” a chromosome along a microtubule toward the nearest pole

51
Q

Nonkinetochore microtubules from opposite poles overlap and

A

push against each other, elongating the cell. (stretches the cell).

(They don’t grab onto the DNA, but they are really important)

52
Q

In telophase,

A

genetically identical daughter nuclei form at opposite ends of the cell

53
Q

Cytokinesis beings during

A

anaphase or telophase and the spindle eventually disassembles.

54
Q

Cytokinesis is NOT part of

A

Mitosis.

They just overlap a bit sometimes.

55
Q

In animal cells, cytokinesis occurs by a process known as

A

cleavage, forming a cleavage furrow.

56
Q

Cleavage furrow is

A

a contractile ring of actin and microfilaments myosin protein.
Like a drawstring pulling it tight, until it pops apart.

57
Q

Cytokinesis in animal cells

A

cleavage- process

cleavage furrow- structure formed

58
Q

In plant cells, cytokinesis occurs by a process known as

A

cell plate formation, which forms a cell plate

59
Q

A cell plate is

A

specialized vesicles grown and then fuse

60
Q

Cytokinesis in plant cells

A

cell plate formation- process

cell plate- structure formed

61
Q

Prokaryotes (bacteria and archaea) reproduce by a type of cell division called

A

binary fission

62
Q

In binary fission,

A

the chromosome replicates (beginning at the origin of replication), and the two daughter chromosomes actively move apart.

63
Q

Prokaryotes do NOT have any

A

mitotic spindles or microtubules that direct this traffic (replication, binary fission)

64
Q

In binary fission, the plasma membrane

A

pinches inward, dividing the cell into two

65
Q

The Eukaryotic cell cycle is regulated by a

A

molecular control system

66
Q

The frequency of cell division varies with the

A

type of cell.

These differences result from regulation at the molecular level.

67
Q

Cancer cells manage to

A

escape the usual controls on the cell cycle

68
Q

The cell cycle appears to be driven by

A

specific chemical signals present in the cytoplasm.

a specific chemical signal is the reason a cell divides

69
Q

The sequential events of the cell cycle are directed by a distinct

A

cell cycle control system, which is similar to a clock

70
Q

The cell cycle control system is regulated by

A

both internal and external controls

71
Q

The clock (cell cycle) has specific checkpoints where

A

the cell cycle stops until a go-ahead signal is received

72
Q

For many cells, the G1 checkpoint seems to be

A

the most important

73
Q

If a cell receives a go-ahead signal at the G1 checkpoint, it will usually

A

complete the S, G2, and M phases and divide

74
Q

If the cell cycle does not receive the go-ahead signal at the G1 checkpoint, it

A

will exit the cycle, switching into a non-dividing state called the G0 phase.

75
Q

In the G0 phase,

A

cells will never divide again.

76
Q

Two types of regulatory proteins are involved in cell cycle control:

A

Cyclins
and
Cyclin-dependent kinases (Cdks)

77
Q

Cyclin-dependent kinases (Cdks) activity fluctuates during the cell cycle because it is

A

controlled by cycles, so named because their concentrations vary with the cell cycle

78
Q

MPF (maturation-promoting factor) is a

A

cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phase

79
Q

Cyclin is what is

A

cycling and is around sometimes but not always

??

80
Q

Cyclin is really high during the

A

G2 and M phase, so cyclin-dependent kinases works best at the G2 and M phase too.

81
Q

An example of an internal signal is that

A

kinetochores not attached to spindle microtubules send a molecular signal that delays anaphase

82
Q

Some external signals are

A

growth factors (paracrine signaling), proteins released by certain cells that stimulate other cells to divide

83
Q

For example, platelet-derived growth factor (PDGF) stimulates the division of

A

human fibroblast cells in culture.
(have to have PDGF if want a cell to divide??)

(external signal?)

84
Q

A clear example of external signals is

A

density-dependent inhibition, in which crowded cells stop dividing.

(As soon as things become dense, packed, crowded, and full, the cells stop dividing.

85
Q

Most animal cells also exhibit

A

anchorage dependence, in which they must be attached to a substratum in order to divide

(has to be stuck to something in order to divide)

86
Q

Cancer cells exhibit neither

A

density-dependent inhibition nor anchorage dependence.

cancer cells just divide and don’t obey those two things. They don’t need any signals or growth factors.

87
Q

Cancer cells do not respond normally to the

A

body’s control mechanisms

88
Q

HeLa cells

A

“immortal cell line”

89
Q

Cancer cells may not need growth factors to grow and divide.

A
  • They may make their own growth factor.
  • They may convey a growth factor’s signal without the presence of the growth factor.
  • They may have an abnormal cell cycle control system.
90
Q

A normal cell is converted to a cancerous cell by a process called

A

transformation

91
Q

Cancer cells that are not eliminated by the immune system form

A

tumors, masses of abnormal cells within otherwise normal tissue

92
Q

If abnormal cells remain only at the original site, the lump is called a

A

benign tumor

93
Q

Malignant tumors invade

A

surrounding tissues and can metastasize, exporting cancer cells to other parts of the body, where they may form additional tumors.

(Malignant tumors grow bigger and bigger. They are really bad)

94
Q

Recent advantages in understanding the cell cycle and cell cycle signaling have led to

A

advances in cancer treatment

95
Q

Cancer results from

A

genetic changes that affect cell cycle control

► Biology (29 decks)

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