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Flashcards in Chapter 12 Deck (37):
1

anaphase

A stage in mitosis or meiosis during which chromosomes are moved to opposite poles of the spindle apparatus.

2

astral microtubules

Mitotic and meiotic microtubules that have arisen from the two spindle poles and interact with proteins on the plasma membrane.

3

benign tumor

A mass of abnormal tissue that appears due to unregulated growth but does not spread to other organs. Benign tumors are not cancers. Compare with malignant tumor.

4

binary fission

The process of cell division used for asexual reproduction of many prokaryotic cells. The genetic material is replicated and partitioned to opposite sides of a growing cell, which is then divided in half to create two genetically identical cells.

5

cell cycle

Ordered sequence of events in which a eukaryotic cell replicates its chromosomes, evenly partitions the chromosomes to two daughter cells, and then undergoes division of the cytoplasm.

6

cell-cycle checkpoint

Any of several points in the cell cycle at which progression of a cell through the cycle can be regulated.

7

cell division

Creation of new cells by division of preexisting cells.

8

cell plate

A flattened sac-like structure formed in the middle of a dividing plant cell from Golgi- derived vesicles containing cell wall material; ultimately divides the cytoplasm into two separate cells.

9

centromere

Constricted region of a replicated chromosome where the two sister chromatids are joined and the kinetochore is located.

10

chromatid

One of the two identical double-stranded DNAs composing a replicated chromosome that is connected at the centromere to the other strand.

11

chromosome

Gene-carrying structure consisting of a single long molecule of double-stranded DNA and associated proteins (e.g., histones). Most prokaryotic cells contain a single, circular chromosome; eukaryotic cells contain multiple noncircular (linear) chromosomes located in the nucleus.

12

cleavage furrow

A pinching in of the plasma membrane that occurs as cytokinesis begins in animal cells and deepens until the cytoplasm is divided into two daughter cells.

13

cyclin

One of several regulatory proteins whose concentrations fluctuate cyclically throughout the cell cycle. Involved in the control of the cell cycle via cyclin-dependent kinases.

14

embryo

A young, developing organism; the stage after fertilization and zygote formation.

15

G1 phase

The phase of the cell cycle that constitutes the first part of interphase before DNA synthesis (S phase).

16

G2 phase

The phase of the cell cycle between synthesis of DNA (S phase) and mitosis (M phase); the last part of interphase.

17

gamete

A haploid reproductive cell that can fuse with another haploid cell to form a zygote. Most multicellular eukaryotes have two distinct forms of gametes: egg cells (ova) and sperm cells.

18

growth factor

Any of a large number of signaling molecules that are secreted by certain cells and that stimulate other cells to grow, divide, or differentiate.

19

interphase

The portion of the cell cycle between one M phase and the next. Includes the G1 phase, S phase, and G2 phase.

20

kinetochore

A protein complex at the centromere where microtubules attach to the chromosome. Contains motor proteins and microtubule-binding proteins that are involved in chromosome segregation during M phase.

21

kinetochore microtubules

Microtubules in the spindle formed during mitosis and meiosis that are attached to the kinetochore on a chromosome.

22

M phase

The phase of the cell cycle during which cell division occurs. Includes mitosis or meiosis and often cytokinesis.

23

M-phase-promoting factor (MPF)

A complex of a cyclin and cyclin-dependent kinase that, when activated, phosphorylates a number of specific proteins needed to initiate mitosis in eukaryotic cells.

24

meiosis

In sexually reproducing organisms, a special two-stage type of cell division in which one diploid (2n) parent cell produces haploid (n) cells (gametes); results in halving of the chromosome number. Also called reduction division.

25

metaphase

A stage in mitosis or meiosis during which chromosomes line up in the middle of the cell.

26

mitosis

In eukaryotic cells, the process of nuclear division that results in two daughter nuclei genetically identical with the parent nucleus. Subsequent cytokinesis (division of the cytoplasm) yields two daughter cells.

27

p53

A tumor-suppressor protein (molecular weight of 53 kilodaltons) that responds to DNA damage by stopping the cell cycle, turning on DNA repair machinery, and, if necessary, triggering apoptosis. Encoded by the p53 gene.

28

polar microtubules

Mitotic and meiotic microtubules that have arisen from the two spindle poles and overlap with each other in the middle of the spindle apparatus.

29

prometaphase

A stage in mitosis or meiosis during which the nuclear envelope breaks down and microtubules attach to kinetochores.

30

prophase

The first stage in mitosis or meiosis during which chromosomes become visible and the spindle apparatus forms. Synapsis and crossing over occur during prophase of meiosis I.

31

Rb protein

A tumor suppressor protein that helps regulate progression of a cell from the G1 phase to the S phase of the cell cycle. Defects in Rb protein are found in many types of cancer.

32

serum

The liquid that remains when cells and clot material are removed from clotted blood. Contains water, dissolved gases, growth factors, nutrients, and other soluble substances. Compare with plasma.

33

sister chromatids

The paired strands of a recently replicated chromosome, which are connected at the centromere and eventually separate during anaphase of mitosis and meiosis II. Compare with non-sister chromatids.

34

somatic cell

Any type of cell in a multicellular organism except eggs, sperm, and their precursor cells. Also called body cells.

35

synthesis (S) phase

The phase of the cell cycle during which DNA is synthesized and chromosomes are replicated.

36

telophase

The final stage in mitosis or meiosis during which daughter chromosomes (homologous chromosomes in meiosis I) have separated and new nuclear envelopes begin to form around each set of chromosomes.

37

tumor suppressor

A protein (e.g., p53 or Rb) that prevents cell division, such as when the cell has DNA damage. Mutant genes that code for tumor suppressors are associated with cancer.