Chapter 12 - The Cell Cycle

Front 1

Genome

Back 1

a cell's total hereditary endowment of DNA

Front 2

Somatic cells

Back 2

all body cells except for the reproductive cells;
diploid

Front 3

Gametes

Back 3

reproductive cells;
sperm cells and egg cells;
haploid

Front 4

Chromatin

Back 4

DNA-protein complex that forms a long, thin fiber

Front 5

Sister chromatids

Back 5

each contains an identical copy of the chromosome's DNA molecule

Front 6

Centromere

Back 6

a region that joins the sister chromatids together to form the chromosome

Front 7

Mitosis

Back 7

the division of the nucleus

Front 8

Cytokinesis

Back 8

the divsion of the cytoplasm

Front 9

Meiosis

Back 9

a variation of cell division which yields daughter cells that have half as many chromosomes as the parent cell;
occurs only in the gonads

Front 10

Mitotic (M) phase

Back 10

includes both mitosis and cytokinesis;
usually the shortest part of the cell cycle

Front 11

Interphase

Back 11

time interval during which cell grows and copies its chromosomes in preparation for cell division;
can comprise 90% of the cell's life cycle;
composed of G1, S, and G2 phases

Front 12

Prophase

Back 12

the stage of mitosis in which the mitotic spindle begins to form;
chromatin fibers become more coiled and condensed

Front 13

Mitotic spindle

Back 13

a structure that consists of fibers of microtubules that begin at the centrosomes and extends to the centromeres of each chromosome

Front 14

Interphase

Back 14

the stage of mitosis in which the single centrosome replicates and separates

Front 15

Prometaphase

Back 15

The third stage of cell mitosis in which the two centrosomes are located opposite each other;
the nuclear envelope fragments;
chromosomes continue to condense

Front 16

Kinetochore

Back 16

a structure of proteins and specific sections of chromosomal DNA at the centromere;
face in opposite directions on the chromosome and attach to the spindle fibers

Front 17

Metaphase

Back 17

the centromeres are at opposite poles of the cell;
chromosomes convene on the metaphase plate

Front 18

Anaphase

Back 18

stage of mitosis in which the paired centromeres separate and the sister chromatids are pulled to opposite poles of the cell

Front 19

Telophase

Back 19

stage of mitosis in which the nuclear envolope begins to reform in each pole of the cell;
a cleavage furrow forms along what was once called the metaphase plate, cytoplasm begins to divide

Front 20

Cleavage furrow

Back 20

a region of the cell that begins as a shallow groove in the cell surface near the old metaphase plate;
cytoplamic side of furrow is a contractile ring of actin and myosin microfilaments that pinch off the cells much like a drawstring

Front 21

Cell plate

Back 21

region of cytoplasmic division in plant cells;
vesicles containing cell-wall material migrate to this area and lay down a cell wall

Front 22

Binary fission

Back 22

"division in half";
a type of cell division utilized by prokaryotes

Front 23

Cell-cycle control system

Back 23

a cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle

Front 24

Checkpoint

Back 24

a critical control point where stop and go-ahead signals can regulate the cycle

Front 25

G0 Phase

Back 25

a nondividing state that will be entered into if cells reach the restriction point and are not ready to replicate

Front 26

Cyclin

Back 26

a protein that gets its name from its cyclically fluctuating conc. in the cell;
attaches to and activates Cdk

Front 27

Cyclin-dependent kinases (Cdk)

Back 27

kinases that drive the cell cycle and are present in constant conc., but usually in an inactive form

Front 28

MPF (maturation promoting factor)

Back 28

triggers the cells passage past the G2 phase into the M phase;
initiates mitosis by phosphorylating a variety of proteins; also initiates itso own breakdown by hydrolysis

Front 29

Growth factor

Back 29

a protein released by certain body cells that stimulates other cells to divide

Front 30

Density-dependent inhibition of cell division

Back 30

a phenomenon in which crowded cells stop dividing;
once a cell population reaches a certain density, the amount of required growth factors and nutrientsavailable to each cell becomes insufficient to allow continued cell growth

Front 31

Anchorage dependence

Back 31

a phenomenon that most animal cells exhibit in which they must be attached to a substratum in order to divide

Front 32

Transformation

Back 32

the process that converts a normal cell to a cancer cell

Front 33

Tumor

Back 33

a mass of abnormal cells within an otherwise normal tissue

Front 34

Benign tumor

Back 34

a tumorous lump in which the cells remain at the original site;
most do not cause serious problems and can be completely removed by surgery

Front 35

Malignant tumor

Back 35

a tumor that becomes invasive enough to impair the functions of one or more organs;
can be fatal;
cells of these tumors are often abnormal in many ways, such as abnormal number of chromosomes, deranged metabolism, and loss of function

Front 36

Metastasis

Back 36

the spread of cancer cells beyond their original site