Chapter 12

Question 1

genome

Answer 1

a cells DNA, its genetic information

Question 2

chromosomes

Answer 2

packages of DNA molecules

Question 3

chromatin

Answer 3

entire complex of DNA and proteins that is the building material of chromosomes

Question 4

somatic cells

Answer 4

all body cells except the reproductive cells

Question 5

gametes

Answer 5

reproductive cells

Question 6

sister chromatids

Answer 6

joined copies of the original chromosome

Question 7

centromere

Answer 7

a region made up of repetitive sequences in the chromosomal DNA where the chromatid is attached most closely to its sister chromatid

Question 8

mitosis

Answer 8

division of genetic material in the nucleus

Question 9

cytokinesis

Answer 9

division of the cytoplasm

Question 10

cell cycle

Answer 10

the life of a cell from the time it is first formed during the division of a parent cell until its own division into two daughter cells

Question 11

mitotic phase

Answer 11

includes both mitosis and cytokinesis; shortest part of cell cycle

Question 12

G1 phase

Answer 12

first gap

Question 13

G2 phase

Answer 13

second phase

Question 14

S phase

Answer 14

synthesis

Question 15

prophase

Answer 15

chromatin condensed

Question 16

metaphase

Answer 16

centromeres go to opposite poles

Question 17

anaphase

Answer 17

separates ta the centromere

Question 18

telophase

Answer 18

two daughter nuclei form

Question 19

cytokinesis

Answer 19

cytoplasm is split and two cells are formed

Question 20

mitotic spindle

Answer 20

structure consists of fibers made out of microtubules and associated proteins; forms in cytoplasm during prophase

Question 21

centrosome

Answer 21

subcellular region containing material that functions throughout the cell cycle to organize the cells microtubules

Question 22

metaphase plate

Answer 22

imaginary plate midway between spindle’s two poles

Question 23

cleavage furrow

Answer 23

a shallow groove in the cell surface near the old metaphase plate

Question 24

binary fission

Answer 24

division in half; asexual reproduction of single-celled eukaryotes

Question 25

origin of replication

Answer 25

specific place on the chromosome where the process of cell division is initiated and the DNA of the bacterial chromosome begins to replicate

Question 26

cell control system

Answer 26

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

Question 27

checkpoint

Answer 27

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

Question 28

cyclin

Answer 28

a protein that gets its name from its cyclically fluctuating concentration in the cell

Question 29

growth factor

Answer 29

protein released by certain cells that stimulates other cells to divide

Question 30

density-dependent inhibition

Answer 30

a phenomenon in which crowded cells stop dividing

Question 31

benign tumor

Answer 31

tumors that do not cause serious problems

Question 32

malignant tumor

Answer 32

includes cells whose genetic and cellular changes enable them to spread to new tissues and impair the functions of one of more organs

Question 33

metastasis

Answer 33

the spread of cancer cells to locations distant from their original site