chapter 12: the cell cycle

Question 1

the cell theory

Answer 1

all organisms are made of cells, and all cells arise from pre-existing cells

Question 2

Rudolf Virchow

Answer 2

proposed that new cells are formed through cell division

Question 3

cell division

Answer 3

the splitting of pre-existing cells to from new cells

Question 4

embryos

Answer 4

newly developing organisms

Question 5

meiosis

Answer 5

leads to the production of sperm and eggs; results in daughter cells that are genetically different from each other

Question 6

gametes

Answer 6

male and female reproductive cells (sperm and eggs)

Question 7

mitosis

Answer 7

leads to the production of somatic cells (non-reproductivee cells); results in daughter cells that are genetically identical to the parent cell

Question 8

somatic cells

Answer 8

non-reproductive, “body-belonging” cells

Question 9

the two ways that nuclei divide before cell division

Answer 9

meiosis and mitosis

Question 10

cytokinesis

Answer 10

the division of the cytoplasm into two distinct cells

Question 11

basic steps of cellular replication

Answer 11

(1) copying the DNA
(2) separating the copies
(3) dividing the cytoplasms to create two complete cells

Question 12

Walther Flemming

Answer 12

in 1879, observed threadlike structures (chromosomes) in the dividing cells of salamander embryos; coined the term mitosis (from the Greek for “thread”)

Question 13

Wilhelm Waldeyer

Answer 13

coined the term chromosome (“colored-body”) in 1888

Question 14

chromosome

Answer 14

consists of a single long DNA double helix that is is wrapped around proteins (histones) in a highly organized manner

Question 15

histones

Answer 15

the proteins around which the DNA is wrapped

Question 16

gene

Answer 16

a region of DNA in a chromosome that codes for a particular protein or RNA

Question 17

chromatid

Answer 17

each of the double-stranded DNA copies in a replicated chromosome

Question 18

cohesions

Answer 18

proteins that join the two chromatids along their length

Question 19

centromere

Answer 19

a specialized region of the chromosome where the connection between the two chromatids remains intact

Question 20

sister chromatids

Answer 20

chromatid copies that remain attached at their centromere

Question 21

M phase

Answer 21

occurs when cells are in the process of separating their chromosomes (“M” = mitotic or meiotic)

Question 22

interphase

Answer 22

the phase during which cells spend most of their time; no dramatic changes in the nucleus are visible; chromosomes uncoil into extremely long, thin structures and no longer appear as individual threads; the cell is either growing and preparing to divide or fulfilling its specialized function in a mulitcellular organism

Question 23

Alma Howard and Stephen Pelc

Answer 23

discovered (using what process? p. 255 review) that DNA replication occurs during a period in interphase; coined the term “cell cycle”

Question 24

S (synthesis) phase

Answer 24

the part of interphase during which chromosomes are replicated

Question 25

cell cycle

Answer 25

the orderly sequence of events that leads a eukaryotic cell through the duplication of its chromosomes to the time it divides

Question 26

G1 phase

Answer 26

the gap between the end of M phase and the start of S phase; in multicellular organisms, cells perform their functional roles during this phase

Question 27

G2 phase

Answer 27

the gap between the end of S phase and the start of M phase; cells uses this phase to prepare for M phase

Question 28

chromatin

Answer 28

DNA wrapped around globular histone proteins (what’s the difference between this and a chromosome? — chromosomes consist of chromatin?)

Question 29

the five subphases within M phase

Answer 29

1. prophase
2. prometaphase
3. metaphase
4. anaphase
5. telophase

Question 30

prophase

Answer 30

chromosomes condense into compact structures

Question 31

spindle apparatus

Answer 31

a structure consisting of microtubules that produces mechanical forces that (1) moved replicated chromosomes during early mitosis and (2) pull chromatids apart in late mitosis

Question 32

MTOCs

Answer 32

“microtubule-organizing centers”; MTOCs define the two poles of the spindle apparatus and produce microtubules

Question 33

polar microtubules

Answer 33

during prophase, microtubules, that extend from each spindle pole and overlap with one another

Question 34

centrosome

Answer 34

a structure that contains a pair of centrioles

Question 35

centrioles

Answer 35

two bundles of microtubules contained in the centrosome

Question 36

cytoplasm

Answer 36

all the contents inside the cell membrane, excluding the nucleus

Question 37

pulse-chase experiment

Answer 37

by (step 1) exposing experimental cells to a high concentration of a modified amino acid and then (step 2) washing it away and replacing it with the normal version of the amino acid, a pulse-chase experiment marks a population of molecules at a particular interval (the pulse) and then follows their fate over time (the chase)

Question 38

microtubules

Answer 38

cytoskeletal components composed of alpha-tubulin polypeptides (at the minus end) and beta-tubulins (at the plus end)

Question 39

prometaphase

Answer 39

“before middle-phase”; …

Question 40

kinetochores

Answer 40

specialized structures at which the cytoplasmic microtubules attach to chromosomes; each sister chromatid has its own kinetochore, which is assembled at the centromere

Question 41

kinetochore microtubules

Answer 41

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