Cell Cycle and tWitosis
THE CELL CYCLE
The cell cycle, or cell-division cycle, is the series of events thot
toke place in o eukoryotic cell betweenits formotion ond the moment
it replicotes itself. These events can be divided in two moin ports:
interphose (in befween divisions phose grouping 6r phase, s phase, G2
phose), during which the cell is forming and corries on with its normol
metobolic functions; the mitotic phose (M mitosis), during which the
cell is replicoting itself. Thus, cell-division cycle is on essentiol process
by which o single-cell fertilized egg develops into o moture orgonism
ond the process by which hoir, skin, blood cells,ond some internol
orgons ore formed.
1.
Whot is meont by the cell cycle or cell division cycle?
Z.Tn whot type
cycle occur?
of
cells
--- prokciryotes or eukaryotes --- does the cell
3. Nqme the 2 main PHASES of
4.
the cell cycle.
is in betweenthe times when o cell is dividing.
5. What is occurring in o cell during interphosa?
6. Whot is occurring during the mitosis phose?
7. A f erlilized cell develops into o
cycle.
8. Nome three things thot form during the cycle.
orgonism during the cell
INTERPHAsE
Interphose is o phose sf the cell cycle, defined only by the sbsence of
cell division. During interphose, the cell obtoins nutrients, ond
duplicotes (copies) its chromotids (genetic moteriol). The genetic
moteriol or chromotids qre locsted in the nucleus of the cell ond ore
mode of the molecule DNA.
9. Whot process NEVER occurs in interphase?
tO. Cells obfain
ond duplicote or copy
their
or genetic mqteriol during interphase.
11.
Where a?e chromotids found in a, cell?
12. Chromqtids sre made of o molecule colled
Chromotids ore connected by the centrome?e ond hove q LONG AND
5HORT ARAA.
CHROMOSOME
I
I
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+*-CENTROMERE
CHROMATID
CHROMATID
Label the parts
of
thechromosome inctuding the long ond short arms.
1.
2.
3.
4.
Most eukoryotic cells spend most of their time in interphase. For
example, human skin cells, which divide obout once a doy, spend roughly Z?
hours in interphose. About 9Q percent of cells are in interphose. Some
cells, such as nerve cells, con stay in inferphose for decades. There are 3
ports of interphose: G1 (growfh 1 in which the cell creates orgonelles ond
begins metobolism), 5 phose (DNA synthesis in which the chromosomes
of the cell are copied) and Gz (growth z in which the cell grows in
preparotion for cell division). Find fhe cell cycle drawingon this
worksheet ond draw an additional line in red around those parts of the
cell cycle diogrom thot ore included in interphose.
13.
fn whot PHASE do most cells spand the majority of their lifietime?
74. Haw often do humon skin cells divide esch doy?
15. How mony hours per doy is o human skin cell in interphose?
16. Whot type of cell moy spen d decodes in interphose insteod
dividing?
17. Nome the 3 stoges in interphose.
18.
whot does 6r stond for ond whot occurs in this stage?
a
J
of
19.
Whot does 5 stond for ond whot occurs in this stage?
20. Whot does Gz stand for snd whot occurs in this stage?
Sometim es the cells extl the cell cycle (usually f rom 61 phose) ond
enter the Go phose" fn the Go phose, cells ore olive ond metobolicolly
sctive, but do not divide. In this phose cells do not copy their DNA ond
do not preparefor cell division. Many cells in the humon body, including
these cells
those in heort muscle, eyes,and broinare in the Gsphase.
If
are domoged they connot be replaced. Agoin find the cell cycle
drowing on this worksheet ond draw an arrow in black on the cell cycle
showing where a cell would enter the G, phose.
21. From stage
of the cell cycle do cells sometimes EXIP
2?.What hoppens to cells thst enfer the Go stage?
23. Nqme 3 types of cells
moture?
thst enter the Go phase when they are
24.Whot hoppens if these cells qre domaged during your lifetime?
The Gr phase is o period in the cell cycle during interphose, ofter
cytokinesis (process whereby a single cell is divided into two identicol
doughter cells whenever the cytoplosm is divided) ond bef ore the 5
phose. For mony cells,this phose is the mojor period of cell growth
during its lifespon. During this stagenew organelles ore being
synthesized (mode), so the cell requires both structural proteins ond
enzymes, resurting in great omount
of protein'l synthesis. coror the
phose g"een on the cell cycledrowing.
'
6t
25. Whal stoge occurs after
cytokinesisl
26. what port
of
the ceil is divided during cytokinesis?
27' what are the newcetls cqlled
ond how do they compore with each
other?
28. What is mojor thing happening
to o cell durin g Ge
29. What ceil structur es are
made in Ge
30. Since proteins ond
there is a great omount of protein
are being rnode during Gl,
occurring.
The s phose, short for synthesis
phose, is o period in the cey cycre
during interphose,between G! phase
ond the Gz phase. Foilowing Gr,
the cell enters the s stage,whenDNA
synthesis
At the beginning of the 5 stoge, eachchromosomeor replicotion occurs.
is composed of one
coiled DNA doubte helix molecule,
which is called o chromotid. At the
end of this stog e, esch chromosome
hos two identicol DNA double helix
'theref
molecules' ond
ore is composed of two sister chromotids.
During s
phose, the centrosome is orso
dupricated. coror the sphose a?ange.
31. Whot does the S phose stond
for?
3?. What hoppens during the S phose?
33. Eoch chromosome originoily is
made of how mony DNA morecures
ond how does this morecure oppeor
in the chromosome?
34-
At theend of s phose eoch chromosome
hos how mony
molecules?
coiledDNA
meiosis. Prokoryotic cells (bacterio), which lqck o nucleus, divide by o
process called binory fission.
42. When a?e chromosomes duplicoted --- bef ore or during mitosis?
43. Whot process follows mitosis?
44.The nucleus is divided during
, while rytoplasm of
the cell is divided during
45. How do the two new cells compare with eoch other?
46.The two new cells ore called
cells.
47. Does mitosis occur in prokoryotes? Explain why or why not.
48. Whot process is used by bocterio to divide ond reproduce?
49. Body cells are colled
ore known os
cells, while reproductive cells
cells.
four
The process of mitosis (division of the nucleus) is divided into
stoges (Prophose, Metaphose, Anaphase, ond Telophose). Immediotely
following nucleor division (mitosis) , the cel! membrone must olso divide
(cytokinesis). Animol cells divide the cytoplasm by constricting the cell
membrone in the middle to form o cleovoge furrow. Plont cells form a cell
plote in the center to divide the cytoplasm. At fnterphase, there is only
one cell, but ofter cytokinesis ther e oretwo identicot celts.
50. Nome the 4 mitotic stoges.
51. How does cytokinesis occur in on onimal cell?
52. How does cytokinesis occur in o plont cell?
+.
During interphose, the genetic moteriot is colled chromatin
ond con
NoT be clearly seen becouse it isn't tightly coired. when prophose
begins, the DNA molecules ore progressivaly shor
tenedond condensed by
coiling, to form visible chromosomes. Enrymes during prophose
breok
down the nuclear membrone ond nucleolus so they
o." no' longervisible.
Spindle fibers olso form in prophase which will attoch
to the
chromosomes- At metophose, the spind le fibers ottoch
themselves to the
centromeres of the chromosomes ond olign the chromosomes qt
the
equotor (middle of the cell). Anophose is the next stoge. The
spindte
fibers shorten ond the centromere splits seporoting the two sister
chromotids- During telophase, thechromosomes poirs (chromotids
sre
pulled to opposite poles of the cell. The nucl ear envelope
ond nucleolus
reform bef ore the chromosomes uncoil. The spindle fiLers disint
egrate.
53. Genetic moteriol is colled
during interphose and
TS / fS NOT clearrly visible.
54. whot makes the chromosomes become visible during prophose?
55. whot is used to help break down the nucleor membrone?
56. Besides the nucleus, whot else is broken down during prophase?
57. what forms during prophose to LATER ottsch ond move
chromosomes?
58. Doubled chromosomes ore hetd together by the
59. Where do chromosomes line up during metophase?
60. During whot stage qre sister chromotids seporoted ond
moved to
opposite ends of the cell?
61. Nome 4 things thot hoppen during telophose.
o.
b.
c.
d.
Name each numbered stage in fhe plant cell cycle diagram:
(inferphase,
metaphase, anaphase, or felophase)
1.
2.
3.
7.
8.
9.
4.
10.
11.
5.
6.
13.
14.
15.
16.
17.
12.
18.
Plant Cells in Mitosis
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Label the stages of the cell cycle & mitosis. LABEL and COLOR
the sfages in the plant cell and animal cell- The sfages should be
colored as follows --- interphase-pink, prophose-light green,
metophose-red,onophase-light blue, ond telophose-yellow. Also lobel
the CENTRIOLES, SPTNDLE FIBERS, CENTROMERE, ond
CHROMOsOMEs.
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