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Cell Reproduction
Chapter 8
Chromosomes
Vs.
Chromatin
Chromosomes
Chromatin
Think of it like
Cookies!
Chromatin
MAKES
Chromosomes
Our cells are constantly needing to
replace themselves.
For example, when we get a paper cut
or any kind of cut, those cells need to
be replaced.
Also, cells in your stomach lining
constantly need to be replaced, and
even bone marrow cells.
Cell Division:
What is it?
The Cell Cycle is a sequence of separate
Division
periods of __________
& __________
Growth
The period where the cell grows in size,
metabolizes, and spends a majority of its
life is _______________
INTERPHASE
Also, during this period, the chromosomes are
duplicated to prepare for cell division.
___________
The period where the cell undergoes
nuclear division and creates 2 daughter
cells is called ____________
MITOSIS
Each daughter cell contains a
Complete
____________
set of the parent cell’s
chromosomes.
75% of a
cell’s life
is spent in
Interphase
Which
phase of
the cell
cycle
takes the
longest?
Copies its
chromosomes
G1
S
G2
 “Checkpoints” = stop
& go-ahead signals to
regulate the cycle
 Regulatory
molecules, usually
enzymes (protein
kinases)
To become active
kinases need a cyclin
to trigger them
Often called “Cdks”
(cyclin-dependent
kinases)
PROPHASE
The first phase = ____________
 This is the ________
longest phase (OF MITOSIS)
 During this phase, chromatin coils to form
visible _____________
chromosomes
 Each chromosome is made up of ___
2 sister
chromatids and are held together by a
__________
centromere
*Remember: The chromosomes are
Interphase
duplicated in ____________
to prepare for
cell division
The TWO together
are
sister chromatids
One
Chromatid
Duplicated
Chromatid
nuclear envelope starts
 In addition, the ________
to disappear and the __________
nucleolus
disintegrates.
centrioles
 In animal cells, ___________
migrate to
opposite ends of the cell and ________
spindle
fibers
________
begin to form.
 In plant cells _______
Spindle _______
fibers form
without centrioles.
METAPHASE
The Second Phase = _____________
• The chromosomes begin to line up along
the _________
of the cell
Equator
attach to the
• The spindle fibers _______
centromeres.
• Each chromatid has its own spindle fiber
attached
The Third Phase = ____________
ANAPHASE
 This marks the ___________
separation of sister
chromatids.
 The centromeres ______
and the
split
______
sister ___________
chromatids are pulled apart to
opposite poles of the cell by shortening
spindle fibers
TELOPHASE
The Fourth Phase = ______________
daughter cells start to
Here two distinct _________
form.
chromosomes unwind, the
In addition, the _____________
break down, the _________
nucleolus
spinder fibers ______
envelope
reappears, a new nuclear __________
membrane begins
forms, and a new double __________
to form between the two nuclei.
Cytokinesis
cytoplasm
 the division of ____________
 Toward the end of telophase in animal
cells, the plasma membrane _______
pinches in
along the equator
cell _________
membrane forms
 In plant cells, a ____
around each cell and new cell ______
wall form
on each side of the cell plate until
separation is complete.
Can you identify any of the stages?
Now the cells are separated, they will
continue in the cell cycle and enter
__________
interphase