Download 8 cell division

Cell Cycle Interactive
Cell Reproduction 2.55
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In most cases, a
living thing grows
because it produces
more cells.
Zygote
blastula
Early gastrula
Late gastrula
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SURFACE-TO-VOLUME RATIO
– Is greater in small cells than in larger cells
– A greater surface area allows materials to enter
and leave the cell at a faster rate
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DNA’s ability to
produce enough
messenger RNA
decreases with an
increase in cell
growth
Results in cell
division – process
whereby the cell
divides into 2
daughter cells
Rates differ from cell
type to cell type
 Are affected by
external conditions
 They have to be
right
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Cells in certain places in the body,
such as the heart and the
nervous system rarely divide, if
they divide at all.
Cells of the skin and digestive
tract grow and divide rapidly due
to daily wear and tear.
 Cells grow until they come into
contact with other cells.
 Cell growth and cell division
are turned on and off to repair
injuries.
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CANCER – is a disorder
in which some cells have
lost the ability to
control their own rate
of growth
Cancer cells do not stop
growing when they
come in contact with
other cells
SKIN CANCER
SKIN CANCER
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Are structures in the cell
that contain the genetic
information that is passed
on from one generation of
cells to the next.
Are not visible in most cells
except during mitosis.
Contain the genetic
information in the form of
DNA
Between cell
divisions, chromatin
forms condensed
and dispersed
regions
 During the early
stages of mitosis, the
chromatin
condenses and the
chromosomes
become visible

 Chromatin
is
composed of
DNA and
protein
After DNA replicates,
the chromosomes
become visible by
condensing
 Sister chromatids – are
two identical parts that
result from DNA
replication
 Are attached at an area
called the centromere

Cell cycle 1.50

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Is the period from the
beginning of one mitosis to
the beginning of the next
mitosis.
Is the period when a cell
grows, prepares for
division, and divides to
form 2 daughter cells which
begin the cycle again
The longest phase of an active
cell cycle is Interphase.
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A period of nondivision
Period of growth, development,
replication, and synthesis
Results in cell growth and development
The chromosome number doubles
Organelles and materials required for cell
division are synthesized
The nucleus synthesizes messenger RNA in
order to direct cell activities
4.28
Interphase can be divided into
three parts:
G1 -
S
-
G2.
Mitosis or M-phase is the part of
the cell cycle when the cell is
actually dividing into two new
daughter cells.
Mitosis can be divided into four
parts:
Telophase
Metaphase
Prophase
Anaphase
1.51
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a period of active
division
Is the M phase
Period when the
nucleus divides
into 2 nuclei
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The first phase of
mitosis (is the longest)
Chromosomes become
visible as a result of the
condensing and coiling
of the chromatin
The centrioles separate
from each other and take
up positions on the
opposite sides (poles)
of the nucleus
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The centrioles
develop a spindle
The spindle fibers
help move the
chromosomes
apart
The nucleolus
disappears and the
nuclear envelope
breaks down
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Is the second
phase of mitosis
(shortest
phase)
Chromosomes
line up across
the center or
equator of the
cell
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Is the third phase of mitosis
Centromeres that join the
sister chromatids split
causing the sister chromatids
to separate and become
individual chromosomes
Chromosomes separate into 2
equal groups near the poles
of the spindle
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Is the final phase of mitosis
Chromosomes begin to unravel
into a tangle of chromatin
The nuclear envelope reforms
around the chromatin
The spindle begins to break
apart, and a nucleolus
becomes visible in each
daughter nucleus
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Is the division of the cytoplasm into 2
individual cells
In animal cells – the
cell membrane moves
inward until it
pinches into nearly 2
equal parts, each
part containing its own
nucleus and
cytoplasmic
organelles
Cleavage furrow
Cell Plate
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In plant cells – a cell
plate forms midway
between the divided
nuclei
and gradually develops
into a separating
membrane in which a
cell wall begins to
appear

Unicellular organisms – it is their
method of reproduction
1 organism
2 organisms
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Multicellular
organisms – in their
body cells
It is used to repair
damaged tissue
or replace cells
and for growth
Parent cell
Daughter cells
A KEGG PATHWAY (next slide) is a collection of manually
drawn pathway maps representing the molecular
interactions and reactions in the cell cycle for:
1. Metabolism
- Carbohydrate, Energy, Lipid, Nucleotide, Amino Acids & More.
2. Genetic Information Processing
3. Environmental Information Processing
4. Cellular Processes
5. Human Diseases and
6. Drug Development
KEGG: The Human Cell Cycle is regulated by many
complex molecular interactions, reactions, and relations.
In this course we have only covered the basics of
the cell cycle. There is much more to learn and
entire careers are made studying the cell cycle.
A college degree in “Cell Biology” can be pursued
at many Universities across the country.
To see what jobs are available for a Cell Biologists check
out the link below for current job offerings in the US:
Cell Biologist Job Openings NOW
THE END!