Download Cell Division - Muchin College Prep Wiki

Before
a cell grows too large, it divides into two
new “daughter” cells in a process called cell
division.
 Before
dividing, each cell must
pass on genetic information to
each new cell.
 The
production of genetically
identical offspring from a single
parent is known as asexual
reproduction.

Offspring produced by sexual
reproduction inherit some of their
genetic information from each
parent.
 Asexual
reproduction is reproduction that
involves a single parent producing an
offspring. The offspring produced are
genetically identical to the single cell that
produced them.
 Asexual
reproduction is a simple, efficient,
and effective way for an organism to
produce a large number of offspring.
 Both
prokaryotic and eukaryotic singlecelled organisms and many multicellular
organisms can reproduce asexually.
 In
sexual reproduction, offspring are
produced by the fusion of two sex cells
– one from each of two parents. These
fuse into a single cell before the
offspring can grow.

The offspring produced inherit some
genetic information from both parents.
 The
genetic information that is
passed on from one generation of
cells to the next is carried by
chromosomes.
 Every
cell must copy its genetic
information before cell division
begins.
 Each
daughter cell gets its own
copy of that genetic information.
Is the picture below an example of asexual reproduction or sexual reproduction? Explain
your answer using the word parent.
 During
the cell cycle, a cell grows, prepares for division,
and divides to form two daughter cells.
 The
eukaryotic cell cycle
consists of four phases: G1, S,
G2, and M.
 Interphase is the time
between cell divisions. It is a
period of growth that consists
of the G1, S, and G2 phases.
The M phase is the period of
cell division.
In
the G1 phase,
cells increase in
size and synthesize
new proteins and
organelles.
In
the S (or synthesis)
phase, new DNA is
synthesized when the
chromosomes are
replicated.
In
the G2 phase,
many of the
organelles and
molecules required for
cell division are
produced.
Ex.
Spindle Fiber
In
eukaryotes, cell division
occurs in two stages:
mitosis and cytokinesis.
Mitosis
is the division of
the cell nucleus.
Cytokinesis
is the division
of the cytoplasm.
 Chromatid
– each strand of a duplicated chromosome
 Centromere
joined
– the area where each pair of chromatids is
Centrioles
– tiny structures located in the cytoplasm of
animal cells that help organize the spindle
 Spindle
– a fanlike microtubule structure that helps
separate the chromatids
During
prophase, the first
phase of mitosis, the
duplicated chromosome
condenses and becomes
visible.
The centrioles move to
opposite sides of nucleus
and help organize the
spindle.
The nucleolus disappears
and nuclear envelope
breaks down.
 During
metaphase, the
second phase of mitosis, the
centromeres of the
duplicated chromosomes
line up across the center of
the cell.
 The
spindle fibers connect
the centromere of each
chromosome to the two
poles of the spindle.
During
anaphase, the
third phase of mitosis,
the centromeres are
pulled apart and the
chromatids separate
to become individual
chromosomes.
 During
telophase, the fourth and final
phase of mitosis, the chromosomes
spread out into a tangle of chromatin.


A nuclear envelope re-forms
around each cluster of chromosomes.
The spindle breaks apart, and a
nucleolus becomes visible in each
daughter nucleus.
 Cytokinesis
cytoplasm.
is the division of the
 Cytokinesis
completes the process
of cell division – it splits one cell
into two.
 In
plants, a cell wall then forms in
between the two new
membranes.
 https://www.youtube.com/watch?v=gwcwSZIfKlM
https://www.youtube.com/watch?v=lpAa4TWjHQ4&index=3
&list=PLwL0Myd7Dk1FFrTjLejW-YCkEO17D9TMd
The
cell cycle is
controlled by
regulatory proteins
both inside and outside
the cell.
The controls on cell
growth and division
can be turned on and
off.
 Internal
regulators are proteins that
respond to events inside a cell. They
allow the cell cycle to proceed only
once certain processes have
happened inside the cell.
 External
regulators are proteins that
respond to events outside the cell.
They direct cells to speed up or slow
down the cell cycle.
 Growth
factors are external
regulators that stimulate the growth
and division of cells. They are
important during embryonic
development and wound healing.
 Cyclins
are a family of proteins that regulate the timing of
the cell cycle in eukaryotic cells.
This graph shows how cyclin levels change throughout the cell cycle in fertilized clam eggs.
Apoptosis
is a process
of programmed cell
death.
Apoptosis plays a role in
development by
shaping the structure of
tissues and organs in
plants and animals.
 Cancer
cells do not respond to
the signals that regulate the
growth of most cells. As a result,
the cells divide uncontrollably.
 Cancer cells divide uncontrollably
to form a mass of cells called a
tumor.
A benign tumor is noncancerous.
A malignant tumor is cancerous
The spread of cancer cells is called metastasis.
Cancers
are caused by
defects in genes that
regulate cell growth and
division.
Some sources of gene
defects are smoking
tobacco, radiation
exposure, defective genes,
and viral infection.
P53:
Tumor Suppressor
Genes
BRCA1: Breast Cancer
Her2/Neu: Ovarian
Cancer
APC: Colon Cancer
 Some
localized tumors can
be removed by surgery.
 Many
tumors can be treated
with targeted radiation.
 Chemotherapy
is the use of
compounds that kill or slow
the growth of cancer cells.
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