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Lesson Overview
Cell Growth, Division, and Reproduction
CHAPTER 10: CELL DIVISION
Lab Biology CP
Lesson Overview
Cell Growth, Division, and Reproduction
Chapter 10: Cell Division
10.1 Cell Growth, Division, and Reproduction
10.2 The Process of Cell Division
10.3 Regulating the Cell Cycle
10.4 Cell Diffentiation
Lesson Overview
Cell Growth, Division, and Reproduction
10.1 Cell Growth, Division, and
Reproduction
Lesson Overview
Cell Growth, Division, and Reproduction
Information “Overload”
Living cells store critical information in DNA.
As a cell grows, that information is used to
build the molecules needed for cell growth.
As size increases, the demands on that
information grow as well. If a cell were to grow
without limit, an “information crisis” would
occur.
Lesson Overview
Cell Growth, Division, and Reproduction
Information “Overload”
Compare a cell to a growing
town. The town library has a
limited number of books. As the
town grows, these limited
number of books are in greater
demand, which limits access.
A growing cell makes greater
demands on its genetic
“library.” If the cell gets too big,
the DNA would not be able to
serve the needs of the growing
cell.
Lesson Overview
Cell Growth, Division, and Reproduction
Exchanging Materials
Food, oxygen, and water enter a cell through the cell
membrane. Waste products leave in the same way.
The rate at which this exchange takes place depends
on the surface area of a cell.
The rate at which food and oxygen are used up and
waste products are produced depends on the cell’s
volume.
The ratio of surface area to volume is key to
understanding why cells must divide as they grow.
Lesson Overview
Cell Growth, Division, and Reproduction
Ratio of Surface Area to Volume
Imagine a cell shaped like a cube. As the length of the sides of a
cube increases, its volume increases faster than its surface area,
decreasing the ratio of surface area to volume.
If a cell gets too large, the surface area of the cell is not large
enough to get enough oxygen and nutrients in and waste out.
Lesson Overview
Cell Growth, Division, and Reproduction
Traffic Problems
To use the town analogy again, as
the town grows, more and more
traffic clogs the main street. It
becomes difficult to get
information across town and
goods in and out.
Similarly, a cell that continues to
grow would experience “traffic”
problems. If the cell got too large,
it would be more difficult to get
oxygen and nutrients in and waste
out.
Lesson Overview
Cell Growth, Division, and Reproduction
Division of the Cell
Before a cell grows too large, it divides into two new
“daughter” cells in a process called cell division.
Before cell division, the cell copies all of its DNA.
It then divides into two “daughter” cells. Each daughter
cell receives a complete set of DNA.
Cell division reduces cell volume. It also results in an
increased ratio of surface area to volume, for each
daughter cell.
Lesson Overview
Cell Growth, Division, and Reproduction
Asexual Reproduction
In multicellular organisms, cell division
leads to growth. It also enables an organism
to repair and maintain its body.
In single-celled organisms, cell division is a
form of reproduction.
Lesson Overview
Cell Growth, Division, and Reproduction
Asexual Reproduction (Mitosis)
Asexual reproduction is reproduction that involves a
single parent producing an offspring. The offspring
produced are, in most cases, 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 single-celled organisms
and many multicellular organisms can reproduce
asexually.
Lesson Overview
Cell Growth, Division, and Reproduction
Examples of Asexual Reproduction
Bacteria reproduce by binary fission. 
 Kalanchoe plants form plantlets.
Hydras reproduce by budding. 
Lesson Overview
Cell Growth, Division, and Reproduction
Sexual Reproduction (Meiosis)
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, but are genetically different.
***Most animals and plants, and many single-celled
organisms, reproduce sexually.
Lesson Overview
Cell Growth, Division, and Reproduction
Comparing Sexual and Asexual
Reproduction
Lesson Overview
Cell Growth, Division, and Reproduction
10.2 The
Process of
Cell Division
Lesson Overview
Cell Growth, Division, and Reproduction
Chromosomes
• 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.
• Cells of every organism have a specific number of
chromosomes. Humans have 46 chromosomes.
Lesson Overview
Cell Growth, Division, and Reproduction
Prokaryotic Chromosomes
•
Prokaryotic cells lack nuclei. Instead, their DNA
molecules are found in the cytoplasm.
•
Most prokaryotes contain a single, circular DNA
molecule, or chromosome, that contains most of the
cell’s genetic information.
Lesson Overview
Cell Growth, Division, and Reproduction
Eukaryotic Chromosomes
•
In eukaryotic cells, chromosomes are located
in the nucleus, and are made up of chromatin.
Lesson Overview
Cell Growth, Division, and Reproduction
• Chromatin is composed of DNA and histone proteins.
Lesson Overview
Cell Growth, Division, and Reproduction
• DNA coils around histone proteins to form
nucleosomes.
Lesson Overview
Cell Growth, Division, and Reproduction
• The nucleosomes interact with one another to form
coils and supercoils that make up chromosomes.
http://www.youtube.com/watch?v=qIe4-fVjmPE
Lesson Overview
Cell Growth, Division, and Reproduction
The Prokaryotic Cell Cycle
• The prokaryotic cell cycle is a regular pattern of growth,
DNA replication, and cell division.
• Most prokaryotic cells begin to replicate, or copy, their
DNA once they have grown to a certain size.
• When DNA replication is complete, the cells divide
through a process known as binary fission.
• The end result is 2 identical daughter cells.
Lesson Overview
Cell Growth, Division, and Reproduction
The Prokaryotic Cell Cycle
• Binary fission is a form of
asexual reproduction during
which two genetically identical
cells are produced.
• For example, bacteria reproduce
by binary fission.
• http://www.youtube.com/watch?v=J6akNY
lkehY
Lesson Overview
Cell Growth, Division, and Reproduction
The Eukaryotic Cell Cycle
• 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.
http://www.sumanasinc.com/webcontent/an
imations/content/mitosis.html
Lesson Overview
Cell Growth, Division, and Reproduction
G1 Phase: Cell Growth
• In the G1 phase, cells
increase in size and
synthesize new proteins
and organelles.
Lesson Overview
Cell Growth, Division, and Reproduction
S Phase: DNA Replication
• In the S (or synthesis)
phase, new DNA is
synthesized when the
chromosomes are
replicated.
Lesson Overview
Cell Growth, Division, and Reproduction
G2 Phase: Preparing for Cell Division
• In the G2 phase, many of
the organelles and
molecules required for
cell division are
produced.
Lesson Overview
Cell Growth, Division, and Reproduction
M Phase: Cell Division
• 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.
Lesson Overview
Cell Growth, Division, and Reproduction
Important Cell Structures Involved in
Mitosis
• Chromatid – each strand of a duplicated chromosome
• Centromere – the area where each pair of chromatids is
joined
• 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
Lesson Overview
Cell Growth, Division, and Reproduction
Prophase
• 1st phase of mitosis
• Duplicated chromosomes
condense and become visible
• Centrioles move to opposite
sides of nucleus and help
organize the spindle
• Spindle forms and DNA strands
attach at a point called the
centromere
• The nucleolus disappears and
nuclear envelope breaks down
Lesson Overview
Cell Growth, Division, and Reproduction
Metaphase
• 2nd phase of mitosis
• Duplicated chromosomes
use centromeres to line
up across the center of
the cell
• The spindle fibers from
each pole connect the
centromere
Lesson Overview
Cell Growth, Division, and Reproduction
Anaphase
• 3rd phase of mitosis
• Centromeres pulled apart
• Chromatids separate to
become individual
chromosomes
• Chromosomes separate
into two groups near the
poles of the spindle
Lesson Overview
Cell Growth, Division, and Reproduction
Telophase
• 4th and final phase of
mitosis
• The chromosomes spread
out into a tangle of
chromatin
• The nuclear envelope
reforms around each group
of chromosomes
• The spindle breaks apart
• Nucleolus becomes visible
in each daughter nucleus
Lesson Overview
Cell Growth, Division, and Reproduction
Cytokinesis
• Cytokinesis is the division of the cytoplasm.
• The process of cytokinesis is different in animal and
plant cells.
Lesson Overview
Cell Growth, Division, and Reproduction
Cytokinesis in Animal Cells
• The cell membrane is drawn in until the cytoplasm is
pinched into two equal parts.
• Each part contains its own nucleus and organelles.
Lesson Overview
Cell Growth, Division, and Reproduction
Cytokinesis in Plant Cells
• In plants, the cell membrane is not flexible enough to
draw inward because of the rigid cell wall.
• Instead, a cell plate forms between the divided nuclei
that develops into cell membranes.
• A cell wall then forms in between the two new
membranes.
http://www.youtube.com/watch?v=3kpR5RSJ7SA
(mitosis)
Lesson Overview
Cell Growth, Division, and Reproduction
The Stages of the Cell Cycle
Interphase
Cytokinesis
Prophase
Telophase
Metaphase
Anaphase
Lesson Overview
Cell Growth, Division, and Reproduction
Sexual Reproduction
2 sex cells (egg and sperm)
come together
Fertilization: joining of an
egg and sperm
Form a zygote
Lesson Overview
Cell Growth, Division, and Reproduction
Diploid and Haploid Cells
Diploid Cells:
When cells have pairs of similar chromosomes
46 chromosomes or 23 pairs
Example: body cells
Haploid Cells:
No pairs (only ½ the number of chromosomes)
23 chromosomes
Example: sex cells
Lesson Overview
Cell Growth, Division, and Reproduction
Sexual Reproduction: Meiosis
Meiosis:
a process that produces
haploid sex cells
Meiosis I
Prophase I
Metaphase I
Anaphase I
Telophase I
Meisois II
Prophase II
Metaphase II
Anaphase II
Telophase II
Lesson Overview
Meiosis I
Cell Growth, Division, and Reproduction
Lesson Overview
Meiosis II
Cell Growth, Division, and Reproduction
Lesson Overview
Cell Growth, Division, and Reproduction
Mitosis vs. Meiosis
Mitosis:
2 new cells
Asexual reproduction
Daughter cells IDENTICAL to parent cells
Meiosis:
4 new cells
Sexual reproduction
Daughter cells NOT identical to parent cells
Lesson Overview
Cell Growth, Division, and Reproduction
10.3
Regulating the
Cell Cycle
Lesson Overview
Cell Growth, Division, and Reproduction
The timing on cell growth and cell division can be turned
on and off.
For example, when an injury such as a broken bone
occurs, cells are stimulated to divide rapidly and start the
healing process. The rate of cell division decreases
when the healing process nears completion.
Lesson Overview
Cell Growth, Division, and Reproduction
The Discovery of Cyclins
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.
Lesson Overview
Cell Growth, Division, and Reproduction
Apoptosis
Apoptosis is a programmed cell death.
Apoptosis plays a role in development by shaping the structure of
tissues and organs in plants and animals.
Lesson Overview
Cell Growth, Division, and Reproduction
Cancer is a disorder in which body cells lose the
ability to control cell growth.
Cancer cells divide uncontrollably to form a mass
of cells called a tumor.
http://www.youtube.com/watch?v=qjjHKDn12qI&feature=related
http://www.youtube.com/watch?v=LEpTTolebqo&feature=related
Lesson Overview
Cell Growth, Division, and Reproduction
A benign tumor is noncancerous. It
does not spread to surrounding
healthy tissue.
A malignant tumor is cancerous. It
invades and destroys surrounding
healthy tissue and can spread to
other organs of the body.
Lesson Overview
Cell Growth, Division, and Reproduction
What Causes Cancer?
Cancers are caused by defects in genes that regulate
cell growth and division.
Some sources of gene defects are smoking or chewing
tobacco, radiation exposure, defective genes, and viral
infections.
A damaged or defective p53 gene is common in cancer
cells. It causes cells to lose the information needed to
respond to growth signals.
Lesson Overview
Cell Growth, Division, and Reproduction
Treatments for Cancer
Some localized tumors can be removed by surgery.
Many tumors can be treated with radiation.
Chemotherapy is the use of compounds that kill or stop
the growth of cancer cells.
http://www.youtube.com/watch?v=XuMPdZjsngQ
Lesson Overview
Cell Growth, Division, and Reproduction
10.4 Cell Differentiation
Lesson Overview
Cell Growth, Division, and Reproduction
All organisms start life as just one cell.
Most multicellular organisms pass through an early stage
of development called an embryo, which gradually
develops into an adult organism.
Lesson Overview
Cell Growth, Division, and Reproduction
Defining Differentiation
The process by which cells become specialized is
known as differentiation.
During development, cells differentiate into many
different types and become specialized to perform
certain tasks.
Differentiated cells carry out the jobs that multicellular
organisms need to stay alive.
Lesson Overview
Cell Growth, Division, and Reproduction
Mapping Differentiation
In some organisms, a cell’s role is determined at a specific point in
development.
In the worm C. elegans, daughter cells from each cell division follow
a specific path toward a role as a particular kind of cell.
Lesson Overview
Cell Growth, Division, and Reproduction
Stem Cells
Stem cells are unspecialized cells from which
differentiated cells develop.
There are two types of stem cells: embryonic and adult
stem cells.
Lesson Overview
Cell Growth, Division, and Reproduction
Adult Stem Cells
Adult organisms contain some types of stem cells.
Adult stem cells are multipotent. They can produce
many types of differentiated cells.
Adult stem cells of a given organ or tissue typically
produce only the types of cells that are unique to that
tissue.
http://www.youtube.com/watch?v=rVh1FZcZZVk
http://www.youtube.com/watch?v=lWfw5en2MEM&feature=related
Lesson Overview
Cell Growth, Division, and Reproduction
Potential Benefits of Stem Cells
Stem cell research may lead to new ways to repair the
cellular damage that results from heart attack, stroke,
and spinal cord injuries.
One example is the approach to reversing heart attack
damage illustrated below.
Lesson Overview
Cell Growth, Division, and Reproduction
Ethical Issues of Stem Cells
Most techniques for harvesting, or gathering, embryonic stem cells
cause destruction of the embryo.
Government funding of embryonic stem cell research is an important
political issue.
Groups seeking to protect embryos oppose such research as
unethical.
Other groups support this research as essential to saving human
lives and so view it as unethical to restrict the research.
http://www.pbs.org/wgbh/nova/sciencenow/3209/04.html