Transcript cell growth, division, and reproduction

Lesson Overview
Cell Growth, Division, and Reproduction
Section 10.1
CELL GROWTH, DIVISION, AND
REPRODUCTION
Lesson Overview
Cell Growth, Division, and Reproduction
Chapter Mystery: Pet Shop Accident
Julia stared into the salamander tank in horror. As an assistant in a pet
shop, Julia had mistakenly put a small salamander in the same tank
as a large one. Just as she realized her error, the large salamander
attacked and bit off one of the small salamander’s limbs.
Acting quickly, Julia scooped up the injured salamander and put it in its
own tank. She was sure it would die before her shift ended. But she
was wrong! Days passed….then weeks. Every time Julia checked on
the salamander, she was more amazed at what she saw.
How did the salamander’s body react to losing a limb?
As you read this chapter, look for clues to help you predict the
salamander’s fate. Think about the cell processes that would be
involved.
Lesson Overview
Cell Growth, Division, and Reproduction
I. Exchanging Materials
a. Food, oxygen, and water enter a cell through the cell
membrane
b. Waste products leave in the same way
c. The rate at which this exchange takes place
depends on the surface area of a cell
d. The rate at which food and oxygen are used up and
waste products are produced depends on the cell’s
volume
e. 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
II. 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.
a. 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
III. Division of the Cell
a. Cell division: process in which a cell divides into two new
“daughter cells” before it grows too large
a. Before cell division the cell copies all of its DNA
a. It then divides into two “daughter” cells
a. each daughter cell receives a complete set of DNA
b. Cell division:
a. reduces cell volume
b. results in an increased ratio of surface area to volume for
each daughter cell
Lesson Overview
Cell Growth, Division, and Reproduction
IV. Asexual Reproduction
a. Asexual reproduction: reproduction that involves a single
parent producing an offspring
i. The offspring produced are, in most cases, genetically
identical to the single cell that produced them
ii. a simple, efficient, and effective way for an organism to
produce a large number of offspring
iii. both prokaryotic and eukaryotic single-celled organisms and
many multicellular organisms can reproduce asexually
Lesson Overview
Cell Growth, Division, and Reproduction
b. Examples of Asexual Reproduction
i. Bacteria reproduce by binary fission
ii. Kalanchoe plants form plantlets
iii. Hydras reproduce by budding
Lesson Overview
Cell Growth, Division, and Reproduction
V. Sexual Reproduction
a. sexual reproduction: offspring are produced by the fusion of
two sex cells – one from each of two parents
b. fuse into a single cell before the offspring can grow
c. offspring produced inherit some genetic information from both
parents
d. most animals and plants, and many single-celled organisms,
reproduce sexually
Lesson Overview
Cell Growth, Division, and Reproduction
VI. Comparing Sexual and Asexual
Reproduction
Fill in the table below:
Lesson Overview
Cell Growth, Division, and Reproduction
Mystery Clue #1
As its wound heals, the salamander’s body cells are dividing to
repair the damage.
In what way is this type of cell division similar to asexual
reproduction?
Lesson Overview
Cell Growth, Division, and Reproduction
Section 10.2
THE PROCESS OF CELL DIVISION
Lesson Overview
Cell Growth, Division, and Reproduction
I. Chromosomes
a. The genetic information that is passed on from one
generation of cells to the next is carried by
chromosomes
b. Every cell must copy its genetic information before cell
division begins
c. Each daughter cell gets its own copy of that genetic
information
d. Cells of every organism have a specific number of
chromosomes
Lesson Overview
Cell Growth, Division, and Reproduction
II. Prokaryotic Chromosomes
a. Prokaryotic cells lack nuclei
b. Instead, their DNA molecules are found in the cytoplasm
c. 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
III. Eukaryotic Chromosomes
a. In eukaryotic cells, chromosomes are located in the nucleus,
and are made up of chromatin
b. Chromatin is composed of DNA and histone proteins.
c. DNA coils around histone proteins to form nucleosomes
d. The nucleosomes interact with one another to form coils and
supercoils that make up chromosomes
Lesson Overview
Cell Growth, Division, and Reproduction
IV. The Prokaryotic Cell Cycle
a. a regular pattern of growth, DNA replication, and cell division
b. most prokaryotic cells begin to replicate, or copy, their DNA
once they have grown to a certain size
c. when DNA replication is complete, the cells divide through a
process known as binary fission
Lesson Overview
Cell Growth, Division, and Reproduction
d. Binary fission: a form of asexual
reproduction during which two
genetically identical cells are
produced
e. For example, bacteria reproduce by
binary fission.
Lesson Overview
Cell Growth, Division, and Reproduction
V. The Eukaryotic Cell Cycle
a. The eukaryotic cell cycle
consists of four phases: G1, S,
G2, and M
b. Interphase: the time between
cell divisions
i. It is a period of growth that
consists of the G1, S, and G2
phases
c. The M phase is the period of cell
division.
Lesson Overview
Cell Growth, Division, and Reproduction
d. G1 Phase: Cell Growth
cells increase in size and
synthesize new proteins
and organelles
Lesson Overview
Cell Growth, Division, and Reproduction
e. S Phase: DNA Replication
new DNA is synthesized
when the chromosomes
are replicated
Lesson Overview
Cell Growth, Division, and Reproduction
f. G2 Phase: Preparing for Cell Division
many of the organelles
and molecules required
for cell division are
produced
Lesson Overview
Cell Growth, Division, and Reproduction
g. M Phase: Cell Division
i.
In eukaryotes, cell
division occurs in two
stages: mitosis and
cytokinesis.
ii. Mitosis is the division
of the cell nucleus.
iii. Cytokinesis is the
division of the
cytoplasm.
Lesson Overview
Cell Growth, Division, and Reproduction
h. Important Cell Structures Involved in
Mitosis
i. Chromatid – each strand of a duplicated
chromosome
ii. Centromere – the area where each pair of
chromatids is joined
iii.Centrioles – tiny structures located in the cytoplasm
of animal cells that help organize the spindle
iv.Spindle – a fanlike microtubule structure that helps
separate the chromatids
Lesson Overview
Cell Growth, Division, and Reproduction
VI. Prophase
a. the first phase of mitosis
b. the duplicated chromosome
condenses and becomes
visible
c. centrioles move to
opposite sides of nucleus
and help organize the
spindle
d. spindle forms and DNA
strands attach at a point
called their centromere
e. The nucleolus disappears
and nuclear envelope
breaks down
Lesson Overview
Cell Growth, Division, and Reproduction
VII. Metaphase
a. the centromeres of the
duplicated chromosomes
line up across the
center of the cell
b. the spindle fibers
connect the centromere
of each chromosome to
the two poles of the
spindle
Lesson Overview
Cell Growth, Division, and Reproduction
VIII. Anaphase
a. the centromeres are
pulled apart and the
chromatids separate to
become individual
chromosomes
b. the chromosomes
separate into two groups
near the poles of the
spindle
Lesson Overview
Cell Growth, Division, and Reproduction
IX. Telophase
a. the chromosomes spread
out into a tangle of
chromatin
b. a nuclear envelope reforms around each cluster
of chromosomes
c. the spindle breaks apart,
and a nucleolus becomes
visible in each daughter
nucleus
Lesson Overview
Cell Growth, Division, and Reproduction
X. Cytokinesis
a. Cytokinesis: the division of the cytoplasm
b. The process of cytokinesis is different in animal and plant cells
Lesson Overview
Cell Growth, Division, and Reproduction
c. Cytokinesis in Animal Cells
i.
The cell membrane is
drawn in until the
cytoplasm is pinched into
two equal parts.
ii.
Each part contains its
own nucleus and
organelles
Lesson Overview
Cell Growth, Division, and Reproduction
d. Cytokinesis in Plant Cells
i.
ii.
iii.
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
Lesson Overview
Cell Growth, Division, and Reproduction
The Stages of the Cell Cycle
Lesson Overview
Cell Growth, Division, and Reproduction
Mystery Clue #2
How might the cell cycles of the cells surrounding the
salamander’s wound be affected?
Lesson Overview
Cell Growth, Division, and Reproduction
Section 10.3
REGULATING THE CELL CYCLE
Lesson Overview
Cell Growth, Division, and Reproduction
The controls on cell growth and 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 slows when the healing process nears
completion.
Lesson Overview
Cell Growth, Division, and Reproduction
I. The Discovery of Cyclins
a. Cyclins: 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
II. Regulatory Proteins
a. Internal regulators are proteins that respond to events inside a
cell
i. they allow the cell cycle to proceed only once certain
processes have happened inside the cell
b. External regulators are proteins that respond to events
outside the cell
i. they direct cells to speed up or slow down the cell cycle
c. Growth factors are external regulators that stimulate the
growth and division of cells
i. they are important during embryonic development and wound
healing
Lesson Overview
Cell Growth, Division, and Reproduction
Mystery Fish #3
How might regulatory proteins be involved in wound healing in
the salamander?
Lesson Overview
Cell Growth, Division, and Reproduction
III. Apoptosis
a. Apoptosis is a process of programmed cell death
b. Apoptosis plays a role in development by shaping the structure of
tissues and organs in plants and animals
c. For example, the foot of a mouse is shaped the way it is partly because
the toes undergo apoptosis during tissue development
Lesson Overview
Cell Growth, Division, and Reproduction
IV. Cancer
a. Cancer is a disorder in which body cells lose the
ability to control cell growth
b. Cancer cells divide uncontrollably to form a mass
of cells called a tumor
i. benign tumor is noncancerous, it does not
spread to surrounding healthy tissue
ii. malignant tumor is cancerous, it invades and
destroys surrounding healthy tissue and can
spread to other parts of the body
iii. The spread of cancer cells is called metastasis
iv. Cancer cells absorb nutrients needed by other
cells, block nerve connections, and prevent
organs from functioning
Lesson Overview
Cell Growth, Division, and Reproduction
V. What Causes Cancer?
a. Cancers are caused by defects in genes that regulate cell
growth and division
b. Some sources of gene defects are smoking tobacco, radiation
exposure, defective genes, and viral infection.
c. 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
VI. Treatments for Cancer
a. Some localized tumors can be removed by surgery
b. Many tumors can be treated with targeted radiation
c. Chemotherapy is the use of compounds that kill or
slow the growth of cancer cells.
Lesson Overview
Cell Growth, Division, and Reproduction
Section 10.4
CELL DIFFERENTIATION
Lesson Overview
Cell Growth, Division, and Reproduction
I. Defining Differentiation
a. Differentiation: the process by which cells become
specialized
b. During development, cells differentiate into many different types
and become specialized to perform certain tasks.
c. Differentiated cells carry out the jobs that multicellular
organisms need to stay alive.
Lesson Overview
Cell Growth, Division, and Reproduction
One of the most important questions in biology is how
all of the specialized, differentiated cell types in the body
are formed from just a single cell.
d. Biologists say that such a cell is totipotent, literally
able to do everything, to form all the tissues of the
body.
e. Only the fertilized egg and the cells produced by the
first few cell divisions of embryonic development are
truly totipotent.
Lesson Overview
Cell Growth, Division, and Reproduction
II. Human Development
a. After about four days of development, a human
embryo forms into a blastocyst, a hollow ball of cells
with a cluster of cells inside known as the inner cell
mass.
b. The cells of the inner cell mass are said to be
pluripotent, which means that they are capable of
developing into many, but not all, of the body's
cell types.
Lesson Overview
Cell Growth, Division, and Reproduction
III. Stem Cells
a. Stem cells: unspecialized cells from which differentiated
cells develop
b. There are two types of stem cells: embryonic and adult stem
cells.
Lesson Overview
Cell Growth, Division, and Reproduction
c. Embryonic Stem Cells
i.
Embryonic stem cells are found in the inner cells mass of the
early embryo
ii.
Embryonic stem cells are pluripotent
iii.
Researchers have grown stem cells isolated from human
embryos in culture
iv.
Their experiments confirmed that embryonic stem cells have
the capacity to produce most cell types in the human body
Lesson Overview
Cell Growth, Division, and Reproduction
d. Adult Stem Cells
i.
Adult organisms contain some types of stem cells
ii.
Adult stem cells are multipotent
iii.
They can produce many types of differentiated cells
iv.
Adult stem cells of a given organ or tissue typically produce
only the types of cells that are unique to that tissue
Lesson Overview
Cell Growth, Division, and Reproduction
IV. Potential Benefits
a. 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
V. Ethical Issues
a. Most techniques for harvesting, or gathering, embryonic stem
cells cause destruction of the embryo.
b. Government funding of embryonic stem cell research is an
important political issue.
c. Groups seeking to protect embryos oppose such research as
unethical.
d. Other groups support this research as essential to saving
human lives and so view it as unethical to restrict the research.
Lesson Overview
Cell Growth, Division, and Reproduction
Mystery Clue #4
Some adult salamander cells never completely differentiate.
What ability do these cells retain?