Transcript Cellular Reproduction

Cellular Reproduction
9
The Big Idea
Cells go through a life cycle that
includes interphase, mitosis, and
cytokinesis.
Section 9.1: Cellular Growth
Main Idea #1
Cells grow until they reach their size limit, then they
either stop growing or divide.
What Limits Cell Size?
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As the cell grows, its volume increases much more rapidly than the
surface area.
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The cell might have difficulty supplying nutrients and expelling
enough waste products.
What Limits Cell Size?
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Transport of Substances
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Substances move by diffusion or by motor proteins.
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Diffusion over large distances is slow and inefficient.
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Small cells maintain more efficient transport systems.
Cell Communication
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The need for signaling proteins to move throughout the
cell also limits cell size.
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Cell size affects the ability of the cell to communicate
instructions for cellular functions.
The Cell Cycle
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Cell division prevents the cell from becoming too large.
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It also is the way the cell reproduces so that you grow and heal
certain injuries.
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Cells reproduce by a cycle of growing and dividing called the
cell cycle.
The Cell Cycle
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Interphase is the stage during which the cell grows, carries
out cellular functions, and replicates.
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Mitosis is the stage of the cell cycle during which the cell’s
nucleus and nuclear material divide.
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Cytokinesis is the method by which a cell’s cytoplasm divides,
creating a new cell.
Interphase
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The first stage of interphase, G1
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The cell is growing, carrying out normal cell
functions, and preparing to replicate DNA.
Interphase
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The second stage of Interphase, S
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The cell copies its DNA in preparation for cell
division.
Interphase
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The third stage of Interphase, G2
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The cell prepares for the division of its nucleus.
Cells Alive
• On laptops, go to
• Click on Interactive Cell Cycle
• Complete Worksheet - “Cells Alive”
Section 9.2: Mitosis and Cytokinesis
Main Idea #2
Eukaryotic cells reproduce by mitosis, the process of
nuclear division, and cytokinesis, the process of
cytoplasm divisions.
Cell Division – Intro
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Cell division in prokaryotes occurs by binary fission.
1. A prokaryote cell copies its DNA.
2. The cell begins to divide.
3. Two identical haploid cells are produced that contain identical
DNA.
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Eukaryotic cell division is much more complex; there are two types.
1. Mitosis - results in new cells with genetic material that is identical
to the original cell
2. Meiosis - reduces the chromosome number by half in the new
cells; ex - sex cells
Mitosis
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Mitosis is the division of the nucleus during cell
division.
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Mitosis is a continuous process that is divided into
four phases: Prophase, Metaphase, Anaphase,
Telophase
Prophase
1. DNA begins to shorten and
tightly coil into the rod-shaped
chromosomes.
2. The nucleolus and nuclear
membrane begin to disappear.
3. Centrosomes and centrioles
begin to appear and start to
move to the opposite ends of
the cell.
Prophase
4. As the centrosomes separate, spindle fibers begin to form and
create a structure known as the mitotic spindle.
5. The mitotic spindle helps to divide the chromatids into equal halves.
6. There are two types of fibers within the mitotic spindle: kinetochore
and polar fibers.
Metaphase
1. This is the easiest phase to
see the chromosomes.
2. Sister chromatids are
pulled along the spindle
apparatus toward the
center of the cell.
3. They line up in the middle
of the cell.
Anaphase
1. The microtubules of the
spindle apparatus begin
to shorten.
2. The sister chromatids
separate.
3. The chromosomes move
toward the poles of the
cell.
Telophase
1. The chromosomes arrive at
the poles and begin to
relax.
2. Two new nuclear
membranes begin to form
and the nucleoli reappear.
3. The spindle apparatus
disassembles.
Cytokinesis
1. In animal cells,
microfilaments constrict,
or pinch, the cytoplasm.
The part that pinches in
and eventually separates
is called the cleavage
furrow.
2. In plant cells, a new
structure, called a cell
plate, forms.
Mitosis Internet Lesson
• http://www.biologycorner.com/workshee
ts/mitosis.html#.Unb7qBahClL
Section 9.3 Cell Cylce Regulation
Main Idea #3
The normal cell cycle is regulated by cyclin proteins.
Abnormal Cell Cycle: Cancer
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Cancer is the uncontrolled growth and division of
cells.
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Cancer cells can kill an organism by crowding out
normal cells, resulting in the loss of tissue function.
Causes of Cancer
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The changes that occur in the regulation of cell
growth and division of cancer cells are due to
mutations.
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Various environmental factors can affect the
occurrence of cancer cells.
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Factors that can cause cancer are called
carcinogens.
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Examples include smoke, sunlight, chemicals,
radiation, etc.
Apoptosis
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Apoptosis is programmed cell death.
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Cells going through apoptosis actually shrink and
shrivel in a controlled process.
Stem Cells
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Stem cells are unspecialized cells that can develop into
specialized cells when under the right conditions.
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After fertilization, the resulting mass of cells divides repeatedly
until there are about 100–150 cells. These cells have not
become specialized.
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Adult stem cells are found in various tissues in the body and
might be used to maintain and repair the same kind of tissue.
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Adult stem cells are less controversial because the adult stem
cells can be obtained with the consent of their donor