Transcript Georgia Performance Standards: Compare and contrast cell

CELL Reproduction (Division)
Georgia Performance Standards:
Compare and contrast cell
reproduction (mitosis) in eukaryotes
and prokaryotes
Essential Questions:
EQ: Why is mitosis necessary in cell reproduction?
EQ: What happens when mitosis goes wrong?
Chapter 9
Cellular Reproduction
What’s wrong with big cells?
 As the cell grows, its volume increases
much more rapidly than the surface
area.
 The cell might have difficulty supplying
nutrients and expelling enough waste
products.
Section 10-1
Ratio of Surface Area
to Volume in Cells
Cell Size
Surface Area
(length x width x 6)
Volume
(length x width x height)
Ratio of Surface Area
to Volume
Go to
Section:
Review: The larger a cell becomes, the more demands the
cell places on its DNA and the more trouble the cell has
moving enough nutrients and wastes across the cell
membrane.
Chapter 9
Cellular Reproduction
Transport of Substances is slow for big cells
 Substances move by diffusion or by
motor proteins.
 Diffusion over large distances is slow
and inefficient.
 Small cells maintain more efficient
transport systems.
Chapter 9
Cellular Reproduction
Cellular Communications are
compromised in big cells
 The need for signaling proteins to
move throughout the cell also limits cell
size.
 Cell size affects the ability of the cell
to communicate instructions for cellular
functions.
Cell Division
• What do you think would happen if a cell
were simply to split into two, without any
advance preparation?
• Would each daughter cell have everything
it needed to survive?
• Every cell must first copy its genetic
information before cell division begins.
• Each daughter cell then gets a
complete copy of that information.
• Cell division is called mitosis
• Each cell has identical DNA
Cell Division
• In eukaryotic cells,
the genetic
information is carried
by chromosomes.
• At the beginning of
cell division, each
chromosome consists
of two identical
“sister” chromatids.
• Chromosomes are
made up of DNA and
protein.
• Each pair of
chromatids is
attached at an area
called the
centromere.
Chapter 9
Cellular Reproduction
The Cell Cycle
 Cell division prevents the cell from
becoming too large.
 The cell reproduces so that you grow and
heal certain injuries.
 Cells reproduce by a cycle of growing and
dividing called the cell cycle.
The Cell Cycle
• During the cell cycle, a cell grows,
prepares for division, and divides
to form two daughter cells, each of
which then begins the cycle again.
Chapter 9
Cellular Reproduction
9.1 Cellular Growth
 Interphase is the stage during which the
cell grows, carries out cellular functions,
and replicates.
 Mitosis is the stage of the cell cycle
during which the cell’s nucleus and
nuclear material divide.
 Cytokinesis is the method by which a cell’s
cytoplasm divides, creating a new cell.
The Cell Cycle
Section 10-2
G1 phase
M phase
S phase
G2 phase
Go to
Section:
Chapter 9
Cellular Reproduction
9.1 Cellular Growth
The Stages of Interphase
 The first stage of interphase, G1
 The cell is growing, carrying out normal
cell functions, and preparing to replicate
DNA.
Chapter 9
Cellular Reproduction
9.1 Cellular Growth
The Second Stage of Interphase, S
 The cell copies its DNA in preparation
for cell division.
Chapter 9
Cellular Reproduction
9.1 Cellular Growth
The Third Stage of Interphase, G2
 The cell prepares for the division of its
nucleus.
Mitosis: Four Stages
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
Chapter 9
Cellular Reproduction
9.2 Mitosis and Cytokinesis
The Stages of Mitosis
 Prophase
 The cell’s chromatin tightens.
 Sister chromatids are attached at
the centromere.
 Spindle fibers form in the cytoplasm.
Chapter 9
Cellular Reproduction
9.2 Mitosis and Cytokinesis
 The nuclear
envelope seems
to disappear.
 Spindle fibers
attach to the
sister chromatids.
Chapter 9
Cellular Reproduction
9.2 Mitosis and Cytokinesis
Metaphase
 Sister chromatids
are pulled along
the spindle
apparatus toward
the center of the
cell.
 They line up in the
middle of the cell.
Chapter 9
Cellular Reproduction
9.2 Mitosis and Cytokinesis
Anaphase
 The microtubules of the spindle apparatus
begin to shorten.
 The sister chromatids separate.
 The chromosomes move toward the
poles of the cell.
Chapter 9
Cellular Reproduction
9.2 Mitosis and Cytokinesis
Telophase
 The chromosomes arrive at the poles and
begin to relax.
 Two new nuclear membranes begin to
form and the nucleoli reappear.
 The spindle apparatus disassembles.
Cytokinesis
• As a result of mitosis, two nuclei—each with
a duplicate set of chromosomes—are
formed, usually within the cytoplasm of a
single cell.
• Cytokinesis: the division of the cytoplasm
itself, ends mitosis.
• Cytokinesis usually occurs at the same time as
telophase.
Cytokinesis
• In most animal cells
– the cell membrane
is drawn inward
until the cytoplasm
is pinched into two
nearly equal parts.
– Each part contains
its own nucleus
and cytoplasmic
organelles.
• In plants cells
– a structure known as
the cell plate forms
midway between the
divided nuclei
– The cell plate
gradually develops
into a separating
membrane.
– A cell wall then begins
to appear in the cell
plate.
Chapter 9
Cellular Reproduction
Section 10-2
Concept Map
Cell Cycle
includes
G1 phase
Go to
Section:
Interphase
M phase
(Mitosis)
is divided into
is divided into
S phase
G2 phase
Prophase
Metaphase
Anaphase
Cytokinesis
Telophase
Bacteria and Viruses
Prokaryote (Bacteria) Structure
 Prokaryotes are
microscopic,
unicellular
organisms.
 They have some characteristics of all cells,
such as DNA and ribosomes.
 Lack a nuclear membrane and other
membrane-bound organelles
Cell Division
• In prokaryotes, the cell first replicates its
genetic information before cell division
begins. Then the cell splits into two parts.
Bacteria and Viruses
Reproduction of Prokaryotes: 2 Types
 Binary Fission: Division of
a cell into two genetically
identical cells
 Conjugation: Two
prokaryotes attach to
each other and exchange
genetic information.
Mitosis Summary
• Every cell must first
copy its genetic
• Mitosis produces
information before cell
two genetically
division begins.
identical daughter
cells with 2 sets of
chromosomes
• Cell division is called
(diploid)
mitosis
Checkpoint Questions
1. Name the 3 main events of the cell cycle.
2. Describe what happens during each of the four phases of mitosis.
3. Describe what happens during interphase.
4. What are chromosomes made of?
5. Compare and contrast how prokaryotic and eukaryotic cells divide?
6. Compare and contrast cytokenesis in plant and animal cells.
What happens
when mitosis
goes wrong?
Chapter 9
Cellular Reproduction
Normal Cell Cycle
 Different cyclin/CDK
combinations signal
other activities,
including DNA
replication, protein
synthesis, and
nuclear division
throughout the cell
cycle.
Chapter 9
Cellular Reproduction
Quality Control Checkpoints
 The cell cycle has built-in checkpoints that
monitor the cycle and can stop it if
something goes wrong.
 Spindle checkpoints also have been
identified in mitosis.
Chapter 9
9.3 Cell Cycle Regulation
Abnormal Cell Cycle: Cancer
 Cancer is the
uncontrolled
growth and division
of cells.
 Cancer cells can kill
an organism by
crowding out normal
cells, resulting in the loss of tissue function.
Chapter 9
Cellular Reproduction
Causes of Cancer
 The changes that occur in the regulation of
cell growth and division of cancer cells are
due to mutations.
 Various environmental factors can affect
the occurrence of cancer cells.
Chapter 9
Cellular Reproduction
Apoptosis
 Programmed cell death
 Cells going through apoptosis actually shrink
and shrivel in a controlled process.
Chapter 9
Cellular Reproduction
9.3 Cell Cycle Regulation
Stem Cells
 Unspecialized cells
that can develop into
specialized cells
when under the right
conditions
Chapter 9
Cellular Reproduction
Embryonic Stem Cells
 After fertilization, the resulting mass of cells
divides repeatedly until there are about
100–150 cells. These cells have not
become specialized.
Chapter 9
Cellular Reproduction
Adult Stem Cells
 Found in various tissues in the body and
might be used to maintain and repair the
same kind of tissue
 Less controversial because the adult stem
cells can be obtained with the consent of
their donor
Stem Cell Movie:
http://learn.genetics.utah.edu/content/tech/stemcells/sctypes/