Chapter 9
Cellular Reproduction and the Cell Cycle
Read Chapter 9 in Textbook
Read pages 85-92 in Cliffs AP (4th) Test Book
Do Sample Questions #1-16 on pg 93-94
Due Nov 5
Mills AP Biology 2002-2003
Chapter 9
Cellular Reproduction and the Cell Cycle
• Topics
–
–
–
–
9.1
9.2
9.3
9.4
The Cell Cycle
Mitosis and Cytokinesis
The Cell Cycle and Cancer
Prokaryotic Cell Division
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.1 Eukaryotic Cell Cycle
• Cell Cycle
– Four stages
• M – Mitotic Phase = mitosis
and cytokinesis
• G1 – growth
• S – DNA replication
• G2 – growth
– Different types of cells and
different species spend
varying amounts of time in
each stage
Animation of Cell Cycle
see next slide
Mills AP Biology 2002-2003
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.1 Eukaryotic Cell Cycle
Broad Bean
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.1 Eukaryotic Cell Cycle
• Cell Cycle Clock
– What controls which cells divide and how often?
• Recent research uncovering some of the mysteries
• May help with understanding abnormal cell growth – such as cancer
– Two critical checkpoints where cell has to be signaled to proceed or
stop
• G1 stage  S stage
• G2 stage  M stage
– Kinases and cyclins are proteins that help regulate the cell cycle
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.1 Eukaryotic Cell Cycle
• Cell Cycle Clock
– Kinases
• Enzymes that activate or
inactivate other proteins by
phosphorylating them
– Removes P from ATP, and
adds it to a protein
• Common way for a cell to “turn
on” a cellular process
• Kinases used to turn on the
cell cycling, but need to be
activated themselves first
– Activated by cyclins
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.1 Eukaryotic Cell Cycle
• Cell Cycle Clock
– Activation of kinases by
cyclins at two critcal
checkpoints
• End of G1 stage  S
stage
• End of G2 stage  M
stage
– Cause cell to continue
cycle
G1 checkpoint
Feedback from the cell determines
whether the cell cycle will proceed to
the S phase, pause, or withdraw into G0
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.1 Eukaryotic Cell Cycle
Mills AP Biology 2002-2003
From Progeria foundation web site: “HGPS (Progeria)is caused by a mutation in
Chapter
9 Cellular
Reproduction
and the
Cell
Cyclethe
the gene called
LMNA
(pronounced,
lamin - a). The LMNA
gene
produces
Eukaryotic
Cells
Lamin A protein, which 9.3
is theHow
structural
scaffolding
thatCycle
holds the nucleus of a
cell together. Researchers now believe that the defective Lamin A protein makes
the nucleus unstable. That cellular instability appears to lead to the process of
• Lack
ofinnormal
premature
aging
Progeria.” control over the cell cycle can
lead to conditions such as
– Psoriasis (uncontrolled growth of skin cells)
Normal life span for a skin
– Progeria
(early death of cells)
cell is 28-30
days. Psoriasis
John Tacket
cells cycle–every
6
days
and
Cancer
(1988-2004) –
don’t exfoliate.
died at age 15.
Average life
span for a child
with progeria is
13yrs. Usually
die of heart
disease atherosclerosis
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• Eukaryotic cells
– We will look at multicelluar
eukaryotes
– Cells divide by two processes
• Mitosis – division of nuclear
material
• Cytokinesis – division of
cytoplasm and other
organelles
• Together these are called the
Mitotic Phase
– We will look first at mitosis
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• Mitosis
– Series of events that divides up replicated
DNA into two identical (genetically)
daughter cells.
• First, lets review a little bit about what
DNA and chromosomes are.
Mitosis in a plant cell
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• Let’s take a closer look at
DNA
– Where is it?
– What is it made of
(chemically)?
– What does it do?
– What’s a gene?
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• DNA refresher
Bases:
adenine
guanine
thymine
cytosine
uracil
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
DNA, DNA, DNA, DNA, …
Mills AP Biology 2002-2003
Sugar and phosphates
Gene
one small
section of
DNA
strand
Base pairs
Single chromatid,
one double strand of DNA
wound around histones
(proteins)
Duplicated DNA
in metaphase of mitosis
sister chromatids
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• A gene is a particular piece of a strand of DNA, that codes for
the production of a particular protein
Gene
one small
section of
DNA
strand
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• Stages of Mitosis (nuclear division)
–
–
–
–
Prophase
Metaphase
Anaphase
Telophase
Cell at end of interphase,
before prophase starts.
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• Prophase (longest phase)
–
–
–
–
–
–
duplicated chromosomes condense to form chromosomes
centrioles (animals only)move to opposite sides (poles) of cell
spindle fibers associate with centromeres on chromosomes
nucleolus and nuclear envelope disappear
mitotic spindle forms
Chromosomes start to move towards equator
Centromere connects
sister chromatids
Asters
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
Prophase
Plant cell
Animal cell
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• Metaphase
– chromosomes align at equator “metaphase plate”
– microtubules attached to centromeres align chromatids, start to pull
apart
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
Metaphase
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• Anaphase
– centromeres separate
– chromatids get pulled to opposite sides (poles)of cell with help of
spindle fibers
– cell elongates
– shortest phase, lasts a few minutes
– cytokinesis begins
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
Anaphase
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• Telophase
–
–
–
–
–
–
chromosomes get to centrioles
spindle fibers and asters disappear
chromosomes start to unwind  chromatin
nuclear envelope re-forms
nucleoli re-form
cytokinesis continues
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
Cell Plate
Telophase
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
Mader Movie Hard drive ..\..\Biology\Biology Clipart Movies Animations
Sounds\Biology movies\Mader VD105 How Chromosomes Separate.MOV
Mills AP Biology 2002-2003
Mitosis Movie 48 sec
..\..\Biology\Biology Clipart Movies Animations Sounds\Biology movies\mitosis.mov
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• Mitosis is followed by cytokinesis
*note Metaphase
and Anaphase labels
are missing
See also
http://www.cellsalive.com/mitosis.htm
Mills AP Biology 2002-2003
Another web animation of mitosis
http://www.johnkyrk.com/mitosis.html
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 How Eukaryotic Cells Divide
Mills AP Biology 2002-2003
Daughter nucleus
Nucleoli in nucleus
Vesicles
containing cell
components,
fusing to form cell
membrane
Mills AP Biology 2002-2003
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.2 Mitosis and Cytokinesis
• What is the purpose of cell division?
– Make duplicate of DNA to pass on
– For unicellular organisms (such as bacteria, paramecium) cell
division = asexual reproduction
– For multicellular organisms, cell division is used for growth and
repair
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.3 The Cell Cycle and Cancer
• Cell Cycle and Cancer
– What allows cancer cells to grow unchecked into large,
invasive, malfunctioning masses of tissue?
– ..\..\Biology\Biology Clipart Movies Animations
Sounds\Biology movies\cell_growth.mpg
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.3 The Cell Cycle and Cancer
• Cell Cycle and Cancer
– Oncogenes
– Tumor Suppressor Genes
• Cancer causing genes
• Could these genes
control the genes for
production of abnormal
cyclin ?
• Malfunctioning cyclin
could lead to
uncontrolled cell growth.
• Usually prevent cancer
• One tumor suppressor
gene (p53 gene) codes for
the production of a protein
(p53) that binds to cyclin
and keeps it from
functioning – stopping cell
growth.
– Keeps cells with mutated
DNA from reproducing,
causes apoptosis
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.3 The Cell Cycle and Cancer
• Cell Cycle and Cancer
– Abnormal development of
cells = tumor
– Tumor develops when there
is failure to control cell
growth
– P53 protein (controlled by
p53 gene – tumor
suppressor gene) is a
protein that monitors cell
growth and checks DNA for
mutations
– Some cancer cells have
faulty or no p53
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.3 The Cell Cycle and Cancer
Figure 9.9 Functions of p53.
If DNA is damaged by a mutagen, p53 is instrumental in stopping the cell cycle and
activating repair enzymes. If repair is impossible, the p53 protein promotes apoptosis.
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.3 The Cell Cycle and Cancer
• Cell Cycle and Cancer
– Apoptosis
• Programmed cell death
• Happens all the time
• Cell contains enzymes (caspases)
that can destroy the cell
• Enzymes are normally inhibited
unless get signals to destroy cell
• Signals can be
– External – as in fetal development
– DNA damage initiates cell death
• Tumor cells have high level of
protein survivin which blocks
apoptosis – cells don’t die
Indicate cell is
undergoing apoptosis
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.3 The Cell Cycle and Cancer
• Characteristics of Cancer Cells
–
–
–
–
–
Lack differentiation
Have abnormal nuclei
Form tumors
Undergo angiogenesis and metastasis
Don’t respond to things that would
normally inhibit cell growth, such as:
• Increased cell density (contact inhibition)
• Unanchored cells
• Not enough growth hormone
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.3 Cell Cycle and Cancer
• Cell Cycle and Cancer
– PBS Cancer Growth Animation (if time) from:
http://www.pbs.org/wgbh/nova/cancer/grow_flash.html
–
Hard drive ..\..\Biology\Biology Clipart Movies Animations Sounds\Biology movies\cancer growth pbs.swf
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.4 How Prokaryotic Cells Divide
• Prokaryotic Cells
– What are they? Who has them?
– Divide (asexually) by a process called binary fission
• How does binary fission work?
– Bacterial Fission Movie
» ..\..\Biology\Biology Clipart Movies Animations Sounds\Biology
movies\bacterial fission.mov
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.4 How Prokaryotic Cells Divide
• Binary Fission
– Simplest form of asexual
reproduction
– Parent divides into 2
approximately equal parts
– Both have identical DNA
– Bacteria and some protozoa
(ameba, paramecium) use
this method
Paramecium fission
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle
9.4 How Prokaryotic Cells Divide
• Binary fission – bacteria
– Single chromosome (DNA)
in loop shape, attached to
plasma membrane
– DNA replicates
– Cell
elongates
and
E.coli,
under
the right
conditions,
eventually
can divide
every separates
20 minutes. How
– Can
happen
veryberapidly
in
many
bacteria
would
possible
the
from acertain
singlebacteria
bacteriaunder
in 7 hours?
right conditions
Over one million!!
Bacterial Fission Movie
»Hard drive ..\..\Biology Clipart and sounds\Biology
movies and animations\bacterial_division.mpeg
Mills AP Biology 2002-2003
Read Connecting the Concepts
and Big Ideas page 167
THE END
Additional sites
http://www.hhmi.org/biointeractive/cancer/animations.html
http://www.hhmi.org/biointeractive/cancer/p53/01.html
Mills AP Biology 2002-2003