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Mills AP Biology 2002-2003
Chapter 9Cellular Reproduction and the Cell Cycle
Read Chapter 9 in TextbookRead pages 85-92 in Cliffs AP (4th) Test
BookDo Sample Questions #1-16 on pg 93-
94Due Nov 5
Mills AP Biology 2002-2003
Chapter 9Cellular Reproduction and the Cell Cycle
• Topics– 9.1 The Cell Cycle– 9.2 Mitosis and Cytokinesis– 9.3 The Cell Cycle and Cancer– 9.4 Prokaryotic Cell Division
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle9.1 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 Cyclesee 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
Chapter 9 Cellular Reproduction and the Cell Cycle9.3 How Eukaryotic Cells Cycle
• Lack of normal control over the cell cycle can lead to conditions such as – Psoriasis (uncontrolled growth of skin cells)– Progeria (early death of cells)– Cancer
John Tacket (1988-2004) – died at age 15. Average life span for a child with progeria is 13yrs. Usually die of heart disease - atherosclerosis
Normal life span for a skin cell is 28-30 days. Psoriasis cells cycle every 6 days and don’t exfoliate.
From Progeria foundation web site: “HGPS (Progeria)is caused by a mutation in the gene called LMNA (pronounced, lamin - a). The LMNA gene produces the Lamin A protein, which is the structural scaffolding that 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 premature aging in Progeria.”
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle9.2 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
Duplicated DNAin metaphase of mitosissister chromatids
Single chromatid, one double strand of DNAwound around histones (proteins)
Base pairs
Geneone smallsection ofDNAstrand
Sugar and phosphates
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
Geneone smallsection ofDNAstrand
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
Plant cellAnimal cell
Prophase
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
Telophase
Cell Plate
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
See also http://www.cellsalive.com/mitosis.htm
*note Metaphase and Anaphase labels
are missing
Mills AP Biology 2002-2003
Another web animation of mitosishttp://www.johnkyrk.com/mitosis.html
Mills AP Biology 2002-2003
Chapter 9 Cellular Reproduction and the Cell Cycle9.2 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 Cycle9.3 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
• Cancer causing genes
• Could these genes control the genes for production of abnormal cyclin ?
• Malfunctioning cyclin could lead to uncontrolled cell growth.
– Tumor Suppressor Genes• 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 Cycle9.3 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 Cycle9.4 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
eventually separates– Can happen very
rapidly in certain bacteria under the right conditions
E.coli, under the right conditions, can divide every 20 minutes. How many bacteria
would be possible from a single bacteria in 7 hours?
Over one million!!
Bacterial Fission Movie»Hard drive ..\..\Biology Clipart and sounds\Biology movies and animations\bacterial_division.mpeg
Mills AP Biology 2002-2003
THE END
Additional siteshttp://www.hhmi.org/biointeractive/cancer/animations.html
http://www.hhmi.org/biointeractive/cancer/p53/01.html
Read Connecting the Concepts and Big Ideas page
167
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