chapter 5: cell growth and division mitosis rap. where is all the genetic information found in a...
TRANSCRIPT
Chapter 5:Chapter 5: Cell Growth and Cell Growth and
DivisionDivision
Mitosis Rap
Where is all the genetic information found in a cell?
• On the genes on the Chromosomes
• Chromosomes are actually strands of DNA and proteins
• If cells were the size of a basketball, your DNA would stretch 40 miles
• We have 6 feet of DNA 6 feet of DNA in each cell!!!!!
Every species has a set number of chromosomes
• Chromosome number: – Number of Chromosomes in a body cell
• Specific for each species of organisms. List– Human – 46Human – 46 – Chimpanzee – 48 – Gorilla – 48 – Potato – 48– Bat – 44– Fruit fly – 8– Mosquito – 6– King Crab – 208– Dog - 78– Horse – 64– Donkey - 62 – Adder’s tongue fern 1,262
How would you duplicate a cell exactly to be certain that both new cells have the identical DNA in each cell?
1. Duplicate the DNA first (this is DNA DNA replicationreplication)
2. Find a way to be certain that the DNA does not get broken or tangled during the process of dividing it into the two new cells
3. Be certain that the new daughter cells will have the exact same set of DNA in each new cell’s nucleus
4. Divide up the cell’s contents. (Cytokinesis)
What would happen if a cell were to just split into two without any advance preparation?
• Imagine trying to divide up pieces of yarn by color if they were all just thrown into a pile together.
–It would take a long time to do this efficiently and accurately.
Instead, it is more efficient to shorten up and then organized the replicated DNA prior to dividing the DNA up evenly into two cells.
This is what happens in The Cell Cycle
Chromosome structureChromosome structure • Before cell division occurs, the DNA is loose in
the nucleus and known as Chromatin Chromatin• DNA starts coiling around proteins called
histoneshistones (like thread on a spool)• DNA shortens up ChromosomeChromosome
Coiling animation• The two identical chromosomes that resulted
from DNA replication will find each other and come together. The two “twins” are called chromatidschromatids & are held together by a centromerecentromere
This strand of DNA is identical to this strand of DNA.
Chromatid
Sister Sister ChromatidsChromatids
Label the structures on the Paired Chromosomes
Why do cells need to reproduce?
• Necessary for:– Repair and replacement of damaged cells– Growth (remember your first baby picture)– Smaller cells are more efficient than are
larger cells.
What would happen to a cell if it continued to grow?
As the size of the cell increases, its volume increases faster than its surface area.
Surface area to volume ratio would decrease.
Makes it difficult to move needed materials in and wastes out of the Makes it difficult to move needed materials in and wastes out of the cell efficiently.cell efficiently.
Calculate the Surface area (Length x width x 6) and Volume (Length3) then the Surface area to Volume ratio (reduce to lowest terms)
The Cell CycleThe Cell Cycle • Entire process that a cell undergoes in cell
division from start to finish.• Cells:
1. grow
2. prepare for division
3. divide to form two daughter cells
4. begin the cell cycle over again.– Cells such as skin, lining of digestive tract and
blood cells go through this process frequently– Introduction
Skin Cells: 20 days
Red Blood Cells: 120 days
Stomach lining cells: 2 days
Brain cells: 30-50 years
Platelets: 10 days
Intestinal lining cells: 3 days
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The Cell The Cell CycleCycle
Divided into 2 parts • InterphaseInterphase– G1 - Cell grows from last cell cycle– S – Synthesis of DNA (DNA makes a copy of
itself)– G2 – Cell growth and gets ready for cell
division– G0 – No cell division – typical of cells like
nerve cells that stop dividing at maturitynerve cells that stop dividing at maturity• MitosisMitosis – – MM phasephase
– Prophase– Metaphase– Anaphase– Telophase– Cytokinesis
How long does the Cell Cycle take in a human cell?
Studies have shown that Studies have shown that the average cell works the average cell works on a on a 24 hr cycle 24 hr cycle as does as does typical cell replication.typical cell replication.Embryonic cells will Embryonic cells will divide every divide every 8 minutes8 minutes!!!!Liver cells could take up Liver cells could take up to a year.to a year.However, many cells will However, many cells will be in Gbe in G00 for long periods for long periods
of time.of time.
InterphaseInterphase • Longest phase in
the Cell Cycle
– over half the time is spent in this phase
• ProphaseProphase – longest phase in Mitosis1. Chromosomes are visible2. Chromatids pair up3. Centrioles (if animal cell) migrate to poles4. Nuclear envelope & nucleolus start to
break down5. Fibers form
Sister Chromatids
Nuclear Membrane &
Nucleolus
Centrioles Fibers
Shorten and Thicken
Begins to break down
Move apart from one another
Form between centrioles (in animal cells)
• MetaphaseMetaphase
– shortest part of Mitosis
1.Sister Chromatids line up on the equator (middle)
Sister Chromatids
Nuclear Membrane
Centrioles Fibers
Become attached to the fibers.
Are moved to middle of cell
Remains dissolved
At opposite ends of cells
Go from the poles to
centromeres
• Anaphase Anaphase – “An away they go!”
1. Chromatids separate
2. Go to opposite poles.
Now called chromosomes!!
1. Fibers shorten up
Sister Chromatids
Nuclear Membrane
Centrioles Fibers
Pulled apart by fibers.
Each chromatid is separate from
its “sister”
Now called a chromosome
Remains dissolved
Still at cell’s poles; Pull each
chromosome toward opposite
ends of the cell
• TelophaseTelophase – “the end” – Final phase
1.Chromosomes reach opposite ends
2.Cell membrane pinches in or Cell plate forms (if plants)
3.Chromosomes uncoil
4.Nuclear membrane & nucleolus reappear
5.Fibers disappear
Sister Chromatids
Nuclear Membrane &
Nucleolus
Cell Membrane
Fibers
Each end of cell has a
complete set of identical
chromosomes.
Begins to reform
Begins to pinch, forming two new cells
Begin to disappear
• CytokinesisCytokinesis Dividing up of cellular
contents.
Occurs simultaneously with Telophase
Mitosis and Cytokinesis
• Cytokinesis differs in animal and plant cells.
In animal cells, the membrane pinches closed.
In plant cells, a cell plate forms.
What was the point of Mitosis?• Results in two identical daughter cellstwo identical daughter cells
• Each cell will have the SAME number of SAME number of chromosomeschromosomes as the original cell
• Each cell will have the SAME function SAME function as the original cells
Mitosis animationsMitosis animationsTry them all!
• http://www.sumanasinc.com/webcontent/animations/content/mitosis.html
• cellsalive.• John Kryk• You tube (really good)• Hybrid (love the music)• http://www.csuchico.edu/~jbell/Biol207/animations/
mitosis.html• Arizona• Movie Clip• McGraw
Mitosis Rap
Mitosis Another
Interphase
Anaphase
Metaphase
Late Prophase
Prophase
Telophase
Checking your understanding MitosisStarting with Prophase, draw a cell undergoing mitosis. Your original cell
has 4 chromosomes.
Make certain to include the nuclear membrane, nucleolus, chromatids, centrioles (animal cell), chromosomes and spindles.
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Give the events occurring in each of the
stages of the Cell CycleCell Cycle
Interphase
Metaphase
Telophase
Anaphase
Prophase
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Cancer cells do not carry out normal, necessary functions.
• Cancer cells are abnormal cell growth due to either a:• malfunction in the Cell Cycle• change in the genes during DNA replication during
the S phase of Interphase
• Cancer cells form disorganized clumps called tumors.• Benign tumors remain clustered and can be removed.• Malignant tumors metastasize, or break away, and can
form more tumors.
Normal cells
Mutated cell
Cancerous cells
Blood cells
• Carcinogens are substances known to promote cancer.• UV radiation• Chemicals such as formaldehyde, asbestos, arsenic, benzene…• Tobacco smoke
• Standard cancer treatments typically kill both cancerous and healthy cells.
Stem cells are unique body cells.• Stem cells have the ability to
– divide and renew themselves– remain undifferentiated in form– develop into a variety of specialized cell types
Some people save the placenta or umbilical cord to harvest these
• The use of stem cells offers many currently realized and potential benefits.
– Stem cells are used to treat leukemia and lymphoma.– Stem cells may cure disease or replace damaged
organs.– Stem cells may revolutionize the drug development
process.
Henrietta LacksHenrietta LacksThe Immortal Hela cellsThe Immortal Hela cells
•Basic Information
•Please Do Now:– Write 4 LINES about your reaction to this video
• Was the action of the scientists right or wrong? Why?• Include at least 1 fact about cancer from your notes
or the video.