chapter 8 cell growth and division
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Chapter 8 Cell Growth and Division. Biology. 10-1 Cell Growth. Adults don’t have bigger cells than kids… they just have MORE of them. Why don’t cells just grow bigger?. DNA overload….DNA would need extra copies to handle “information demand” - PowerPoint PPT PresentationTRANSCRIPT
Chapter 8Cell Growth and Division
Biology
10-1 Cell Growth
Adults don’t have bigger cells than kids… they just have MORE of them
Why don’t cells just grow bigger?
DNA overload….DNA would need extra copies to handle “information demand”Too difficult to get enough nutrients and oxygen IN and waste products OUT
The world's tallest man in 2007 7’9”,
Bao Xishun and his 5’6” wife…most peoplewith acromegalic gigantism eventually die because of complications fromheart problems. "Keeping the blood going round such an enormous circulationbecomes a huge strain for the heart,"
What would happen?What would happen? Calculate ratio of surface area to volume
L * W * # of sides= surface areaL * W * H= VolumePractice problem: if cell was a cube and its sides were 1cm each ….figure SA?Figure V…What if the cell were 3cm? SA? V?What is the ratio?
Volume increases faster than surface area
1*1*6=6 SA1*1*1=1 VRatio 6:1
3*3*6=54 SA3*3*3=27 V
Ratio 54:27 reduce… 2:1The decrease in ratio of SA to V- makes
it harder for the cell to move needed products in and out.
Cell division solves…
The problem of information storage… because each daughter cell gets it’s own DNAThe problem of being too big and inefficient because although the cell grows some… daughter cells will still be smaller than the parent
10-2 Cell Division : is mitosis4 sections of the cell cycle: G phases, S phase, mitosis, cytokinesis
Cell Division
Mitosis Cytokinesis
Division of the nucleusDivision
of the cytoplasm
In Bacteria …prokaryotes
Have circular DNAAnd only 1 piece of DNA called plasmidThe process by which bacteria reproduce is called binary fission (not mitosis)
10-2 Cell Division In eukaryotes the chromosomes carry the genetic information and they live inside the nucleusChromosomes are made up of DNA and proteins (called histones)
Centromere is made of proteinSpindle fibers are made of microtubulessister chromatids are duplicate halves
Karyotype- Tells # of chromosomes in that body cell
Growth & Repair
Interphase
Baby Cell (daughter cell) grows and matures here…and eventually is mature enough to divide a.k.a.…time in between cell division
3 steps of Interphase1. G1- cell grows, and makes new
proteins and organelles2. S phase- DNA is replicated3. G2- molecules and organelles needed
for cell division are produced.
Now ready for MitosisPMAT
Prophase- longest, chromosomes become visible/ centrioles go to the polesSpindle fibers start to formNuclear envelope starts to break down
Mitosis….
Metaphase (middle)Last only a few minutesChromosomes line up across the MIDDLE of the cellCentromeres connect to the spindle fibers
Mitosis…
Anaphase (the fingers)Centromeres split , splitting chromosomes into 2 setsChromosomes move away from each other to the poles- being pulled by spindle fibers
Mitosis
Telophase (the peanut)Chromosomes begin to disappear from viewNuclear envelope re-formsSpindles break apartNucleolus reforms…end mitosis
CytokinesisNucleus and contents have split but what about the rest of the cell….?Cell membrane is drawn inward until cytoplasm is eventually pinched into two equal partsIn plants cell plate eventually becomes the cell wall
Cell plate >
http://www.biostudio.com/d_%20Mitosis.htm
10-3 Regulating the Cell Cycle
Cell growth and cell division are carefully controlled
Cells grow when there is space , then when they bump into other cells they stopA cut in your hand?
http://www.pearsonsuccessnet.com/snpapp/iText/products/0-13-181118-5/ch10/sb4501f1.html
What signals the cell to start dividing?
A set of proteins called cyclins control the timing of cell division…Internal Regulators- tell cell to divide based on what is happening inside the cell (PMAT timing)External Regulators- tell cell to divide based on what is happening outside the cell (wound healing , embryonic development)
CancerA disorder in which some of the body’s own cells (whose DNA is damaged) lose the ability to control growth…Cells grow out of control and form masses called tumorsSometimes these cells break free and spread throughout the bodyThese cells lack the proteins that tell them to stop growing and ignore the bordering cells telling them to stop
Causes of Cancer
Viral Infection (commercial)Radiation (sun, x-rays ) Smoking tobaccoAnything known to cause cancer cells to develop is called a carcinogen….
Identifying the Number of Chromosomes…
Not all living things have the same number of chromosomes..Humans: 46Fruit flies: 8Carrots: 18**worksheet
Haploid vs Diploid
Haploid: half Diploid: Double
But first figure out where you are at?Body cell(regular cell) is already DiploidSperm/egg cell (sex cell) is already Haploid
Differences between animal and plant cells-
Plants have a cell wall and a cell membrane- so when they pinch…it’s called a cell plate.The cell plate becomes the cell membrane – then the cell wall develops next.
Cell plate >
The End…
Cytokinesis—Prophase---M phase---G1—G2-----Metaphase---Telophase----Anaphase-----