Chapter 8 Cell Growth and Division

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Chapter 8Cell Growth and Division

• Biology

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10-1 Cell Growth

• Adults dont have bigger cells than kids they
  just have MORE of them

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Why dont 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

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• The world's tallest man in 2007 79,
• Bao Xishun and his 56 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,"

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What would happen? Calculate ratio of surface
area to volume

• L W of sides surface area
• L W H Volume
• Practice 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?

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Volume increases faster than surface area

• 1166 SA
• 1111 V
• Ratio 61
• 33654 SA
• 33327 V
• Ratio 5427 reduce 21
• The decrease in ratio of SA to V- makes it harder
  for the cell to move needed products in and out.

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Cell division solves

• The problem of information storage because each
  daughter cell gets its own DNA
• The problem of being too big and inefficient
  because although the cell grows some daughter
  cells will still be smaller than the parent

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10-2 Cell Division is mitosis4 sections of the
cell cycle G phases, S phase, mitosis,
cytokinesis
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In Bacteria prokaryotes

• Have circular DNA
• And only 1 piece of DNA called plasmid
• The process by which bacteria reproduce is called
  binary fission (not mitosis)

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10-2 Cell Division

• In eukaryotes the chromosomes carry the genetic
  information and they live inside the nucleus
• Chromosomes are made up of DNA and proteins
  (called histones)

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Centromere is made of proteinSpindle fibers are
made of microtubulessister chromatids are
duplicate halves
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Karyotype-

• Tells of chromosomes in that body cell

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Growth Repair
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Interphase

• Baby Cell (daughter cell) grows and matures
  hereand eventually is mature enough to divide
• a.k.a.time in between cell division

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3 steps of Interphase

• G1- cell grows, and makes new proteins and
  organelles
• S phase- DNA is replicated
• G2- molecules and organelles needed for cell
  division are produced.

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Now ready for MitosisPMAT

• Prophase-
• longest,
• chromosomes become visible/
• centrioles go to the poles
• Spindle fibers start to form
• Nuclear envelope starts to break down

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Mitosis.

• Metaphase (middle)
• Last only a few minutes
• Chromosomes line up across the MIDDLE of the cell
• Centromeres connect to the spindle fibers

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Mitosis

• Anaphase (the fingers)
• Centromeres split , splitting chromosomes into 2
  sets
• Chromosomes move away from each other to the
  poles- being pulled by spindle fibers

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Mitosis

• Telophase (the peanut)
• Chromosomes begin to disappear from view
• Nuclear envelope re-forms
• Spindles break apart
• Nucleolus reforms
• end mitosis

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Cytokinesis

• Nucleus 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 parts
• In plants cell plate eventually becomes the cell
  wall

Cell plate gt
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http//www.biostudio.com/d_20Mitosis.htm
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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 stop
• A cut in your hand?

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• http//www.pearsonsuccessnet.com/snpapp/iText/prod
  ucts/0-13-181118-5/ch10/sb4501f1.html

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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)

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Cancer

• A disorder in which some of the bodys own cells
  (whose DNA is damaged) lose the ability to
  control growth
• Cells grow out of control and form masses called
  tumors
• Sometimes these cells break free and spread
  throughout the body
• These cells lack the proteins that tell them to
  stop growing and ignore the bordering cells
  telling them to stop

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Causes of Cancer

• Viral Infection (commercial)
• Radiation (sun, x-rays )
• Smoking tobacco
• Anything known to cause cancer cells to develop
  is called a carcinogen.

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Identifying the Number of Chromosomes

• Not all living things have the same number of
  chromosomes..
• Humans 46
• Fruit flies 8
• Carrots 18
• worksheet

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Haploid vs Diploid

• Haploid half
• Diploid Double
• But first figure out where you are at?
• Body cell(regular cell) is already Diploid
• Sperm/egg cell (sex cell) is already Haploid

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Differences between animal and plant cells-

• Plants have a cell wall and a cell membrane- so
  when they pinchits called a cell plate.
• The cell plate becomes the cell membrane then
  the cell wall develops next.

Cell plate gt
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The End
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