10-1 Cell Growth

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10-1 Cell Growth

• Growth and Development!!

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Definitions

• Histones
• Telomeres
• Somatic cells
• Chromatin
• Chromosomes
• Centromeres
• Spindle fibers

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Parts of a Chromosome

• Chromosome Long threads of DNA that consist of
  genes.
• Humans have 46 chromosomes
• Histones proteins DNA wraps around. Makes it
  condensed!!!
• Chromatin Loose DNA when it is not condensed.
  DNA only condenses during mitosis and meiosis.

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• Chromatin - A complex of DNA and proteins in the
  cell nucleus that condenses to form chromosomes
  during cell division(loose DNA).
• Chromosomes Condensed Chromatin(X)
• They are the same stuff, just in different forms
• Centromeres Center point where chromatids are
  attached.
• Spindle Fibers - Fibers that pull part the
  chromosomes during mitosis.

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Parts of the Chromosomes

• Telomere DNA molecules at the end of the
  chromosomes that do not code for genes. They
  keep the DNA from unraveling.
• ChromatidOne half og the duplicated chromosome.
• Centromere Each sister chromatid is held
  together at the centromere.
• ALL OF THIS IS FORMED AFTER REPLICATION!!!

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Some Definitions

• Histones proteins that DNA will wrap around.
  This helps the DNA to fit.
• Telomeres End of DNA molecules to prevent them
  from attaching to each other. They do not
  contain genes.
• Somatic Cells body cells
• Produced through mitosis
• Has 46 chromosomes (23 pairs)

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Parts of the Chromosomes
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Chromatin condenses in chomosomes before mitosis
begins

• Chromatin

• Chromosomes

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Histone
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Parts of a Chromosome
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When Do New Cells Need to Form?

• A. Growth - More cells
• B. Maintenance (repair and replacement)--gt
  intestinal lining/RBCs)
• C. Asexual reproduction
• D. Formation of sex cells (Meiosis)

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Problem with Being Too Big!!

• The volume gets too big for the surface area.
• The cell membrane cannot control all the movement
  in and out when the volume is too large.
• Your cells cannot too large either. The surface
  area must be in the correct ratio of the volume.
• Neurons are very long and skinny so that ration
  is correct.

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2. TOO BIG! Cell membrane cannot control all
movements of materials

• The larger a cell grows the more trouble it has
• moving enough nutrients in
• Moving all the waste materials out

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3rd Problem - Too Big

• 3. DNA overload
• Your DNA controls all activities in the cell.
  When the cell gets too big then the DNA cannot
  control all activites.

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3rd problem DNA overload
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Radius 1cm S.A. _____ V ______ Ratio SAV
___
Radius 2cm S.A. ___50cm2__ V
__33cm3____ Ratio SAV 5033_or 1.511
Radius 1cm S.A. __13cm2___ V __4cm3____ Ratio
SAV _134 or 3.251__
Radius 3cm S.A. _____ V ______ Ratio SAV
___
Radius 3cm S.A. __113cm2_ V
___113cm3___ Ratio SAV _113113 or 11__
S.A. 4 (pi) r 2

1. As the spheres get larger what happens to the
   SAV ratio?

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Cell Cycle

• Life Cycle of the cell! Most of the time your
  cells are growing. Divide after the cell has
  gotten too big!

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The Cell Cycle and Mitosis
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Cell Cycle life of a cell

• The life of a cell. It has a pattern of cell
  growth, DNA replication, and cell division.
  Results in two new daughter cells.

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The Cell Cycle

• The sequence of growth and division of a cell.
• 95 of cell cycle in interphase(growth)
• 5 of cell cycle in mitosis(division)

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M Phase, Cell Division and Mitosis
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3 Main Events of a Cell Cycle

• 1. Interphase
• G1 - growth
• S DNA replication
• G2 growth and prepare for division

• 2. Mitosis Phase nucleus dividing
• Prophase
• Metaphase
• Anaphase
• Telophase
• 3. Cytokinesis cell division

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The Cell Cycle - series of events that cells go
through as they grow and divide

• The cell cycle is divided into two halfs
• Interphase - period of the cell cycle between
  cell divisions
• Mitosis phase and cytokinesis period of time
  when mitosis and cell division occurs

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Parts of Interphase

• G1 Phase(growth)
• Cell grows
• Synthesize new proteins and organelles
• Doing their jobs
• Longest phase of cell cycle

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S Phase

• S Phase(synthesis)
• Chromosomes(DNA) are replicated
• Key proteins associated with replication are made
  (centromeres

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Gap 2 Phase

• G2 Phase(growth)
• Shortest of the 3 phases of interphase
• Organelles and molecules for cell division are
  produced (centrioles)
• Check-up phase before mitosis

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• Whats
• Missing?

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Cell Cycle

• http//www.cellsalive.com/mitosis.htm
• http//www.johnkyrk.com/mitosis.html

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Parts of Interphase

• G1 Phase(growth)
• Cell grows
• Synthesize new proteins and organelles
• Doing their jobs
• Longest phase of cell cycle

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S Phase

• S Phase(synthesis)
• Chromosomes(DNA) are replicated
• Key proteins associated with replication are made
  (centromeres

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Gap 2 Phase

• G2 Phase(growth)
• Shortest of the 3 phases of interphase
• Organelles and molecules for cell division are
  produced (centrioles)
• Check-up phase before mitosis

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G - 0 Stage
This is a stage of interphase that SOME cells
enter. Cells such as nerve and white blood do
not divide often so they enter this stage of rest.
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Animated Cycle
http//www.cellsalive.com/cell_cycle.htm
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What stops cell from growing?

• Proximity to neighbor cells.
• Cells in a petri dish will continue to grow until
  they come into contact with other cells.
• Similarily, skin around a wound
• After a cell has quit growing, it is time to
  divide!!!
• Mitosis
  

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MITOSIS
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Mitosis
Division of the nucleus. Followed by
cytokinesis!!! The daughter cells are identical
to one another and to the original parent cell.
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Mitosis

• Prophase
• Metaphase
• Anaphase
• Telophase

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Prophase

• Longest phase of mitosis
• Chromatin condenses into chromosomes
• Spindle fibers form and attach to centrioles
• Nuclear membrane dissappears
• Nucleolus breaks down

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Prophase
Plant Cell
Animal Cell
Photographs from http//www.bioweb.uncc.edu/biol1
110/Stages.htm
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ProphaseThe cell prepares for nuclear division

• Animal Cell
• Packages DNA into chromosomes

• Plant cell
• Packages DNA into chromosomes

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Metaphase

• Centromeres line up across the center of the cell
• Spindle fibers connect to centromeres

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Anaphase

• Chromosomes
• are pulled apart by spindle into individual
  chromatids.
• The chromatids
• are now considered
• Chromosomes!!

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Anaphase

• Centromeres split
• Sister chromatids are pulled apart to opposite
  poles of the cell
• Each chromatid is now a separate chromosome

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Telophase

• Nuclear envelopes (2) and nucleolus reform
• Chromosomes begin to uncoil
• Spindle fibers disappear.

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Mitosis Animation
http//www.cellsalive.com/mitosis.htm
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Animal Mitosis -- Review
Interphase                                                              Prophase                                                             
Metaphase                                                              Anaphase                                                             
Telophase                                                              Interphase                                                             
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Plant Mitosis -- Review
Interphase                                                              Prophase                                                             
Metaphase                                                              Anaphase                                                             
Telophase                                                              Interphase                                                             
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Cytokinesis

• Cytoplasm divides
• Two new daughter cells are now separate

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Cytokinesis

• http//www.johnkyrk.com/mitosis.html

• The cytoplasm pinches in half
• Animal - cleavage furrow
• Plants - cell plate

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In plant cells, a cell plate forms. The cell
plate is synthesized by the fusion of multiple
membrane-bounded vesicles. Their fusion supplies
new plasma membrane for each of the two daughter
cells. Synthesis of a new cell wall between the
daughter cells then occurs at the cell plate.
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Apoptosis

• Cell death. Factors that signal genes to produce
  self destructive enzymes. Not sure why.
• EX webbing of toes on an embryo.

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Cyclins
Protein that controls cell division.. They can
make cells grow in a petri dish. Doesnt work on
all cells.
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Controls on Cell Division
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Cancer

• Class of disease caused by uncontrolled cell
  division. Arises when the regulation of the cell
  cycle breaks down. The cells continue to divide
  with the absence of internal and external growth
  factors.
• Benign tumor cancer cells remain in one mass
  and usually can be removed.
• Malignant cancer cells break away from the
  cancer cells to other parts of the body.

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Why are cancer cells so dangerous?

• Cancer cells cannot perform the duties needed by
  the body. Too many cancer cells and the body
  cannot perform the processes needed to live. A
  large tumor can apply pressure to other organs
  and affect the processes of organ.

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What causes cells to form cancer?

• Cancer cells comes from regular cells that have
  damage in one of the two genes that makes the
  proteins for cell cycle regulation.
• Oncogene gene that accelerates the cell cycle.
• Gene 2 breaks cell cycle.
• A mutation in these 2 genes can be inherited or a
  carcinogen can cause a mutation in these genes.

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Causes of Cancer

• Carcinogen Substances known to cause the cell
  cycle genes to mutate and cell divide
  uncontollably.
• Various forms of cancer have many causes
• Smoking
• Radiation
• Viral infections
• The common thread in all cancers is that control
  over the cell cycle has broken down.
• Over 50 of cancer cells have a defect in the p53
  gene.

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p53 antioncogene

• p53 is a tumor suppressor gene found mutated in
  about half of human cancers.
• It encodes a gene regulatory protein that is
  activated by damaged DNA and is involved in
  blocking further progression of the cell cycle.

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Oncogenes SRC, proto-oncogene tyrosine-protein
kinase
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Treatments for Cancer

• Radiation and chemotherapy used to kill the
  cancer cells and stop division. They kill good
  and bad cells.

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Stem Cells

• Stem cells are a type of body cell that have the
  ability to
• Divide and renew themselves
• Remain undifferentiated
• Develop into a variety of specialized cells.

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Chromosomes
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• Defined Tightly coiled DNA
• Forms during cell division
• New chromosomes created for new cells
• 2 Parts
• 1) Chromatids two identical parts of a
  chromosome
• 2) Centromere Joins chromatids together

Chromosomes
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Karyotype

• Defined Picture of an individuals chromosomes
• Identify sex chromosome defects
• Size of final pair identifies sex
• Same size XX female
• Different size XY male
• Normal human will have 46 chromosomes

Female
Male
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Down Syndrome Whats Wrong?

• Writing notation
• 1st total chromosome
• 2nd Sex chromosomes
• 3rd extra or missing
• Down Syndrome 47, XY, 21

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Turners Syndrome Whats Wrong?

• Write the notation for Turners Syndrome.
• 45, X, -23
• or
• 45, XO, -23

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Pataus Syndrome Whats Wrong?

• Write the notation for Pataus Syndrome.
• 47, XY, 13

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Klinefelters Syndrome Whats Wrong?

• Write the notation for Klinefelters Syndrome.
• 47, XXY, 23

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Diploid Cells

• Diploid Cells Cells with the full set of
  chromosomes
• Paired chromosomes
• Half of our chromosomes come from each parent (23
  from each parent)
• Somatic (non-sex) cells are diploid
• Created by mitosis
• Ex Skin, Muscle, Nerve, Blood Cells

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What is the human diploid chromosome number?

• RememberDiploid total number of chromosomes
• Answer 46

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What is the human somatic chromosome number?

• RememberSomatic cells are non-sex cells
• Somatic cells are diploid
• Diploid cells have the full set of
  chromosomes
• Answer 46

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How many chromosomes are in brain cells?

• RememberBrain cells are non-sex cells
• Somatic cells are non-sex cells
• Somatic cells are diploid
• Diploid cells have the full set of
  chromosomes
• Answer 46

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Haploid Cells

• Haploid Cells Cells with ½ the total number of
  chromosomes
• Gametes (sex cells) are the only haploid cells
• Ex Sperm, Egg, Pollen
• Chromosome number is reduced by meiosis
• How do humans get 46 chromosomes?

Haploid sperm cell (23)
Haploid egg cell (23)
Diploid zygote (46)
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What is the human haploid chromosome number?

• RememberHaploid half number of chromosomes
• Answer 23 chromosomes

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What is the human gamete chromosome number?

• RememberGamete cells are sex cells
• Sex cells are haploid
• Haploid cells have ½ the set of chromosomes
• Answer 23

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How many chromosomes are in female egg cells?

• RememberEgg cells are sex cells
• Sex cells are gametes
• Gamete cells are haploid
• Haploid cells have ½ the set of chromosomes
• Answer 23

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Rat Karyotype

• What is the diploid chromosome number?

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Rat Karyotype

• What is the haploid chromosome number?

21
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Rat Karyotype

• How many chromosomes would be in somatic cells?

42
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Rat Karyotype

• How many chromosomes would be in brain cells?

42
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Rat Karyotype

• How many chromosomes would be in gamete cells?

21
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Rat Karyotype

• How many chromosomes would be in egg cells?

21
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Rat Karyotype

• How many chromosomes would be in muscle cells?

42
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Rat Karyotype

• How many chromosomes would be in sperm cells?

21
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Rat Karyotype

• Is this a male or female rat?

male
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Quick Review

• Chromsomes are tightly coiled strands of DNA
• Diploid (somatic) cells contain the entire set of
  chromosomes
• Haploid (gametes) cells contain only ½ the total
  number of chromosomes

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Limit of cell size?

• 1. TOO SMALL - There will not be enough room for
  all the organelles to carry out the processes
  needed.

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Cells Divide at Different Rates

• The rate of cell division is determined by the
  bodys need for that type of cell.
• Nerve cells do not divide because they do not
  die like our skin cells.
• A new layer of skin is replaced every 3 weeks.
  The lining of your intestines has to be replaced
  often because of the wear and tear. This is also
  skin cells.