The Cell Cycle

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The Cell Cycle Cell Division
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Animated Cycle
http//www.cellsalive.com/cell_cycle.htm
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Chromosomes

• A eukaryotic chromosome is a molecule of DNA
  together with associated proteins
• Chromosome
• Structure made of DNA and associated proteins
• Carries part or all of a cells genetic
  information

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Types of Chromosomes

• There are two types of eukaryotic chromosomes
  autosomes and sex chromosomes
• Autosomes
• Paired chromosomes with the same length, shape,
  centromere location, and genes
• Any chromosome other than a sex chromosome
• Sex chromosomes
• Members of a pair of chromosomes that differ
  between males and females

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Chromosome Structure
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Chromosome Number

• A eukaryotic cells DNA is divided into a
  characteristic number of chromosomes
• Chromosome number
• Sum of all chromosomes in a cell of a given type
• A human body cell has 23 pairs of chromosomes
• Diploid
• Cells having two of each type of chromosome
  characteristic of the species (2n)

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Examples of Chromosome Number
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Chromosome Structure

• Sister chromatid
• One of two attached members of a duplicated
  eukaryotic chromosome
• Centromere
• Constricted region in a eukaryotic chromosome
  where sister chromatids are attached

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Five Phases of the Cell Cycle

• G1 - primary growth phase
• S synthesis DNA replicated
• G2 - secondary growth phase
• collectively these 3 stages are called interphase
• M - mitosis
• C - cytokinesis

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Cell Cycle
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Interphase - G1 Stage

• 1st growth stage after cell division
• Cells mature by making more cytoplasm
  organelles
• Cell carries on its normal metabolic activities

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Interphase S Stage

• Synthesis stage
• DNA is copied or replicated

Two identical copies of DNA
Original DNA
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Interphase G2 Stage

• 2nd Growth Stage
• Occurs after DNA has been copied
• All cell structures needed for division are made
  (e.g. centrioles)

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Sketch the Cell Cycle
DNA Copied
Cells Mature
Cells prepare for Division
Daughter Cells
Cell Divides into Identical cells
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MITOSIS
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Mitosis
The process of cell division which results in the
production of two daughter cells from a single
parent cell. The daughter cells are identical
to one another and to the original parent cell.
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Mitosis can be divided into stages

• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase Cytokinesis

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InterphaseThe cell prepares for division

• Animal Cell
• DNA replicated
• Organelles replicated
• Cell increases in size

• Plant Cell
• DNA replicated
• Organelles replicated
• Cell increases in size

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

• Animal Cell
• Chromosomes line up at the center of the cell
• Spindle fibers attach from daughter cells to
  chromosomes at the centromere

• Plant Cell
• Chromosomes line up at the center of the cell
• Spindle fibers attach from daughter cells to
  chromosomes at the centromere

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Metaphase
Plant Cell
Animal Cell
Photographs from http//www.bioweb.uncc.edu/biol1
110/Stages.htm
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AnaphaseThe chromosomes divide

• Animal Cell
• Spindle fibers pull chromosomes apart
• ½ of each chromosome (called chromotid) moves to
  each daughter cell

• Plant Cell
• Spindle fibers pull chromosomes apart
• ½ of each chromosome (called chromotid) moves to
  each daughter cell

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Anaphase
Plant Cell
Animal Cell
Photographs from http//www.bioweb.uncc.edu/biol1
110/Stages.htm
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TelophaseThe cytoplasm divides

• Plant Cell
• DNA spreads out
• 2 nuclei form
• New cell wall forms between to nuclei to form the
  2 new daughter cells

• Animal Cell
• DNA spreads out
• 2 nuclei form
• Cell wall pinches in to form the 2 new daughter
  cells

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Telophase
Plant Cell
Animal Cell
Photographs from http//www.bioweb.uncc.edu/biol1
110/Stages.htm
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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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Uncontrolled Mitosis

• If mitosis is not controlled, unlimited cell
  division occurs causing cancerous tumors
• Oncogenes are special proteins that increase the
  chance that a normal cell develops into a tumor
  cell

Cancer cells
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Uncontrolled Cell Division
http//www.bing.com/videos/search?qcelldivision
cancervideoFORMVIRE1viewdetailmid0B79506B3F
3C60B48CB90B79506B3F3C60B48CB9
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MEIOSIS
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Meiosis
Meiosis is the type of cell division by which
germ cells (eggs and sperm) are produced. One
parent cell produces four daughter cells.
Daughter cells have half the number of
chromosomes found in the original parent cell
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Meiosis
During meiosis, DNA replicates once, but the
nucleus divides twice.
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Meiosis
Four stages can be described for each division of
the nucleus.
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Meiosis I

First division of meiosis
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First Division of Meiosis

• Prophase 1 Each chromosome duplicates and
  remains closely associated. These are called
  sister chromatids.
• Metaphase 1 Chromosomes align at the center of
  the cell.
• Anaphase 1 Chromosome pairs separate with sister
  chromatids remaining together.
• Telophase 1 Two daughter cells are formed with
  each daughter containing only one chromosome of
  the chromosome pair.

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Prophase I
http//everyschool.org/u/logan/cellreproductionx/r
ogersa/research/meiosis.html
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Prophase I
http//everyschool.org/u/logan/cellreproductionx/r
ogersa/research/meiosis.html
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Metaphase I
http//everyschool.org/u/logan/cellreproductionx/r
ogersa/research/meiosis.html
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Telophase I
http//everyschool.org/u/logan/cellreproductionx/r
ogersa/research/meiosis.html
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Meiosis

• Second Division of Meiosis

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Second Division of Meiosis

• Prophase 2 DNA does not replicate.
• Metaphase 2 Chromosomes line up at the center of
  the cell
• Anaphase 2 Centromeres divide and sister
  chromatids move separately to each pole.
• Telophase 2 Cell division is complete.
• Four haploid daughter cells are formed.

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Prophase II
http//everyschool.org/u/logan/cellreproductionx/r
ogersa/research/meiosis.html
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Metaphase II
http//everyschool.org/u/logan/cellreproductionx/r
ogersa/research/meiosis.html
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Telophase II
http//everyschool.org/u/logan/cellreproductionx/r
ogersa/research/meiosis.html
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Meiosis
http//www.biosci.uga.edu/almanac/bio_103/notes/ap
r_3.html.
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Meiosis Animation
http//www.rothamsted.bbsrc.ac.uk/notebook/courses
/guide/movie/meiosis.htm
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Differences in Mitosis Meiosis

• Mitosis
• Asexual
• Cell divides once
• Two daughter cells
• Genetic information is identical

• Meiosis
• Sexual
• Cell divides twice
• Four haploid daughter cells
• Genetic information is different

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Comparison Animations
http//www.pbs.org/wgbh/nova/baby/divi_flash.html
http//www.usoe.k12.ut.us/curr/science/sciber00/
7th/genetics/sciber/animatin.htm