Title: DNA and Cell Division
1DNA and Cell Division
2 Mitosis in Animals
3Background Information
Once an egg becomes fertilized, cellular
divisions begins, eventually producing a whole
organism
All cells derived from the zygote contain the
same genetic material
An Integrated Organism
4Organization of DNA
- All cells have DNA (chromosomes).
- Almost all cells divide for reproduction, growth
or repair. - Each new cell needs the exact same DNA as the
original cell. - The original cell is called the mother cell and
the two new cells are called daughter cells. - The DNA in the nucleus must replicate before the
cell divides.
5Chromosome Number in Different Species
Common Name Genus and Species Diploid ChromosomeNumber
Buffalo Bison bison 60
Cat Felis catus 38
Cattle Bos taurus, B. indicus 60
Dog Canis familiaris 78
Donkey E. asinus 62
Goat Capra hircus 60
Horse Equus caballus 64
Human Homo sapiens 46
Pig Sus scrofa 38
Sheep Ovis aries 54
6Number of genes in sequenced genomes
- E. coli 4300
- Yeast 6000
- Roundworm 18,600
- Fruit fly 13-14,000
- Mosquito 13-14,000
- Mouse 30-35,000
- Human 30-35,000
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8A non-dividing cell
- 90 of a cells life is spent growing, not
dividing - This phase is called interphase
- The DNA in this phase is not condensed thus is
chromatin - At some point during this phase the DNA is
doubled or replicated - Two copies are made, one for each of the new
cells
9- Once replication occurs, the chromatin folds up
to form chromosomes - This only occurs when the cell is about to divide
- The duplicated chromosomes attach to each other
at the centromere - Each individual copy of one chromosome is known
as a chromatid - When chromatids are joined at the centromere,
they are known as a single chromosome.
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11sister chromatids
centromere
A piece of DNA or chromosome in an undividing
cell
Same piece now has replicated and super coiled
ready for cell division.
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13Also during interphase
- Additional organelles are produced
- Cell membrane enlarged to allow cell growth
- When the cell becomes too big to function it must
divide - What would the SA/V ratio of this cell belarge
or small?
14Interphase
- The cell grows
- New organelles are formed
- Duplicate chromosomes are produced
- The chromosomes are uncoiled and invisible
- This uncoiled chromosomes are known as a
chromatin
15Cell division/reproduction
- Interphase is not considered to be part of cell
reproduction. - It is simply the growth of the cell and the
duplication of the chromosomes. - Cell reproduction consists of two separate stages
known as mitosis and cytokinesis. - Cell division mitosis cytokinesis
- A parent cell will produce 2 daughter cells.
16In cell division each chromosome is replicated
and then the cell (and nucleus) divides
17Cell Reproduction
- Original cell divides into two genetically
identical daughter cells - Complete set of genetic information passed onto
each daughter cell - DNA must be accurately duplicated before cell
division - Mitosis paired chromatids separate and move to
opposite ends of the cell - Cytokinesis cytoplasm organelles divide into
roughly equal halves
18http//www.stolaf.edu/people/giannini/flashanimat/
celldivision/crome3.swf
Mitosis Animation
19MITOSIS/ CELL DIVISION
- Stages include
- Prophase
- Metaphase
- Anaphase
- Telophase
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21Mitosis
Nucleolus disappears Nuclear envelope breaks down
Chromosomes condense and shorten
Duplicated chromosomes remain elongated
LateInterphase
EarlyProphase
LateProphase
Metaphase
Centromeres align at cells equator
Microtubules attach to Centromeres
Centrioles have also been duplicated
Centrioles begin to move apart Spindle forms
22Mitosis
Spindle fibers pull chromatids to opposite poles
Cytoplasm divided along equator
Chromosomes begin unwinding
NextInterphase
Anaphase
Telophase
Cytokinesis
Nuclear envelope re-forms, spindle fibres
disappear
Each daughter gets 1 nucleus half of cytoplasm
Chromatids become independent chromosomes
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25 Prophase
- Chromatin condenses (into chromosomes)
- Chromosomes appear as Xs.
- Nuclear envelope dissolves (DNA free in cell)
- Animals cells only Centrioles move to opposite
ends of cell form spindle fibers - Centromere attaches to spindle fibre
26Metaphase
- Each chromosome lines up in the middle of the
cell. - Highly organized so that both cells get exactly
the same DNA. - Spindle fibers attached to centromeres of
chromosomes
27Anaphase
- Each pair of chromatids splits at the centromere
- Each chromatid is now an individual chromosome
- Paired chromosomes are pulled to opposite ends by
spindle fibres
28Telophase
- Chromosomes end up at separate poles, spindle
fibers begin to dissolve. - New nuclear envelope begins to form around
chromosomes - chromosomes begin to uncoil
- Cell starts to pinch off through cytokinesis
29Cytokinesis
- Division of all the rest of cell parts but not
equally (organelles) - Animals cell membrane pinches to form two cells
- Plants new cell plate created between the two
cells (becomes cell wall)
30The Cell Cycle An Overview
- 1)Interphase
- 2)Mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
- 3)Cytokinesis
- Cell Division (Cell Reproduction) mitosis
cytokinesis
31Use an Acronym
- For Mitosis
- Prophase P
- Metaphase M
- Anaphase A
- Telophase T
- Make a sentence
- Please Meet At Ten
- Phil, Mary, And Tom
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34Figure 11-2
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37Links
- http//en.wikipedia.org/wiki/TrisomyTrisomy
- http//www.medgen.ubc.ca/wrobinson/mosaic/mos_how.
htm
38Mitosis Drawing
- Fold a large sheet of paper in 3
- You should have 3 columns on the front and 3 on
the back - You will draw a cell in each stage of mitosis and
include a written description of what is
occurring at each stage - Stages Interphase, Prophase, Metaphase,
Anaphase, Telophase, Cytokinesis - Notice that there are 6 stages and 6 coulmns on
your sheet...1 stage per column!
39Some facts
- 500,000 deaths per year (more males)
- Older age group stricken more often
- More than 100 types of cancer, many due to
mutations triggered by environmental factors - Highest cancer incidence male -
prostate female - breast - Highest cancer deaths lung
40Normal cells in culture
- Organized structure
- Limited cell growth
- No overlapping
41Cancer cells in culture
- Disorganized
- Overlapping structure
- Uncontrolled cell growth
42Some images to make this real look first at
normal skin
43Cancerous Skin
44What causes a normal cell to become a cancer cell?
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