Download Mitosis PPT

Cell Division
Mitosis
Why do they have to be so
small?
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Why not keep growing – why divide?
Surface area to Volume ratio
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Too much volume, too little space for it to get in
Diffusion happens at the same rate, but
smaller volume means less dist. to travel.
Surface to Volume Ratio
1 cm2 to 1 cm3
4 cm2 to 8 cm3
9 cm2 to 27 cm3
Diffusion happens at the same rate –
it all depends on the distance it
has to travel.
Now We Know Why, but what
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Mitosis is the division of the nucleus
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Focus is on getting equal and correct
chromosomes to each new cell
Most multicellular organisms are
DIPLOID (2n) – two copies of each
chromosome
Compared to a haploid cell which only has
one copy
 What type of cell in our bodies are
haploid? Diploid?
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What does it look like for
humans?
Cell Cycle
Nucleus: full of DNA
Ruptured nucleus
Interphase
Prophase
Metaphase
Anaphase
Telophase/cytokinesis
What Controls Cell Division?
What if it won’t stop?
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Cancer is the
uncontrolled growth
and reproduction of
cells
Tumors
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Benign (non spreading)
Malignant (spreading)
All depends on access
to blood vessels
Viruses and Cancer
Viruses
When Viruses attack
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If it goes lytic, then that cell will die
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And potentially those surrounding it
When you deal with prophages
(lysogenic) it all depends on when it
turns lytic and where the DNA inserts
The when often depends on environment
 The where depends on the DNA
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DNA – base pairing
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G pairs with C
A pairs with T
GACCAGGTCGACCTTATTACGACATGACAGATACCATAGAATGGACAAGG
CTGGTCCAGCTGGAATAATGCTGTACTGTCTATGGTATCTTACCTGTTCC
It all Depends on Where
Newly inserted viral DNA making a
prophage
GACCAGGTCGACCTTATTACGACAT
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GACAGATACCATAGAATGGACAAGG
If it inserts in non-coding DNA, then no big
deal
But, if it inserts in the middle of gene, then
that gene is no longer functional
Then it just depends on what the gene was.
US Mortality, 2001
Rank
Cause of Death
No. of
deaths
% of all
deaths
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1.
Heart Diseases
700,142
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2.
Cancer
553,768 22.9
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3.
Cerebrovascular diseases
163,538
6.8
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4.
Chronic lower respiratory diseases
123,013
5.1
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5.
Accidents (Unintentional injuries)
101,537
4.2
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6.
Diabetes mellitus
71,372
3.0
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7.
Influenza and Pneumonia
62,034
2.6
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8.
Alzheimer’s disease
53,852
2.2
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9.
39,480
1.6
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10. Septicemia
32,238
1.3
Nephritis
29.0
Source: US Mortality Public Use Data Tape 2001, National Center for Health Statistics, Centers for Disease Control and
Prevention, 2003.
Change in the US Death Rates* by Cause,
1950 & 2001
Rate Per 100,000
600
586.8
1950
500
2001
400
300
245.8
200
193.9
180.7
194.4
100
57.5
48.1
21.8
0
Heart
Diseases
Cerebrovascular
Diseases
Pneumonia/
Influenza
* Age-adjusted to 2000 US standard population.
Sources: 1950 Mortality Data - CDC/NCHS, NVSS, Mortality Revised.
2001 Mortality Data–NVSR-Death Final Data 2001–Volume 52, No. 3.
http://www.cdc.gov/nchs/data/nvsr/nvsr52/nvsr52_03.pdf
Cancer
Cancer Death Rates*, All Sites Combined,
All Races, US, 1975-2000
Rate Per 100,000
300
Men
250
Both Sexes
200
Women
150
100
*Age-adjusted to the 2000 US standard population.
Source: Surveillance, Epidemiology, and End Results Program, 1975-2000, Division of Cancer
Control and Population Sciences, National Cancer Institute, 2003.
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976
0
1975
50
Cancer Death Rates*, for Men, US,
1930-2000
100
Rate Per 100,000
Lung
80
60
Stomach
Prostate
40
Colon & rectum
20
*Age-adjusted to the 2000 US standard population.
Source: US Mortality Public Use Data Tapes 1960-2000, US Mortality Volumes 1930-1959,
National Center for Health Statistics, Centers for Disease Control and Prevention, 2003.
2000
1995
1990
1985
1980
1975
1965
1960
1955
1950
1945
1940
1935
1970
Liver
Leukemia
1930
0
Pancreas
5000
100
4500
90
4000
80
3500
70
Per capita cigarette consumption
3000
60
2500
50
Male lung cancer death rate
2000
40
1500
30
1000
20
500
10
Age-Adjusted Lung Cancer Death
Rates*
Per Capita Cigarette Consumption
Tobacco Use in the US, 1900-2000
Female lung cancer death rate
2000
1995
1990
1985
1980
1975
1970
1965
1960
1955
1950
1945
1940
1935
1930
1925
1920
1915
1910
1905
0
1900
0
Year
*Age-adjusted to 2000 US standard population.
Source: Death rates: US Mortality Public Use Tapes, 1960-2000, US Mortality Volumes, 1930-1959, National
Center for Health Statistics, Centers for Disease Control and Prevention, 2002. Cigarette consumption: US
Department of Agriculture, 1900-2000.
What is Cancer?
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Cancer is a disease
of old age
It’s typically a build
up of mutations in
genes that control
the cell cycle
We keep seeing
more cancer
because we live
longer
Metastasis – Cancer with car
keys
1. The tumor grows
2. Mutates genes that promote vessel
formation (VEGF) – helps it get food
3. Forms a displasia (see left) – begins
to invade surrounding tissue
4. Eventually breaks through the blood
vessels and spreads
What are some things that
play a role in the cell cycle?
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Cyclin
VEGF
CDC’s
Telomerase
p53
Rb
p16ink4a
E2F
Big T, middle T, small T
Ras
Myc
Jun
etc., etc., etc
How can we stop it?
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Some of it you can’t – Why?
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Mutations happen by accident in ~ 1 in a
1,000,000 replications of DNA
We have over 1 Trillion cells – do the
math – they’re (mutations) are going to
happen
Be smart – don’t: smoke, drink
excessively, get sun burns, etc
How do we treat it?
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Surgery, if possible, to remove the tumor
Chemotherapy – Chemical therapy,
specifically cytotoxins to go and kill specific
cells
Radiation treatment – typically a focused
high intensity beam of X-rays which both
disrupt cell growth but also and mainly
cause blood vessels to thicken and
eventually close off