Transcript CELL DIVISION

Atypical or Abnormal Cell Division
CELL DIVISION
Mitosis Gone Awry
• Mutations are
changes in the
molecular structure
of DNA that
ultimately creates
diversity
• Carcinogens,
radiation viruses and
other factors can all
cause mutations.
http://www.youtube.com/watch?NR=1&v=Hm03rCUODqg
Breast cancer cells dividing
(3 days time lapse)
Mutations in somatic
cells aren’t passed to
offspring
There are two different types of
mutation:
• A) Gene Mutations
– A new alleles for a trait suddenly appears on the
chromosome that carries the gene
Damage to Chromosome Structure
• Large scale mutations that damage chromosome structure can
occur when something unusual happens during crossing over.
Translocation – the transfer of a chromosome segment to a nonhomologous chromosome.
Deletion - occurs when a chromosome segment breaks off, resulting
in the loss of some genes
Duplication – occurs when part of a chromosome is repeated
Inversion – occurs when a piece of a chromosome is rotated so that
the order of genes in the segment is reversed.
Atypical Meiosis
• NONDISJUNCTION – the uneven separation of
homologous chromosomes during Anaphase.
Mutations in gametes
• Mutations in meiosis are inherited by offspring though
no disorder was evident in the parent
• By age 42, 90% of a woman’s eggs are chromosomally
abnormal. Thus, at age eighteen, 1:2,000 live births
results in Down Syndrome. By age 42 that rises to 1:25
Trisomy 21
• Down Syndrome – there is an extra chromosome
in either the egg or sperm making 47 in the
zygote
Genetic Screening
• Amniocentesis
– withdraw
fluid and cells
from the
amniotic sac
surrounding the
fetus to look at
chromosomal
abnormalities
http://video.about.com/pregnancy/Amni
ocentesis.htm
Trisomy 8,9,13,16,18
• http://www.youtube.com/watch?v=-QJF0Cs4f9s
• March is Trisomy Awareness month. I photographed this
series of portraits at the SOFT (Support for Families with
Trisomy 18, 13 and Related Disorders) conference in
Roanoke, Virginia during July 2009. I am trying to raise
awareness that while only 10% of these kids survive their
first year the ones that do live a rich life. Expectant parents
are often told that Trisomy is incompatible with life and I
am trying to share their unique beauty through these
digital images. These children and young adults do not pose
for photographs but can be captured being themselves,
living in the moment. Most are non-verbal so I see it as an
honor to help tell their stories visually.
• http://www.youtube.com/watch?v=-u2nbfgpP3U