Transcript Lecture Chpt. 15 Genetics.errors

Nondisjuncti
on
Homologous
pairs do not
move apart
during
Meiosis
Nondisjuncti
on
aneuploidyabnormal number
-2n + 1 ex. Down’s
trisomic
- 2n - 1 ex. Turner’s
monosomic
monosomic
Turner’s
Syndrome
trisomic
Trisomy 21
Trisomic 2n + 1
Down Syndrome /
Trisomy 21
Turner Syndrome
X
monosomic 2n
-1
2N
+ 1 (2N + 2, 2N + 3)
Genotype: XXY
(XXXY, XXXXY)
Phenotype: male, but
sexual development Klinefelter’s
may be poor. Often
Syndrome
taller than average,
mental development
fine (XXY), usually
sterile.
More X = more mental
problems
Kleinfelter’s Syndrome
Klinefelter’s
Syndrome
Comment: I have read that George
Washington may have had Klinefelter’s.
Taller than average, no children
2N
+1
Genotype:
XXX
Phenotype: taller
female, but sexual
development poor.
(Mental impairment
common in many
reports, not in
others???)
Trisomy X
Edward’s Syndrome
Edward’s Syndrome
Edward’s Syndrome
•
•
•
•
Also known as Trisomy 18
Almost every organ system is affected.
1:10,000 live births.
Children with full Trisomy 18 generally
do not live more than a few months.
• Characteristics: small jaw, low-set ears,
and a strawberry-shaped head.
Patau Syndrome
• This person would suffer from serious
eye, brain, & circulatory defects as
well as cleft palate.
• 1:5000 live births. Children rarely live
more than a few months.
Patau Syndrome
Tall
Jacob’s Syndrome XYY
Lean
Acne prone
Crooked eye
Anger difficulties
Some cognitive
difficulties
Translocations
Prader-Willi
Deletion on
chromosome
15 - father
imprinted
Angelman
Deletion on
chromosome
15 - mother
imprinted
Gene
expression
and inheritance
depends on which
parent passed on
the gene.
Usually
caused
by different
methylations of the
DNA.
Imprints are
"erased" in gamete
producing cells and
re-coded by the
body according to
its sex.
Prader-Willi
Syndrome and
Angelman
Syndrome
Both lack a small
gene region from
chromosome 15.
Male imprint:
Prader-Willi
Female imprint:
Angelman
Gene Mutations
Chromosome “M”
-small circles of DNA
located in mitochondria and
plastids of plants.
Mitochondria reproduces itself
and it passes it DNA along to its
daughter organelle only.
Chromosome “M”
- All “M” Chromosomes come
from mom
These genes help form proteins
involved in respiration. Defects in
these genes cause Mitochondrial
diseases such as mitochodrial
myopathy, diabetes, heart
disease, Alzheimer’s disease.
Cummulative mutations may role
play in aging