DNA, Genes, Chromosomes,
and Cells
• Your body is made of trillions of cells, each
one with a nucleus.
• Inside each nucleus are 46 chromosomes.
You got 23 from mom, 23 from dad
• Chromosomes are made of many genes
http://www.connectmydna.com/the-science/
• Genes are made of long sections of DNA
(deoxyribonucleic acid)
DNA
http://abcnews.go.com/blogs/business/2013/04/letter-on-dna-structure-sells-for-record-5-3-million/
• Some of the genes you inherit are
dominant, some of the them are recessive.
• Scientists can look at these genes on your
chromosomes and use them to help
diagnose disease or provide better
treatment.
http://cpmc.coriell.org/
You may soon go to your doctor with a picture of your chromosomes
Karyotype
Normal babies have cells with 46
chromosomes
Normal sperm and egg cells each
have 23 chromosomes
A picture of a cell’s chromosomes
is called a karyotype.
Chromosomes are paired up and
lined up according to their patterns
and size.
We use “cartoon” versions of
chromosomes to make our task
easier.
The different
patterns on
chromosomes
are different
genes for
traits
A karyotype can be used to
diagnose a disease or determine
gender
Boys are XY, girls are XX for
chromosome #23
Sometimes there are extra or
missing chromosomes
Turner’s Syndrome (one X)
Klinefelter’s Syndrome (XXY)
Cri du Chat Syndrome (deleted part
of chromosome 5)
Down Syndrome (3 copies of #21)
Karyotypes can be made for a fully
formed human or for a developing
fetus.
Why would a parent want to know a
child’s karyotype?
To determine risk of a
genetic disorder or the
gender of the child.
Early testing can help parents
prepare physically and
emotionally for the birth of their
child. They can be better
prepared to meet the needs of
their child with early
intervention and care.
Even plants can have a karyotype
made of their chromosomes for
identification purposes
Genetic testing can now be used to
search for potential diseases
• Breast/ovarian cancer
(#17 and 13)
• Alzheimer’s (#19)
• Cystic Fibrosis (#7)
• Autism (#15 is different if
the person has this
disease-not yet known
why this happens)
Genetic testing can also be used to
determine gender, especially in
cases of elite athletes.
http://www.hhmi.org/biointeractive/gendertest/gendertest.html
http://www.nytimes.com/2010/04/08/sports/08sportsbriefs-semenya.html
http://news.bbc.co.uk/2/hi/programmes/newsnight/9373209.stm
Your task:
• You will receive a sample of chromosomes
from a developing fetus.
• You must arrange the chromosomes
according to size and pattern into a
karyotype.
• You will then determine the gender and
disease this child may have (if any).
• Conclusion questions and karyotype are
due on Thursday.
Instructions:
1. Carefully cut apart the chromosomes, do NOT lose any!
2. Using the “Normal Karyotype” as your guide, arrange the patient’s
chromosomes according to the same pattern.
3. Glue/Tape the chromosomes into place on the attached paper.
4. Compare your patient’s karyotype to the normal karyotype and the disease
chart to determine, what disease, if any, the child has.
Genetic Disorder
Down's Syndrome
Turner's Syndrome
Klinefelter Syndrome
3 copies of chromosome
21
one X only for chromosome
23
XXY for chromosome 23
1 in 800
1 in 2000
1 in 750
1 in 50,000
mental retardation, eyes
slant upwards,
prone to heart
defects and
respiratory
problems.
normal female in childhood,
normal intelligence,
fails to fully undergo
puberty and will
remain infertile
male, normal in appearance
and intelligence, sterile,
may show some female
characteristics (breast
development, feminine
body shape)
distinctive cat-like cry in
babies, respiratory
problems,
shortened life
span is possible
Triple X Syndrome
Edward's Syndrome
Patau Syndrome
Trisomy 23
karyotype change
XXX for chromosome 23
3 copies of chromosome 18
3 copies of chromosome 13
XYY for chromosome 23
How often does it
occur?
1 in 700
1 in 6,000
1 in 15,000
1 in 2,000
karyotype change
How often does it
occur?
Physical
Symptoms
Genetic Disorder
Physical
Symptoms
female with normal
intelligence and
appearance, may
be sterile
feeding and breathing
difficulties,
developmental delays,
deformation of head
and face, cardiac
defects, often results
in early death
mental retardation, cleft
palate, extra fingers and
toes, incomplete
development of internal
organs, often results in
early death
Cri du Chat Syndrome
deleted part of
chromosome 5
male with low mental
ability, normal in
appearance
Genetic
Disorder
Down Syndrome
karyotype
change
3 copies of
chromosome 21
How often
does it
occur?
1 in 800
Physical
Symptoms
mental
retardation, eyes
slant upwards,
prone to heart
defects and
respiratory
problems.
http://www.ndss.org/
Genetic
disorder
Turner
Syndrome
karyotype
change
one X only for
chromosome 23
How often
does it
occur?
1 in 2000
Physical
Symptoms
normal female
in childhood,
normal
intelligence,
fails to fully
undergo
puberty and will
remain infertile
http://www.turnersyndrome.org/
welcome-turner-syndromesociety-us
Genetic
disorder
Klinefelter
Syndrome
karyotype
change
XXY for
chromosome 23
How often
does it
occur?
1 in 750
Physical
Symptoms
male, normal in
appearance and
intelligence,
sterile, may show
some female
characteristics
(breast
development,
feminine body
shape)
http://ghr.nlm.nih.gov/condition/klinef
elter-syndrome
Genetic
disorder
Cri du Chat
Syndrome
karyotype
change
deleted part of
chromosome 5
How often
does it
occur?
1 in 50,000
Physical
Symptoms
distinctive catlike cry in babies,
respiratory
problems,
shortened life
span is possible
http://www.fivepminus.org/
Genetic
disorder
Triple X
Syndrome
karyotype
change
XXX for
chromosome 23
How often
does it
occur?
1 in 700
Physical
Symptoms
female with
normal
intelligence and
appearance, may
be sterile
http://www.mayoclinic.com/health/trip
le-x-syndrome/DS01090
Genetic
disorder
Edwards
Syndrome
karyotype
change
3 copies of
chromosome 18
How often
does it occur?
1 in 6,000
Physical
Symptoms
feeding and
breathing
difficulties,
developmental
delays, deformation
of head and face,
cardiac defects,
often results in
early death (fewer
than 10% live for a
year)
http://www.trisomy18.org/s
ite/PageServer?pagename
=parents_whatisT18
Genetic
Disorder
Patau Syndrome
karyotype
change
3 copies of
chromosome 13
How often
does it
occur?
1 in 15,000
Physical
Symptoms
mental
retardation, cleft
palate, extra
fingers and toes,
incomplete
development of
internal organs,
often results in
early death
http://www.ncbi.nlm.nih.gov/pubmedhe
alth/PMH0002625/
Genetic
Disorder
Trisomy 23
karyotype
change
XYY for
chromosome 23
How often
does it
occur?
1 in 2,000
Physical
Symptoms
male with low
mental ability,
normal in
appearance
http://ghr.nlm.nih.gov/condition/47
xyy-syndrome