Karyotypes Karyotypes
KaryotypesKaryotypes
Chromosomes are DNAChromosomes are DNA
Chromosome PartsChromosome Parts
centromere
chromatids
Each half is identical to the other. X shaped chromosomes form after DNA replication.
Normal KaryotypesNormal Karyotypes
What are the stripes on the chromosomes?
Homologous chromosomes
Sex chromosomes XX=girl XY=boy
DNA ReplicationDNA Replication
After DNA ReplicationAfter DNA Replication
When something goes wrong.When something goes wrong. Trisomy 13Trisomy 13
Down SyndromeDown Syndrome Nondisjunction of chromosome #21.Nondisjunction of chromosome #21. 47 chromosomes.47 chromosomes. Your chances of a down syndrome baby Your chances of a down syndrome baby
goes up as women get older.goes up as women get older.
Klinefelter syndromeKlinefelter syndrome
Extra X Extra X chromosome in a chromosome in a male.male.
XXYXXY Small male Small male
genitals, breast genitals, breast development, wide development, wide hips, and poor hips, and poor beard growth, beard growth, sterile.sterile.
Klinefelter syndromeKlinefelter syndrome
Extra Y Extra Y chromosome in a chromosome in a male.male.
XYYXYY Very tall man.Very tall man. Not much Not much
difference.difference.
Klinefelter syndromeKlinefelter syndrome
Extra X chromosome in a female.Extra X chromosome in a female. XXXXXX Can’t tell at all.Can’t tell at all. No difference from XX.No difference from XX.
Turner syndromeTurner syndrome
Only one X.Only one X. Female.Female. XX Underdeveloped Underdeveloped
sex organs.sex organs. Short, and sterile.Short, and sterile.
cri du chat (cry of the cat)cri du chat (cry of the cat) Deletion in Deletion in
chromosome 5.chromosome 5. Babies cry like a Babies cry like a
cat’s meow.cat’s meow. Characteristic Characteristic
facial features.facial features.
2 Kinds of Mutations2 Kinds of Mutations Point mutationsPoint mutations = one base pair is = one base pair is
changed. (changes the protein)changed. (changes the protein) Chromosome mutationsChromosome mutations = large changes = large changes
in chromosomes. (changes many genes)in chromosomes. (changes many genes) Chromosome mutations can happen if Chromosome mutations can happen if
meiosis goes wrong.meiosis goes wrong.
Sometimes it is beneficial.Sometimes it is beneficial.
Humans have 99% the same DNA as Humans have 99% the same DNA as chimpanzees.chimpanzees.
Chimpanzees have an extra chromosome.Chimpanzees have an extra chromosome. The theory is that two chromosomes fused The theory is that two chromosomes fused
evolving the human race.evolving the human race. Play Video. – 5:05-7:30 – 5:05-7:30
Testing for chromosomal disordersTesting for chromosomal disorders AmniocentesisAmniocentesis UltrasoundUltrasound Karyotyping Karyotyping
The Doctor’s RoleThe Doctor’s Role
Perform tests to Perform tests to remove cells.remove cells.
Extract the DNA.Extract the DNA. Do a karyotype Do a karyotype
match the match the homologous homologous chromosomes chromosomes
Seek help from a Seek help from a Genetic Counselor. Genetic Counselor.
What’s wrong here?
The Human Genome ProjectThe Human Genome Project
If we can determine the baby’s karyotype If we can determine the baby’s karyotype then can we determine it’s genes?then can we determine it’s genes?
Yes, thanks to the human genome project Yes, thanks to the human genome project we can do a test for certain genes.we can do a test for certain genes.
In the future we could test for designer In the future we could test for designer traits.traits.