KaryotypesOuhday S., Drew E., D.J. C.

What are karyotypes?

Karyon = kernel, seed, or nucleus

the number and appearance of chromosomes in the nucleus of a eukaryotic cell

Chromosomes: an organized structure of DNA & protein found in cells

23 pairs (23 from each parent)

karyogram--compare pairs, sizes, position of centromere

Giemsa dye-staining

What are karyotypes even used for?

Karyotypes (or karyograms of karyotypes) are often used to determine things about a fetus.

A blood sample is taken from the mother, and by looking at the karyotype, chromosomal abnormalities can be determined.

Observed to see chromosomal and genetic differences between species and within the same species over time.

# of chromosomes, the shape/size of chromosomes, and sex of an individual can be observed among other things.

How karyotyping is done.Staining

Giemsa dye after cell division

Can use almost any cell or tissue

1. Blood drawn

2. Amniocentesis (to test amniotic fluid)

3. Sample grows

4. Stained

History

Karl Wilhelm von Nägeli first observed chromosomes (via plant cells) in 1842

1920’s-T.S. Painter, XX/XY system for determining sex (not XX/X0)

48 chromosomes

1955/1956, Joe Hin Tijo correctly determined # of chromosomes (46)

Karl Wilhelm von Nägeli

Joe Hin Tijo

T.S. Painter

Abnormalities/Diseases

Turner Syndrome

missing or incomplete X chromosome

develop as females

Down Syndrome

error in cell division...extra 21st chromosome

impairments in both cognitive ability and physical growth

Patau Syndrome

trisomy of chromosome

occurs in approximately one out of every ten-thousand to sixteen-thousand infants

Turner Syndrome

Down Syndrome

Patau Syndrome

Questions!

Who first observed chromosomes?

Karl Wilhelm von Nägeli

What’s the Greek word that “karyotypes” was derived from?

Karyon

What’s the name of the dye used to stain karyotypes?

Giemsa

Who determined the right number of chromosomes in the human karyotype?

Joe Hin Tijo

How many chromosomes are in the average human karyotype?

46

To get a karyotype of the fetus, a ___ sample is taken from the mother.

Blood

Define “amniocentesis”

the sampling of amniotic fluid using a hollow needle inserted into the uterus, to screen for developmental abnormalities in a fetus

Define “trisomy”

a condition in which an extra copy of a chromosome is present in the cell nuclei, causing developmental abnormalities

Which disease is caused by a missing or incomplete X chromosome?

Turner Syndrome

Which chromosome is affected if someone has Down Syndrome?

21st

Which chromosome is affected if someone has Patau Syndrome?

13

Virtual Activity Time!

http://learn.genetics.utah.edu/content/begin/traits/predictdisorder/

Video Time!

Youtube

http://www.youtube.com/watch?v=q8errsrd4FE

http://www.youtube.com/watch?v=F5Zz0sQPrI0

http://www.youtube.com/watch?v=IHhwGM4Fx6U

Hands-On Activity Time!