Download Understanding Your Karyotype

Understanding Your Karyotype
A karyotype is an organized profile of a person's
chromosomes. In a karyotype, chromosomes are
arranged and numbered by size, from largest to smallest.
This arrangement helps scientists quickly identify
chromosomal alterations that may result in a genetic
disorder.
To make a karyotype, scientists take a picture of
someone's chromosomes, cut them out and match them
up using size, banding pattern and centromere position
as guides.
Human Karyotype (Normal)
Be a lab scientist! Make a karyotype here:
http://learn.genetics.utah.edu/content/begin/traits/karyotype/
Is your “paper” karyotype normal?
Using Karyotypes to Predict Genetic Disorders
A normal human karyotype has 46 chromosomes:
22 pairs of autosomes and 2 sex chromosomes.
What happens when a person has something
different, such as:

Too many or too few chromosomes?

Missing pieces of chromosomes?

Mixed up pieces of chromosomes?
1. Too many or too few chromosomes
To understand how our cells might end up with too
many or too few chromosomes, we need to know
how the cells normally get 46 chromosomes.
First we need to understand meiosis. Meiosis is the
cell division process that produces egg and sperm
cells (gametes), which normally have 23
chromosomes each.
Play Meiosis animation here:
http://learn.genetics.utah.edu/content/begin/tour/mitosis.swf
Sometimes chromosomes are incorrectly distributed into
the egg or sperm cells during meiosis. When this
happens, one cell may get two copies of a particular
chromosome, while another cell gets none.
Click Here: How to use a karyotype to identify genetic disorders
Some examples of genetic disorders that are caused by
an abnormal number of chromosomes are:

Down Syndrome

Turner Syndrome

Klinefelter Syndrome

Triplo X Syndrome
Click on the links above for information on each disorder.
http://www.biology.iupui.edu/biocourses/N100/2k2humancso
maldisorders.html
2. Missing pieces: deletions of chromosome
sections
Examples of genetic disorders caused by chromosomal
deletions are:

Cri du chat Syndrome

Williams Syndrome
In some cases, genetic material is missing from a
chromosome. Such chromosomes are said to have
deletions. Deletions of the tips of chromosomes are called
terminal deletions. Internal deletions, where a
chromosome has broken, lost material, and rejoined, are
called interstitial (pronounced in-ter-STIH-shul)
deletions.
3. Mixed-up pieces: chromosomal translocations
If someone has these translocations, will their genes be
affected? Find out in these examples:

Reciprocal Translocation: Philadelphia chromosome

Robertsonian Translocation
A translocation is a chromosome rearrangement in which
part of a chromosome breaks off and then reattaches to a
different chromosome. Different types of translocations
that can occur include:
Quick Review!
What are some differences between Mitosis and Meiosis??
What are some similarities between Mitosis and Meiosis??
Beginning # of cells
Ending # of cells
Purpose
What types of cells
use the process (In
which organs/tissues
do these processes
occur)?
Are haploid or diploid
cells formed?
Are the new cells
identical to the
“parent” cell?
MITOSIS
MEIOSIS
1
1
Your assignment follows!! Partner Up!
Prenatal Testing : Partner Assignment
With a partner, write a short, persuasive paper on the
following topic:
The use of prenatal tests such as chorionic villus
sampling and amniocentesis to determine the genetic
makeup of a baby.
These tests are done by sampling some of the
cells/tissues of a developing fetus in a pregnant mother,
usually during the 12th – 18th week of pregnancy. Do you
approve of these tests? Are they ethically justified?
Paragraph One: Briefly describe either chorionic villus
sampling OR amniocentesis. Include the following:
A description of the procedure
When the test is performed
What the test can show
Who should have the test performed
Potential side – effects/ dangers
Advantages/Disadvantages of the test
Write in your own words!
Paragraph Two: Give reasons why you personally
support or do not support the prenatal test you’ve
chosen. Cite data from research to support your
argument.
BIBLIOGRAPHY: Using Easybib, cite at least two different
sources that you used to write your paper.
NO WIKIPEDIA!!!