a self guided lesson teaching students about chromosomal disorders due to nondisjunction.

1. Learning From
Karyotypes

2. Be a genetic councilor!
 People- like all living things- have DNA in their cells which
helps to determine how they look and how they function.
 DNA molecules are coiled up around proteins (like thread on
a spool) to make chromosomes.
 Chromosomes can be used by genetic councilors to learn
things about people.
 Click  Genetic Councilors to learn about genetic councilors.
 If chromosomes are damaged (chromosomal mutations)
health problems can result.

3. 1. Karyotype
Definition: Picture of chromosomes, can be used to find out the
gender of a person and also to diagnose some genetic
disorders
How is a karyotype made? ( process):
• make chromosomes coil up in cell
• stain chromosomes
• find chromosomes using a microscope
• take a picture of chromosomes
• cut apart chromosomes, pair them up and line them up
according to their number.

4. This picture shows
how the
condensed and
stained
chromosomes
would look
under a
microscope 

5. The NEXT slide shows a finished karyotype. Use it to
answer the following questions in your notebook:
 What characteristics are used to match up the chromosomes?
 Are the chromosomes lined up in the karyotype in any sort of
order? Explain.
 How many chromosomes do humans have in each cell?
 Why do you think chromosomes come in pairs?

7. Check your answers…..
 What characteristics are used to match up the karyotypes?
The bands made by the stains, the length of the chromosomes, the placement of
the centromere
 Are they lined up in the karyotype in any sort of order?Yes
 Explain- Largest to smallest
 How many chromosomes do humans have in each cell? 46
 What is the gender of the person for whom this karyotype was made? female
 How do you know? 2 X chromosomes
 How would the karyotype look different if it were the other gender? There
would be an X chromosome AND aY chromosome
 Why do chromosomes come in pairs? One of each pair comes from each
parent

8. Determining gender
 Notice that the last pair of chromosomes is labeled with letters
instead of numbers.
 The last pair of chromosomes are the sex determining
chromosomes.
 The longer chromosomes are called X and the shorter one is called
Y
 If the person has one X and oneY chromosome (one long
chromosome and one short chromosome) the person is male
 If the person has two X chromosomes ( 2 long chromosomes) the
person is female.
 On the next slide determine the gender of patientA and patient B

10. Now try making your own karyotype:
 Click this link:
 http://learn.genetics.utah.edu/content/begin/traits/karyotyp
e/

11. Karyotypes are used to diagnose
CHROMOSOMAL disorders
 Chromosomal
Disorders
 Affects a part of or an entire
chromosome (can affect many
genes)
 Usually results in a syndrome
(collection of symptoms)
 Can result from mutations such as…
• Too many chromosomes
• Too few chromosomes
• Broken or damaged chromosomes

12. How are karyotypes used?
 Use the link below to learn
about the procedures used to
obtain cells for karyotyping
 http://www.nlm.nih.gov/medli
neplus/ency/article/003935.ht
m
 Once you are at this site
research the following and
record your findings in your
notebook:
 Normal results for a karyotype
 Examples of disorders that can
be detected by an abnormal
karyotype.

13. Be a Genetic Councilor
 Click on the patient histories below and for each patient,
complete their karyotype.
 In your lab notebook write a brief report for each patient
telling me three things:
1) whether the patient is male or female
2) what is specifically wrong with the chromosomes in the
karyotype
3) what genetic disorder the karyotype shows.
 Patient Histories