Biology
Unit 3: Genetics
Grading Category 6 LT 5
Name: __________________________
Period: _____
Karyotype Activity
Background:
Occasionally chromosomal material is lost or rearranged during meiosis. Such changes are so severe
that the pregnancy ends in miscarriage – or fertilization does not occur at all. It is estimated that one in
156 live births have some kind of chromosomal abnormality.
Some of the abnormalities associated with chromosome structure and number can be detected by a
test called a karyotype. A karyotype can show prospective parents whether they have certain
abnormalities that could be passed on to their offspring, or it may be used to learn the cause of a
child’s disability. Karyotypes can also reveal the gender of a fetus or test for certain defects through
examination of cells from uterine fluid – a procedure called amniocentesis – or through sampling of
placental membranes. Over 400,000 karyotype analyses are performed each year in the U.S. and
Canada.
To create a karyotype, chromosomes from a cell are stained and photographed. The photograph is
enlarged and cut up into individual chromosomes. The homologous pairs are identified and arranged in
order by size (with the exception of the sex chromosomes; these appear last). These tests are typically
done on a sample of blood, although any body cell could be used. The cell must be undergoing mitosis
– preferably in metaphase – so that the chromosomes are replicated, condensed, and visible under a
microscope.
(adapted from: http://www.slic.wsu.edu/bios/biol107/107Karyotypesp05.pdf)
Directions:
1. Go to http://learn.genetics.utah.edu/content/begin/traits/
2. Click on “Make A Karyotype”.
3. Follow the instructions highlighted in blue to make your own karyotype.
4. When complete, answer the following questions:
a. Was the karyotype you created haploid or diploid? Explain. (If you do not know what
these words mean, look it up online.)
b. What the individual male or female? Explain.
5. Go back to the original page.
6. Click on “Using Karyotypes to Predict Genetic Disorders”.
Biology
Unit 3: Genetics
Grading Category 6 LT 5
Name: __________________________
Period: _____
7. Watch the video that shows “Normal Meiosis”. Fill in the blanks below.
a. Meiosis begins with a cells containing _____ chromosomes total so it is haploid/diploid
(circle one).
b. When the chromosomes are copied, there are _____ chromosomes total.
c. The cell completes the first division and has ______ chromosomes total.
d. The cell completes the second division and has _____ chromosomes total.
e. The result is _____ (#) cells (either _________ or ________ cells, which have ______
chromosomes total and are haploid/diploid (circle one).
8. Watch the video that shows “Fertilization”. Fill in the blanks below.
a. Egg and sperm cells contain ______ chromosomes each so they are called
haploid/diploid (circle one).
b. When egg and sperm join, they form a _____________________ with ______
chromosomes total, so this new offspring is haploid/diploid (circle one).
9. Watch the video that shows “Abnormal Meiosis”. Answer the question below.
a. What kind of errors can occur during meiosis?
10. Watch the video that shows “Trisomy” & “Monosomy”. Answer the question below.
a. What is trisomy?
b. What is monosomy?
11. Using the chart on the next page, take the quiz at the bottom of the webpage to predict the
genetic disorders (or lack of) for each fertilization event shown.
a) x + x
e) 21 x + 21 x
b) x + no sex chromosome
f) xy + x
c) x + y
g) 21 + 21 21
d) xx + y
h) x + no sex chromosome
Biology
Unit 3: Genetics
Grading Category 6 LT 5
Name: __________________________
Period: _____
Description of Possible Genetic Disorders
Chromosomal
Make-up
46 XX
46 XY
Name of Genetic
Disorder
Normal Female
Normal Male
Trisomy 13
Patau Syndrome
Trisomy 18
Edwards Syndrome
Trisomy 21
Down Syndrome
XXY
Klinefelter’s Syndrome
XXX or XXXX
Triple X
XO
Turner’s Syndrome
XYY
Jacob’s Syndrome
Arm Missing From
#5
Crit du Chat
14, 14/21,
21, 21
14/21 Translocation
Down Syndrome
14, 14/21, 21
14/21 Translocation
Description
No Apparent Genetic Disorder
No Apparent Genetic Disorder
This syndrome causes severe abnormal cerebral functions
and virtually always leads to death in early infancy. The baby
will have very pronounced clefts of the lip and palate, broad
nose, small cranium, and nonfunctional eyes.
Frequency 1/15,000 live births
Produces severe mental retardation and a highly
characteristic pattern of malformations including elongation
of the skull, a narrow pelvis, low set ears and small mouth.
Nearly all babies born with this abnormality die in early
infancy.
Frequency 1/5,000 live births
One of the most common causes of mental retardation.
Characteristic features generally include a short stature,
broad hands, stubby fingers and toes, a wide rounded face,
and a large protruding tongue. Frequency 1/750 live births
(greater as the mother ages)
Babies are male and generally appear normal.
Characteristics include a tall stature, small testicles and
sterility. Frequency 1/1,000 live male births
Generally these females are normal both mentally and
physically and are fertile. Frequency 1/1,000 lie female
births
Females with this disorder appear normal before puberty
although they may be shorter with a chunky build. At sexual
maturity, the secondary sex characteristics do not develop
and no ova (eggs) are produced. Frequency 1/2,500 live
female births
Men with this abnormality are tall and have a low mental
ability. Frequency 1/1,000 live male births
Babies with this disorder have a distinctive cat-like cry, are
severely mentally retarded, and have a small cranium.
Frequency 1/100,000 live births
Same signs and symptoms as a normal down syndrome child.
The only difference is that the extra chromosome 21 is
attached to one of the chromosome 14s.
No apparent genetic disorder but may be a carrier for the
14/21 translocation down syndrome baby.