MLS 007 (Human Cytogenetics)
STUDENT ACTIVITY SHEET
BS MEDICAL TECHNOLOGY / SECOND YEAR
Session # 1
Materials:
LESSON TITLE: HISTORY OF GENETICS, TECHNOLOGY
& SOCIETY
LEARNING OUTCOMES:
Upon completion of this lesson, the nursing student can:
1. Make a timeline of discoveries in Cytogenetics
2. Discuss theories of Genetics
Book, pen and notebook, class list
References:
1. Gersen, SL & Keagle, MB (2005). The Principles
of Clinical Cytogenetics 2nd ed, Humana Press Inc.,
New Jersey
2. Sigma Documentaries (2017). History of
Research on Genetics
SUBJECT ORIENTATION (10 minutes)
The classroom instructor for this subject, Human Cytogenetics, is
. A course syllabus is given to the
students which contains the course description, topics to be discussed and dates when to discuss them, calendar of
activities, classroom policies, grade computations, and course requirements.
MAIN LESSON (50 minutes)
.
Firstly, the students are asked to read the topic which is found on page 3-6, Section I: Basic Concepts and Background,
Chapter 1: History of Clinical Cytogenetics from the reference book ahead of time. The students are asked to watch a video
presentation by Sigma Documentaries entitled “History of Research on Genetics.” Students are also given a link to the video
presentation so they can review it at home. While they are watching, they are asked to write down the scientists mentioned,
their discoveries as well as the date (if available). This will serve as their footnote which will then be entitled “Timeline of
Genetic Discoveries.”
Additional scientists and their discoveries are found in the reference book. For five (5) minutes, students are asked to
arrange their timeline combining the scientists found on the video presentation and those which are found on the reference
book. They will be given another 5 minutes to review their timeline.
After the five-minute review, students are asked to fill in the missing names of the scientists in the story presented below.
Assessment Activity 1: “History of Clinical Cytogenetics”
The beginning of human cytogenetics is generally attributed to Walther Flemming(1), an Austrian cytologist and
professor of anatomy, who published the first illustrations of human chromosomes in 1882. He also referred to the
stainable portion of the nucleus as chromatin and first used the term mitosis. In 1888, Waldeyer (2) introduced the word
chromosome, from the Greek words for “colored body”, and several prominent scientists of the day began to formulate the
idea that determinants of heredity were carried on chromosomes. After the “rediscovery” of Mendelian inheritance in
1900, Sutton 3) (and, independently at around the same time, Boveri) formally developed a “chromosome theory of
inheritance”. He combined the disciplines of cytology and genetics when he referred to the study of chromosomes as
Cytogenetics.
Owing in part to improvements in optical lenses, stains, and tissue manipulation techniques during the late 19th and early
20th centuries, the study of cytogenetics continued, with an emphasis placed by some on determining the correct number
of chromosomes, as well as the sex chromosome configuration, in humans. Several reports appeared, with differing
estimates of these. For example, in 1912, von Winiwarter (4) concluded that men have 47 chromosomes and women
have 48 (5). Then, in 1923, Painter (5) studied (meiotic) chromosomes derived from the testicles of several men who had
been incarcerated, castrated, and ultimately hanged in the Texas State Insane Asylum. Based on this work, he definitively
reported the human diploid chromosome number to be 48 (double the 24 bivalents he saw), even though, 2 years earlier,
he had preliminarily reported that some of his better samples produced a diploid number of 46. At this time, he also proposed
the X and Y sex chromosome mechanism in man. One year later, Levitsky (6) formulated the term karyotype to refer to
the ordered arrangement of chromosomes. Despite continued technical improvements, there was clearly some difficulty in
properly visualizing or discriminating between individual chromosomes.
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In 1952, Hsu
(7) reported that, rather than depending on histologic sections, examination of chromosomes could be
facilitated if one studied cells grown with tissue culture techniques published by Fisher
(8). He then demonstrated the
value of this method by using it to examine human embryonic cell cultures, from which he produced both mitotic metaphase
drawings and an ideogram of all 48 human chromosomes! As with other significant discoveries, correcting this inaccuracy
required an unplanned event—a laboratory error. Its origin can be found in the addendum that appears at the end of his
paper: It was found after this article had been sent to press that the well-spread metaphases were the result of an accident.
Instead of being washed in isotonic saline, the cultures had been washed in hypotonic solution before fixation.
(This story is an excerpt from the reference book).
CHECK FOR UNDERSTANDING (25 minutes)
To check for understanding, students are given 10 minutes to open their books to check if they got the correct answers.
They are asked to take this privilege to review their timeline for another activity.
After ten minutes, students are asked to provide the contributions of the scientists in the table below.
Assessment Activity 2
Instructions: The names of the scientists who contributed in the field of Genetics are presented on the column “WHO?”
Provide their significant contributions on the column “WHAT?”
WHO?
WHAT?
1. Walther Flemming
• Published the first illustrations of human chromosomes in
1882
• Referred to the stainable portion of the nucleus as
chromatin and first used the term mitosis
2. Waldeyer
• Introduced the word chromosome, from the Greek words
for “colored body.”
3. Sutton
•
•
4. Boveri
•
5. von Winiwarter
•
Concluded that men have 47 chromosomes and women
have 48.
6. Painter
•
7. Levitsky
•
Reported the human diploid chromosome number to be 48
(double the 24 bivalents he saw), even though, 2 years
earlier, he had preliminarily reported that some of his better
samples produced a diploid number of 46
Formulated the term karyotype to refer to the ordered
arrangement of chromosomes.
8. Fisher
•
9. Hsu
•
10. Pomerat
•
11. Ford and Hamerton
•
12. Joe Hin Tjio
•
Formally developed a “chromosome theory of inheritance.”
Combined the disciplines of cytology and genetics when he
referred to the study of chromosomes as cytogenetics.
developed the chromosomal theory of inheritance and the
idea of chromosomal individuality.
Rather than depending on histologic sections, examination
of chromosomes could be facilitated if one studied cells
grown with tissue culture techniques
Examined human embryonic cell cultures, from which he
produced both mitotic metaphase drawings and an
ideogram of all 48 human chromosomes
Reported a “hypotonic shock” procedure after he hypotonic
solution caused water to enter the cells via osmosis, which
swelled the cell membranes and separated the
chromosomes, making them easier to visualize
Worked out a method for pretreating cells grown in culture
with colchicine so as to destroy the mitotic spindle
apparatus and thus accumulate dividing cells in the
metaphase
Learned about the procedures and worked with Hamerton
and Ford to further improve upon them.
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Education (College of Medical Technology)
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13. Levan
•
Reported that the human diploid chromosome number
appeared to be 46, not 48
•
learned the colchicine and hypotonic method in Hsu’s
laboratory at the Sloan-Kettering Institute in New York.
Reported that the human diploid chromosome number
appeared to be 46, not 48
Made the suggestion that Down syndrome could perhaps
be the result of a chromosomal aberration, but the science
of the time could neither prove nor disprove his idea; this
would take almost three decades.
•
14. Waardenburg
•
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15. Lejeune
•
Studied the chromosomes of fibroblast cultures from
patients with Down syndrome
16. Ford et al.
•
17. Jacobs and Strong
•
18. Jacobs
•
19. Murray Barr
•
20. Lyon
•
Reported that females with Turner syndrome have 45
chromosomes, apparently with a single X chromosome and
no Y
Demonstrated that men with Klinefelter syndrome have 47
chromosomes, with the additional chromosome belonging
to the group that contained the X chromosome
A female with sexual dysfunction was also shown by
Jacobs to have 47 chromosomes and was believed to have
an XXX sex chromosome complement
Was studying fatigue in repeatedly stimulated neural cells
of the cat and observed a small stained body on the
periphery of some interphase nuclei, and his records were
detailed enough for him to realize that this was present
only in the nuclei of female cats.
Developed the single active X chromosome mechanism of
X-dosage compensation in mammals.
21. Patau et al.
•
22.Edwards et al.
•
23.Nowell and Hungerford
•
24.Torbjorn Caspersson
•
25.Drets and Shaw
•
Described two similar infants with an extra “D group”
chromosome who had multiple anomalies quite different
from those seen in Down syndrome
Described “A New Trisomic Syndrome” in an infant girl
with yet another constellation of phenotypic abnormalities
and a different autosomal trisomy
Reported the presence of the “Philadelphia chromosome” in
chronic myelogenous leukemia, demonstrating, for the first
time, an association between chromosomes and cancer.
Observed that when plant chromosomes were stained with
fluorescent quinacrine compounds, they did not fluoresce
uniformly, but rather produced a series of bright and dull
areas across the length of each chromosome.
Described a method of producing similar chromosomal
banding patterns using an alkali and saline pretreatment
followed by staining with Giemsa, a compound developed
for identification, in blood smears, of the protozoan that
causes malaria
LESSON WRAP-UP (10 minutes)
A. Work Tracker
Mark (encircle) the session you have finished today in the tracker below. This is simply a visual to help you track how
much work you have accomplished and how much work there is left to do.
You are done with the session! Let’s track your progress.
B. Think About Your Learning
Let’s check your learning experience! Answer the following below.
1. Which part of the lesson is the most difficult?
2. Which part of the lesson you did well?
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Education (College of Medical Technology)
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(For next session, review Section 1, Chapter 2 and Chapter 3 of the Clinical Cytogenetics book)
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Education (College of Medical Technology)
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