Science – 7
Video: Greatest Discoveries in Biology (Cell Division)
Name: KEY
Date: _______________
Scientist
Year
Contribution
Walther Flemming
1881
Published book on cell
division. Described
cell division in great
detail using more
powerful microscope
and dying techniques.
Found chromosomes in
cells.
Discovered that
chromosomes split.
Named the process
mitosis.
Edouard Van
Beneden
1883
Observed that sex cells
had half the number of
chromosomes of
regular cells.
August Weismann
1887
Discussed HOW sex
cells could end up with
half the number of
chromosomes. Named
the process meiosis.
Hans Driesch
1890’s Used sea urchins to
investigate how cells
differentiate into
specific cell types.
Questions:
1. What is cell division?
Cell division is the process a cell goes through to duplicate itself.
2.
Why did Flemming look at the TAIL of a tadpole to observe cell division?
He looked at the tail because it was growing so that’s where cell division would
place
3.
Why was the discovery of chromosomes splitting during mitosis important?
take
It explains how one cell can turn into a multicellular organism with many interacting
cells.
4.
What was the difference, in number, between body cells and sex cells in the roundworms
observed by Von Beneden?
Nearly all of the cells contained 4 chromosomes, except for the sperm and egg
which contained only 2.
cells,
5.
Weissman’s experiments showed that at some point, a developing organism signals its
cells to divide the number of chromosomes in half. What is this process called?
The process is called meiosis.
6.
7.
What is “cell differentiation?”
Cells receive their assignments for specific jobs in the adult organism. Examples are
legs, arms or eye cells.
What are cells that can develop into ALL cell types called?
Stem cells.
8.
Why is stem cell research so important? What is the potential of stem cells?
It shows that cells’ roles are not always predetermined and that certain stem cells might
be able to be used to treat disease. In regenerative medicine it has been
shown that
stem cells can repair tissue in muscle, in the brain and in the liver.