Meselson and Stahl
Illustration of Mitosis and Meosis
Pages 1-9 of In Depth Meosis and Mitosis (229-237)
Video on Meselson and Stahl: https://www.youtube.com/watch?v=3RQfSdTrIIk
Cyclins and CDK: https://www.youtube.com/watch?v=rzuri2GX9Oo
One of the best ways of proving you understand a concept is to explain it to someone else. In this
case, I want you to take the following vocabulary and define the terms, words, or phrases for me.
Definitions should not exceed 100 words each. Make sure you
are using your own words in the
definition; do not copy them from another source. Words to be defined are
For week 5, we’re looking at DNA is replicated. Please define these
terms from the readings and
videos. All of the words appear in the readings, but you are encouraged to look at other resources
to help with your definitions:
se read the readings in the folder “Readings for Week 5” as well as watching the videos
linked within the document.
Answers should range from 50 to 200 words. Students are to use
their own words and not copy text from another source unless specifically as
ked to. Make sure
your response answers the question asked. Some questions are opinion questions; there is no
right or wrong answer, but I want you to make it clear you have thought about the question being
1) Start by watching the video on Mendelso
n and Stahl,
read the paper. This experiment
is often cited as one of the most elegant in biology. I want you to identify the parts of the
experiment. What was the hypothesis going they were examining? What were the alternatives?
2) The experiment wa
s done using
and separating out the DNA for examination. We have
discussed using the right model organisms for the each experiment. Why was
choice for this experiment?
3) It’s apparent that the structure of DNA was newly discovered,
and the explanation of DNA
replication incorporates the new discovery to explain replication. If this experiment had done
prior to the discovery of the structure of DNA, what aspects of their discovery would help
explain some of the structure of DNA? What
did they learn here that helps support the Watson
structure of DNA?
4) The researchers also discovered that DNA maintains its sequence when heated but loses its
structure. This is important for
DNA replication. Name another process within the ce
ll where it
is important to know that DNA can change its structure without losing sequence information?
5) Please watch the two remaining videos about phosphorylation and cyclins. Phosphorylation
allows for proteins that have already been made to have mult
iple different functions. Adding a
phosphate group changes what can be bound to each protein, changing its role in the cell. Why
would it be easier to for a cell to simply add a phosphate group to change a protein’s function
than to simply build a new prot
6) Please read the illustrated file called “Illustration of
and Mitosis”. There’s a lot of
information in this file. Compare mitosis and
. What are two differences between the two
that are most obvious to you?
Please note that you have an addit
ional reading file in this week
Please read the first 9
pages of the file called “In Depth
and Mitosis” (Up to page 237). This is a difficult text.
Think of this reading, the movie on cyclins, and t
he illustrated text. This talks about a new type
of modification similar to phosphorylation called ubiquitination. Unlike the addition of
phosphates, adding ubiquitin targets the cell for
t need you to answer the
following question, but think about it for class.
With all you know about the cell cycle, why is it
tant that cyclins pass information along quickly and then experience a rapid depletion?