To Read:

Meselson and Stahl

Illustration of Mitosis and Meosis

Pages 1-9 of In Depth Meosis and Mitosis (229-237)


Online Video:

Video on Meselson and Stahl:


Cyclins and CDK:

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:



Dispersive Replication








Sister Chromatids


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,

and then

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

  1. coli

and separating out the DNA for examination. We have

discussed using the right model organisms for the each experiment. Why was

  1. coli

a good

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

and Crick

(And Franklin)

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

s folder.

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



I don

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?



Last Updated on January 19, 2018