Download Name: Date: Period: Part I. The Lac Operon. Follow this link: http:

Name:________________________________ Date:_______________ Period:______________
Part I. The Lac Operon. Follow this link: http://phet.colorado.edu/en/simulation/gene-machine-lacoperon. Now press the green “Run Now!” button. Follow the instructions to open the java applet.
Once you have this open, answer the questions below with as much detail as possible. Recall that the
purpose of this worksheet is not to get quick, right answers but to comprehend what you are
visualizing.
Why do genes require promoters?
What is the purpose of an operator?
Drag the lac promoter to the stretch of DNA. Do NOT drag the lacZ gene to the DNA. What happens?
Why is this?
Now try dragging the lacZ gene to the DNA and note what happens.
Why do the proteins disappear over time?
Inject some lactose (about 25 molecules should do it) into the simulation. Note what happens.
Specifically, what is lactose being converted into?
Note that the lac enzyme continues to be produced even in the absence of lactose. Why is this a
problem? Try dragging the lac operator gene onto the stretch of DNA. What is the result?
Now try adding the lacI promoter and gene to the stretch of DNA. What happens?
Again, add some lactose (and again, 25 molecules should work well) into the simulation. What is the
INITIAL result of adding lactose when both genes are activated?
Do not add any more lactose and watch what transpires. Note what happens and why this occurs. How
could you re-activate the lacZ gene?
How was the lacZ gene turned off in the first place?
Now try the lactose transport tab and insert all of the promoters and genes. Add some lactose and
watch to see what transpires. What is the role of the lacY gene? How does this help the system?
Part II. Hox genes. Visit this website: http://www.dnaftb.org/37/index.html. Now read through the
concept tab. Once completed click on the animation tab and begin answering the questions below.
Recall that the purpose of this worksheet is not to get quick, right answers but to comprehend what
you are visualizing.
What are the stages of fruit fly development (you may want to draw them)?
What does the simulation mean by polarity?
Quickly sketch an embryo then label and define anterior, dorsal, ventral and posterior.
How do embryos use proteins to identify the different sections?
What is a "gap" gene?
What is a pair-rule gene?
Why is it likely that ancestors of fruit flies had 2 pair of wings? What gene causes them to have only one
pair of wings?
What are halteres?
What are hox genes? What might occur if a hox gene mutated?
Describe each of the following mutant flies (you may want to draw them):
kruppel mutant
fushi tarazu mutant
Ubx mutant
Antp mutant
Go to the tab labeled problem and complete the following questions.
What will happen to an embryo that doesn't have BICOID protein?
What will happen if BICOID is overexpressed?
What kind of gene is HAIRY?
What kind of gene is EYELESS?
Read http://www.newscientist.com/blogs/shortsharpscience/2011/08/treehoppers-put-obsoletegenet.html then answer the following question.
In your own words, describe how the treehoppers got their unique helmets.
Part III. Go to the following website: http://learn.genetics.utah.edu/content/epigenetics/. Click on
“The Epigenome at a Glance” link then watch the video and complete the following questions.
The epigenome is a second layer of structure, what does it consist of?
How do you know when a gene is inactive?
What is the purpose of relaxing active genes?
How is the epigenome flexible?
Now press back. Click on “Gene Control” then read the information, play with the interactive and
answer the following questions.
What is GFP and what is its purpose during this experiment?
Describe what happens at the protein, mRNA and gene level when you add AdoMet to your DNA.
Describe what happens at the protein, mRNA and gene level when you add Valproic Acid to your DNA.
How does cancer get started?
Describe how methylation affects cancer cell growth.
Now press back. Click on “Epigenetics & Inheritance” then read the information and answer the
following questions.
Does inheritance only happen through DNA? If not, what else does inheritance happen through and
how?
What is reprogramming? Does reprogramming affect all genes the same?
What are some major challenges to proving epigenetic inheritance?
What are some implications for evolution?
Now press back. Click on “Lick your rats” then read the information, play with the interactive (click go
under “what kind of mother are you”) and answer the following questions.
Can nurturing behavior of a parent affect the epigenome of their offspring?
What is the GR gene?
Use the rat licking simulation (told you, you would lick rats today!) and note what happens below. Try to
get three different responses and identify what is happening to the GR gene for each one.
In mice, is neglect that causes anxious behavior a bad thing? Why or why not?
Are epigenetic patterns permanent?