Analogies are often effective strategies for communicating complex materials and concepts. In BCHM 100 we have already encountered at least two analogies, DNA as a “blueprint for life” and as a “recipe for life”. Although we argued in class that the recipe analogy is superior and that the blueprint analogy has some flaws (there is no picture of you in the nucleus of your cells), even the flawed analogy of the blueprint has some value. For example, it does at some level communicate that like the information in DNA, a blueprint contains the information needed to construct a building to those who are competent to interpret them.

The in-class components of this assignment are as follows:

1)      Form groups of 3 people.

2)      Identify as a group the essential components (things, actions, etc.) that need to be “analogized” to describe PKU.  If you are unsure of some aspects of the topic, please ask for clarification!

3)      Decide which of the following would form the best basis for an analogy for PKU:

a)      water/pipe/bucket

b)      cars/highway

c)       key/lock

4)      Using the specific focus of the analogy that you have chosen, develop an analogy that explains as much of PKU as possible and as clearly as possible. You are free to invoke as many other items or details as you wish so long as you base your analogy around the specific focus you have been assigned. Remember that an analogy is meant to be simpler and easier to understand than the original concept, not more difficult!

5)      Be ready to present your analogy to another group and defend why the basis you chose is the best one to describe PKU.

6)      Critique another group’s analogy by describing 3 strengths and 3 weaknesses of their analogy.


The homework assignment is to create a new analogy to explain PKU that does not use any of the items discussed in class. Describe this analogy as outlined below using a typed response of no more than two pages, single spaced in 11 point font. Each individual in class should generate their own independent analogy for this homework assignment (no groups).


1)      Describe your analogy in the same amount of detail as would be required to explain PKU to someone who has little background in biochemistry.

2)      Provide a list that explains how each item or action in your analogy corresponds to an item or action in the assigned topic.

3)      Discuss strengths and weaknesses of your analogy.


Each part is worth 5 points.

1.   Analogy quality

a.    Does the analogy reasonably accurately describe what happens ina

person with PKU? 

b.   Have the important points of PKU been captured by the analogy?If

not, were they discussed as weaknesses of the analogy? 

c.    Is the analogy easy to understand? 

d.   Is the analogy explained at sufficient depth such that someone with

little background in biochemistry could understandit? 

e.    Are therefactual inaccuracies?


2.   List of analogy components 


a.    Phenylalanine

b.   Phenylalanine hydroxylase

c.    Phenylalanine hydroxylationto tyrosine

d.   PKU / defective phenylalanine hydroxylase

e.    Phenylpyruvate

f.    Phenylalanine aminotransferase

g.    Pyruvate

h.   Phenylpyruvate blocking pyruvate transporter

i.     Production of ATP

j.    Mitochondria


3.   Discussion of strengths and weaknesses

a.    Have the weaknesses of the analogy been identified and discussed?

b.   Have the strengths of the analogybeen identified and discussed?


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