Monday, 13 February 2012

Using simple Java Applets In Genetics Theory Lessons

Hairy Hands, the genetics of mid-digital hair
 - sex chromosomes and sex linked genes

Young people are very self-conscious, small imperfections can take on huge proportions.  Understanding the causes can often help people to accept these things, but Science can also bring hope for a cure in the future. 

Hairy Situation: Problem Page

Dear TeenHealthFX,
hey this is really embarrising for me! i have hair all over the back of my hands and on my knuckles! 
and it just looks gross is there any thing i can do to get rid of it or make it less noticable
Signed: Hairy Hands-Help
Dear Hairy Hands-Help!,
Unwanted hair is embarrassing for everyone and whether you are male or female.
It is normal to have some hair on your hands and knuckles regardless of gender.  
It is controlled (at least partly) by your genes.
Signed: TeenHealthFX
Biologists since Gregor Mendel use experiments to confirm theoretical ideas about inheritance of genes.  Sometimes the first ideas are not the whole story.  The example of mid-digital hair is a great example of how a hypothesis has been disproved in experiments and gradually improved through time.

Imagine that you are the agony aunt TeenHealthFX.  Find out all the genetics about hair on the fingers, so that you can explain the latest understanding of the genetics of mid-digital hail.  Keep notes using the worksheets on this page.  Use this information to write a reply to reassure 'Hairy Hands Help' on your magazine page.

Essential Questions
Is mid-digital hair simple genetics, caused by one gene with two alleles?
Could the genetics be more complicated, sex-linked or caused by multiple alleles?
Is there anything 'Hair Hands' can do?

Students take on the role of an agony aunt trying to find out about the genetics of mid-digital hair.
First hypotheses are not always reliable and our understanding is improved by tiral and improvement. 
The three worksheets gradually lead students to test developing ideas about the genetics, as they get more refined.  The sheets cover simple dominance, sex-linked inheritance, and then multiple alleles.

Running the Activity

By following these worksheets students will see how the theory and experiment bring about these advances in our understanding.  Students actively build ideas through experience and reflection. This is the constructivist approach.

Students complete the Essential Notes worksheet  about the inheritance of colour blindness and hemophilia as examples of sex linkage. Use your Biology text book.  Activate previous knowledge and be sure students understand the basics.

Do the three short worksheets below Resource
- which take things to the next level and include Ratios and Punnet squares.
- the simple Java applets in yellow model meiosis and random alleles producing offspring.

Complete these worksheets to learn more about the genetics of hairy hands:

  1. Human Genetics 1 - The First Sign of Madness - (Word document.)

    Use the java applet Gamete Maker - this aims to improve on picking beads from beakers by showing the actual chromosome inside each gamete.
    The letters represent the Allele for the mid-digital hair gene:
    H is dominant allele for Hair,  h is the recessive allele for no-hair
  2. Human Genetics 2 - New Evidence Casts Doubt  (Word document)
The Gamete Maker for sex-linked genes shows the alleles inside the gametes as before.  With sex-linked genes the alleles are found on the X-chromosome.  A sperm cell can contain either X or y chromosomes and the shape of the blue chromosome represents this.  The y chromosome doesn't carry the allele for mid-digital hair:  Possible alleles:   XH  Xh , or  y-
This last sheet explores a third explanation, which suggests five alleles, multiple alleles which control the number of fingers which the hair grows on.
Resources - Web 2.0
Only the two java applets above are required.

Technician preparation list. 
Hand lenses - could be useful for looking at hair on fingers.
No other special requirements for this activity.

Aims to consolidate student understanding of punnet squares, phenotype ratios and the scientific method.
The develop an understanding of sex linked genes and notation of sex linked inheritance.

Completion of the four word documents will provide evidence of understanding.
Human Genetics 3 - is intended as extension, as are the links below.
A good open eneded summative task could be to write an agony aunt reply to "Hairy hand help" explaining the latest understanding of the genetics of mid-digital hair.

Syllabus links
Topic 4 SL Genetics


Alternative Ways
As a practising teacher I know that activities work best when adapted to student interests and that these are not always the same in every school. Please add your ideas to the comments section below.

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