Wednesday, January 26, 2011

How Will Genetic Tests Determine Who We Are, and What We'll Do, Now and in the Future?

Do Now Punnett Squares

Please answer these following questions on the blank worksheets distributed last week.

Question #1:

In pea plants, yellow peas are dominant over green peas.

Use a Punnett square to predict the genetic outcome (offspring) of a cross between two plants for yellow peas that yield a small amount of green peas.

Question #2:

The long hair of persian cats is recessive to the short hair of siamese cats. Complete a Punnett Square when a a purebred persian is mated with a purebred siamese cat.

Question #3:

The black coat of persian cat is dominant to the brown and tan coat of siamese. Complete a Punnett Square when a a purebred black persian is mated with a purebred brown siamese cat.

Question #4:

In four o'clock flowers, red plants are purebred for the dominant allele (R) of the gene for flower color. Plants with white flowers are purebred for the recessive (r) allele of the same gene. Plants with pink flowers have one of each of the two alleles. Complete a Punnett square that is expected when plants with pink flowers are intercrossed.

Question #5:

In humans, brown eyes (B) are dominant over blue (b). A brown-eyed man marries a blue-eyed woman and they have three children, two of whom are brown-eyed and one of whom is blue-eyed. Draw the Punnett square that illustrates this marriage.
Suppose one of the brown-eyed children marries someone with blue eyes. Use the second Punnett square to predict their offspring.

And here are some good Punnett practice problem sites. In fact, the problems above (and likely the questions on the midterm) come from these sites.

The Association for Biology Laboratory Education has a really good .pdf handout on the step by step procedure to solving Punnett square problems. eMINTS has a good list of Punnett square sites. And here is my own list:
If you're daring, try the challenging Berkeley University problems ( the answers are here)

So practice, practice, practice... Bring any problems you have difficulty with to class, and we'll work them out together.

Genetic Diseases

You got married last year, and now you're going to be a parent in six months! You went to your obstetrician for an amniocentisis, and just got the results: the fetus has some genetic defects on Chromosome 7, making it least 50% likely that your child will have Autism. Further, Williams syndrome is likely, as defects on the CLIP2 gene have been observed. That's a lot of ATCGs...


The table below lists everybody's genetic research assignments. Please fill out the forms distributed in class during the midterm to organize your research. Go to the Genetics Home Reference website to do your research. The following steps will help guide you through the research:

  • Click on the Genetic Diseases box
  • Either look for the name alphabetically, or by the body system the disease affects
  • Once you have identified a specific genetic disease, click on one of the gene abbreviations (MLH1, etc.) to go to the specific gene related to the disease.
  • This will take you to a webpage listing specific information on that particular genetic defect. You can fill out your worksheet from this page.
For example,

cystic fibrosis CFTR 7q31.2


Let's practice tracking Hurricane Hanna, using a Hurricane tracking sheet.

Urban Ecosystems

Consider the "Tree of Heaven," ("ToH"). It serves as an anchor in many urban ecosystems. I'm sure you have all seen it, walking down Brooklyn's sidewalks, seeing it sprout up from the cracks. It is categorized as part of the "Quassia" family, Sue Sweeney claims that it is as much a "part of the urban landscape as the Norway rat, the cockroach, and the feral cat. Many urban wildlife lovers agree. Extensive procedures have been developed to control its growth. Its pharmaceutical effects on incurable diseases has also been researched. Its effects on the urban landscape have also been examined in Europe.

Use the links to answer the questions on the worksheet provided in class. We will share out the results of our research in about 45 minutes.

The Law of Unintended Consequences

Causeway Street

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