Worksheet 2 for Genetics Chapter

Life Science

Worksheet #2 for CH 4 & 5

Includes “Human inheritance”, 

     “Genetic disorders”, and “Advances in Genetics”

• 1. How are sex chromosomes different than other chromosomes?

Sex chromosomes (X and Y) do not have a partner chromosome unless they are both X's

• 2. Describe what a sex-linked trait is?  Also, give an example of one.

Sex-linked traits are the traits that are found on the X and Y chromosomes.  The X can carry many more alleles than the Y can.  The Y is considerably smaller.

• 3. How does understanding how sex-linked traits work explain why men are more likely to be color blind? Explain it using this diagram...

Since the Y chromosome is so small, it does not carry very many alleles.  For example: the X chromosome carries the trait Colorblindness.  The Y chromosome carries no information about colorblindness.  Since Boys are XY, if their X has colorblindness and their Y says nothing about colorblindness... the boy is colorblind.  If a girl is XX and one of the X's is colorblind and the other is not... then she is not colorblind.  The girl would have to have both X's contain the allele for Colorblindness in order for the girl to be colorblind.  THEREFORE: boys are more likely to be colorblind than girls.

• 4. Where do we get our chromosomes from?

half of our 46 from mom and half from dad

• 5. Choose one genetic disorder.  Explain its cause and how it affects the person with the disorder

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DOWN SYNDROME

1. cause:  3 copies of Chromosome #21 instead of two copies

1. affect on the person: small mouth, heart problems, mental disabilities, short neck...

• 6. Name one benefit of understanding genetics.

We can predict the next generation with some accuracy.

We can identify genetic abnormalities within families and make responsible choices for future.

We may someday be able to treat genetic disorders.

We can breed improved crops and livestock.

• 7. Choose 2 of the following and explain how these are being used today as well as their benefits: 

1. Selective breeding-  featherless chickens have been bread in order to allow them to survive in tropical climates and provide protein to the people living there
2. Cloning -  we may some day be able to help endangered species to survive by providing more organisms for reproduction.    Click here for our video from class
3. Genetic engineering -  We can alter crops to make them produce more food or be resistant to more insects/diseases.  This allows more people to be fed.

• 8. Name 2 possible problems that could be caused from misusing our knowledge of genetics.  Avoid extreme examples like mutant teachers with three heads.

People may create a group of clones who they will not allow the same human rights that we give to other humans.  They may be second class citizens.

Clones could be used for harvesting organs.

Dangerous animals may be cloned and introduced into an environment which is not prepared for them and ecosystems could be severely altered.