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Non- Mendelian Genetics and Chromosomal Inheritance
1. Define the nature and give an example of incomplete dominance, codominance, multiple
alleles, pleiotropy, epistasis, and polygenic inheritance. Which type of inheritance involves the
suppression of one locus over another? Which type involves more than two "gene forms" per
characteristic? Which one involves a heterozygote with an intermediate phenotype?
2. Is phenotype entirely due to the genes an organism carries? What other factors might
influence phenotype? Give and example of this.
3. What is Mendel's Law of Independent Assortment? What type of gene locus arrangement
would cause this "law" to be false? What types of ratios are seen in the F1 of a cross where
Mendel's Law fails? What does "linked genes" mean?
4. If linked genes stay together (sort together) during meiosis, why how could any offspring be
produced where the linked genes have been shuffled or switched? What process would cause
this? When in meiosis does this happen? Would the distance between the two linked genes have
any effect on the frequency of shuffling by this method?
5. How is gender (sex) determined in humans? In birds? How are autosomes different from the
sex chromosomes?
6. What chromosome combination results in Kleinfelters Syndrome? In Turner's Syndrome? In
Trisomy 21 (Down's Syndrome)? Which deviation from normal is better "tolerated" by the
human body -- extra or too few chromosomes?
7. Be able to write a sex-linked cross correctly using X and Y chromosome symbols and
superscripts. Show how to write the possible gametes, use a Punnett Square, and figure out the
genotypic and phenotypic ratios.
8. Name two different genetic diseases that are X (sex) linked. Are these diseases expressed
more often in males than females, and why is this?
9. What is a Barr Body? What types of cells have Barr Bodies. How does this explain the
different colors of fur on a female calico cat? How many Barr Bodies would a Kleinfelters man
have? A person with Turner's Syndrome?
Bios 140 Study Guide
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