Dr. Reichler’s Bio 301L   MWF 11am-noon    Print Name:_________KEY____________
Exam #1   February 16, 2007

    Read each question carefully and don’t hesitate to ask if a question seems unclear.  If possible, answer each question in the space provided, but if needed, continue on the back.  If you use a drawing as part of your answer, be sure to also include a written explanation. These questions have specific answers, although for some, more than one answer is possible.  To receive full credit you must clearly and fully answer the question being asked.  This exam is worth 103 points with the points for each question noted in parentheses.

1. Using rules one and two of Strong Inference answer the following question:  Who are people in the Middle East most closely related to? (8pts)
Should propose at least two hypotheses and one experiment to eliminate the hypotheses.  For example:  Hypos- Middle Easterners are most closely related to Europeans.  Middle Easterners are most closely related to Asians.  Middle Easterners are most closely related to Africans.  Expt- Compare the mtDNA of people from these regions and see who has the fewest differences with Middle Easterners.

2. You read a report stating that someone’s sense of humor is genetically determined.  The researchers only tested twins that lived apart.  Did these researchers use Strong Inference?  Why or why not? (6pts)
No.  Because they did not try to disprove any hypothesis, they only have data from twins in different environments.  OR  They did not get reliable results because they have no controls.  OR  They only had a single hypothesis.

3. Both ionic bonds and covalent bonds can lead to atoms with positive and negative charges.  What is different about the formation of charged atoms in ionic and covalent bonds? (6pts)
Ionic bonds involve the donation or acceptance of electrons leading to charged atoms (ions).  Covalent bonds involve sharing of electrons, but the sharing can be unequal leading to charged atoms.

4. Describe how all four bimolecules are involved in determining ABO blood type. (8pts)
Nucleotides/DNA code for proteins (amino acids) that give rise to the different carbohydrates (sugars) on the membrane (lipids) of the RBC.

5. Below is a cartoon of a protein embedded in a membrane.  The protein has both polar and non-polar amino acids.  Show where the polar and non-polar amino acids are located, and explain why they are located where you indicated. (6pts)
Polar amino acids on the outside near the polar water and polar heads of the lipids.  Non-polar amino acids on the inside near the non-polar tails of the lipids.

6. What would be the effect on a protein if three nucleotides were added to the coding region of the gene? (8pts)
There would be an additional amino acid.

7. Relate the Y chromosome to two of the perspectives about genes. (8pts)
Any two of:
Y chromosome has genes that code for proteins that cause maleness.
Y chromosome does not have the same genes as the X chromosomes, and therefore males are more likely to suffer from defects (diseases) on the X chromosome.
The Y chromosome is inherited from dad.
Genes on the Y chromosome change the development of the fetus from female to male.

8. If a haploid cell replicates its DNA, is it now diploid?  Why or why not? (6pts)
No.  The DNA is an exact copy, so there are not pairs of similar information.  The DNA is identical, not diploid.

9. Identical twins should have identical DNA.  If one of the twins has a viral infection, how could this viral infection cause a difference between the twins’ DNA? (8pts)
The virus could have entered the lysogenic cycle in which it inserted its DNA into the host cell’s DNA.

10. Would vole monogamy be explained as having a more genetic or environmental cause?  Why? (8pts)
Genetic- different levels of the oxytocin/vasopressin receptor, which is coded for by a gene, can explain differences in prairie and montane vole monogamous behavior.  But these differences arose from the different species evolving in different environments with different availability of resources.

11. Give two possible genotypes of parents that could lead to offspring with AB blood type. (8pts)
Any two of:  AA x BB, AO x BO, AO x BB, AO x BO…

12. If a male is colorblind, a recessive allele on the X chromosome, does that tell us about his father’s or mother’s DNA?  Why? (8pts)
Males inherit their X chromosome from mom, so male X linked traits tell us about mom’s DNA.

13. Why do you have more of your mom’s DNA than your dad’s DNA? (6pts)
MtDNA is inherited only through the egg.  OR  Males have a small Y chromosome from Dad and a larger X chromosome from mom.

14. When researchers compared individual’s mitochondrial DNA, they found people from different geographic locations with similar mitochondrial DNA sequences.  What does this indicate about our ancestors’ behavior? (6pts)
They must have commonly migrated.  The spread of different DNA throughout the planet shows this pattern of ancient migration.


Bonus:  Over the same period of time, why would the number of mutations present in nuclear DNA be higher than in mitochondrial DNA?  (3 pts)
Because the nuclear DNA has more non-coding DNA.  Mutations in coding regions are typically fatal, and therefore not passed on.  So since mtDNA has very little non-coding DNA, the number of mutations for a given time that gets successfully passed on would be lower.