Dr. Reichler’s Bio 301L   MWF 9-10am    Print Name:_____________KEY_____________
Exam #1   September 26, 2005

    Read each question carefully and don’t hesitate to ask if a question seems unclear.  Answer each question in the space provided, and 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. When designing an experiment using the rules of Strong Inference, what is the goal of the experiment?  (8 pts)
To disprove one or more hypotheses.

2. Describe one process that involves DNA that would be part of defining a cell as living.  (8 pts)
Any one of:
DNA has information passed on during reproduction.  Changes in DNA are involved in evolution.  DNA is used to make proteins that help the cell respond to the environment and/or are used to do metabolism.  Proteins from derived from DNA organize the cell/organism.  

3. If today there are 100 radioactive carbon 14 atoms (half-life 5,730 years), and after 5,730 years there are 50 carbon 14 atoms and 50 nitrogen atoms.  A) Where did the nitrogen atoms come from?  B) How many nitrogen atoms will there be after another 5,730 years (11,460 total years)?  (4 pts)
A)  as carbon-14 decays a neutron releases an electron becoming a proton changing the element from carbon to nitrogen.
B)  75

4. Lithium chloride is held together by an ionic bond, with lithium positively charged and chloride negatively charged.  Lithium has three protons.  How many electrons does it normally have, and how many electrons does it have when it forms the ionic bond in lithium chloride?  (4 pts)
Normally 3, in LICl 2

5. Describe the function of two different biomolecules that can be found in the nucleus of a cell.  (8 pts)
Any two of:
Nucleotides- DNA and RNA- contain information for gene expression.
Sugars- as part of DNA/RNA.
Lipids- as nuclear membrane.
Proteins-(any one of:) package DNA, enzymes like RNA polymerase, nuclear cytoskeleton.

6. Heart muscles respond to the hormone epinephrine by contracting, while muscles controlling blood flow relax in response to epinephrine.  Based on this information, would you expect the cells in these two muscles to be expressing the same or different genes?  Explain.  (8 pts)
Different genes.  The presence of different effectors, or receptors, lead to different responses from the same signal.

7. If you knew the amino acid sequence of a protein, would you know the exact sequence of the mRNA for this protein?  Why or why not?  (6 pts)
No, because of the redundancy of the genetic code, most amino acids are coded by multiple codons.

8. Give two reasons that the sequence of an mRNA is different from the DNA from which it is transcribed.  (8 pts)
Any two of:
Addition of cap and tail.  Deletion of introns.  RNA has U DNA has T.  The RNA sequence is complementary to the DNA.

9. If human love follows the model we discussed for voles, could you get an unfaithful lover to become faithful by injecting them with oxytocin?  Why or why not?  (6 pts)
No, the difference in monogamy stems from different quantities of receptors not different amounts of hormone.  Adding extra hormone to someone with few receptors will not change behavior.

10. If researchers showed that there is a high correlation in extent of gum chewing between adopted children and their adoptive families, would this infer a genetic or environmental basis for gum chewing?  Explain.  (8 pts)
Environmental, because adoptive children and their families are not genetically related the similarities would likely come from their shared environment.

11. If three consecutive nucleotides in the coding region of a gene were deleted, what specific change would occur in the protein?  (8 pts)
Either:  It would be missing one amino acid  OR  It would have two incorrect amino acids, but the rest would be correct.

12. How can a change in DNA cause a cell to lose the ability to perceive an environmental stimulus?  (8 pts)
If the receptor is not made, no perception can take place.

13. In what case would transcription take place but not translation?  (8 pts)
When the final product is RNA, as in rRNA or tRNA.

14. You are studying Casitermino, a protein found in the cell membrane.  Apply rules 1 and 2 of Strong Inference (the parts prior to actually doing any experiments) to answer the following question:  What is the function of Casitermino?  (8 pts)
Make multiple hypotheses and at least one experiment to disprove the hypotheses.  Example:  Casitermino is a transport protein.  Casitermino is an enzyme.  Delete Casitermino and see what activity the cell loses.

Bonus:  What is BDNF and what is its relevance to differences in human personality?  (3 pts)
BDNF is a neuron growth factor.  Depending on what version of the gene you have correlates with neuroticism.