Dr. Reichlerıs Bio 325          TTh 12:30-2pm           Print Name:________KEY________________

Exam #3   April 13, 2004


            Answer each question as succinctly as possible in the space provided.  If needed, continue on the back.  If you use a drawing as part of your answer, be sure to also include a written explanation.  Read each question carefully and donıt hesitate to ask if a question seems unclear.  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.  Each question is worth 6 pts, unless otherwise noted, for a total of 103 points possible for this exam.


1.     Do large quantities of DNA indicate an organism with many genes?  Why or why not?  (4pts)

No, organisms have various amounts of non-gene DNA so DNA quantity is not necessarily indicative of gene quantity.



2.     We have previously discussed that microRNA is coded for by DNA with complementary base pairs across a single strand, so that the microRNA is initially produced as a double-stranded RNA.  Because microRNAs are so small, many regions of a cellıs DNA might fit this pattern.  If you found a DNA sequence with complementation across a single strand, how would you know if it was really a microRNA or not?

Test whether the proposed microRNA is expressed or not.



3.     DNA polymerase is a gene family in mammals.  Some members of this gene family are constantly expressed while others are expressed at specific times.  What explains the different expression patterns of the various members of the DNA polymerase gene family?

Some DNA polymerases are expressed only during replication, others constantly to help in DNA repair.



4.     Why would genetic engineering of male mitochondrial DNA create a trait that could not be successfully passed on to future generations?

Only female mitochondrial DNA is passed on.  Sperm do not provide any mitochondrial DNA to offspring.



5.     If you wanted to express a human antibody in bacteria, what human cells would you use as your source material, why would you use these cells, and what technique would you use to prepare the human gene for expression in bacteria?

B-cells.  B-cells express the antibody mRNA, which is needed for use with reverse transcriptase to make cDNA, the coding region without introns.



6.     What role do restriction enzymes play during genetic engineering of bacteria, and what special characteristic of restriction enzymes makes inserting a gene into bacteria easier?

Restriction enzymes are used to cut the plasmid and the gene of interest.  If the restriction enzymes cut unequally leaving sticky ends/overhangs, then ligating the gene of interest and the plasmid will be much easier due to the base pairing of the complementary sticky ends?



7.     You are trying to insert a gene into a plasmid, but the plasmid you are using does not have the lacZ gene.  How might you check whether the gene had been successfully inserted into the plasmid?

Use PCR, design specific primers for the inserted gene.  If it amplifies,the gene is present.



8.     With the planting of more genetically modified crops, what will be the effect on the use of herbicides in agriculture?  Why?

Any of:  They will increase, most genetically modified crops are herbicide resistant so the use of herbicides may increase.  They will decrease, use of herbicide resistant crops will allow farmers to treat their crops more selectively and therefore use less herbicides.



9.     During DNA replication, what is happening to the hydrogen bonds and covalent bonds on both the original (template) and new DNA strand?

Original: hydrogen bonds broken, covalent bonds unchanged.  New:  hydrogen bonds made, covalent bonds formed.



10.  If primase were not functioning, what would be the effect on DNA replication?  What would and would not occur?

Would- unwinding of DNA.  Would not- everything else; no copying by DNA polymerase etc.



11.  What information could be inferred from where in an adult human body telomerase was expressed?

Any of:  this is an area of constant DNA replication/ cell division; gametes are being produced, skin cells or stomach lining, cancer



12.  Why is it important to have some non-gene DNA at the ends of chromosomes?

So that during DNA replication, when some DNA is lost, genes are not damaged.



13.  How would a disease that left an individual healthy, but sterile, affect that individuals evolutionary success?

Evolution relies on reproduction.  Without ability to reproduce, no evolutionary success.



14.  What technological advances have allowed researchers to differentiate between social and sexual monogamy?

DNA fingerprinting/RFLPs/DNA sequencing.  The ability to determine paternity/maternity of offspring.



15.  Why does sterilizing males seldom work as effective pest control?

The females will mate with other males.



16.  Why is social monogamy more common in birds than in mammals?

In birds the external development of the eggs means it is often best for both parents to assist in incubating/feeding eggs/offspring.  Mammalian females can solely  support the offspring during gestation and after birth due to internal development and lactation.



17.  If an advantage of sexual reproduction is increased genetic diversity, how might females increase the genetic diversity of their offspring?

By mating with multiple males.




Bonus:  As stated in chapter 2 of ³The Myth of Monogamy², what does testicle size tell us about monogamy?  (3pts)

Larger testicles are correlated with less monogamy.  Multiple partners means that male sperm must compete to fertilize the egg(s).  Larger testicles can produce more sperm giving a reproductive advantage in non-monogamous situations.