Basic Q's for Molecular Biology

Richard Hall rhall at
Wed Apr 14 13:05:58 EST 1999

All good questions.
Standard questions all.
You will learn much as you work them out.
Enjoy the experience.


At 3:53 PM +0000 4/14/99, Jin-wook B. Paeng wrote:
>1. Why is DNA more stable than RNA?
>2. What would happen if we put DNA duplex into pure distilled water?
>3. Why is thymine used in DNA instead of uracil?
>4. The whole E. coli genome is about 4.6 Mbp. How many copies of it
>are in 1 micro gram
>of DNA sample?
>5. Promoter is the region located at the 5' end of genes. It is
>recognized by RNA
>polymerases and the recognition is the most important step for the
>initiation of gene
>expression. If we assume there are one thousand promoters with an
>identical sequence in E.
>coli genome, what should be the minimum length of this promoter
>sequence, assuming that
>RNA polymerases recognize bases as we read alphabets?
>6. What is the average size of the DNA fragments that are obtained
>from the full digestion
>by 2 different restriction enzymes in a single reaction mixture, in
>which one is 6 base and
>the other one is 4 base recognition?
>7. The communication of information in life is done by the
>complementarity of molecules.
>Protein sequence is determined by mRNA sequence, which is in turn
>copied from DNA
>sequence. We call this flow of information from DNA to RNA to protein
>as the central
>dogma of life. RNA can easily be copied from DNA by the molecular
>complementarity since
>they use the same complementary pairs of bases. (The difference
>between uracil and thyme
>does not hinder the complementarity.) In contrast, protein has no such
>complementarity as in between DNA and RNA. Then, how can the
>information in protein
>sequence be copied from mRNA? What is the key step in this
>inter-lingual communication?
>8. Transcription is the process of making RNA from DNA. (Translation
>is making protein
>from mRNA.) Chromosomes are either closed circles (for eubacteria and
>archaebacteria) or
>very long linear strings (for eukaryotes). What would happen
>physically on these
>chromosomes while a region within them is being transcribed?
>9. What is the fundamental reason that we can only separate DNA
>fragments of about one
>thousand bases or so at the very best using the current sequencing
>10. What is the most important discovery done by James D. Watson for
>the elucidation of
>DNA structure?

Richard Hall, Associate Professor of
Comparative Animal Physiology
Division of Sciences and Mathematics
University of the Virgin Islands
St. Thomas, USVI  00802

rhall at

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