Sorry if this question has been asked in the past, I am studying Bio in
college and had a question I cannot find an answer for.
As I understand it, DNA is 'unzipped' by protiens to make RNA which is then
used to execute the production of some other needed protien etc. I know
that the nucleotides occur in some given order as determined by the organism
which is not the same order for any other organism (DNA fingerprint). I
also know that the nucleotide sequence on one strand has a complementary
sequence on the other starnd of the 2x helix. Since that complementary
sequence can also occur on the first strand, which starnd of the 2x helix is
used to access the info for the process? Given the possibility, I guess,
that either strand could be used, the nucleotide sequences don't necessarily
mirror each other, so how is it that the 'correct' strand of the helix is
I hope this question is clear enough to be understood, any help would be
On Mon, 18 Oct 2004 22:49:50 -0700, "Brandon" <[Only registered users see links. ]>
The word is protein.
The RNA polymerase, the enzyme that makes the RNA copy, recognizes
start sites, which are on the correct strand. Look up "promoter". In
bacteria, it is fairly simple. In higher organisms, it is more
complex, but the same end result.
Right, I have read about the promoter, but I am hung up on the part where
there is only one codon for the start code. So how is it that the
polymerase gets the correct strand given that the same codon is in multiple
locations? Does it already "know" what the base sequence is going to look
like and there fore skips over obviously incorrect base sequences, or are
the codons different on DNA than they are on RNA, resulting in more variety
of start and stop codons than just start= AUG, Stop = UAA,UAG,UGA as in RNA?
"Larry Farrell" <[Only registered users see links. ]> wrote in message
In fact it is not, at least not so far as we have been taught. This class
is an examination in topics of biology and the prof. is an entomologist to a
microbiologist. The answers received for the questions asked are adequate
only for the purpose of exams in the class and the level of understanding
necessary to pass, not for the more literal understanding that I am looking
for. Otherwise I would not have posted the question here.
On Wed, 20 Oct 2004 10:59:33 -0700, "Brandon" <[Only registered users see links. ]>
The promoter and the start codon are unrelated. The former is the
recognition site for starting RNA synthesis; the latter is the start
site for protein synthesis (and is basically irrelevant to RNA
synthesis, thus is irrelevant to what you are asking).
The promoter is long enough to adequately deal with the problem. That
is, you have properly described the problem. Not surprisingly, biology
has figured it out. The promoter is asymmetric, and is long
enough/rare enough that (most) transcription only starts in the right
Once an mRNA has been made, a simple model is that translation then
starts at the first start codon. Actually, in the real world it is
more complex than that, but that is a simple idea to start with.
Do you have any molecular biology or microbiology book?
Thanks, that is helpfull in clearing up some of my problems. Unfortunately,
this is just a "topics" class and not one that goes into the sort of detail
that I would like to see in a science class. So I have neither a molecular
biology or microbiology book. I must say though, that the class has my
interest peaked. I hadn't considered biology as a major since highschool,
but have considered it since starting this class. (currently working toward
a business degree)
I was the one who sent the short, rather snippy, reply to your first
post directing you to look in your book or ask your instructor. The
reason for that reply is that the newsgroup gets lots of questions from
student that essentially ask those who read the group to do assigned
homework for the student, and your post came across very much that way.
Your posts since then have clarified the situation and I think a more
reasonable response is in order.
I will again direct you to a book for in depth coverage of this issue,
but this time not your text. Go to the library and get either a
microbiology book or a molecular biology book, preferably an
introductory text in either case, and start digging. It really isn't
possible to explain all of the ins and outs of transcription in a short
message in a newsgroup, and pictures are *really* helpful. After some
reading there, and reaching a provisional understanding of the
processes, come back and ask specific questions, which can be easily
It seems really strange to me that any college/university would offer a
course in which topics such as molecular processes would be discussed
without the instructor being to provide some useful information. I must
also admit that it seems strange that any biologist, no matter what
their specialty, would not have some understanding of basic molecular
processes (but that comments comes from a perspective of 32 years of
university teaching in Microbiology so it probably is biased).
This is being posted in the newsgroup because I tried to send it
directly to your e-mail address as above and got it bounced back as
undeliverable because the account had been discontinued or disabled.
You might want to check on that issue.
Larry D. Farrell, Ph.D.
Professor of Microbiology
Idaho State University
On Tue, 26 Oct 2004 23:43:33 -0700, "Brandon" <[Only registered users see links. ]>
Ok. Many biology books, including those used for "biol 1" deal with
this at some level.
A book I might suggest...
D P Clark & L D Russell, Molecular Biology made simple and fun, 2/e.
Cache River Press, 2000. ISBN
1889899046. This book is intended for both a general audience and a
wide range of science students. It presents the basics
of molecular biology in a way that is readable and fun, yet
scientifically quite sound. It may be helpful as an introduction for
some students. Others will just find it fun.
For a brief preview of the book, check their web site: [Only registered users see links. ]
It is an inexpensive paperback (about $35 I think), available mainly
thru them directly. It is readable by high school kids or your mother.
So it would not be a big investment to get it, and you could easily
find a good home for it when/if done. Could be a good place to start,
if you would like to do some reading on your own.
And by the way, there is much need for people who combine business and
biology. The biotech industry has been one of the great booms of the
last couple of decades, with -- presumbaly -- much more to come.