DNA

Pages which contain `DNA':

module not yet titled
electrophoresis of DNA and proteins
the Sanger method of DNA sequencing
LINKAGE MAPPING
In humans, 1 cM is roughly 1 million nucleotide pairs (bp) of DNA.
The future of genetic research
year the idea of defining an organism by the sequence of its DNA bases
Large Molecules
Diagram Structure of DNA and RNA
DNA Structure
Control of the Cell Cycle
DNA together with associated proteins. This process of doubling the
The period during which DNA replication occurs is not spread
DNA replication is accomplished during a discrete window of time, termed
hours, during which time the entire complement of chromosomal DNA is
completion of DNA synthesis and chromosomal replication in S phase,
Use of DNA in Identification
Use of DNA in Identification
Use of DNA in Identification
Dr. Eric S. Lander at the "Winding Your Way through DNA" symposium,
in DNA coding among human beings. . . .
in this audience who has the same DNA sequence as anyone else.
And indeed, your DNA sequence is unique amongst all DNA sequences of
someone who has the same DNA sequence. But apart from that, your DNA
DNA sequence behind here in some form in some biological tissue, in
Thus is born the notion of DNA identification. And it was quickly
realized that this DNA identification would be especially useful in
until it was possible to read DNA.
DNA gives us rich results, and just as detailed as a fingerprint, in
out a DNA text in its entirety. It would be a wonderful thing if we
we do DNA comparisons, we can't read all three billion letters. What is
By taking that DNA and cutting it with an enzyme that recognizes a
radioactive DNA from this region, one can visualize bands
site, and the next site, and compare it to the DNA patterns taken from
If Suspect #1 has a different DNA pattern than the evidence, the
relates to the crime. But that evidence sample of DNA cannot possibly
Suspect #2's DNA corresponds perfectly at each of the four places of
Those are simply the ideas underlying DNA fingerprinting, as it's
popularly called, or DNA typing or DNA identification,as we prefer to
call it. Within five years of the notion of DNA spelling differences
Selmar, Lifecodes, and others, which grew up to provide DNA typing
DNA typing lab in the Hoover Building in Washington. There were dramatic
ad). "DNA Fingerprinting Links the Criminal to the Crime," with the
typically, about mistaken identity being the problem, because DNA from
immediately upon DNA testing. Many rapists, because of this, now
In essence, DNA evidence is rapidly becoming, in principle, an
done right. Fights erupt over DNA fingerprinting
well-regulated the practice is. For example, DNA fingerprints should
of a DNA fingerprint, which was used in a criminal case in New York.
good. It was the first case in which DNA fingerprinting was actually
of the different DNA patterns of different genes vary across the
Similar things are known for other types of DNA differences. And so
gestation, of an NRC report called, "DNA Technology in Forensic Science."
for the laboratory practice of someone who will create a DNA fingerprint
creating national databases of everyone's DNA type. That way, when a
segment sample and get its DNA pattern, and compare it to a database of
everyone's DNA pattern and find out whose it was. There are many people
is a marvelous technology to amplify DNA. It allows you to take a
specific region of DNA on the chromosome, and by using little black
in principle it is possible to start from the DNA of a single cell and
get enough DNA to analyze it. That makes it possible not just to
could get one microgram, one millionth of a microgram of DNA, or semen
standard techniques, but in fact even shed hair has enough DNA at its
root. A urine sample, saliva sample, will have enough DNA in most
DNA to trace from the seal of the envelope.
sneeze on something, my DNA is there, too. And so there is tremendous
at times kidnapped and blindfolded from the streets of Buenos Aires,
markers, but this was not terribly powerful in these cases. DNA
powerful, unique sequences of DNA would be needed. And so Dr. King's
group turned to looking at a particular bit of DNA called the
mitochondria DNA. It exists in a little organelle - a little package
outside the nucleus of the cell. It's a small bit of DNA, and what's
read snippets of unique, variable sequence mitochondrial DNA, I can
kidnapped by the military. She was tortured and eventually released.
the courts do DNA testing. Mitochondrial DNA sequences were obtained
Let me also mention to you two other applications of DNA identification
but plants as well. One of the great uses of DNA fingerprinting turns
in fact, now you can do DNA fingerprinting on corn plants, and many
large seed companies routinely maintain databases of the DNA
And then, very briefly, the ultimate in DNA paternity testing. As I
York Times a story about DNA taken from a 40-million-year-old termite,
preserved in amber. And DNA sequencing by PCR has been done on this
DNA paternity testing way back, it brings us to our common origins as
consequences. No one sets out to develop DNA identification, the
looking at DNA spelling differences for the purpose of criminology
DNA spelling differences has had consequences in all of these areas.
Excerpted from the "Winding Your Way through DNA" symposium
An Interview with DNA Forensics Authority Dr. Bruce Weir
An Interview with DNA Forensics Authority Dr. Bruce Weir
An Interview with DNA Forensics Authority Dr. Bruce Weir
The term "DNA fingerprinting" was coined by British geneticist Alec
Jeffreys only ten years ago. Since that time, DNA forensics has become
an important tool in law enforcement. In some cases, the DNA tests have
cases have put the spotlight on DNA forensics and created the impression
controversies surrounding DNA evidence.
mean when we say DNA fingerprinting?
A: DNA fingerprinting, or DNA profiling, as I prefer to
call it, characterizes a small portion of our DNA. It is a way of
identifying the DNA content of an individual. We think of fingerprints
identical twins have different fingerprints. In contrast, DNA typing,
because it uses a very small fraction of the DNA, is certainly not
involved. It is also possible to extract DNA from exotic things like
they may obtain DNA samples from a skeleton.
crime scene be commingled with all kinds of other DNA from bacteria,
flora, etc.? How is this extraneous DNA excluded?
A: The methods used in forensic DNA are not so much
concerned with excluding extraneous DNA as with the identification of
human DNA. The probes used are very specific for human DNA.
forensic DNA testing. Are the laboratories using PCR to look at
the RFLP method is that it requires a relatively large amount of DNA
techniques offer the advantage of requiring only trace amounts of DNA,
frequency of the pattern, we rely on a statistical model. A DNA profile
would not overstate the strength of the evidence. The DNA databases
laboratory work would be the weak link in the chain of DNA forensics?
to confirm conclusions, etc. One criticism of forensic DNA profiling as
techniques in DNA profiling. Is one RFLP the same as the next? What
specificity in DNA profiling would be a combination of RFLP plus a PCR?
much debate on the validity of DNA forensics and the statistical
accuracy of DNA profiling?
about and examined the issues carefully who remain critical of DNA
module not yet titled
genomic DNA vs.cDNA
repetitive DNA in eukaryotes
Examples of Viral Replication Pathways
the recombinant DNA is replicated, it passes the viral DNA onto all of
7.01Recombinant DNA Practice Problem
7.01Recombinant DNA Practice Problem
7.01Recombinant DNA Practice Problem
When you do a ligation with a cut vector and insert DNA, there
Solutions to Recombinant DNA Practice Problem
a) So that the DNA can be replicated, so that the daughter cells will
up DNA. Ampicillin kills the un-transformed (and therefore uninteresting) ones.
d) i) If you insert DNA into the EcoRI site, it will add sequence within
Basic Virus Structure
DNA or RNA . A number of viruses contain their genetic information in RNA
instead of DNA). Viruses survive and reproduce by infecting a cell and
The DNA is injected into the bacteria through the baseplate.
Biological Macromolecules
nucleotides found in DNA and RNA
Structure and Function of Organelles
This is where the DNA is kept and RNA is transcribed. RNA is
supporting evidence. Mitochondria have their own DNA and their own
Recombinant DNA Chapter Directory
Recombinant DNA Chapter Directory
Recombinant DNA Chapter Directory
Southerns, Westerns, and Northerns: Molecular Cloning Techniques
Theory: Complementarity
Basic Definitions
Overview
Gel
Transfer to Solid
Blocking
Preparing the
Hybridization
Washing
Detecting of
Summary of Blots
Cloning a Gene By Hybridization
DNA Fingerprinting
DNA Fingerprinting in Human Health and Society
An Interview with DNA Forensics Authority Dr. Bruce Weir
Use of DNA in Identification: A talk by Eric Lander
7.012 Cloning Project: Agricultural Biotechnology
b) Using this data, design a recombinant DNA strategy to render plants
The sequence of the insert DNA has revealed 3 long open reading frames
1) Construct a plasmid library of wild-type bacterium Y DNA in
3) The only colonies to grow would contain a plasmid with insert DNA
Hypertextbook Chapters
Recombinant DNA
Lwoff's Pathways - Viral Replication
called the lytic pathway. They enter and inject a host cell with DNA,
inject their DNA into the host cell - but instead of taking over the
host cell and using it to make viruses, the injected DNA can become
the recombinant DNA is replicated, it passes the viral DNA onto all of
DNA Fingerprinting in Human Health and Society
DNA Fingerprinting in Human Health and Society
DNA Fingerprinting in Human Health and Society
during the 1930s, each person has a unique DNA fingerprint. Unlike a
altered by surgery, a DNA fingerprint is the same for every cell,
treatment. Consequently, DNA fingerprinting is rapidly becoming the
An additional application of DNA fingerprint technology is the diagnosis
The Structure of DNA
also have different DNA sequences. The more varied the organisms, the
more varied the DNA sequences. DNA fingerprinting is a very quick way
to compare the DNA sequences of any two living organisms.
Making DNA Fingerprints
DNA fingerprinting is a laboratory procedure that requires six steps:
1: Isolation of DNA.
DNA must be recovered from the cells or tissues of the body. Only a
example, the amount of DNA found at the root of one hair is usually
Special enzymes called restriction enzymes are used to cut the DNA at
bacteria, will cut DNA only when the sequence GAATTC occurs. The DNA
electrophoresis. The DNA pieces are passed through a gel made from
3: Transfer of DNA to nylon.
The distribution of DNA pieces is transferred to a nylon sheet by
pattern called the DNA fingerprint. Each probe typically sticks in only
6: DNA fingerprint.
The final DNA fingerprint is built by using several probes (5-10 or
Uses of DNA Fingerprints
DNA fingerprints are useful in several applications of human health care
DNA fingerprinting is used to diagnose inherited disorders in both
programs, genetic counselors use DNA fingerprint information to help
other programs, prospective parents use DNA fingerprint information in
depend on the information contained in DNA fingerprints. By studying
the DNA fingerprints of relatives who have a history of some particular
disorder, it is possible to identify DNA patterns associated with the
FBI and police labs around the U.S. have begun to use DNA fingerprints
hundreds of cases have been decided with the assistance of DNA
Another important use of DNA fingerprints in the court system is to
applications, DNA fingerprints bring an unprecedented, nearly perfect
Because every organ or tissue of an individual contains the same DNA
collect DNA fingerprints from all personnel for use later, in case they
are needed to identify casualties or persons missing in action. The DNA
"DNA fingerprints witness for the prosecution." Discover. June 1988, p. 44.
DNA Identity Testing Information Package. Available from LifeCodes,
Genetic Witness -- Forensic Uses of DNA Tests. U.S. Office of
module not yet titled
nucleotides in DNA and RNA
the discovery of the double helical structure of DNA
other key elements of the structure of DNA and its implications for DNA replication and RNA transcription
alternative structures of DNA
the significance of the Messelson and Stahl experiment in the determination of how DNA replicates
the enzymes involved with DNA replication, RNA transcription, and protein translation
Central Dogma Directory
The Identification of DNA as the Biochemical Material
DNA Replication
Cloning Genes
Cloning Genes
another. In this experiment, the DNA of one microorganism recombined
with the inserted DNA sequence of another, and thus had been edited to
The methods used in rDNA technology are fairly simple. We take, for
it into the DNA of Escherichia coli, a bacterium that inhabits the human
of copies of themselves, and each bacterium carries in its DNA a
DNA and paste, or splice, it into plasmid DNA, a special kind of DNA
in a very precise way a specific base sequence of the DNA molecule. With
the human DNA molecule that specifies insulin production can be
This segment is "glued" into place using an enzyme called DNA
ligase. The result is an edited, or recombinant, DNA molecule. When this
recombinant plasmid DNA is inserted into E. coli, the cell will be able
This highly simplified description of rDNA technology does not fully
genetic processes. But we can begin to understand how, by using rDNA, it
7.012 Genetics Supplementary Handout Page 1
DNA.
where l and n are,0.05cM apart. (In Drosophila, 0.05cM is roughly 25000 bp of DNA.
Prokaryotic Gene Regulation
'lac gene' would have been defined as the minimum piece of DNA that
could function on its own - that is, the smallest DNA fragment that
subject to regulation - an mRNA copy is made from the DNA and
these are regions of DNA that code for proteins. These genes produce
DNA sites -
these are regions of DNA which are involved in gene expression or
DNA to affect expression of adjacent structural genes. Generally,
lac operon promoter DNA site. This is where RNA polymerase
same DNA molecule that this inactive promoter would normally signal for
lac operon operator DNA site. This is where the lactose
DNA molecule that the inactive operator would normally regulate.
cell, far from the piece of DNA that
places in the cell, or acting on different pieces of DNA. In the lac operon,
DNA sites cannot diffuse throughout the cell and only act on the adjacent
DNA. This is called acting in cis also by analogy to chemistry: in
same piece of DNA. In the lac operon, lac P and lac O
the wild-type lacZ gene because promoters only work on the DNA
chromosome on a plasmid. A plasmid is another circular DNA molecule present
E. coli
molecules of DNA and 15,000-30,000 ribosomes.
approximately 70 percent water, 15 percent protein, 1 percent DNA, 6
approximately l/500 as much DNA as is contained in a single cell of a
is also used extensively in research on recombinant DNA ("genetic
Nucleic Acids
4 Nucleic Acids
Deoxyribonucleic Acid (DNA) contains four nucleotide bases.
7.012 DNA Sequencing Section Problem
7.012 DNA Sequencing Section Problem
Given the following double-stranded piece of DNA:
MIT Biology Hypertextbook: Enzyme Mechanisms
ex. Deoxyribonuclease, or DNase catalyzes
DNA ---> dNMP nucleotides
Membrane Proteins Introduction
It must keep its molecules of life ( DNA , RNA , and its assortment of
module not yet titled
DNA recombination in phage
Culturing cells in vitro
that its DNA sequences are in order. In the event that the cellular DNA
repair its DNA, erasing as many mutations as possible, before it
proceeds into S to copy its DNA. In doing so, the cell minimizes the
their DNA has been replicated. Thus, there is an intracellular monitor
which checks on the progress of DNA replication and prevents premature
for ensuring that once a DNA molecule has been replicated in one S
DNA Structure.
DNA Structure.
DNA Structure
This is the molecular structure of DNA . A slightly more simplified diagram
DNA Structure. The four nitrogenous bases of DNA are arranged along
the sugar-phosphate backbone in a particular order (the DNA sequence),
thymine (T), while cytosine (C) pairs with guanine (G). The two DNA strands
Characteristics of Prokaryotes and Eukaryotes
They both have DNA as their genetic material.
organelles , while prokaryotes do not. The DNA of prokaryotes floats
freely around the cell; the DNA of eukaryotes is held within its
The DNA of eukaryotes is much more complex and therefore much more
extnsive than the DNA of prokaryotes.
Solutions to exercises for Mendelian Genetics Chapter
Drosophila, 0.05cM is roughly 25000 bp of DNA.
Polymerase Chain Reaction - Xeroxing DNA
Polymerase Chain Reaction - Xeroxing DNA
Polymerase Chain Reaction - Xeroxing DNA
laboratories and doctor's offices, relies on the ability of DNA-copying
produce millions of copies of a single DNA segment in a matter of hours.
In nature, most organisms copy their DNA in the same way. The PCR mimics
enzymes called polymerases make a copy of all the DNA in each
chromosome. The first step in this process is to "unzip" the two DNA
chains of the double helix. As the two strands separate, DNA polymerase
The four nucleotide bases, the building blocks of every piece of DNA,
To copy DNA, polymerase requires two other components: a supply of the
four nucleotide bases and something called a primer. DNA polymerases,
whether from humans, bacteria, or viruses, cannot copy a chain of DNA
DNA is called a primer. Once the primer is made, the polymerase can
A PCR vial contains all the necessary components for DNA duplication: a
piece of DNA, large quantities of the four nucleotides, large quantities
of the primer sequence, and DNA polymerase. The polymerase is the Taq
separates the two DNA chains in the double helix. This is done simply by
But the primers cannot bind to the DNA strands at such a high temperature, so
the primers bind or "anneal" to the ends of the DNA strands. This takes about
contains a G, it adds a C to the new chain, and so on to the end of the DNA
of a cycle, each piece of DNA in the vial has been duplicated.
DNA piece can act as a new template, so after 30 cycles, 1 million
copies of a single piece of DNA can be produced! Taking into account the
In one application of the technology, small samples of DNA, such as those
There are three related sections on DNA fingerprinting, read whichever
DNA Fingerprinting in Human Health and Society
An Interview with DNA Forensics Authority Dr. Bruce Weir
Use of DNA in Identification: A talk by Eric Lander
Southerns, Northerns, Westerns, & Cloning: Molecular Searching Techniques
These are techniques for analyzing cellular macromolecules: DNA,
Purves, Oriens, and Heller pp. 315-8. DNA-RNA hybridization is
example: the two strands of a DNA double-helix bind because they have
1) DNA-DNA. A single-stranded
DNA (ssDNA) probe molecule can form a double-stranded, base-paired
hybrid with a ssDNA target if the probe sequence is the reverse
2) DNA-RNA. A single-stranded DNA (ssDNA) probe molecule can
search for one DNA molecule, or one RNA molecule, or one protein
of different proteins. When the cell is broken open to extract DNA, RNA,
or protein, the result is a complex mixture of all the cell's DNA, RNA,
DNA cut with restriction enzymes - probed with radioactive DNA.
RNA - probed with radioactive DNA or RNA.
value - if you mix a solution of DNA with a solution of radioactive
preparing DNA, RNA and protein samples for electrophoresis.
Preparing DNA for Southern Blots
DNA is first cut with restriction enzymes and the resulting
double-stranded DNA fragments have an extended rod conformation without
different units for DNA, RNA, and protein:
DNA: Molecular weight is measured in base-pairs, or
On most gels, one well is loaded with a mixture of DNA, RNA, or
Sample 2 is what a sample of total DNA cut with a restriction enzyme,
Staining DNA
DNA is stained with ethidium bromide (EtBr), which binds to nucleic
aids. The DNA-EtBr complex fluoresces under UV light.
After the DNA, RNA, or protein has been separated by molecular
used. DNA, RNA, and protein stick well to nitrocellulose in a
The DNA, RNA, or protein can be transferred to nitrocellulose in
Note: In a Southern Blot, the DNA molecules in the gel are
probe to hybridize to them. To do this, the DNA is transferred using a
strongly alkaline buffer, which causes the DNA strands to separate -
in a blocking solution which contains a high concentration of DNA, RNA,
Radioactive DNA probes for Southerns and Northerns
double-stranded DNA fragment. The process usually begins with a
long, this results in 2 to 10 DNA fragments of different lengths. If the
identified on the gel. The band is then cut out of the gel and the DNA
the isolated DNA is a pure population of identical double-stranded DNA
The DNA restriction fragment (template) is then labeled by
1) The template DNA is denatured - the strands are separated - by
2) A mixture of DNA hexamers (6 nucleotides of ssDNA) containing all
base-pair. They pair at many sites along each strand of DNA.
3) DNA polymerase is added along with dATP, dGTP, dTTP, and radioactive
one that is incorporated into the DNA strand) is synthesized from
This process is diagrammed below (labeled DNA shown in gray):
DNA copy of both strands of the template for use as a probe.
end up with a plasmid which contains a fragment of human DNA which
of the actin gene from another organism and human chromosomal DNA.
DNA-DNA hybridization is usually used for this.
Although Southern blotting involves DNA-DNA hybridization, it is
not a useful procedure for cloning a gene. If we were to cut human DNA
the human actin gene DNA from either the gel or the filter because at
For this reason, separating the DNA fragments by molecular
separated, each containing a different fragment of human DNA.
1) Isolate genomic (chromosomal) DNA from human cells.
2) Create a plasmid library of human DNA restriction fragments. This
different plasmid with a different inserted piece of human DNA.
make their plasmid DNA single-stranded, and bind the DNA onto the
filter. There are now spots of single-stranded plasmid DNA on the
spot corresponding to a place on the filter where DNA from the human
in broth and extract their plasmid DNA. It contains a fragment of human
DNA containing the actin gene.
Solving Problems
Solving Problems
You extract genomic DNA from a red, a pink, and a white plant; digest
nitrocellulose. You have a cDNA for the R gene which you use as a
1) What is the alteration in the R-gene DNA of the mutant r allele?
EcoRI: Digestion of this region of DNA should produce 5 fragments in
-Because the probe is a cDNA, that is, it only includes the
important. Also, since hybridization occurs after the DNA fragments have
HindIII: Digestion of this region of DNA should produce 5 fragments in
the DNA at all EcoRI sites and at all HindIII sites. This should
altered between the two DNA's.
sequencing the DNA of the R and r alleles to find the exact differences.
half as much DNA in each band.
digestion. Assuming that the DNA is the same in both sexes (How could
by doing a Southern blot of DNA from males and from females, probed with
throughout - that would require sequencing the DNA from both - but it