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DNA
Tutorial
Return
to www.101science.com home page.
DNA (deoxyribonucleic acid), the giant molecule that carries genetic information in living things, is made up of just a few chemical building blocks that bond together in very particular ways.
A typical molecule of DNA consists of two
strands that are linked together. A segment can be visualized as a ladder-like structure:
(Actually DNA looks like a twisted ladder or a spiral staircase, a shape commonly called a helix or, since there are two strands in the structure, a double helix. Here we are focusing just on the structure of the ladder.)
In our flat unrealistic model picture we are visualizing the DNA as made of two strands, a left and a right,
which are linked in the middle. In reality, since the ladder is twisted, there really is
no "right" or "left," but we use that terminology here since it
applies to the model graphs. The square shapes and diamonds you see in the middles of the
"rungs" are the links, which are meant to represent the different chemical bonds between the two strands
of DNA.
Each of the two strands of DNA consists of a sequence of nitrogenous bases, and any one of
four such bases can appear on a strand. (The DNA also contains other molecular building
blocks like sugars and phosphate groups, but the nitrogenous bases are the genetically
important part.) The four bases and our geometric representation of each are as follows:
Base
Representation
adenine
thymine
cytosine
guanine
These four bases are usually referred to by their leading initials: C (cytosine), G (guanine), A (adenine) and T (thymine). The shapes used here were selected intentionally. Note what happens when a C appears on the left strand . . .
. . . and a G in the corresponding spot on the right strand . . .
The two bases hook up nicely!
The solid bond the two bases form is indicated by the closed solid in the middle. Similarly with A and T:
In the construction of DNA, C can only be matched with G and A only with T. All four can be part of a strand. Pictorially you can see that here when the bases just don't match up . . .
. . . or simply do not form a closed bond . . .
Thus once you specify the sequence of bases on one strand, the sequence on the other is determined. For example, if the left strand is
then the right strand must be
Graphically, we can represent the resulting piece of DNA as
You can modify the vectors L and R above as
much as you like to help reinforce these concepts. Make L as long as you wish and enter a
sequence of As, Gs, Cs and Ts. Then fill in the vector R of the same length with the
correct right strand sequence. Inspect the resulting graph to see if everything bonded
correctly.
Check these sites -
FREE
Software (pDRAW32) to draw DNA Analysis Charts
http://www.acaclone.com/
pDRAW32 lets you enter a DNA name and
coordinates for genetic elements, such as genes, to be plotted on your DNA
plots. pDRAW32 lets you "clone" fragments of DNA generated by
virtual digestion with restriction enzymes and optionally blunted at one or both
ends. Up to 3 fragments may be cloned at a time (can you replicate that in the
lab?). Each fragment may be inverted relative to its original orientation.
Genetic elements contained in the cloned fragments are transferred to the cloned
DNA. (...and much more!)
DNA - The Code http://www.dnai.org/a/index.html
DNA - Manipulation http://www.dnai.org/b/index.html
DNA - Genome http://www.dnai.org/c/index.html
DNA - Applications http://www.dnai.org/d/index.html
DNA - Chronical http://www.dnai.org/e/index.html
DNA - Timeline http://www.dnai.org/timeline/index.html
DNA - From the Beginning http://www.dnaftb.org/dnaftb/
Chemistry of DNA
Brooks Design-Contemporary Graphics "Art Theory 101/ Database" .
How Cells Work http://www.howstuffworks.com/cell4.htm
DNA Fingerprinting http://www.howstuffworks.com/dna-evidence3.htm
DNA From The Beginning http://vector.cshl.org/dnaftb/
Explain exon in DNA Terms
[PDF] Explain in detail what would happen if a self-splicing intron that
Genetic Polymorphisms in the Human Xeroderma Pigmentosum Group A
Conference 12: Regulation of Genes, Recombinant DNA
Emory Pediatric Endocrinology - Recent Abstracts
Knowledge Representation in the Genome: New Genes, Exons, and
[PDF] Explain in detail what would happen if a self-splicing intron that
DNA, Protein Synthesis, Gene Expression and Regulation, Biotechnologj
Exon/intron structure of aldehyde dehydrogenase genes supports the
Programmed DNA rearrangement from an intron during nuclear
The function of introns. ISIS - The intron database
The amount if DNA in each human cell nucleus is approximately four
DNA Laboratory Activities
GeneTree DNA Testing Laboratory
SWBIC - Educational Activities & MaterialsClassroom & Laboratory Activities - The Institute for Genomics
Koshland Science Museum - Teachers and Learning - Create a DNA
FORENSIC DNA DATABASE/LABORATORY ACCREDITATION
Natural Resources DNA Profiling and Forensic Centre/About Us
Solicitation for Forensic DNA Lab Improvement Program . MENU TITLE
Primer on Molecular Genetics from the U.S. Department of Energy
NEW! FREE Software (pDRAW32) to draw DNA Analysis Charts http://www.acaclone.com/ pDraw32 DOWNLOAD software - pDRAW32 lets you enter a DNA name and coordinates for genetic elements, such as genes, to be plotted on your DNA plots. pDRAW32 lets you "clone" fragments of DNA generated by virtual digestion with restriction enzymes and optionally blunted at one or both ends. Up to 3 fragments may be cloned at a time (can you replicate that in the lab?). Each fragment may be inverted relative to its original orientation. Genetic elements contained in the cloned fragments are transferred to the cloned DNA. (...and much more!)
We found an excellent Genetics tutorial: Morgan. You will have to register to view it but it is free. http://morgan.rutgers.edu/MorganWebFrames/htmldocs/register.html
http://www.nhgri.nih.gov/ - National Human Genome Research Institute)
DNA
Laboratory Activities - The
Woodrow Wilson National Fellowship Foundation
http://www.woodrow.org/
DNA without tears!
A simple experiment using phenopthalein and tubes of water to demonstrate the epidemiology of HIV-1
Fun with Sephadex G-25 columns!
Students "translate" a lima bean DNA extraction procedure
Learn how to use the spectrophotometer and micropipette
Bacterial tranformations using antibiotic resistant plasmids
Introduction to electrophoresis
Measuring UV using yeast cells...adapted from KSU's Yeast Project
Two activities for karyotyping: a paper cut out method and a lab usinghuman cells
Procedure to ligate fragments of genomic DNA from spinach into a vector plasmid; this recombinant DNA is then used to transform Escherichia coli cells.
Inserting a spinach genomic clone into a plasmid
A couple of easy techniques which can be used to observe the development of a chick embryo
The purpose of this lab is to grow plants in tissue cultures and to see what effect the different concentrations of hormones have on embryodevelopment
This activity allows students to strip away the cell walls of plant cells (using enzymes) and then observe the resulting spherical protoplasts
Using restriction enzymes to digest thymus DNA
An experiment using bacterial cultures to simulate a small scale "epidemic"
A relatively simple plant transformation experiment
Students simulate tests done in the field to determine the active ingredients in plants
This ecological laboratory uses the biotechnological tool of the bioassay to demonstrate the effects of toxic substances on living organisms
 |
networked
moving images for the life sciences >NEW
LIFESIGN SITE!<
|
| Title: Biochemical Basis of Biology - Tape 3 - Manipulating DNA |
|
Description:
Covers cutting DNA, electrophoresis of DNA, DNA
amplification, and cloning DNA
|
|
Keywords: dna, double helix, restriction enzymes, electrophoresis, agar, agarose gel, gel, polymerase chain reaction, pcr, amplification, gene, insertion, plasmid, bacterial plasmid, colony, picking colonies, bacterial transformation, ethidium bromide, primers, complementation, blue white test, |
|
Right
Holder: Biochemical society, 59 Portland Place, London W1B
1QW Telephone 020 7580 5530 fax 020 7637 7626
|
| Further Information: http://www.biochemistry.org/education/default.htm |
| Title: Biochemical Basis of Biology - Tape 2 - DNA & Protein Synthesis |
|
Description:
Covers the measurement of protein synthesis by means of
radioactivity, the mechanism of protein synthesis and viruses,
bacteriophages and the Hershey and Chase experiment.
|
|
Keywords: trna, triplet codes, initiation factors,elongation factors, release factors, viruses, foot & mouth, chicken pox, hiv, polio, vaccination, tobacco mosaic virus, adenovirus, envelopes, cell invasion, synthesis of rna, release, plaques, hershey, chase, hershey & chase |
|
Right
Holder: Biochemical society, 59 Portland Place, London W1B
1QW Telephone 020 7580 5530 fax 020 7637 7626
|
| Further Information: http://www.biochemistry.org/education/default.htm |
| Title: Biochemical Basis of Biology - Tape 1 - Cell Structure and energy production |
|
Description:
Covers the electron microscope, subcellular fractionation,
mitochondrial respiration and the light reaction of
photosynthesis
|
|
Keywords: Subcellular fractionation, transmission electron microscope, mitochondrial respiration, oxygen electrode, citric acid cycle, electron transport chain, adp, adpi, atp, oxidative phosphorylation, light reaction, chlorophyll, starch, co2, h2o, carbohydrate, photosystem 1, photosystem 2, photosystems 1 & 2, |
|
Right
Holder: Biochemical society, 59 Portland Place, London W1B
1QW Telephone 020 7580 5530 fax 020 7637 7626
|
| Further Information: http://www.biochemistry.org/education/default.htm |
Please see our comprehensive "Science Terminology" page.
Click on the book title below to learn more about this book and to order.
Unraveling DNA : The Most Important Molecule of Life - Maxim D.
Frank-Kamenetskii; Paperback
