Molecular Genetics is the study of the DNA and RNA molecules and how these molecules carry the code for all of the structures and functions necessary for an organism to survive. DNA and RNA are nucleic acids and are universally the same in chemical structure in all living things. RNA is found in cells in three types: Messenger RNA, Transfer RNA, and Ribosomal RNA.
22 pairs are autosomes, chromosome responsible for taking care of structural and chemical functions in the organism. The last pair of chromosomes are the sex chromosomes that determine the gender of the organism. Females have two X chromosomes, and males have an X and a Y. The karyotype here is male.
Irregularities in the chromosomes can cause defects in the offspring. For example, the karyotype at the left shows a child with Down's Syndrome. In this instance, there are three 21st chromosomes when there should be only two. The characteristic almond shaped eyes, short thick tongue, mental disabilities, and and the simian line on the palm are a result of this chromosomal error.
Other disease are caused by damage to the chromosome as in Fragile X where there is a break in the arm of a chromosome. Fragile X is the leading cause for mental retardation.
Other defects caused by chromosomal changes may be the result of a translocation of one chromosome to another. In this instance a chromosome breaks and the piece is moved to a different nonhomologous chromosome where it becomes attached. Inversion occurs when a piece of a chromosome becomes rotated and the gene order is reversed. Addition occurs when a piece of a chromosome breaks off and becomes attached to a homologous chromosome. Deletions occur when the chromosome breaks and some genes become lost or missing. Whatever the genes lost encoded for would become abnormal in the individual organism. Check out some of these genetic disorders and their causes:
Click on the chromosome to the left to learn all about karyotyping.. Click on Genetic Disorders when the site opens.
Try your hand at matching chromosome pairs in this activity by clicking on the chromosome. Click on genetic disorders when the site opens! Look for activity on right.
Your Complete Genetics Tutorial
Click on the chromosome to reach the Rutger's Waksman Institute Tutorial on Classical and Moleucluar Genetics.
Click on theRNA to learn about another important nucleic acid in living organisms. When redirected to new site location, click on Bringing RNA into view.
National DNA Day...
April 25th, 2003 celebrating the completionof the Human Genome Project.
Click on DNA Day to learn more about our program.
Terms releated to Molecular Genetics you should know:
DNA...a molecule found in the nucleus of cells that carries genetic information coded in triads of nitrogen bases.
exon...a bse sequence in a DNA molecule which is eventually transcribed in an mRNA molecule.
gene therapy...manipulatin of genes, usuallin in a fetus, which corrects some genetic error.
genetic code...base triplets in a DNA moleucle that specify particular amino acids.
I gene...regulatory section on an RNA molecule that codes for a repressor gene according to the operon theory.
ligase...an enzyme that joins two DNA segments together.
messenger RNA...RNA molecules that "read" the genetic message stored in DNA molecules and then use the message to direct the synthesis of protein.
mutagen...any substance or form of energy that can produce a change in the base sequence of a DNA or RNA molecule.
nitrogen base....organic compounds consisting of ring compounds that contain at least one nitrogen atom; one of the components from which nucleic acids are made.
operon...a group of genes that control the function of other genes on an RNA molecule.
plasmid...a small, ciruclar molecule of DNA present in bacterial cells.
rDNA research...the process by which a segment of the DNA of one organism is transferred to the DNA of a second organism by laboratory means.
replication...the process by which DNA molecules are duplicated.
transcription...the process by which the genetic code stored n a DNA molecule is transferred to a newly formed mRNA molecule in the nucleus of a cell.
transfer RNA...a molecule which collects amino acids from "raw materials" available in the cell and then transfers them to mRNA molecules during protein synthesis.
transposon...a genetic element capable of moving from one DNA molecule to anoter DNA molecule or from one region of a DNA molecule to another region of the same molecule.
uracil...one of the nitrogen bases found only in RNA molecules
vector...any substance or organism which can be used to insert a fragment of DNA into a host cell during recombinant DNA procedures.
introns...DNA code which is not tranlsated into protein.
Learn about the human genome project and the future of genetics by clicking on the DNA molecule on the left.
Learn the fascinating story of how genetics is being used to find the Lost Tribes of Israel by clicking on the DNA molecule on the left.
Click on the DNA moleculue to learn how to do a DNA fingerprint.
DNA fingerprinting...the process.
Click and open to discuss ethical issues through scenarios for genetically linked diseases
Genetics and the Law....what the future holds.
Important terms to know and understand:
Recombinant DNA Research....the process by which a segment of the DNA of one organism is transferred to the DNA of a second organism in order to change the characteristics of the second organism. Example...tomatoes with a peanut gene introduced so the skin of the tomato will not split when it becomes very ripened.
Eugenics...the study of ways by which the characteristics of future can be altered (improved, supporters say) by the social control over bredding of present generations. Example...in the early 1900's the sterilization of children with Down's syndrome.
Screening Laws... laws which require newborn children to be tested for certain genetic disorders in order that the children may receive the ealriest possible treatment for such disorders. Example...every child in U.S. is tested for PKU a debilitating disease that can be corrected with diet if treated early.
Cloning...the process by which identical copies of an orginal DNA molecule, cell, or individual are made from a single ancestor molecule or cell.
Artificial Insemination...the mechanical fertilization of an egg by means of sperm cells that have been removed fromt he male donor.
Amniocentesis...the process by which amniotic fluid containing fetal cells is removed from a pregnant woman in order to examine the fetus for possible genetic disorders.
Genetic Counseling...counseling which is offered to potential parents about the probable future health of their prospective child, such information having been based on family histories, amniocentesis and other background information.
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Click on "Listen to Lecture" or View slides for the contents of a lecture on Genetic Counseling and its role in society.
Photogallery of Scientists Whom Pioneered the Fields of Genetics
Rosalind Frankllin
Xray Crystallographer of DNA
Barbara McClintock
"Jumping Genes"
Gregor Mendel
"The Father of Genetics"
Francis Crick, British Nobel Prize for DNA.
Maurice Wilkins Nobel Prize for DNA
James Watson, U.S.
Nobel Prize for DNA
Speaking genetically...terms to know and understand.....
Allele... varying forms of a gene at a specific locus that can be distinguished by the effects they produce on phenotypes.
autosome...a chromosome other than those such as X and Y that determine the sex of an organism.
chromosome...the discrete unit of DNA combined with protein found in the nucleus of eucaryotic cells; carries genetic information.
cross...a mating
diploid...used to refer to a cell that contains chromosome pairs.
dominant...used to refer to a gene whose phenotype is expressed when only a single "dose" or copy of the gene is present.
gamete...a reproductive cell, such as an egg or a sperm; ususally haploid; some species may also be haploid, however.
gene...a sequence of DNA bases that codes for the production of a specific protein or regulator of protein synthesis.
genotype...the specific genes an individual has for a particular trait.
haploid...(monoploid) used to refer to a cell that contains one member of each pair of chromosomes naormally associated with that species.
heredity...the sum total of genetic information an individual receives from its parents at the time of conception.
heterozygous...refers to a pair of genes (or an individual with that pair of genes) inwhich the two alleles are different.
homozygous...refers to a pair of genes ( or the individual with that pair of genes)
in which the two alleles are the same.
phenotype...the expression of the gene, how the trait looks.
recessive...used to refer to a gene whose phenotype is expressed only if present in a double "dose" or two copies.
zygote...the cell resulting from the union of egg and sperm.
White type are you? The Genetics of Blood typing:
Blood Phenotypes:
A
B
AB
O
Possible genotypes:
AA, AO, OA
BB, BO, OB
AB, BA
OO
Universal Donor....Blood type O ...can give blood to anyone .
Universal Recipient....Blood type AB...can receive blood from anyone.
Page Index:
*DNA Molecule
*Chromosomes and Karyotyping
*Genetic Disorders & types of mutations
*Genetics Vocabulary
*Genetics and the Law
* Blood typing
* Scientists Photogallery
From Start to Finish......
From the nuclear DNA where the genetic information is housed, transcription by m-rna brings the needed information to the ribosome.
T-rna then translates the code into a viable protein molecule made by joining the correct number and sequences of amino acids. Proteins are then assume their roles as catalysts, and building materials.
What does molecular genetics and biotechnology mean for our future?
Having reviewed this site and its links....
1. What is the history of DNA? Who discovered it's structure, how and when?
2. How do these three processes, replication, transcription and translation, insure continuity in the traits of offspring in future generations?
What can contribute to errors in the codes?
Can you site specific examples of errors and their end result?
3. Do you know the genetic causes and effects of the the following genetic disorders?
Marfans Syndrome
Tay Sachs
Down's Syndrome
Hemophelia
Cystic Fibrosis
Huntington's Chorea
Klinefelter's Syndrome
Turner's Syndrome
Fragile X
4. What is a pedigree? What information can it provide?
5. What is the significance of mitochondrial DNA?
6. Describe each of the following process and the resulting information it provides.
DNA fingerprinting
Amniocentisis
Karyotyping
7. What is the purpose of genetic counseling? Who should use it?
8. What are the ethical issues surrounding cloning, DNA fingerprinting, and genetic screening?
Princeton Univversity Moleuclar Biology Program
click above
This page was last updated on: June 21, 2005
This page was designed by Johnnie Bennett, New Jersey State Teacher of the Year, 1993, for use by her students at Montclair Kimberley Academy in Montclair, New Jersey.
Johnnie Bennett is currently a biology a Biology teacher with 33 years experience.
This site is dedicated to the thousands of U.S. Military Personnel now serving throughout the world in effort to secure the safety of our homeland. In honor and support of the families of those men and women currently serving in Afghanistan and Iraq. To them, we wish to express our gratitude for the sacrifices they have made.
Justen Thomas Bennett, Specialist Ist infantry U.S. Army, Bamberg, Germany. Returned February 5th, 2004 after a year in Iraq.
Lt. Commander William David Bennett, U.S. Navy, VR-52 Squadron, Willow Grove Pennsylvania. Serving for 35 years.
Learn the how and why of cloning by clicking on Dolly and her mother!! Open the text file below and print it out to use as an answersheet for the questions.
Go to the top of this page, and under the page title, click on the words transcription and translation to answer some of the other questions on your worksheet.
Click on the link at left to create a timeline of the work done by the scientists listed on your worksheet, listing the year they achieved their success and a sentence describing their accomplishment. .
Multiple alleles...when there are more than two allele options for a given trait as in blood typing. (A, B,AB,O).
Polygenic inheritance...when several genes enhance the expression of a phenotype as in height, hair color, eye color, skin tones.
Codominance...when both alleles are expressed and result in a different phenotype than either homozygous dominant or homozygous recessive. ( Bb resulting in black hairs and white hairs producing a gray appearance but not gray hairs.)
Incomplete dominance...when the heterozygote produces a phenotype which is a blend of the homozygous dominant and homozygous recessive. ( red, pink and white carnations.
Just click on the green box.
When the site opens, click on "class notes".
Choose "genetics" and you will have the opportunity to practice punnett squares and review genetics online. Great site...good resource.
Click on the DNA at the left...find your own genotype
Click on the DNA at the left...Click on genetics when page opens. Make selection from topics listed.
Genetics Textbook Online
DNA Interactive Site....Learn all there is to know about DNA
