Illustrates how studying one family's pedigree can reveal an entire history of passing on a genetic disorder such as SCA1.
This animation illustrates how mistakes made during DNA replication are repaired.
DNA's chemical properties can be harnessed for a variety of biotechnology applications.
DNA has a double helix structure. If untwisted, DNA looks like two parallel strands. Each strand has a linear sequence of A, C, G, and T. The precise order of the letters carries the coded instructions. One strand is a complementary image of the other: A always pairs with T, and C always pairs...
The structure of DNA, discovered by James Watson and Francis Crick, suggests a mechanism of replication. The double helix unwinds, and each strand acts as a template for the construction of the new DNA molecule.
Using information from molecular research, this 3-D animation shows how DNA is replicated at the molecular level. It involves an enzyme that unwinds the DNA, and other enzymes that copy the two resulting strands.
Both strands of the DNA double helix act as templates for the new DNA strands. Incoming DNA is unraveled by the enzyme helicase, resulting in the 3' strand and the 5' strand. The 3' strands and the 5' strands are replicated by a DNA polymerase enzyme but in different ways.
A useful technique for narrowing down the location of a gene involves comparing the chromosomes of affected siblings. Two sisters with Rett syndrome allow researchers an opportunity to map the most likely location of the gene by excluding areas of the chromosome that are not alike.
Environmental and cultural factors can affect whether a new human mutation becomes common in a population.
A demonstration by Dr. Meyer showing how a balance of molecular elements trigger genetic pathways that determine the sex of a C. elegans worm.
Kangaroo-like hopping when spinal cord excitatory interneurons cross the midline to stimulate both sides.
Dr. Zoghbi demonstrates how mice that have been given the gene responsible for spinocerebellar ataxia 1 (SCA1) are tested on a device called a rotarod to quantify the amount of ataxia present.
Genetic evidence shows that humans evolved in Africa and continue to evolve.
How humans perceive bitter taste, and the evolution of taste perception.
How has the amazing diversity of plants and animals evolved? What can fossils, butterflies, and stickleback fish tell us about the deep common ancestry of all living forms?
Comparing the artificial selection of dogs and corn with the natural selection of the stickleback fish.
The genetic mechanisms by which evolution occurs, and an overview of the evidence for evolutionary theory.
How and why butterflies and fruit flies got their spots, and the fossil record for human evolution.
As part of the 2003 Holiday Lectures on Science, Dr. Bert Vogelstein and Dr. Huda Y. Zoghbi discuss how their patients have led to a deeper understanding of the genetic and molecular bases of neurological disorders and cancer. Thanks to these patients, researchers can now apply the knowledge...
Although there are numerous kinds of cancer, all stem from alterations that allow cell division to outstrip cell demise.
The identification of hundreds of genes involved in the formation and spread of cancer is leading to promising new methods for diagnosis, prevention, and treatment.
Mutations in key genes can lay waste to the nervous system. By studying large families predisposed to developing these genetic disorders, scientists can identify the responsible altered gene.
Girls with Rett syndrome develop normally for about 18 months and then begin to regress. With the help of affected girls and their families, Dr. Zoghbi and her collaborators searched for the gene responsible for this neurological disorder.
Genetic research benefits health, but also raises thorny ethical issues.
Dr. Friedman shows how leptin rewires neural circuits, and how population studies may identify obesity genes.
Dr. Lander explores human genetic variation and how it may affect individual susceptibility to certain diseases.
Four talks focus on sex determination—the molecular and genetic mechanisms that determine whether an organism will be male, female or a hermaphrodite.
Is it a boy or a girl? Dr. David Page looks at how we define male and female and summarizes the development of human sex characteristics.
Dr. Barbara Meyer explains the value of studying model organisms and introduces the nematode C. elegans.
Having too many chromosomes can lead to too much gene expression. Dr. Meyer explains how the gene that controls dosage compensation in C. elegans works.
Dr. Page explains how successive inversions and deletions of the Y chromosome during mammalian evolution have reduced it to its present form—small and sparsely populated with genes.
Four lectures highlight the research of two scientists who have made groundbreaking discoveries elucidating the molecular basis of circadian clocks—the internal timekeepers that govern fluctuations in behavior and physiology on a 24-hour cycle.
Although tiny in size, the fruit fly has had a major impact on our understanding of circadian rhythms.
Dr. Rosbash discloses how scientists have persuaded Mother Nature to reveal the inner workings of the fruit fly's biological clock.
Dr. Takahashi describes the powerful strategies that he and others have harnessed for understanding biological clocks in mammals.
In four lectures, Richard P. Lifton, MD, PhD, and Christine E. Seidman, MD, discuss their groundbreaking work in using genetic and molecular approaches to understand cardiovascular diseases.
The discovery of DNA as the basis of heredity led to an explosive growth of knowledge about the human genome and allowed the identification of genes that predispose people to different diseases.
Although heart disease typically occurs after middle age, seemingly fit and healthy young individuals can die suddenly from unrecognized heart disease.
Molecular genetic approaches have identified genes that, when mutated, cause either increased or decreased blood pressure.
Lactose tolerance, sickle cell anemia, and bitter taste perception are three examples of recently evolved human traits.
Explore principles of taxonomy by sorting seashells according to their morphological characteristics and constructing an evolutionary tree.
Learn why verifying a person's gender may be harder than you think.
The following classroom-ready resources complement The Making of the Fittest: Natural Selection and Adaptation, which describes the physical and genetic evolutionary changes in rock pocket mouse populations.
A lesson that requires students to transcribe and translate portions of the wild-type and mutant rock pocket mouse Mc1r genes and compare sequences to identify the locations and types of mutations responsible for the coat color variation described in the film.
An advanced lesson that describes the role of mutations in the birth and death of genes. It includes background information, examples, video clips, and animations.
The following classroom-ready resources complement The Making of the Fittest: Natural Selection in Humans, which describes the connection between malaria and sickle cell anemia—one of the best-understood examples of natural selection in humans.
A hands-on activity that uses simulations with beads to teach students about population genetics, the Hardy-Weinberg principle, and how natural selection alters the frequency distribution of heritable traits.
A lesson that requires students to work through a series of questions pertaining to the genetics of sickle cell disease and its relationship to malaria. These questions will probe students' understanding of Mendelian genetics, probability, pedigree analysis, and chi-square statistics.
Construct evolutionary trees by sorting seashells. To accompany the lecture series Exploring Biodiversity: The Search for New Medicines and the Sorting Seashells Click and Learn interactive.
To accompany the lecture series Learning from Patients: The Science of Medicine.
Topics include: DNA structure and function, DNA replication, damage to DNA and eukaryotic chromosomal structure.
Interactively explore topics in biology with the Click and Learn app. Now available from the Apple App Store,...
Students explore the genetic changes associated with lactose tolerance/intolerance and how the trait is inherited in families.
Recent advances in DNA sequencing technology have led to a better understanding of the many genes that play a role in brain development.
Understanding that cancer is caused by mutations in genes that regulate cell proliferation has led to the development of targeted drug therapies.
Over the past decade, the application of advanced DNA sequencing techniques has greatly increased our understanding of the genetic basis of autism.
Dr. Christopher Walsh discusses how genomic science has made enormous contributions to our understanding of the genetic causes of autism.
Dante is a 10-year-old boy born with hemimegalencephaly—an enlargement of half his brain.
This activity can be used in conjunction with the short film The Double Helix. It introduces students to the classic experiment by Matthew Meselson and Franklin Stahl, which revealed that DNA replication follows the semiconservative model.
In this video Dr. Charles Sawyers provides an overview of the types of genes that, when mutated, can lead to the development of cancer.
These two hands-on activities are based on a Howard Hughes Medical Institute 2013 Holiday Lectures on Science video featuring researcher Dr. Charles L. Sawyers.
App version of the popular virtual lab, introducing you to the science and techniques used to analyze the threespine stickleback fish.
Explore the phases, checkpoints, and protein regulators of the cell cycle in this highly interactive Click and Learn and find out how mutated versions of these proteins can lead to the development of cancer.
When heated to a temperature of around 180°C, corn bursts open with a “pop” in mere hundredths of seconds.
Coral reefs, how they are threatened by climate change, and how to protect them.
Dr. Eric Lander takes us on a tour of this remarkable genetic century, describing the rapid advances in DNA sequencing technologies and information science.
Dr. Zoghbi shows how a mouse that has been given the gene responsible for Rett syndrome exhibits some of the same neurological symptoms as human Rett patients.
Where and when did humans arise? What distinguishes us from other species? Did our distant ancestors look and behave like us?
Topics include: natural selection, artificial selection, population genetics, human adaptations and evolution, and phylogenetics.
A hands-on activity in which students analyze the results of genetic crosses between stickleback fish with different traits.
Penn State University anthropologist Dr. Nina Jablonski walks us through the evidence that the different shades of skin color among human populations arose as adaptations to the intensity of ultraviolet radiation in different parts of the world.