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The complex systems of high school dating and chemical reactions may have more in common than you think. Explore five rules for speeding up chemical reactions in the lab that might just land you a date to a dance!

2:34 video Foot odor might make you cringe with embarrassment in the airport security line, but chemistry can help you beat stinky feet. In this week's Reactions video, we answer all your foot-focused questions and share some tips to stop the smell. 

In molecular biology, ligation refers to the joining of two DNA fragments through the formation of a phosphodiester bond. An enzyme known as a ligase catalyzes the ligation reaction. In the cell, ligases repair single and double strand breaks that occur during DNA replication. In the laboratory, DNA ligase is used during molecular cloning to join DNA fragments of inserts with vectors - carrier DNA molecules that will replicate target fragments in host organisms.

2 min -intro overview Chemical reactions need a catalyst to provide a site for the reaction and control the energy flow. Catalysts are made up of enzymes.

In biology classes, students are typically taught that spontaneous generation does not take place. And yet, at the origin of life, life had to arise without parents from abiotic processes. What were those processes that gave rise to the first life?  This case study uses an interrupted format to guide students through the Miller-Urey experiment of 1953, which showed that organic molecules could be produced from abiotic precursors and conditions thought to be prevalent on the early Earth. The case also addresses the more speculative implications about where these reactions may have taken place to create the organic building blocks of life on this planet. The first three parts of the case, which explore the Miller-Urey experiment, are ideal for introductory biology courses and take about 45-50 minutes to complete. The remaining sections, which explore whether such chemical reactions took place in outer space, were used in a non-major astrobiology course and require a further hour to complete.

The Miller-Urey experiment was the first attempt to scientifically explore ideas about the origin of life. Stanley Miller simulated conditions thought be common on the ancient Earth. The purpose was to test the idea that the complex molecules of life (in this case, amino acids) could have arisen on our young planet through simple, natural chemical reactions. The experiment was a success in that amino acids, the building blocks of life, were produced during the simulation. The finding was so significant that it kick started an entirely new field of study: Prebiotic Chemistry. Scientists now have reason to believe that the gases used in the Miller-Urey simulation were not actually the same as those of the ancient atmosphere. Because of this, many experiments have since been done, testing a wide variety of atmospheres and different environmental conditions. The results are overwhelming: the molecules of life can form under a wide variety of ancient Earth-like conditions. Many questions about the origin of life remain to be answered but these findings give strong support to the idea that the first living cells on Earth may have emerged from natural chemical reactions.

You will learn about "Dalton's Atomic Theory" in this video. John Dalton was an English chemist who is very well known today for his work in the development of atomic theory. Let us learn the postulates of Dalton's atomic theory. All matter, whether an element, a compound or a mixture are made up of very tiny particles called atoms. All atoms of a given element are identical in size, mass and chemical properties. Atoms of different elements differ in size, mass and chemical properties. Atoms are indivisible particles which can neither be created nor destroyed in a chemical reaction. Atoms combine together in fixed whole number ratios to form compounds. In a chemical reaction, atoms only get rearranged. An atom of an element does not change into the atom of another element.

October 16 is World Anesthesia Day, celebrating the 170th anniversary of the first successful demonstration of surgical anesthesia. Prior to then, surgery was really unpleasant, to put it mildly -- surgeons turned to alcohol, narcotics and even smacking their patients on the head to induce unconsciousness. Fortunately, anesthesia now allows tens of thousands patients every day to avoid the pain and memories of their procedures. But how does anesthesia work? This week, Reactions looks at scientists' current understanding of what happens when you go under.

The sun shines a massive amount of energy onto the Earth's surface every day. What if humans could take a cue from plants and use sunlight to make their own food? From chloroplasts to carbon dioxide, Reactions creates a hypothetical photosynthetic human and gives a quick crash course on the chemistry of photosynthesis.

Common in cuisine all around the globe, onions are renowned for their ability to make us all look like cry babies. In Reactions' latest video, we get to the bottom of this teary phenomenon and reveal exactly what chemical mechanisms trigger it. The video also features a few chemistry-backed tips you can try at home to stop the tears before they start.

Researchers have pinpointed a catalytic trigger for the onset of Alzheimer's disease - when the fundamental structure of a protein molecule changes to cause a chain reaction that leads to the death of neurons in the brain.

In this video Paul Andersen explains how the chloroplast in plants harnesses power from the Sun to form high energy molecules like glucose. The structure of a chloroplast as well as a brief discussion of the light reaction and Calvin cycle are included.

This case study focuses on the relationship between evolution and plasticity using a hands-on, inquiry-based approach. Students view examples from the literature that illustrate the difference between nature and nurture, or the relative contributions of genes and the environment in shaping phenotypes. Using the Trinidadian guppy system as an example, students learn about seminal work in the field in addition to exploring quantitative genetic techniques used to partition phenotypic variance between genes (G) and the environment (E). They use real data from one of the publications cited in the case to graph reaction norms illustrating GxE interactions at the family and population level. The inquiry-based approach means that students are introduced to new concepts in a stepwise fashion, and asked to develop and build their understanding using causal, explanatory evidence. The case concludes with an exercise in which students apply their knowledge to a real conservation problem in Trinidad and Tobago, where guppies are native. This case would be appropriate for an upper level biology, genetics, or evolution course.

The Hawaiian Bobtail squid has a remarkable symbiotic relationship with a species of marine bacteria that can produce light by a controlled chemical reaction. Also featured on the HHMI DVD, Exploring Biodiversity: The Search for New Medicines, available free from HHMI.

You're probably aware of eight basic blood types: A, AB, B and O, each of which can be "positive" or "negative." They're the most important, because a patient who receives ABO +/- incompatible blood very often experiences a dangerous immune reaction. For the sake of simplicity, these are the types that organizations like the Red Cross usually talk about. But this system turns out to be a big oversimplification. Each of these eight types of blood can be subdivided into many distinct varieties. There are millions in all, each classified according to the little markers called antigens that coat the surface of red blood cells.

4 min animated video illustrating activation energy, substrate, catalyst, products, reaction rate

This game reviews introductory chemistry, including organic compounds and chemical reactions. After you open the game in the PowerPoint attachment, click on slideshow and then view show to operate in full screen mode.  Clicking on a number in the gameboard brings you to a question. When that question has been answered click on the yellow box in the lower right corner and you'll be brought back to the gameboard screen.  Spaces for questions that have already been answered will now appear blank, just like on the TV show.  One way to organize this game is to divide your class into groups of 3-4 students, with a spokesperson for each group and a system for rotating among the groups.  Each group in turn can choose a category and point value, and you will show the question.  The group has a set time to decide on their answer.  If their answer is correct, they earn the points.  If their answer is not correct, the first spokesperson for another group to raise their hand can answer the question to earn the points (with the obvious exception of the true/false items).

Its accuracy has made DNA evidence virtually unassailable. A landmark report published by the National Research Council in 2009 dismissed most forensics as unproven folk-wisdom but singled out DNA as the one forensic science worthy of the name. Yet in recent years Hampikian and other geneticists have begun to question the technology. Thanks to a series of advances-including the polymerase chain reaction, which can multiply tiny amounts of DNA-it's now possible to detect DNA at levels hundreds or even thousands of times lower than when DNA fingerprinting was developed in the 1980s. Investigators can even collect "touch DNA" from fingerprints on, say, a glass or a doorknob. A mere 25 or 30 cells will sometimes suffice. This heightened sensitivity can easily create false positives

It's a sinister condition that affects millions of Americans: addiction. Whether it's alcohol, drugs, food or gambling, it can ruin lives. In support of National Recovery Month, which calls attention to substance abuse issues and treatment services, Reactions takes a look at the chemistry behind addiction.