Temporal coding of pitch in the cat auditory nerve. (Left)... - Figure 7 of 11. Sulli's Biology: Ch 8 Photosynthesis. Photosynthesis! Even Spongebob likes it! Homeostasis takes energy. Where does it come from? Energy is the ability to do work. Organisms are doing work all the time. Even when at rest, organisms are using energy for things such as transporting molecules across the cell membrane, building proteins, responses to chemical signals, and contracting muscles. Energy can be found in many forms including light, sound, heat, and chemical. The energy used in ATP is found in the bonds between the phosphate groups. Storing Energy ADP (adenosine diphosphate) is a compound that looks almost like ATP, except that it has two phosphate groups instead of three. This characteristic of ATP makes it exceptionally useful as a basic energy source for all cells.
Analogy When a phosphate group is added to an ADP molecule, ATP is produced. Heterotrophs and Autotrophs The energy for all organisms to live ultimately comes from the sun. Autotroph - organisms that make their own food from the sun's energy. Lesson 8.2. What is the shape of a molecule? - George Zaidan and Charles Morton. The Concept of Symmetry in Biology. MIT discovers the location of memories: Individual neurons. Update 12/2/15: We've now followed up on this story: The more we learn about memory, the weirder it gets. The original continues below. MIT researchers have shown, for the first time ever, that memories are stored in specific brain cells.
By triggering a small cluster of neurons, the researchers were able to force the subject to recall a specific memory. By removing these neurons, the subject would lose that memory. As you can imagine, the trick here is activating individual neurons, which are incredibly small and not really the kind of thing you can attach electrodes to. To do this, the researchers used optogenetics, a bleeding edge sphere of science that involves the genetic manipulation of cells so that they're sensitive to light. Now, just to temper your excitement, we should note that MIT's subjects in this case are mice -- but it's very, very likely that the human brain functions in the same way. Optogenetics: A wireless, optical router for your brain. Ready for the Bleeding Edge Science Word of the Day? Optogenetics. It’s even weirder than it sounds, too: optogenetics is the manipulation of a cell’s functions with light (usually lasers).
Today, American startup Kendall Research has announced that it has made a wireless optogenetics device that the company’s founder calls “a wireless router for the brain.” To understand the importance of optogenetics, and to marvel at the magic of hooking your brain up to a network with a wireless router, we have to first look at how researchers currently investigate cell function, and thus just how groundbreakingly different the optogenetic approach is. Basically, as it stands, we have very limited control animal cells — especially brain cells.
We know that neurons communicate by firing an electric signal, but we don’t know how a cluster of electrical impulses magically becomes a mental image of an elephant, the sensation of love, or a eureka-like idea. Now, back to the “wireless router” claim. Weekly biological research | E-books and Blogs Job. Review Proposals on Elance. 24.1 Functional Groups and Classes of Organic Compounds. Skills to Develop To know the major classes of organic compounds and identify important functional groups. You were previously introduced to several structural units that chemists use to classify organic compounds and predict their reactivities. These functional groups, which determine the chemical reactivity of a molecule under a given set of conditions, can consist of a single atom (such as Cl) or a group of atoms (such as CO2H). The major families of organic compounds are characterized by their functional groups. Figure 24.1.1 summarizes five families introduced in earlier chapters, gives examples of compounds that contain each functional group, and lists the suffix or prefix used in the systematic nomenclature of compounds that contain each functional group.
Figure 24.1.1: Major Classes of Organic Compounds The first family listed in Figure 24.1.1 is the hydrocarbons. Figure 24.1.2: Common Nomenclature for Aromatic Ring Substitutions Summary. Samarotto, Review of Krebs. Chemical bond. A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds; or through the sharing of electrons as in covalent bonds. The strength of chemical bonds varies considerably; there are "strong bonds" or "primary bonds" such as covalent or ionic or metallic bonds, and "weak bonds" or "secondary bonds" such as dipole–dipole interactions, the London dispersion force and hydrogen bonding.
Since opposite charges attract via a simple electromagnetic force, the negatively charged electrons that are orbiting the nucleus and the positively charged protons in the nucleus attract each other. An electron positioned between two nuclei will be attracted to both of them, and the nuclei will be attracted toward electrons in this position.
This attraction constitutes the chemical bond. Overview of main types of chemical bonds W.