Biochemistry, Nanotechnology, and the Future Help (page 3)
Introduction to Biochemistry and Nanotechnology
Chemistry is life! This should be everywhere on shirts and billboards! Chemistry describes the basic building blocks of matter. Atoms, molecules, sub-atomic particles, solids, liquids, and gases make up everything we know to exist in our world.
The fact that chemistry plays a big role in our lives is good news for people interested in working in chemistry or in fields that make use of specific element interactions. There are nearly as many practical applications as fields of study. Let’s look at a few of them.
The word biochemistry describes the chemistry of living systems. Some of these were described when we talked about organic chemistry and the molecules that make up living things.
One of the ways that changes take place in organic molecules is through the life cycle of microorganisms. A single-celled organism, through its metabolism , builds up or breaks down organic molecules.
The biological molecules that make up living cells, organs, systems, and the environment can be divided into four types: proteins, carbohydrates, nucleic acids , and lipids . Most of these molecules are simple structures covalently bonded to similar molecules, but some can reach incredible sizes in molecular terms. They are called macromolecules . Figure 18.1 shows an example of a macromolecule: β -carotene (the yellow color in carrots).
Organic protein molecules serve different functions for living systems. Some offer structural strength, as in the chitin shells of crabs and bone of mammals, some provide transport, as in hemoglobin, some act as blueprints for cell and organ development (DNA), some serve as messengers (hormones) between body organs, and some speed up metabolic reactions (enzymes).
The molecular weight of proteins ranges from 6 × 10 3 to millions of atomic mass units.
Proteins are made up of small molecules that contain an amino group (−NH 2 ) and a carboxyl (−COOH) group. These molecules are called amino acids .
Most protein reactions are made up of many different combinations of amino acids reacting with water, salts, and other elements to create or enhance needed functions. Amino acids can contain a variety of non-protein ions like some of the metals (Zn 2+ , Fe 2+ , Mg 2+ ). For example, the hemoglobin molecule uses iron as a critical part of its function of transferring oxygen within living systems. Amino acids are bonded by peptide (C–N) bonds .
In 1908, a German chemist and medical researcher, Paul Ehrlich, working with aniline dyes in the staining of disease-causing microorganisms discovered that these chemical solutions could also kill the organisms without killing the patient. He shared the Nobel Prize for Medicine with Elie Metchnikoff in 1908 for his work. Two years later, Ehrlich developed the first antibacterial agent, salvarsan, to treat syphilis. Because of his interest in treating diseases with chemical cures, he became known as the father of chemotherapy .
There are many other areas where biochemistry led to important applications. In 1993, Kary Mullis received the Nobel Prize for Chemistry for the invention of a polymerase chain reaction technique for amplifying deoxyribonucleic acid (DNA). That same year, Canadian chemist Michael Smith also received the Nobel Prize for Chemistry for his technique of splicing foreign gene segments, designed to modify the production of a specific protein, into another organism’s DNA. This opened the gates to a flood of research on designer proteins and molecules produced for a specific purpose.
Designed proteins are now being used for everything from better medicines, like insulin to treat diabetes and artificial fabrics to treat and protect burn patients, to industrial foams that clump and eliminate spills from oil tankers and medicines to counteract biological poisons.
For centuries, the environment was so vast and scarcely populated that to humans it was limitless. Wood was used freely, refuse was left wherever convenient, and as long as you are upstream, you could dump whatever you wanted into the rivers and the ocean. Now due largely to better medicines and health care, people are living to their seventh, eighth, and ninth decades. Entire populations are no longer getting wiped out by disease.
Scientists began to look at humankind’s impact on this planet as the world’s population swelled to 6 billion and more. Chemists are becoming mystery investigators. The environment is a very complex mixture of elements with different concentration spikes in many areas. Industrial cities have higher levels of metals and acids in their air than rural countryside areas. Scientists must work together to combine all available information from air and water samples as well as those from industrial emissions in order to piece together the puzzle of total environmental impact. The interconnectedness of all forms of life also affects the complexity of environmental pollution.
In 1995, three chemists, Mario Molina, Sherman Rowland, and Paul Crutzen, warned world leaders of damage being done to the O 3 (ozone) layer. This natural layer of O 3 molecules, located from 9 to 30 miles up into the atmosphere, protects the Earth from cancer-causing and damaging ultraviolet radiation from the sun. They discovered that human-made compounds of nitrogen oxides and chlorofluorocarbon (CFC) gases, used as refrigerants and propellants in spray cans, reacted with atmospheric ozone and reduced it. For their work, they received the 1995 Nobel Prize for Chemistry.
In response to the ozone depletion problem, chemists began looking for replacement refrigerants that didn’t affect ozone. Substitutes were found and the environmental problem lessened.
Many of the elements used today were discovered using cutting-edge technology and equipment. Since the 1960s, many of the elements added to the Periodic Table were human-made and not found in nature. These molecules have unheard of uses that many research and applications chemists and biochemists are just beginning to understand.
Chemists working in the plastics industry came under heavy criticism when landfills became overloaded with the new, disposable containers of plastic and a softer compound called Styrofoam. Environmentalists sounded the alarm for consumers to think before they bought products, especially fast food, that came in these containers.
In order to meet the new concern, chemists doubled their interest in the biodegradability of plastic products. They found that the addition of complex carbohydrates (polysaccharides) to plastics allowed microorganisms to break down the plastic products.
Molecules that can be broken down into simpler elements by microorganisms are called biodegradable.
Carbohydrates make up a large group of organic compounds containing carbon, oxygen, and hydrogen.
Carbohydrates have the general formula of C x (H 2 O) y . There are three main groups of carbohydrates. The first are the simple sugars or monosaccharides . Some of these are the simple fruit sugars, fructose and glucose, with the formula C 6 H 12 O 6 . The simple milk sugar that many people with milk sensitivities have trouble with is lactose. The second group is known as the complex sugars or disaccharides . These are combined sugars that make up honey and table sugar, sucrose and maltose (C 12 H 22 O 11 ). Complex carbohydrates with complicated, folded structures make up the starch added to plastics, as well as cellulose of plant cell walls and rayon (processed cellulose). They have the formula (C 6 H 10 O 5 ) n where n is an extremely large number. These are commonly called macromolecules because of the number of elements and huge size compared to simple molecules. Figure 18.2 shows the structure of glucose and cellulose.
One major drawback to most of the radioactive elements discovered and produced in greater than the extremely small amounts found in nature is that they accumulate in the environment. Land, water, and air are affected by radioactive contamination. Depending on the wind or water flow, radioactive levels remain in place or are spread over a wide region. Different elements have very different decay rates .
Radioactive decay occurs when certain element isotopes are lost and there is a release of energy in the form of radiation (alpha and beta particles and gamma rays).
The three main types of radiation given off during the breakdown of radioactive elements are alpha (α) and beta (β) particles, and gamma (γ) rays. Gamma rays are high-energy electromagnetic waves like light, but with a shorter, more penetrating wavelength. Though alpha and beta particles are dangerous to living things since they penetrate cells and damage proteins, gamma rays are much more penetrating and harmful, stopped only by thick, dense metals like lead.
The waste produced in different forms of matter transformation must eventually be broken down. This is an area of ongoing concern and study for many governments who are trying to figure out how to dispose of radioactive wastes from nuclear power plants and atomic weapons. Protecting their populations from handling accidents or terrorist nuclear threats will continue to promote research in understanding the reactivity and degradation of radioactive compounds and elements.
Research started from the middle of the 1900s and on pointed toward particles of even smaller dimensions than atoms, called hadrons and leptons .
Hadrons are made up of baryons and mesons . Baryons are made up of protons, neutrons, and other short-lived particles. Mesons are made up of pions, kaons , and other short-lived particles. Leptons are made up of electrons and different types of neutrinos ( tau and muon ). You can’t really see or measure any of these, but only record their effects. It is a lot like the wind. Leaves can blow around like crazy, but unless there is dust in the air, you can’t see exactly what is happening.
Hadrons are also made up of even tinier particles called quarks . Six kinds of quarks have been described. They are: up, down, charm, strange, top , and bottom . Each has a different charge and there are also anti-quarks with the opposite charges of their twin.
Strange and charming molecular chemists work with protons, electrons, and neutrons as we have seen throughout our study of chemistry. Quarks and quark theory occupy the thoughts of the theoretical physicist. These scientists search for insight into nuclear binding energy, the energy that keeps various nucleons together in the nucleus, and how everything comes together in the greater picture of chemical interactions.
The subject of the tsunami (really big wave) of current scientific research is in the area of nanotechnology . An entire special issue, the September 2001 issue of Scientific American , was devoted entirely to the topic. The “big guns” in the field described their work in the areas of Medical Nanoprobes, Buckytube Electronics, Living Machinery, Atom-Moving Tools, New Laws of Physics, and Nano Science Fiction. The cover story of Scientific American’s January 2003 issue describes “The Nanodrive.” Through the use of individual silicon molecules and etching onto a special polymer medium, computer drives of the future will process and perform data storage tasks of several gigabytes of information on a chip the size of a postage stamp.
Nanotechnology is the study of elements at the single atom level or 10 –9 (1 billionth of a meter) scale.
To put the nanometer scale into everyday measurements, think of the size of a person 2 meters tall (about 6 feet). A gnat, 2 millimeters long is 1000 times smaller than a person 2 meters tall. One cell in a gnat’s body has a nucleus of about 2 micrometers long or 1000 times smaller than the size of the entire gnat’s body. A nanoscale molecule is roughly 2–10 nanometers long or 1000 times smaller than the length of the nucleus of a gnat’s cell.
Nanomolecules are super small!
American molecular chemist, Richard Smalley, at Rice University in Houston, Texas, studies atoms and molecules at the nanomolecular level. His research with soccer ball-shaped carbon molecules led him to receive the 1996 Nobel Prize for Chemistry along with Robert Curl, Jr. and Harold W. Kroto for the discovery of fullerenes (C 60 ). Smalley’s current research is directed toward fullerene nano structures and involves the investigation of carbon single-wall nanotubes , nanoscale tubular structures built of graphene sheets (fullerenes). His research is geared toward the development, production, characterization, and use of tubular fullerene molecules, nanotube single-crystal growth, nanotube fibers, and other nanotechnology materials and applications.
Currently the “star” of worldwide nanotechnology attention is focused on molecular electronics. Dr. James M. Tour, head of the molecular electronics effort at the Center for Nanoscale Science and Technology at Rice University, whose work focuses on the super small world of nanotechnology, has proposed experiments in which computer electronics are built from the “bottom up,” molecule by molecule. Bottom up nanoscale construction is patterned after nature, with molecules forming cells that form tissues that form organs that form systems that finally form a total organism or person.
Molecular electronics uses individual molecules or very small groups of molecules (carbon, oxygen, hydrogen, and nitrogen) to serve as transistors, conductors, and other electrical parts of computers and circuits.
Current computer processing “chips” are built from the “top down” in incredibly clean (dust-free) environments onto etched gold plates.
Tour’s scientific research areas include molecular electronics, chemical self-assembly, carbon nanotube modification and composite formation, and synthesis of molecular motors and nanotrucks (molecules that bind and transport other molecules back and forth a short distance using an external electrical field) to name a few.
Tour has also attracted the interest of the National Science Foundation and others in his mission to teach chemistry, physics, biology, and materials science at the nanomolecular level through the animated adventures of actual molecules chemically synthesized in his Rice University laboratory. This project, called NanoKids , seeks to open up science with computer animation, music, and a MTV style and make nanoscale science learning fun and simple.
Nanotechnology research has gained the attention of international companies like IBM and Microsoft. Computer circuitry built 100 times smaller than the tiniest components today seems almost miraculous. Molecular chemists are talking about building with atoms and molecules that are not visible with the strongest microscopes.
So how do we know this can be done? Simple chemical interactions and known properties of the elements are used. In fact, most nanomolecules are carbon-based polymers that are very similar to naturally occurring substances that handle electrical impulses all the time, like brain neurons.
Similar to their transferal of electrical impulses in the body, individual molecules alternate between two forms. They act like molecular on/off light switches and can store information or pass it along in a split second or less.
Research is being done to build nanodrives that write, read, and erase data using atoms and molecules, would hold several gigabytes of data and fit on the top of one key from a computer keyboard.
The future of chemistry is as big as our planet and as small as nanomolecules that can never be seen by the human eye. Research and applications of chemistry that consider everything from the purification of our air, to the speed of our computers will be increasingly important for decades to come. The materials and machines of science fiction will become reality as humankind grows in its knowledge of this fascinating science.
Practice problems for these concepts can be found at – Biochemistry and Nanotechnology Practice Test
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