How did researchers discover that cellular functions are carried out by proteins working in a complex?
536417
Many of the orignal studies were based on mutations in bacteria which halt growth or have other phenotypes, where it was found that mutations could be labeled into several groups, and that if bacteria from different groups mated, then the phenotype is restored.  From this it was deduced that the mutations were in coding regions for proteins that exist in a network ie A to B to C, and usually proteins like A and B were in a complex.  Today its a large part of cell and molecular biology to figure out if proteins are in complexes, and what the complex does.  Its not necessarily important that A and B are in a complex, but what that complex does; since that is the proteni function in cells.  So if A and C are in a complex, the complex has a certain function.  if B and C are in a complex, then there is a different function.  Drug companies have been exploiting this type of knowledge for a long time, but what is more impt is the understanding of how proteins interact with other proteins, and how they regulate cellular functions.  Once this is understood, then drugs can be rationaly designed.  Even then, however, it's not possible to guarantee patient efficacy.  \n\nWe just had a great lecture by Gordon Mills, an expert in the PTEN protein pathway, and he talked about the dozens of drugs made against various members of this pathway, and noted that so far none of these drugs are effective in patients, although they work in the test tube and in mice.  So, drug discovery is a very difficult issue and takes billions of dollars for one drug to be delivered to market (and 10 years or more).
1135493
Biology has become such a vast research enterprise that it is not generally regarded as a single discipline, but as a number of clustered sub-disciplines. This article considers four broad groupings. The first group consists of those disciplines that study the basic structures of living systems: cells, genes etc.; the second group considers the operation of these structures at the level of tissues, organs, and bodies; the third group considers organisms and their histories; the final constellation of disciplines focuses on their interactions. It is important to note, however, that these boundaries, groupings, and descriptions are a simplified characterization of biological research. In reality, the boundaries between disciplines are fluid, and most disciplines frequently borrow techniques from each other. For example, evolutionary biology leans heavily on techniques from molecular biology to determine DNA sequences, which assist in understanding the genetic variation of a population; and physiology borrows extensively from cell biology in describing the function of organ systems.
3712
In 1824, Rene Dutrochet discovered that "the cell is the fundamental element in the structure of living bodies, forming both animals and plants through juxtaposition." However, the first sightings of the internal action of the cell were made by Robert Brown. In Berlin, Johannes Muller created connections between biology and medicine, prompting the connective thinking of his students, such as those of Theodore Schwann. Schwann created the term "cell theory" and declared that plants consisted of cells. This declaration was made after that of Matthias Schlieden's (1804 - 1881) that animals are composed of cells.\n\nLeeuwenhoek was first to describe cells and coined the word more than 100 years before, but he didn't really make the leap to how fundamental the unit was.
313675
do you mean interactions BETWEEN nucleic acids and proteins?  If so there's a lot of ways you can study that - you can do a footprint analysis - digest the nucleic acid in the presence of the protein and see what piece gets protected to see where the protein binds if you know the identity of the two interacting molecules.  If you don't know their identity you can try a gel-shift assay where DNA will move at different rates on a gel in the presence and absence of various proteins.  If you know the protein but not the DNA you can try an affinity column with the protein immobilized and then try to determine which DNA sequences bind.  You can also try to determine the crystal structure of a co-crystal if you have a lot of the two materials.  good luck!
1003762
Hi.  I am a scientist who works in the pharmaceutical/biotech industry.  In my field, we do a wide variety of things:\n\nIn terms of cell-based drug discovery assays, we can take cells from a person, grow them in petri dishes and test new drugs that we've developed on them to see if the cells live or die in response to the drug. (Of course, this is in very VERY general terms; it's much more complicated than that).  If we want to test a variety of cell types against a variety of chemical compounds, we can use automated technology called High Throughput Screening... In HTS, very sophotisticated robots carry out 96 or 384 experiments at a time.   \n\nMolecular biologists can change cells by adding viruses or DNA plasmids and allowing the virus or plasmid to assimilate itself into the host cells's normal DNA.  This process is called transfection.  This is useful if you want to overexpress a gene or condition that you want to study or model/test a drug against.  Molecular biologists can also clone these plasmids and grow more of them for large-scale experiments.  Two other common techniques that molecular biologists use are PCR (in which we can look at an organism's  genes) and Western Blots (that allows us to look at certain proteins that are produced / expressed within cells).\n\nHistologists can take tissues and use immunohistochemistry (IHC) to detect the presence of certain proteins or other characteristics of the cells.  In IHC, antibodies which targe a certain cellular protein are applied to a preserved tissue and that antibody can then be detected by fluorescence or an enzyme-based coloration process.  \n\nThese are just a few of the techniques that we use to develop new drug therapeutics.  Be aware that the process to develop one drug from start to finish takes about 15-20 years and about $1billion, which might give you an idea of exactly how complicated it can get once you get into detail on the topic.
734251
dna is a chemical code inside every living cell that determines how the cell functions.
959642
the body works like a system because: different cells perform different functions.  A group of cells which perform the same function, make up a tissue.  An organ is made up from a number of different tissues all working together to perform a specific function.  \n\nFor example; certain cells have the ability to contract and relax.  One group of these cells are know as smooth muscle cells - they all have similar structure and function the same way.  A group of these cells working together, make up smooth muscle tissue.  The stomach is made up of a number of different types of tissues, including smooth muscle tissue.  Each tissue in the stomach has a certain job to do.  The smooth muscle tissue is responsible for mixing the food with the various enzymes that other tissues in the stomach produce.  The stomach is an organ because it is made up of many tissues all doing different things in order to accomplish a common goal or goals.  The goals of the stomach are to begin the chemical digestion of food and to churn the food to mix it with the enzymes.\n\nHope this makes sense - it turned out to be a bit wordy.
1109393
enzymes are specialized proteins that act as catalysts that speed up chemical reaction in the living cells
860299
biochemistry\nClick to learn more...\nscience concerned chiefly with the chemistry of biological processes; it attempts to utilize the tools and concepts of chemistry, particularly organic and physical chemistry, for elucidation of the living system. The science has been variously referred to as physiological chemistry and as biological chemistry. Molecular biology, a term first used in 1950, is used to describe the area of research, closely related to and often overlapping biochemistry, conducted by biologists whose approach to and interest in biology are principally at the molecular level of organization. The related field of biophysics brings to biology the techniques and attitudes of the physicist. Cell biology is concerned with the organization and functioning of the individual cell and depends greatly on biochemical techniques. As the study of life forms demonstrated similar or even identical processes occurring in widely divergent species, it has taken the biochemist to unravel the underlying chemical basis for these phenomena. Biochemists study such things as the structures and physical properties of biological molecules, including the proteins, the carbohydrates, the lipids, and the nucleic acids; the mechanisms of enzyme action; the chemical regulation of metabolism; the molecular basis of genetic expression; the chemistry of vitamins; chemoluminescence; biological oxidation; and energy utilization in the cell. The study of the chemistry of the immune response offers the possibility of treatment and cure for such diseases as AIDS and lupus.\n\n   1.   The study of the chemical substances and vital processes occurring in living organisms; biological chemistry; physiological chemistry.\n   2. The chemical composition of a particular living system or biological substance: viral biochemistry.
20677
That's a great question. There's a whole field called developmental biology that researches how organisms develop from single cells into complex organisms. The short answer is that different genes get turned on and turned off at the right times, and this causes cells to divide, move, differentiate (turn into different kinds of cells) and make connections with other cells. A lot of work has been done and a lot of work is still being done on figuring out exactly what the signals are that make this happen in an organized way.\n\nAn important reason that a lot of people work on this, in addition to understanding our world and ourselves better, is that the genes that work during development are often the genes that get messed up in cancer and other diseases. By understanding their normal role, we can better understand what happens when they aren't working right.
1185018
Well, there are quite a few ways. You could look and see that DNA has A bonded to  T and G bonded to C (which you could look up their exact make-up to discern them from other compounds, they are just simple nucleotides which form a chain to create what we call DNA). \n\nYou could tell by how their subunits are connected. DNA will have repetitive phosphodiester linkages (bonds between a  phosphate of one nucleotide and a carbon of another) which hold it together. Proteins on the other hand will have peptide linkages (bonds between a carboxyl group of an amino acid to an amino group of another; amino acids are much like nucleotides in DNA, they form chains to create proteins). \n\nDNA will be in a double helix, while proteins will be in all sorts of conformations (which is where they get their uses). \n\nSince proteins are just chains of amino acids you could recognize the specific amino acids on proteins (there are only 21 and all of their structures are known. note:*Ohio State University claims to have found a 22nd* ), thus making the substance a protein and not DNA since DNA has no amino acids in it. \n\nBut assuming  you could only look at the atoms like your question states and not how or what they they are connected to, you could still discern DNA from protein. DNA has phosphate since nucleotides (the things that make up DNA) are composed of a nitrogenous base, a deoxyribose sugar, and a phosphate group, while proteins have amino acids (none of which have phosphates) connected by carbons and nitrogens. So if for some reason you have the known number of atoms in two substances, but didn't known how they were connected and you were asked which one is the protein and which one is the DNA sequence. You would conclude that the one with the phosphate is indeed the DNA.
233031
One function of proteins is structural.  They are kind of like the framework of a cell, known as a cytoskeleton.  Proteins also make up structural features such as your hair.  The second function of proteins in the human body is a biochemical function.  Our enzymes are proteins.  Without them we would not be able to digest our food, use the energy we get from food, repair our cells, carry oxygen from the air we breathe around our body, fight off infection, and many, many other things.  Proteins are so important to the human body that the function of our DNA is to code for our proteins!  That's what DNA mostly does, it just tells our body what protiens to make and in what amounts.
234588
It is called biochemestry
654214
In humans and other mammals, the process is orchestrated in the developing embryo by a set of proteins called "Hox proteins" that control the timely expression of genes -- and thereby control the production of the "next stage" proteins needed for embryonic development. The action of Hox proteins must, in turn, be coordinated to assure the accurate development of an embryo; that coordination involves another set of proteins that act as molecular choreographers. \n\n"Failure of the molecular systems that control development prevents normal embryonic growth, and alterations in these control systems can lead to a wide variety of cancers," explains Kamal Shukla, program director in NSF's division of cellular and molecular biosciences, which funds the research. "Understanding the molecular mechanisms that control normal embryonic development is the first step in developing strategies to prevent these errors, or to repair them when they have gone wrong." Cynthia Wolberger at Johns Hopkins and Michael Cleary at Stanford have made a major step forward in the understanding of these crucial molecular events, Shukla believes. \n\nThis research, which uses x-ray crystallography, has led to the determination of the atomic structure of "HoxB1" and a protein called Pbx1, all bound to a fragment of DNA. Pbx1 plays a central role in the modulation of Hox protein function, and mutations in it have been implicated in some childhood leukemias. By visualizing how Pbx1 interacts with a Hox protein and with DNA, Wolberger and colleagues have determined the precise way in which the proteins interact with one another to control development. \n\nPbx1, by interacting with Hox proteins, is able to control the expression of many different types of proteins, says Wolberger. "Understanding how they interact with partner proteins such as Pbx1 and with DNA is key to knowledge of the mechanism by which a developing organism grows from a single fertilized egg cell into a fully differentiated creature with head and tail, arms and legs."
452841
Yes, it is C, pardner.\n\nHelps cell to continually turn over intracellular proteins before they get too old or nonfunctional. Breaks them up into lttle pieces. On the macro level, keeps you looking like yourself instead of slowly fading away.\n\n"Lysosomes contain various hydrolytic enzymes that are capable of digesting nucleic acids, polysaccharides, fats and proteins. The inside of a lysosome is acidic."\nhttp://biology.about.com/library/weekly/...\n\n2004 Nobel Prize:\n"Proteasomes are complex structures inside cells that break down proteins. Ubiquitin proteasome system is a barrel-shaped multi-protein complex that can specifically digest other proteins into short polypeptides and amiino acids in an ATP-driven reaction."\nhttp://en.wikipedia.org/wiki/proteasome...\n\n\nHere is a good site for checking out things in this subject area. It is a wonderful biology site.\n\nhttp://users.rcn.com/jkimball.ma.ultrane...\n\nThe Golgi apparatus functions in transporting materials out of the cell. \n\nDon't forget to pull up the urls and read more.
861172
they make proteins. And they aren't a cell, they're just part of a cell. So, for instance, if your body needs some insulin, the nucleus sends the ribosomes the instructions in the form of messenger RNA, and transfer RNA brings the appropriate amino acids to the Ribosomes, where the desired protein (in this case, insulin) is assembled out of amino acids.
80083
Let's get semantical on you.\n\nWhat is biology?... the study of life, right?\n\nWhat is life? Or maybe better way of phrasing that question is: What is alive?\n\nAnything that meets all the following criteria:\n\nAble to obtain and use energy. \nAble to reproduce.\nAble to respond and adapt to their environment. \n\nSo when we study biology we study things that can do these different things and, more specifically, we study how living things do these different things. Basically, we're trying to understand how living things live.\n\nNow, back to you question concerning chemistry...\n\nHow do you suppose living things are able to do all the things on the list above? You guessed it: CHEMISTRY.\n\nAll the processes above are carried out by chemical reactions that take place between different molecules. Most of these reactions include tiny sub-microscopic machines called proteins. All these proteins are doing is carrying out very specific chemical reactions.\n\nSo when you boil it all down, biology is nothing more than the study of chemical processes that take place in living systems. In fact, it's these chemical processes that allow for life to begin with.