ÿþ<html> <head> <title>STRUCTURE OF PROTEINS </title> </head> <body background="penguin.jpg"> <h1><font color=red ><img src="filter.gif">ALBUMIN</font></h1> <embed src="albumin 1.pdb" width=300 height=300 frank=no display3D=ball&stick script="set background yellow;set ambient 200; zoom 125" startspin=false> <font size=5 color=red ><P> The image above is the structure of an albumin.Serum albumin, often referred to simply as albumin is the most abundant plasma protein in humans and other mammals. Albumin is essential for maintaining the osmotic pressure needed for proper distribution of body fluids between intravascular compartments and body tissues. The human version is human serum albumin. Bovine serum albumin, or BSA, is commonly used in molecular biology laboratories. Albumin is negatively charged. The glomerular basement membrane is also negatively charged; this prevents the filtration of albumin in the urine. In nephrotic syndrome, this property is lost, and there is more albumin loss in the urine. Nephrotic syndrome patients are given albumin to replace the lost albumin. Because smaller animals (for example rats) function at a lower blood pressure, they need less oncotic pressure to balance this, and thus need less albumin to maintain proper fluid distribution. Among the functions of this unique molecule are Maintains osmotic pressure,transports thyroid hormones,transports other hormones, particularly fat soluble ones,transports fatty acids ("free" fatty acids) to the liver,transports unconjugated bilirubin,transports many drugs,competitively binds calcium ions (Ca2+) and as buffers pH. </font> <h1><font color=red ><img src="filter.gif">DEOXYRIBONUCLEIC ACID</font></h1> <embed src="dna.pdb" width=300 height=300 frank=no display3D=ball&stick script="set background yellow;set ambient 200; zoom 125" startspin=true> <font size=5 color=red><P> Deoxyribonucleic acid (DNA) is a nucleic acid  usually in the form of a double helix  that contains the genetic instructions monitoring the biological development of all cellular forms of life, and many viruses. DNA is a long polymer of nucleotides (a polynucleotide) and encodes the sequence of the amino acid residues in proteins using the genetic code, a triplet code of nucleotides. DNA is thought to date back to between approximately 3.5 to 4.6 billion years ago.[1] In complex eukaryotic cells such as those from plants, animals, fungi and protists, most of the DNA is located in the cell nucleus. By contrast, in simpler cells called prokaryotes, including the eubacteria and archaea, DNA is not separated from the cytoplasm by a nuclear envelope. The cellular organelles known as chloroplasts and mitochondria also carry DNA. DNA is often referred to as the molecule of heredity as it is responsible for the genetic propagation of most inherited traits. In humans, these traits can range from hair color to disease susceptibility. During cell division, DNA is replicated and can be transmitted to offspring during reproduction. Lineage studies can be done based on the facts that the mitochondrial DNA only comes from the mother, and the male Y chromosome only comes from the father. </font> <h1><font color=red ><img src="filter.gif">RIBOSOME</font></h1> <embed src="ribosomes.pdb" width=300 height=300 frank=no display3D=ball&stick script="set background yellow;set ambient 200; zoom 125" startspin=true> <font size=5 color=red><P> A ribosome is an organelle composed of ribosomal RNA and ribosomal proteins (known as a Ribonucleoprotein or RNP). It translates Messenger RNA (mRNA) into a polypeptide chain (e.g., a protein). It can be thought of as a factory that builds a protein from a set of genetic instructions. Ribosomes can float freely in the cytoplasm (the internal fluid of the cell) or bind to the endoplasmic reticulum, or to the nuclear envelope. Since ribosomes are ribozymes, it is thought that they might be remnants of the RNA world. The structure and function of the ribosomes and associated molecules, known as the translational apparatus, has been of research interest since the mid 20th century and is a very active field of study today. </body> </html>
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