Human Genetic Code and Human Chromosomes:

Chromosomes as discussed previously are the lengths of DNA grouped together, between 5000 and 50,000 genes per Chromosome. Not only do the genes between species vary, but the number and length of chromosomes. For instance a garden pea for instance has 14 chromosomes, a potato 48 and a crayfish 200.

Human Genetic Code and Human Chromosomes: There are 46 chromosomes in the living cell of a human being and these chromosomes carry the genetic information that decides how a person will grow- whether he or she will be dark or fair, short or tall, blue-eyed or brown. But the sex cells, the female egg and the male sperm each have only 23 chromosomes. They fuse at conception to make a cell containing 46 chromosomes, half from each partner and it is this mixing of two sets of characteristics that creates the diversity of human life. Thus, Chromosomes are often spoken of as 23 pairs. The major difference between humans are the 23rd chromosomes - X and y. The Chromosome X is much larger and has more genetic information than the smaller y chromosome. o women have 2 X chromosomes and 0y chromosomes, while o men have 1X and 1y chromosome. However, sperm produced by men can be of two types, X or y. In terms of bases, the entire DNA code of the human being is around 3 Billion, or 3 gigabytes of memory potential for chemical triple-base code. However up to 85% of the entire DNA code appears to code chemical material, the rest is currently classed as "junk DNA' by the experts in this field. This non-coding material is found throughout the code for functioning and redundant genes as well as on its own. It is also estimated that only around 5% of all DNA of a human being is functioning, the rest (10%) being redundant genes. There is estimated to be 100,000 genes in the genetic pool for humans. Estimated percentage of Human DNA coding genes If the DNA contained in the 46 human chromosomes were laid out end to end it would stretch several metres in length. Thus there is a very large amount of genetic detail embedded in these very long DNA strands, yet they are folded and compacted into the tiny space of the cell nucleus, which is only a few microns in diameter

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Deoxyribonucleic acid (DNA)

Deoxyribonucleic acid (DNA) is the basic genetic material of most living organisms. Although a large and apparently complex molecule, the structure of DNA is in fact astonishingly simple. A single DNA molecule consists of two separate strands wound around each other to form a double-helical (spiral) structure. Each strand is made up of a combination of just four chemical components known as nucleotides- all of which have the same basic composition. Each nucleotide consists of a sugar molecule (deoxyribose) linked to a phosphate group to form the helical backbone; different nucleotides are distinguished only by the identity of the nitrogen-based unit called the nucleotide base bonded to the sugar molecule.

The four bases are:

(A) adenine (C) cytosine (G) guanine (T thymine

The bases lie in the central region of the double helix, with each base linked by hydrogen bonds to specific complementary base on the partner strand. The base pair rule states that wherever you have an A on one strand, there will be a T at the same relative position on the other strand; wherever you have a G on one strand, you will have a C on the other strand. In addition, the number of molecules of A in a sample always equals the number of molecules of T. Similarly, the number of C molecules always equals the number of molecules of G. DNA is therefore basically a linear information macro molecules much like the long strips of computer tape used in the first computers. A typical DNA base sequence might be: 5'-AGCTTATTGCATAAGCGCGAT-3' 5' and 3' These refer to the left-hand and the right-hand ends respectively of a DNA or RNA base sequence.

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Gene families

A gene family is a group of genes that share important characteristics. In many cases, genes in a family share a similar sequence of DNA building blocks (nucleotides). These genes provide instructions for making products (such as proteins) that have a similar structure or function. In other cases, dissimilar genes are grouped together in a family because proteins produced from these genes work together as a unit or participate in the same process.

Classifying individual genes into families helps researchers describe how genes are related to each other. Researchers can use gene families to predict the function of newly identified genes based on their similarity to known genes. Similarities among genes in a family can also be used to predict where and when a specific gene is active (expressed). Additionally, gene families may provide clues for identifying genes that are involved in particular diseases. Sometimes not enough is known about a gene to assign it to an established family. In other cases, genes may fit into more than one family. No formal guidelines define the criteria for grouping genes together. Classification systems for genes continue to evolve as scientists learn more about the structure and function of genes and the relationships between them

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Deoxyribonucleic Acid

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences. DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder. An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell

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RNA 5' Cap:

The 5' cap is a specially altered nucleotide end to the 5' end of precursor messenger RNA and some other primary RNA transcripts as found in eukaryotes and, as a special exception, caliciviruses such as norovirus. The process of 5' capping is vital to creating mature messenger RNA which is then able to undergo translation. Capping ensures the messenger RNA's stability while it undergoes translation in the process of protein synthesis, and is a highly regulated process which occurs in the cell nucleus. 5' cap structure Ribose structure showing the positions of the 2', 3' and 5' carbonsThe 5' cap is found on the 5' end of an mRNA molecule and consists of a guanine nucleotide connected to the mRNA via an unusual 5' to 5' triphosphate linkage. This guanosine is methylated on the 7 position directly after capping in vitro by a methyl transferase. It is referred to as a 7-methylguanosine cap, abbreviated m7G/ Further modifications include the possible methylation of the 2' hydroxy-groups of the first 3 ribose sugars of the 5' end of the mRNA. The methylation of both 2' hydroxy-groups is shown on the diagram

Functionally the 5' cap looks like the 3' end of an RNA molecule (the 5' carbon of the cap ribose is bonded, and the 3' unbonded). This provides significant resistance to 5' exonucleases… Capping process The starting point is the unaltered 5' end of an RNA molecule. This features a final nucleotide followed by three phosphate groups attached to the 5' carbon. 1. One of the terminal phosphate groups is removed (by a phosphatase), leaving two terminal phosphates. 2. GTP is added to the terminal phosphates (by a guanylyl transferase), losing two phosphate groups (from the GTP) in the process. This results in the 5' to 5' triphosphate linkage. 3. The 7-Nitrogen of guanine is methylated (by a methyl transferase). 4. Other methyltransferases are optionally used to carry out methylation of 5' proximal nucleotides.

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Biochemistry-protiens:

Proteins are linear polymers built from 20 different L-α-amino acids. All amino acids possess common structural features, including an α carbon to which an amino group, a carboxyl group, and a variable side chain are bonded. Only proline differs from this basic structure as it contains an unusual ring to the N-end amine group, which forces the CO–NH amide moiety into a fixed conformation.The side chains of the standard amino acids, detailed in the list of standard amino acids, have different chemical properties that produce three-dimensional protein structure and are therefore critical to protein function. The amino acids in a polypeptide chain are linked by peptide bonds formed in a dehydration reaction. Once linked in the protein chain, an individual amino acid is called a residue, and the linked series of carbon, nitrogen, and oxygen atoms are known as the main chain or protein backbone. The peptide bond has two resonance forms that contribute some double-bond character and inhibit rotation around its axis, so that the alpha carbons are roughly coplanar. The other two dihedral angles in the peptide bond determine the local shape assumed by the protein backbone.

Due to the chemical structure of the individual amino acids, the protein chain has directionality. The end of the protein with a free carboxyl group is known as the C-terminus or carboxy terminus, whereas the end with a free amino group is known as the N-terminus or amino terminus. Protein is generally used to refer to the complete biological molecule in a stable conformation, whereas peptide is generally reserved for a short amino acid oligomers often lacking a stable three-dimensional structure. However, the boundary between the two is not well defined and usually lies near 20–30 residues. Polypeptide can refer to any single linear chain of amino acids, usually regardless of length, but often implies an absence of a defined conformation..

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Biomolecule

A biomolecule is any organic molecule that is produced by living organisms, including large polymeric molecules such as proteins, polysaccharides, and nucleic acids as well as small molecules such as primary metabolites, secondary metabolitess, and natural products. As organic molecules, biomolecules consist primarily of carbon and hydrogen, nitrogen, and oxygen, and, to a smaller extent, phosphorus and sulfur. Other elements sometimes are incorporated but are much less common. Types of biomolecules A diverse range of biomolecules exist, including: * Small molecules: Lipid, phospholipid, glycolipid, sterol Vitamin Hormone, neurotransmitter Carbohydrate, sugar Disaccharide * Monomers: Amino acids Nucleotides Monosaccharides * Polymers: Peptides, oligopeptides, polypeptides, proteins Nucleic acids, i.e. DNA, RNA Oligosaccharides, polysaccharides (including cellulose) Lignin

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