How Dna Determines Characteristics of Organisms

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Genetically inherited traits depend upon genes found in DNA (de-oxy ribose nucleic acid), the fundamental molecule of chromosomes. DNA carries the information that determines what physical and genetic characteristics can be found in organisms. It does not dictate all of an individual's characteristics, because many aspects of most species are shaped features of the environment in which they live. DNA codes for mRNA which binds with a molecule of transfer RNA in the ribosomes, this tRNA carries a corresponding amino acid, which is coded for by the mRNA. When the MRNA and tRNA bind the amino acid is deposited and binds with an adjacent amino acid forming a polypeptide chain and eventually (after modification by other organelles) forms a protein codes for proteins. A piece of DNA coding for a protein is called a gene. When the protein is produced, we say that the gene is expressed different form of the gene are called alleles which are codes which produce different proteins that lead to characteristics of an organism in general. Proteins are the expressed traits of organisms. Sometimes single proteins other times groups of proteins which account for the phenotype of an organism All organisms begin life a single cell. In the case of humans the cell contains one set of chromosomes contributed by the mother, and one set of chromosomes contributed by the father, all of which contain DNA from the respective parent and carry genetic information that will be passed on to the offspring. As the fertilized egg divides and the cells are instructed by the DNA to differentiate to become all of the different cell types required by the human, the DNA molecules of the fertilized egg must be duplicated over and over, so that each of our trillions of cells contains an exact copy of the DNA contained in the fertilized egg. DNA replication must be tremendously accurate to ensure that

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