DNA
Wikipedia
Introduction to Scientific Processes
Deoxyribonucleic acid (DNA) is a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic hereditary information. The two DNA strands are known as polynucleotides as they are composed of monomers called nucleotides. Each nucleotide is composed of one of four nitrogenous bases (cytosine [C], guanine [G], adenine [A] or thymine [T]), a sugar called deoxyribose, and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone.
It is the sequence of these four bases along the backbone that encodes genetic information. Bases of the two polynucleotide strands are bound together by hydrogen bonds, according to base pairing rules (A with T and C with G), to make double-stranded DNA. The bases are divided into two groups-- pyrimidines and purines. In DNA, the pyrimidines are thymine and cytosine whereas the purines are adenine and guanine. The two strands of DNA run in opposite directions to each other and are thus antiparallel. DNA is replicated once the two strands separate.
A gene is a unit of heredity that corresponds to a region of DNA that influences the form or function of an organism in specific ways. DNA is found as linear chromosomes in eukaryotes, and circular chromosomes in prokaryotes.
A chromosome is an organized structure consisting of DNA and histones. The set of chromosomes in a cell and any other hereditary information found in the mitochondria, chloroplasts, or other locations is collectively known as a cell's genome.
In eukaryotes, genomic DNA is localized in the cell nucleus, or with small amounts in mitochondria and chloroplasts. In prokaryotes, the DNA is held within an irregularly shaped body in the cytoplasm called the nucleoid. The genetic information in a genome is held within genes, and the complete assemblage of this information in an organism is called its genotype. Genes encode the information needed by cells for the synthesis of proteins, which in turn play a central role in influencing the final phenotype of the organism.
It is the sequence of these four bases along the backbone that encodes genetic information. Bases of the two polynucleotide strands are bound together by hydrogen bonds, according to base pairing rules (A with T and C with G), to make double-stranded DNA. The bases are divided into two groups-- pyrimidines and purines. In DNA, the pyrimidines are thymine and cytosine whereas the purines are adenine and guanine. The two strands of DNA run in opposite directions to each other and are thus antiparallel. DNA is replicated once the two strands separate.
A gene is a unit of heredity that corresponds to a region of DNA that influences the form or function of an organism in specific ways. DNA is found as linear chromosomes in eukaryotes, and circular chromosomes in prokaryotes.
A chromosome is an organized structure consisting of DNA and histones. The set of chromosomes in a cell and any other hereditary information found in the mitochondria, chloroplasts, or other locations is collectively known as a cell's genome.
In eukaryotes, genomic DNA is localized in the cell nucleus, or with small amounts in mitochondria and chloroplasts. In prokaryotes, the DNA is held within an irregularly shaped body in the cytoplasm called the nucleoid. The genetic information in a genome is held within genes, and the complete assemblage of this information in an organism is called its genotype. Genes encode the information needed by cells for the synthesis of proteins, which in turn play a central role in influencing the final phenotype of the organism.