Genetic information (DNA) and chromosome aberrations
A genome is all of the genetic information that an organism possesses, in other words, it is the blueprint of the organism and refers to its chromosomes.
The genome (chromosomes) resides within the nucleus of each of the approximately 6 billion cells that make up a person.
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About Genetic Information (DNA) and Genomics
The genome is all of the genetic information that an organism possesses, or in other words, the blueprint of the organism, and refers to its chromosomes. Genomes (chromosomes) exist in the nucleus of each of the approximately 6 billion cells that make up a human being.
Human somatic cells contain 22 pairs of autosomes and one pair of sex chromosomes (XY in males and XX in females). Sperm have 22 autosomes and either an X or Y chromosome, while the egg has 22 autosomes and an X chromosome, called the genome; DNA is wrapped around what is called histone proteins and further folded to form chromosomes.
DNA and the four bases
Genetic information was first discovered by Watson and Crick in 1953 with the discovery of the DNA double helix, followed by the approximate decoding of the human genome in 2001 and the decoding in 2003. The DNA sequence is determined by a combination of four bases: adenine (A), guanine (G), thymine (T) and cytosine (C).
DNA can also self-replicate and pass this information on to offspring.
The base sequence of a gene is transcribed by RNA polymerase into mRNA by the four letters A, G, C, and T on DNA. The synthesized mRNA directs protein synthesis on ribosomes in human cells and specifies the amino acid sequence of the protein.
The flow from DNA self-replication to DNA to RNA to protein is common in all organisms, not just humans, and is called the central dogma. The information that occurs in this central dogma can begin to explain gene expression anywhere in DNA, RNA, and protein.
Genetic Composition and Chromosomal Aberrations
A gene is part of a single DNA molecule that has non-coding (non-coding portion) sequences called introns between the regions that encode the amino acid sequence for the protein called exons.
Intron sequences are not reflected in the protein product. Exons are the genetic parts that determine the amino acid sequence of the protein. The introns and exons are mutually exclusive.
Most genes in the human genome also have at least one (usually several) introns. Many genes are longer than the length of all introns combined, which is longer than the length of all exons combined.
Chromosomes are either numerically or structurally abnormal and may involve multiple autosomes, sex chromosomes, or both simultaneously. Chromosome abnormalities have significant clinical and social consequences.
The most well-known and important type of chromosome abnormality is an aneuploidy, an abnormality in the number of chromosomes (aneuploidy) that results in the presence of an extra or fewer chromosomes and is associated with either physical or mental developmental abnormalities or both.