Chromosome
Chromosome: A carrier of genetic information that is visible under an ordinary light microscope. Each human chromosome has two arms, the p (short) arm and the q (long) arm. These arms are separated from each other only by the centromere, which is the point at which the chromosome is attached to the spindle during cell division. The 3 billion base pairs in the human genome are organized into 24 chromosomes. All genes are arranged linearly along the chromosomes. Generally the nucleus of a human cell contains two sets of chromosomes’one set given by each parent. Each set has 23 single chromosomes: 22 autosomes and an X or a Y sex chromosome. (A normal female has a pair of X chromosomes; a male has an X and Y pair.) A chromosome contains roughly equal parts of protein and DNA. The chromosomal DNA contains an average of 150 million nucleotide building blocks, called bases. DNA molecules are among the largest molecules now known.
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- Chromosome 1
Chromosome 1: The largest human chromosome, comprising approximately 10% of the human genome. Chromosome 1 contains over 240 million base pairs and over 3000 genes including the UROD gene for porphyria cutanea tarda, the GBA gene for Gaucher disease, the GLC1A gene for glaucoma, the HPC1 gene for prostate cancer, and the PS2 gene for […]
- Chromosome 11 childhood leukemia
Chromosome 11 childhood leukemia: A new type of childhood leukemia in which a piece of chromosome 11 has been translocated (broken off and attached itself to another chromosome). Children with this type of leukemia have a particularly poor prognosis (outlook). They have very high white blood counts and a high frequency of central nervous system […]
- Chromosome 2
Chromosome 2: The second largest chromosome in the human genome. Chromosome 2 contains over 240 million base pairs and more than 2500 genes, including the ETM2 gene for essential tremor, the MSH2 and MSH6 genes for colon cancer, and the PAX3 gene for Waardenburg syndrome. The ETM2 gene for essential tremor (uncontrollable shaking) of the […]
- Chromosome 3
Chromosome 3: One of the largest human chromosomes, comprising approximately 6.5% of the human genome. Chromosome 3 has between 1,100 and 1,500 genes of the estimated 30,000 to 40,000 genes in the human genome. Among the genes on chromosome 3 are the HGD gene for alkaptonuria, the BTD gene for biotinidase deficiency, the CPOX gene […]
- Chromosome 4p- syndrome
Chromosome 4p- syndrome: The 4p- syndrome or Wolf-Hirschhorn syndrome, is a chromosome disorder due to partial deletion of the short (p) arm of chromosome 4. It is, therefore, also called the 4p- syndrome. Features of the syndrome include midline defects with a scalp defect, widespaced eyes, broad or beaked nose, oral facial clefts (cleft lip/palate); […]