AneuploidyAneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human somatic cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any number of complete chromosome sets is called a euploid cell. An extra or missing chromosome is a common cause of some genetic disorders. Some cancer cells also have abnormal numbers of chromosomes.
ChromosomeDNA molecule containing genetic material of a cellDifferent representations of chromosomesMain parts of a condensed chromosomeCondensed chromosome (purple rod) inside a bone marrow erythrokaryocyte undergoing mitosisDiagram of a duplicated and condensed metaphase eukaryotic chromosome: ChromatidCentromereShort armLong armA chromosome is a package of DNA containing part of or all of the genetic material of an organism.
Chromosome segregationChromosome segregation is the process in eukaryotes by which two sister chromatids formed as a consequence of DNA replication, or paired homologous chromosomes, separate from each other and migrate to opposite poles of the nucleus. This segregation process occurs during both mitosis and meiosis. Chromosome segregation also occurs in prokaryotes. However, in contrast to eukaryotic chromosome segregation, replication and segregation are not temporally separated.
Homologous recombinationGenetic recombination between identical or highly similar strands of genetic materialFigure 1.
Genome instabilityGenome instability (also genetic instability or genomic instability) refers to a high frequency of mutations within the genome of a cellular lineage. These mutations can include changes in nucleic acid sequences, chromosomal rearrangements or aneuploidy. Genome instability does occur in bacteria.
OncogeneAn oncogene is a gene that has the potential to cause cancer. In tumorcells, these genes are often mutated, or expressed at high levels. Most normal cells undergo a preprogrammed rapid cell death (apoptosis) if critical functions are altered and then malfunction. Activated oncogenes can cause those cells designated for apoptosis to survive and proliferate instead.
MitosisMitosis () is a part of the cell cycle in eukaryotic cells in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis is an equational division which gives rise to genetically identical cells in which the total number of chromosomes is maintained.
ApoptosisForm of programmed cell deathApoptosis (from Ancient Greek: ἀπόπτωσις, romanized: apóptōsis, lit. 'falling off') is a form of programmed cell death that occurs in multicellular organisms and in some eukaryotic, single-celled microorganisms such as yeast. Biochemical events lead to characteristic cellular changes (morphology) and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, DNA fragmentation, and mRNA decay.
Chromosomal translocationIn genetics, chromosome translocation is a phenomenon that results in unusual rearrangement of chromosomes. This includes "balanced" and "unbalanced" translocation, with three main types: "reciprocal", "nonreciprocal" and "Robertsonian" translocation. Reciprocal translocation is a chromosome abnormality caused by exchange of parts between non-homologous chromosomes. Two detached fragments of two different chromosomes are switched.
Colorectal cancerCancer of the colon or rectumMedical conditionColorectal cancer, also known as bowel cancer, colon cancer, intestinal cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine), characterized by the uncontrolled growth of colon cells that can invade or spread to other parts of the body. Signs and symptoms may include blood in the stool, a change in bowel movements, weight loss, abdominal pain, and fatigue.
PolyploidyCondition where cells have more than two sets of chromosomesThis image shows haploid (single), diploid (double), triploid (triple), and tetraploid (quadruple) sets of chromosomes. Triploid and tetraploid chromosomes are examples of polyploidy.Polyploidy is a condition in which the cells of an organism have more than two paired sets of (homologous) chromosomes.
PloidyPloidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomalgenes. Here sets of chromosomes refers to the number of maternal and paternal chromosome copies, respectively, in each homologous chromosome pair—the form in which chromosomes naturally exist.*As an Amazon Associate I earn from qualifying purchases.