The ____ of chromosomes to properly separate during meiosis results in ____ in the chromosome content of gametes and subsequently in ____ arising from such gametes.
Failure; Variation; offspring
____ often tolerate an abnormal genetic content, but, as a result, they often manifest ____ _____. Such genetic variation has been an important factor in the evolution of ____.
Plants; unique phenotypes; plants
In _____, genetic information is in a delicate _____ whereby the gain or loss of a chromosome or part of a chromosome, in an otherwise diploid organism often leads to ____ or to an _____ phenotype.
animals; equilibrium; lethality; abnormal
The _______ of genetic information within the _____ of a diploid organism may be tolerated by that organism but may affect the _____ of gametes and the _____ of organisms arising from those gametes.
Rearrangement; genome; viability; phenotypes
Chromosomes in humans contain ___ ____ regions susceptible to breakage which lead to _____ phenotypes
fragile sites; abnormal phenotypes
Chromosome aberration
Any duplication, deletion, or rearrangement of the otherwise diploid chromosomal content of an organism
Chromosome mutation
the process resulting in the duplication, deletion, or rearrangements of the diploid chromosomal content of an organism
Aneuploidy
A condition in which the chromosome number is not an exact multiple of the haploid set
2n +- X chromosomes
Monosomy
An aneuploidic condition in which one member of a chromosome pair is missing. Having a chromosome number of 2n-1 (Aneuploidy)
Trisomy
The condition in which a cell or an organism possesses two copies of each chromosome except for one, which is present in three copies.
2n + 1 (aneuploidy)
Euploidy
A cell with a chromosome number that is an exact multiple of the haploid number.
Multiples of n
Polyploidy
When more than two sets of chromosomes are present.
3n, 4n, 5n, etc. Polyploidy arises as the result of total nondisjunction of chromosomes during mitosis or meiosis. It is important because Polyploidy has long been recognized as a prominent force shaping
Klinefelter syndrome
a genetic disorder in human males caused by the presence of one or more additional X chromosomes. Klinefelter males are usually XXY instead of XY. This syndrome can include enlarged breasts, small testes, sterility and mild mental retardation.
Turner Syndrome
A genetic condition in human females caused by a 45,X genotype. Such individuals are phenotypically female but are sterile
Nondisjunction
A cell division error in which homologous chromosomes in meiosis or the sister chromatids in mitosis fail to separate and migrate to opposite poles. Responsible for defects such as monosomy and trisomy.
Diploidy
A condition in which each chromosome exists in pairs having two of each chromosome
Triploidy
The condition in which a cell or an organisms possesses three haploid sets of chromosomes
Tetraploidy
4n
Autopolyploidy
Polyploid condition resulting from the duplication of one diploid set of chromosomes. Multiples of the same genome.
Allopolyploidy
polyploidy condition formed by the union of two or more distinct chromosome sets with a subsequent doubling of chromosome number. Multiples of closely related genomes. (Amphidiploidy)
Monosomy vs. Trisomy
Monosomy: develop more slowly, exhibit reduced body size, and have impaired viability.
Trisomy: more viable than monosomy, addition of large autosome is usually lethal, produces a unique phenotype
Haploinsufficiency
In a diploid organism, a condition in which an individual possesses only one functional copy of a gene with the other inactivated by mutation. The amount of protein produced by the single copy is insufficient to produce a normal phenotype, leading to an a
Pseudodominance
the expression of a recessive allele on one homolog owing to the deletion of the dominant allele on the other homolog
Patau syndrome
A condition in which a person has an extra chromosome 13. (trisomy)
Edwards Syndrome
A condition that causes severe developmental delays due to an extra chromosome 18 (trisomy)
Polyploidy originates in two ways: #1
The addition of one or more extra sets of chromosomes, identical to the normal haploid complement of the same species resulting in autopolyploidy
Polyploidy originates in two ways: #2
The combination of chromosome sets from different species occurring as a consequence of hybridization resulting in allopolyploidy
Colchicine
In the preparation of karyotypes, it is used for collecting a large population of cells inhibited at the metaphase stage of mitosis
Endopolyploidy
The increase in chromosome sets within somatic nuclei that results from endomitotic replication
Deletion
a chromosomal mutation, also referred to as a deficiency, involving the loss of chromosomal material.
Duplication
a chromosomal aberration in which a segment of the chromosome is repeated
Inversion
a chromosomal aberration in which a chromosomal segment has been reversed
Nonreciprocal Translocation
involves the transfer of genes from one chromosome to another, nonhomologous chromosome. Both chromosomes are not split evenly.
Reciprocal translocation
a chromosomal aberration in which nonhomologous chromosomes exchange parts
Duplication roles in evolution
Over evolutionary periods, the duplicated gene may change sufficiently so that its product assumes a divergent role in the cell.
Duplication roles
When any part of the genetic material is present more than once in the genome.
1. Gene redundancy:
2. Produce phenotypic variation:
3. Important source of genetic variability during evolution
Robertsonian translocation
a chromosomal aberration created by breaks in the short arms of two acrocentric chromosomes followed by fusion of the long arms of these chromosomes at the centromere. AKA centric fusion
Familial down syndrome vs primary down syndrome
Familial down syndrome: translocation of chromosome 21
Down syndrome (trisomy 21): trisomy of chromosome 21
Gene dosage
Gene dosage is the number of copies of a gene present in a cell or nucleus. An increase in gene dosage can cause higher levels of gene product if the gene is not subject to regulation from elsewhere in the body.
Position effect
change in expression of a gene associated with a change in the gene's location within the genome
Dicentric chromatid consequences
a chromosome having two centromeres, which can be pulled in opposite directions during anaphase of cell division
Acentric chromatid consequences
chromosome or chromosome fragment with no centromere
Importance of Fragile sites in Cancer and syndromes
a specific heritable point on a chromosome that tends to form a gap or constriction and may tend to break when the cell is exposed to partial replication stress. Common fragile sites are of interest in cancer studies because they are frequently affected i
Acrocentric chromosome
chromosome with the centromere located very close to one end
Disomy
2n
Tetrasomy
2n + 2
Pentasomy
2n + 3
_____ chromosomes cause greater genetic imbalance than ___ ones.
Larger ; smaller
An _____ in gene dosage can cause ______ levels of gene product if the gene is not subject to regulation from elsewhere in the body.
Increase; higher;