CH 8 (1) Chromosome Change in Structure and Number

These flashcards cover key vocabulary and concepts related to chromosome structure, rearrangements, and their genetic implications.

Chromosomal rearrangements

Changes that affect the structure of chromosomes, including deletions, duplications, inversions, and translocations.

Deletion

Removal of a segment of DNA from a chromosome.

Duplication

Increase in the number of copies of a chromosomal region.

Inversion

A chromosomal rearrangement that involves a half-circle rotation of a chromosomal segment.

Translocation

The movement of a chromosomal segment from one chromosome to another.

Reciprocal translocation

A chromosomal rearrangement where parts of two nonhomologous chromosomes exchange places.

Nonreciprocal translocation

A chromosomal rearrangement where unequal exchanges occur between nonhomologous chromosomes.

Homozygosity

Having two identical alleles for a particular gene, which can lead to lethal consequences in deletions.

Heterozygosity

Having two different alleles for a particular gene, which can cause phenotypic consequences when mutations are present.

Aneuploidy

The presence of an abnormal number of chromosomes in a cell, either more or less than the normal diploid number.

Euploidy

A condition where a cell has complete sets of chromosomes.

Monoploidy

Having only one copy of each homologous chromosome.

Polyploidy

Condition in which a cell has more than two complete sets of chromosomes.

Trisomy

A type of aneuploidy where there are three copies of a particular chromosome.

Monosomy

A type of aneuploidy where there is only one copy of a chromosome instead of two.

Karyotype

The number and appearance of chromosomes in the nucleus of a eukaryotic cell.

Phenotypic consequences of deletions

Variations in phenotype resulting from loss of genetic material; can be lethal in homozygotes and affect gene dosage in heterozygotes.

Crossing-over

The exchange of genetic material between homologous chromosomes during meiosis.

Aberrant crossing-over

Non-standard crossing over that can result in chromosomal rearrangements.

Fluorescent in situ hybridization (FISH)

A technique used to detect chromosomal rearrangements using fluorescently labeled DNA probes.

Gene dosage effects

The impact of the number of copies of a gene on the phenotype; can lead to mutant phenotypes.

Notch+ gene

A gene that is sensitive to dosage effects; mutations can lead to abnormal phenotypes due to its haploinsufficiency.

Deletion loop

A structure formed during meiosis in deletion heterozygotes, representing the portion of the chromosome that is deleted.

Reversion analysis

A method for identifying deletions where a mutant gene cannot revert to a normal phenotype due to a deleted region.

Polytene chromosomes

Giant chromosomes that are formed by repeated DNA replication without cell division, often studied in Drosophila larvae.

Robertsonian translocation

A chromosomal rearrangement that involves two acrocentric chromosomes forming a single metacentric chromosome.

Chronic myelogenous leukemia

A type of cancer linked to a reciprocal translocation between chromosomes 9 and 22.

Phenotypic effects of inversions

Inversions can disrupt genes or affect their regulation without adding or removing DNA.

Translocation homozygote

An organism that has two identical arrangements of chromosomes resulting from a translocation.

Translocation heterozygote

An organism that carries two different arrangements of DNA due to a translocation.

Chromosome painting

A technique used to visualize specific chromosomes or chromosomal regions using different fluorescent dyes.

Genetic map distance

Measurement of the distance between genes on a chromosome; can be altered by chromosomal rearrangements.

Tetrasomy

A type of aneuploidy where there are four copies of a particular chromosome.

Duplication loops

Structures formed when duplicated regions of chromosomes loop out during meiosis.

Gene mapping

Techniques used to determine the location of genes on chromosomes.