Chapter 5 - Mapping in Eukaryotes

chromosome exchange, crossing over

linkage

the tendency of genes located close together on the same chromosome to be inherited together

crossing over

the physical exchange of DNA segments between homologous chromosomes during meiosis, producing new allele combinations

recombination

the process by which genetic material is rearranged, creating new allele combinations; includes crossing over and independent assortment

coefficient of coincidence

a measure of how often double crossovers actually occur compared to how often they are expected, used in genetic mapping

somatic cell hybridization

fusion of different types of somatic cells (often from different species) to study gene location and expression

heterokaryon

a cell that contains two or more distinct nuclei from different origins within a shared cytoplasm

synkaryon

a cell formed when the nuclei in a heterokaryon fuse into a single, hybrid nucleus

synteny testing

method for determining whether two genes are located on the same chromosome by checking for their co-segregation in hybrid cells

restriction fragment length polymorphisms (RFLPs)

variations in DNA sequence that change restriction enzyme cut sites, producing different fragment patterns after digestion

short tandom repeats (STRs)

DNA regions with repeating units of 2–6 base pairs, highly variable and used in genetic profiling

single-nucleotide polymorphisms (SNPs)

single base-pair differences in DNA sequence among individuals, the most common form of genetic variation

bioinformatics

the use of computational tools to store, analyze, and interpret biological and genetic data

sister chromatid exchange (SCE)

reciprocal exchange of DNA between sister chromatids during cell division, used as a marker of DNA repair activity

harlequin chromosomes

chromosomes that show alternating light and dark staining of sister chromatids after SCE, making exchanges visible under a microscope

DNA helicase

an enzyme that unwinds the DNA double helix by breaking hydrogen bonds, allowing replication and repair processes to occur