Chromosomal Aberrations (deletions, duplications, transversions, and translocations)

deletions are

missing part of a chromosome

terminal deletion

produces acentric fragment which is lost during cell division

intersitial deleteion

requires 2 breaks

effects of deletions include

1. centromere loss

2. imbalance of gene products produced

3. causing a homolog to posses a visible mutant phenotype

Haploinsufficiency

single copy of gene is not enough to allow the wild type phenotype to occur

pseudodomiance

expression of normally recessive phenotype becuase there is no homologous allele due to gene expression

duplications

have an extra copy of part of the chromosome

a compensation loop forms in heterozygous individuals with

tandem mutation

inversions have a

segment of chromosome removed, flipped around, and reinserted

paracentric inversion

inverted area does not include a centromere

pericentric inversion

inverted area does inculde a centromere

dicentric bridges seen in anaphase 1 break at

random location

acentric fragments are typically

lost

recipricol translocations

two nonhomologous chromosomes exchange arms

no gain or loss of DNA

Non-recipricol translocations

a segment from one chromosome is moved to a nonhomologous chromsomes

robertsonian translocations

two telocentric chromosomes combine toghter to make a metacelntric chormosome

What syndrome can be a result of translocation

familial down syndrome

isochromsome

two chromosome 21s joined together