Ch 8 Flashcards
Chromosome breakage and rejoining is an important cause of
chromosome rearrangement
Duplication
a loop forms during prophase I in the duplicated region of the chromosome
phenotypic consequences of duplications generally come from imbalanced gene dosage
larger the duplicated region, the greater the likelihood that the duplication affects phenotype
Roughly half of human genes are members of gene families that were created by
duplication and divergence
Deletions often lead to
imbalanced gene dosage
Haploinsufficiency
Caused by…
one copy of a gene is insufficient for normal function.
Deletion heterozygosity
Inversions can cause two types of problems
Changes in gene expression
Reduced fertility when recombination occurs within the inverted region
Inversion causes changes in gene expression if
the inversion breakpoint falls within a gene
the inversion places a gene in new regulatory environment
Translocations
Can be reciprocal (most common) or non-reciprocal
Common and play a significant role in health.
Reduce the percentage of viable gametes.
Can alter gene regulation
when a gene is placed in a new regulatory environment and can inactivate genes
when the translocation break point occurs within the gene.
Can create hybrid genes born of fusion between two separate
Robertsonian Translocations
Creates a long and a fragmented chromosome
14 and 21 fusion
Aneuploidy
occurs when there are more or fewer copies than normal of a particular chromosome
Aneuploidy occurs ____ and it is virtually ____
Frequently
always harmful
Mitotic Aneuploidy occurs through
Failure to separate sister chromatids
Detachment of chromosomes from spindle fibers
Mitotic aneuploidy is an important source of
genetic mosaicism
Autopolyploidy can arise from ____ during mitosis or meiosis
nondisjunction
Allopolyploidy
Hybridization occurs between closely related species, resulting in a sterile hybrid.
Chromosome doubling
allotetraploid comes from the joining of
two diploid genomes
