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- Variation in Chromosome Structure
- Natural variation exists in chromosome structure
- Mutations can alter chromosome structure
- The loss of genetic material in a deficiency tends to be detrimental to an organism
- Deficiencies can be detected using cytological, genetic, and molecular techniques
- Duplications tend to be less harmful than deletions
- A gene duplications produced the bar-eye phenotype in Drosophila
- Duplications provide additional material for gene evolution, sometimes leading to the formation of gene families
- Inversions often occur without phenotypic consequences
- Inversion heterozygotes may produce abnormal chromosomes due to crossing over
- Unbalanced translocations usually have detrimental phenotypic effects
- Individuals with balanced translocations may produce abnormal gametes due to the segregation of chromosomes
- Variation In Chromosome Number
- Aneuploidy causes an imbalance in gene expression that is often detrimental to the phenotype of the individual
- Aneuploidy in humans causes abnormal phenotypes
- Variations in euploidy occur naturally in a few animal species
- Variations in euploidy can occur in certain tissues within an animal
- Variations in euploidy are common in plants
- Natural And Experimental Ways To Produce Variations In Chromosome Number
- Meiotic nondisjunction can produce aneuploidy or polyploidy
- Mitotic nondisjunction or chromosome loss can produce a patch of tissue with an altered chromosome number
- Changes in euploidy can occur by autopolyploidy, alloploidy, and allopolyploidy
- Allodiploids are often sterile, but allotetraploids are more likely to be fertile
- Experimental treatments can promote polyploidy
- Cell fusion techniques can be used to make hybrid plants
- Monoploids produced in agricultural and genetic research can be used to create homozygous and hybrid strains
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