Which of the following are necessary characteristics of balancer chromosomes? Please select all that apply.

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Balancer chromosomes are used to maintain (often lethal) alleles in a population. It must therefore be easy to distinguish the heterozygote from the two possible homozygotes, and this is normally achieved using marker genes that are co-inherited with the alleles. In order to ensure that the target allele is always inherited with the marker, crossing-over must be suppressed between the target allele and the marker. This is usually done by inverting parts of the chromosome. Balancer chromosomes are only relevant in organisms with homologous pairs of chromosomes (i.e., not haploids). Balancer chromosomes still require a centromere, in order to be able to segregate at meiosis.

Which of the Following Are Necessary Characteristics of Balancer Chromosomes