Question

Define C value paradox.

Answer 1

The C-value is the amount of DNA in the haploid genome of an organism. It varies over a very wide range, with a general increase in C-value with complexity of organism from prokaryotes to invertebrates, vertebrates, plants.

Answer 2

The C-value is the amount of DNA in the haploid genome of an organism. It varies over a very wide range, with a general increase in C-value with complexity of organism from prokaryotes to invertebrates, vertebrates, plants. The C-value paradox is basically this: how can we account for the amount of DNA in terms of known function? Very similar organisms can show a large difference in C-values (e.g. amphibians). The amount of genomic DNA in complex eukaryotes is much greater than the amount needed to encode proteins. For example: Mammals have 30,000 to 50,000 genes, but their genome size (or C-value) is 3 x 109 bp.

3×109base pairs3000base paires (average gene size)=1×106(“gene capacity”).(4.5.1)

Drosophila melanogaster has about 5000 mutable loci (~genes). If the average size of an insect gene is 2000 bp, then

1×108base pairs2×103base pairs=>50,000 “gene capacity”.(4.5.2)

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