Figure 12

Gene expression by length of gene. The bins for the x-axis are the quantiles of the length distribution for those genes which have expression data. There are 50 bins each containing 2% of the distribution: in each bin n ~ 277. The 10%, 50% and 90% quantiles are gene lengths 1211, 14975 and 91253. 95% confidence limits are shown by the upper and lower lines in (a) and the error bars in (b). a) Probability that a gene is expressed by length of gene: The bulk of the figure shows that on average increasing length of gene implies an increasing probability that the gene is expressed. However, extremely short genes have a high probability of always being expressed and very long genes are less likely to be expressed. b) Average expression level of genes that are expressed by length of gene: The expression level is quoted in arbitrary linear units.