Our laboratory develops new methods that link a genetic function such as transcription, splicing, or signal transduction, to a barcoded reporter that can be identified and measured by next-generation sequencing (rather than say luminescence or fluorescence). This allows us to molecularly multiplex hundreds to thousands of such experiments in a single flask, and to use large-scale DNA synthesis as a way to explore these sequence-function relationships. In this talk, I will discuss two of our lab's efforts in bringing these practices to problems in human biology. In the first, we explore how extant human genetic variation affects the process of exon recognition during pre-mRNA splicing using a new multiplexed assay in human cell lines. We find a surprisingly large number of rare genetic variants lead to large-effect loss of exon recognition. In the second, we develop a new reporter for G-protein coupled receptor signal transduction and use this system to characterize signal transduction for all possible single amino acid mutations to the beta-2-adrenergic receptor and uncover novel motifs required for signal transduction. In addition, we use this system to explore questions of ligand specificities in mammalian olfactory receptors.