Deciphering neural circuit computations during behavior

Gene expression refers to the process through which the instructions in our DNA are converted into a functional product, such as proteins.
It involves two main processes: transcription and translation.

The first step in gene expression where the DNA sequence of a gene is copied into messenger RNA (mRNA).
This occurs in the nucleus of eukaryotic cells.
The mRNA strand undergoes processing, which includes:
- Capping: Addition of a protective cap on the mRNA which facilitates export from the nucleus and translation.
- Polyadenylation: Addition of a poly-A tail that protects the mRNA from degradation and assists in translation.
- Splicing: Removal of introns (non-coding regions) and joining of exons (coding regions) to form a mature mRNA strand.

The process by which the sequence of nucleotides in mRNA is translated into a sequence of amino acids, forming a protein.
This process occurs in the ribosomes and involves:
- Ribosomes reading the sequence of codons in mRNA (three-nucleotide sequences).
- Transfer RNA (tRNA) bringing the appropriate amino acids to the ribosome.
- Formation of a polypeptide chain which folds into a functional protein.

Transcriptomics is the study of the transcriptome, which encompasses all the RNA molecules produced in a cell or organism at a given time.
It provides insights into which genes are actively expressed under specific conditions.

Common techniques used in transcriptomic studies include:
- Microarrays: Platforms that measure the expression levels of thousands of genes at once through hybridization of RNA to complementary probes.
- RNA-Seq: Next-generation sequencing technique that allows for the comprehensive assessment of the transcriptome, enabling quantification of RNA levels as well as detection of novel transcripts.
- qPCR: Quantitative Polymerase Chain Reaction used to amplify and quantify specific RNA sequences, often used to validate results obtained from other methods.

Provides critical insights into:
- Developmental biology: Understanding how gene expression changes during development.
- Disease pathology: Identifying changes in gene expression associated with diseases such as cancer or autoimmune disorders.
- Drug responses: Evaluating how different drugs can affect gene expression profiles.

Understanding gene expression and transcriptomics requires a consideration of the cellular context, including:
- The type of cell and its specific functions.
- External stimuli that can influence gene expression, such as hormones, stress, and other environmental factors.
- Cellular pathways and networks that regulate expression levels.