Question

What is in the $5'$ UTR?

Answer 1

Hint: The $5'$ untranslated region is known as leader sequence. The leader sequence is a region of mRNA which directly codes for initiation codon. The $5'$ untranslated region is important for the regulation of translation process as- the transcript has different mechanisms in viruses, prokaryotes and eukaryotes. The untranslated regions have points for ribosomes during translation.

Complete answer-
$5'$ untranslated region serves as the initiation point for the ribosome synthesis and can elaborate RNA secondary and tertiary structures and also translate a cap-dependent or cap-independent manner. RNA structures in $5'$ untranslated region example- RNA G- quadruplexes, may serve as steric blocks for scanning ribosomes and the eukaryotic initiation factor.
$5'$ untranslated region recruits the ribosome entry sites to $5'$ UTRs in a cap-independent manner. Some are required in regular physiological conditions and tend to integrate with RNA chaperons reading open frames and G-quadruplex structures for function.
The initiation factor has a specialized function in translating directly or chemically modified $5'$ UTRs in mRNA to selective internal initiation. In vivo RNA structure proving technologies use chemical modifiers to assess the RNA structure inside cells.
Single-nucleotide resolution chemical RNA structure is to explore the state of folding to the transcriptome in living cells. The models for $5'$ untranslated region impact the translation validated by compensatory mutagenesis.

Note:
RNA molecules can fold intricate shapes and provide control to the gene expression beyond the sequence. The current mechanic structures of $5'$ untranslated region have methodologies to explore them. These structures have cap-dependent translation through helicase mediated RNA structures and internal ribosome entry sites.