Question 1:
Exons are gene fragments whose DNA sequence after transcription is found in mature mRNAs. This part of the gene is most often coding.
The size of the exons in the genomes follows a log-normal distribution, with an average length of about 150 nucleotides, knowing that in eukaryotes, each gene contains several exons and introns (an average of 8) so the size is 8*150 = 1200 bp.
Question 2:
Introns are fragment of a gene located between two exons. Introns are present in immature mRNA and absent in mature mRNA. "Non-coding" fragment of the gene.
The introns average in a gene is 3365 bp including 3'UTR and 5'UTR and intermediate introns.
I would say landslide because it does cause because of the lost of friction.
<h2>Neural crest </h2>
Explanation:
The neural crest likely forms: neurons and glia of the peripheral nervous system
- The neural crest are bilaterally paired strips of cells arising in the ectoderm at the margins of the neural tube
- In the body region, neural crest cells also contribute the peripheral nervous system (both neurons and glia) consisting of sensory ganglia (dorsal root ganglia), sympathetic and parasympathetic ganglia and neural plexuses within specific tissues/organs
- The nervous system is made up of specialized cells which includes nerve cells (or neurons) and glial cells (or glia)
- Neurons are the basic functional units of the nervous system, and they generate electrical signals called action potentials, which allow them to quickly transmit information over long distances
- Glia are also essential to nervous system function, but they work mostly by supporting the neurons
