The process of gene expression (the flow of information inside cells) follows: DNA –> RNA –> Proteins.
DNA holds the instructions in the form of genes to synthesize proteins and RNA, which are considered to be molecular machines of cells. During gene expression, DNA is first transcribed into RNA (Transcription – to make mRNA), then followed by the translation of RNA into proteins. In prokaryotes such as bacteria, transcription and translation take place simultaneously. However, in eukaryotes, transcription is completed first before translation can start.
In this process the sequence of nucleotides in genes determine the sequence of amino acids in proteins. Remember, amino acids are the building blocks (monomers) of proteins. Alterations in a DNA sequence can lead to changes in amino acids which can have strong effects on a protein’s structure and its function. For example, a single substitution of a nucleotide (or point mutation) in DNA results in drastic changes in protein function that may lead to a condition known as seen in sickle cell anemia.
Consider the examples of sickle cell anemia and cystic fibrosis, explain how the gene modification leads to change in protein function. (Note: provide the name of the affected gene for each disease and explain the effect of nucleotide changes. You can use your book or references from previous discussions (week #4).
Efforts to correct errors in gene function have been tried for the past few decades, but most have not shown consistent positive outcomes in clinical applications. However, in the past 10 years, the discovery of CRISPR-CAS9 system appears to introduce new exciting ways to correct errors in genes and paves the way for new approaches in gene editing. For this part, answer the following questions:
What does CRISPR stand for? Which types of organisms harbor/contain this system? What is the CRISPR-Cas9 system function in those organisms?
For medical applications, provide a guide how the CRISPR-Cas9 can be used to fix gene errors in cystic fibrosis or any other genetic disorders. (use the reference listed below)
Gene editing using CRISPR-Cas9 is not without ethical dilemma. Can you provide examples where the clinical application of CRISPR-Cas9 can lead to ethical issues? Provide one older example and a recent one. Read this paper:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4403038/
