Question

Please have a different answer than the other post, and use layman's terms as well

hhmi Biolnteractive Using CRISPR to identify the Functions of Butterfly Genes Activity Student Handout This document is made available by the Howard Hughes Medical Institute. Using this document, you agree to use this document in accordance with the Terms of Use. INTRODUCTION Scientists have determined the complete DNA sequences of the genomes for many organisms, including humans. By analyzing patterns in those sequences, they can estimate how many genes an organism has - humans, for example, have about 20,000. But sequence patterns alone don't specifically show what each gene does. How can we figure this out? In this activity, you will explore a tool that can be used to determine a gene's function. You will then design your own version of this tool to examine genes that affect the colors and patterns on butterfly wings. PART 1: Using CRISPR-Cas9 to Inactivate Genes One way to determine a gene's function is to inactivate, or "knock out," that gene and then observe the effect on a cell or organism. Scientists can inactivate genes in cells growing in a lab or in model organisms, such as flies or mice. #1. With a partner, discuss what it means to inactivate a gene and how it could be done. Record your ideas. - 2. Can you think of additional ways to find out what genes do? Record one or two ideas. CRISPR-Cas9, or CRISPR for short, is a biotechnology tool that can edit or inactivate specific genes. To learn more about the CRISPR-Cas9 system, you can explore the "How It Works" section of the CRISPR-Cas9 Mechanism and Applications Click & Learn. As shown in the Click & Learn, the CRISPR-Cas9 tool uses a DNA-cutting enzyme, or nuclease, called Cas9. Cas9 was discovered in bacteria as a way for bacteria to fight off viruses. Scientists combine Case with an RNA molecule called a guide RNA to form a Cas9-RNA complex. Part of the guide RNA matches a target DNA sequence within the gene that the scientists want to inactivate. You will now go through each step in the process of using CRISPR-Cas9 to inactivate a gene, using a sequence from an actual gene as an example.

Answer 1

1. Gene inactivation is the process where the activity of a gene is turned off for a while. This mostly occurs during transcription and it is very common in gene regulation. This is a mechanism that occurs in nature that will enable the adaptation to new environmental changes by controlling the amount of protein synthesized in the end. Most time only a tiny portion of the genes are active while the rest remain turned off. It could happen based on environment, developments, mutations or hormones. Ways in which genes can be inactivated includes:
>> DNA methylation- Here methyl groups are added to the CpG islands of the promoter region and thus they turn off the gene and then suppress transcription.
>> siRNA molecules- these molecules prevent the specific mRNA molecule from undergoing translation into the protein by endonuvleolytic cleavage and thus rendering the gene inactive.
>> Gene therapy- a technique where new genes are inserted in the place of mutated or abnormal genes. In this process mutated genes can be knocked out or inactivated.
>> Gene knockout- a newly engineered DNA sequence is inserted into the stem cells of organisms.

2.
>> By using a reporter gene in place of coding region of the gene.
>> DNA microarrays- tiny spots of DNA are adhered to a solid base that facilitates learning the expression of genes.
>> Overexpression of the targeted gene
>> Use of genetic mosaics- two different genetic makeup within the same system.