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Name: Diana Nicolas Class : lab week 5 Date: 20 February 2021

. In a few words, describe what you know about gene therapy . Gene therapy is an experimental technique that uses genes to prevent disease or treat

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? Sam's parents don't have retinitis pigmentosa (RP). How can RP be an inherited condition 1.

mother and father don't have retinitis pigmentosa, you can still have the eye disease when at least one parent carries an altered gene associated with the trait.

Extension Questions: ? How do our brains convert information from light entering our eyes into an image • clear gel-like substance that fills the back of the eye and supports the retina. The retina receives the image that the cornea focuses through the eye's internal lens and transforms this image into . electrical impulses that are carried by the optic nerve to the brain ? What is disease? How do organisms get diseases • Infectious diseases commonly spread through the direct transfer of bacteria, viruses or other germs from one person to another. This can happen when an individual with the bacterium or virus touches, kisses, or coughs or sneezes on someone who isn't infected. ? What is a genetic mutation and what are its effects • gene mutations are so severe that they prevent an embryo from surviving until birth. How is searching for a treatment for a genetic disease different from that for a disease caused

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? by something else, such as bacteria or viruses are caused by mutations that are inherited from the parents and are present in an individual at birth, like sickle cell disease You collect blood samples, which contain DNA, from a patient with RP and their relatives. Some of the relatives have RP and some do not. Outline a strategy for using these samples to . identify the disease-causing mutation in the patient First of all we have to identify the gene which causes pigmentation in retina. The blood

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samples will have to run in a gel electrophoresis. The patient with RP will be the marker for the mutation. Non-mutated and mutated DNA will differ in size, so we will know it’s a large mutation or not by looking at the gel electrophoresis plate. If it’s unseen it’s samall, therefore the mutation is small. A genome sequencing can be done. The ones matching with the patient’s will be the mutated DNA. Then the site and type of mutation can be checked by comparing the patient’s genome to a normal genome ? How can mutations in different genes be associated with a single disease • The mutations in different genes can lead to causing the same disease because different genes

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might be responsible for change in protein production pattern or disrupt signals which can cause the disease :Extension Questions

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? Why would a researcher use a pedigree to study a disease • • Many characteristics of an organism are controlled by more than one gene. Likewise, many • • of the biochemical processes and pathways involve proteins produced by different genes. . Explain how this relates to the existence of many different mutations that cause RP Can you think of any other diseases or conditions that are caused by mutations in different • • ?genes A scan of Sam’s genome for the 100 most common mutations known to cause RP didn’t find

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? anything. How can you explain this result Neutral mutation have no effect. An example would be silent point mutation. They do not

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change the amino acids in the proteins they encode. That’s why they are neutral. They do not . have an observation effect on the phenotype Sam has a mutation in a gene that affects the function of a transfer RNA (tRNA). Human cells

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have 20 different types of tRNAs, and each adds a different amino acid to growing peptide . chains, which form proteins •

Yes because it affects protein synthesis. If certain amino acids aren’t adding it slows protein production

Based on what you know so far, would you expect this mutation to affect all proteins produced

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. in Sam’s cells? Explain your reasoning After thinking about this, there are 20 different types of tRNAs for 20 amino acids, so if one is

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mutated that doesn’t mean all will be affected What evidence could you collect to confirm that the mutation identified in Sam’s DNA causes

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:symptoms of RP? Extension Question A model organism can be used to confirm that the mutation identified in Sam’s DNA cause

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.symptoms of RP Some mutations are lethal and others are not. Explain the difference between these two types • • . of mutations in terms of cellular function Doctors may be able to inject a functioning copy of the gene mutated in Sam’s DNA in the

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cells of his eyes. If the procedure were successful, would you expect Sam to regain his vision? ?Why or why not Successful gene therapy will prevent further vision loss • If the doctors successfully inject the functioning copy of the mutated gene in the DNA of Sam

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then the eyes will not restore complete gain of vision; however it’d prevent further loss of the vision :Extension Question • In your own words, explain why researchers use model organisms such as zebrafish. Can you • •

? name any other model organisms Other than identifying a target for gene therapy, how does identifying a disease-causing

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? mutation help a patient and their family This helps healthcare professional assess risk factors for developing a c certain condition in the offspring. It is also important because an individual can take necessary steps that will reduce his/her risk factors. For individuals who are at a higher risk of certain fatal cancers, healthcare professionals can recommend effective screening techniques and therapy for the treatment

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