Why do muscle cells and nerve cells from one individual have the same genetic information but completely different structures and functions?
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Your genes play an important role in your health, but so do your behaviors and environment, such as what you eat and how physically active you are. Epigenetics is the study of how your behaviors and environment can cause changes that affect the way your genes work. Unlike genetic changes, epigenetic changes are reversible and do not change your DNA sequence, but they can change how your body reads a DNA sequence. Gene expression refers to how often or when proteins are created from the instructions within your genes. While genetic changes can alter which protein is made, epigenetic changes affect gene expression to turn genes “on” and “off.” Since your environment and behaviors, such as diet and exercise, can result in epigenetic changes, it is easy to see the connection between your genes and your behaviors and environment. How Does Epigenetics Work?Epigenetic changes affect gene expression in different ways. Types of epigenetic changes include: DNA MethylationDNA methylation works by adding a chemical group to DNA. Typically, this group is added to specific places on the DNA, where it blocks the proteins that attach to DNA to “read” the gene. This chemical group can be removed through a process called demethylation. Typically, methylation turns genes “off” and demethylation turns genes “on.” Histone modificationDNA wraps around proteins called histones. When histones are tightly packed together, proteins that ‘read’ the gene cannot access the DNA as easily, so the gene is turned “off.” When histones are loosely packed, more DNA is exposed or not wrapped around a histone and can be accessed by proteins that ‘read’ the gene, so the gene is turned “on.” Chemical groups can be added or removed from histones to make the histones more tightly or loosely packed, turning genes “off” or “on.” Non-coding RNAYour DNA is used as instructions for making coding and non-coding RNA. Coding RNA is used to make proteins. Non-coding RNA helps control gene expression by attaching to coding RNA, along with certain proteins, to break down the coding RNA so that it cannot be used to make proteins. Non-coding RNA may also recruit proteins to modify histones to turn genes “on” or “off.” Example: Study of newborn vs. 26-year-old vs. 103-year-old DNA methylation at millions of sites were measured in a newborn, 26-year-old, and 103-year-old. The level of DNA methylation decreases with age. A newborn had the highest DNA methylation, the 103-year-old had the lowest DNA methylation, and the 26-year-old had a DNA methylation level between the newborn and 103-year-old (1). Example: Smokers vs. non-smokers vs. former smokers Smoking can result in epigenetic changes. For example, at certain parts of the AHRR gene, smokers tend to have less DNA methylation than non-smokers. The difference is greater for heavy smokers and long-term smokers. After quitting smoking, former smokers can begin to have increased DNA methylation at this gene. Eventually, they can reach levels similar to those of non-smokers. In some cases, this can happen in under a year, but the length of time depends on how long and how much someone smoked before quitting (2). SummaryRead the full fact sheet
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Support groupsFrom other websitesContent disclaimerContent on this website is provided for information purposes only. Information about a therapy, service, product or treatment does not in any way endorse or support such therapy, service, product or treatment and is not intended to replace advice from your doctor or other registered health professional. The information and materials contained on this website are not intended to constitute a comprehensive guide concerning all aspects of the therapy, product or treatment described on the website. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions and to ascertain whether the particular therapy, service, product or treatment described on the website is suitable in their circumstances. The State of Victoria and the Department of Health shall not bear any liability for reliance by any user on the materials contained on this website. Why do muscle and nerve cells have different proteins but the same DNA?In fact, there is a common set of genes to which they can both bind, but differences between their DNA-binding regions allow each of the two proteins to also turn on their own unique sets of genes, which is what enables one to make muscle cells while the other makes neurons.
Why do nerve cells from the same organism have such different functions?These cells are different because they use the same set of genes differently. So even though each of our cells has the same 20,000 or so genes, each cell can select which ones it wants to “turn on” and which ones it wants to keep “turned off”.
Would a neuron and a muscle cell from the same individual have the same DNA?We learned in biology class that every cell in the body has the same DNA. Whether a heart cell, skin cell or muscle cell—they all read from the same genetic blueprint.
Do nerve cells and muscle cells have the same genes but express different subsets of them?A nerve cell and a muscle cell have the same genes, but express different subsets of them. Microfilaments and microtubules are part of the cytoskeleton.
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