BIOM20001 Lecture 26: 26-27 Epigenetic control of gene expression in normal development and disease A

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plumdeer622

29 Sep 2018

School

University of Melbourne

Department

Biomedicine

Course

BIOM20001

Professor

All

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Document Summary

26-27 epigenetic control of gene expression in normal development and disease. Changes in the epigenetic modifications allow the expression of specific subsets of genes, which determines the type of cell produced. Only 10 or so genes active in a cell at any one time. Epigenetic marks are like punctuation marks in the genome. Epigenetic marks help to enable the expression of restricted subsets of genes within each cell type during differentiation and development. Epigenetics: the study of changes in gene expression that occur without changes in dna sequence. Removal and resetting of epigenetic markers occurs at gametogenesis. These are the two main times this occurs. (some definitions do not include mitotic heritability. ) Dna packaging into chromatin: double helix to metaphase chromosome. Chromatin compaction correlates with expression, related to accessibility of transcriptional machinery to the dna (dna recombination and repair machinery) The nucleosome: 146 bp of dna wrapped around a histone octamer (2 x h2a, 2 x h2b, 2 x h3,

Related Questions

Part III â Just How âIdenticalâ Are We?

Elise had been home from college for a week, and she was still preoccupied with Shannonâs diagnosis and her own potential risk for mental illness. Elise expressed her anxiety and concerns to her mother one night after dinner. âElise,â her mother said, âyour concerns are perfectly valid, and you have every reason to want to get more information. Why donât we make you an appointment to consult with a psychiatrist?â Elise decided to make the appointment the next day. * * * * * Elise left Dr. OâBrienâs offi ce feeling that some of the weight had been lifted from her shoulders. On the car ride home, she thought about the things that Dr. OâBrien had said to her during their consultation. âIt was good of you to come in to see me, Elise. You are absolutely right to have concerns for yourself when your identical twin has been diagnosed with schizophrenia. Research shows that schizophrenia is almost 50% heritable, and since you share nearly identical DNA with your sister, that puts you at a higher risk for developing this disease as well.â âFifty percent may sound like a scary number, but remember that schizophrenia is a very complex disease, and 50% of what causes schizophrenia is due to things other than your DNA.â âWell, like what? What else could be contributing to Shannonâs schizophrenia that wouldnât necessarily aff ect me?â Elise asked. Dr. OâBrien replied, âTh ere are many, many environmental infl uences that seem to play a role in the development of this disease, such as increased stresses and anxiety, or diffi cult relationships with other people. Interestingly, there is some groundbreaking research that is going on that suggests that the environment itself might even play a role at infl uencing oneâs DNA at the molecular level. Th is concept is called epigenetics. An example of epigenetics in nature is the calico cat. Each calico cat has a unique orange and black fur color pattern because of alterations, called epigenetic changes, which occur within the cells that produce coat color during the catâs development. Research in the fi eld of epigenetics suggests that individuals with schizophrenia appear to have some of these epigenetic changes to their DNA that are due to environmental infl uences, and that these alterations could be contributing to their development of mental illness.â âBut wouldnât I also have these âepigenetic alterationsâ in my DNA?â Elise asked. âNot necessarily, because you and Shannon have not experienced completely identical environments throughout your lives. For example, you and Shannon have had diff erent teachers and jobs throughout high school. And I also understand that you spent many childhood summers with a friend and her family out in the Grand Canyon, while your sister was off at swim camps. If you are interested, I can give you some literature to read about this subject.â Elise was defi nitely interested. She took the articles and headed home.

1. Briefly describe what you know about the structure of DNA and how DNA is packaged in a cell.

2. At the molecular level, speculate on some ways that the environment might have an infl uence on DNA and its packaging