What is the name of the chemical which covers DNA and histones?
tags
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What is the name of the layer formed by the tags?
Epigenome
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What does the epigenome determine of the DNA-histone complex?
It's shape
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What makes the DNA sequence different to the epigenome?
The DNA code is fixed whereas the epigenome is flexible as it responds to environmental changes
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During early development what can affect the epigenome of the offspring?
The nutrition provided by the mother
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Apart from environmental factors, what internal factors may also alter the epigenome?
Hormones
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Describe four steps as to how the epigenome is altered
1. Environmental signal stimulates proteins to carry its message inside the cell 2. It is then passed by a series of other proteins into the nucleus 3. The message passes to a specific protein that can be attached to a specific sequence of bases -->
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on the DNA 4. Once attached the protein has two possible effects- acetylation of histones or methylation of DNA
-->
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What is another word for the DNA-histone complex?
Chromatin
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Where the association of histones is ____, the chromatin is ___ condensed hence accesible by _____ _____ which can initiate the production of mRNA to _____ a gene
weak, less, transcription factors, express
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To express a gene, there has to be increased/decreased acetylation?
Increased
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To express a gene, there has to be increased/decreased methylation?
Decreased
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What is acetylation?
A process by which an acetyl group is added to a molecule
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What is the process by which an acetyl group is removed from a molecule?
Deacetylaion
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How does decreased acetylation result in a gene becoming switched off?
Decreased acetylation increased the positive charges on histones hence increases its attraction to negative phosphate groups on DNA, making the association between DNA and histones stronger preventing transcription fcators accessing DNA
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What process adds a methyl group to a molecule?
Methylation
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How does methylation inhibit the transcription of a gene?
- preenting the binding of transcription factors to the DNA - Attracting proteins that condense the DNA-histone complex making the DNA inaccessible to transcription factors
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When there is decreased acetylation but increased methylation what type of chromatin is formed?
heterochromatin
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When there is increased acetylation but decreased methylation what type of chromatin is formed?
Euchromatin
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What is thought to happen to epigenetic tags during the the earliest stages in development in a sperm and egg?
A specialised cellular mechanism searches the genome and erases its epigenetic tags in order to return the cells to a genetic 'clean slate' but a few epigenetic tags escape this process and pass unchanged from parent to offspring
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Can epigenetic changes increase the incidence of mutations?
Yes
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How can drugs treat diseases with epigenetics?
The drugs can inhibit certain enzymes involved in either histone acetylation or DNA methylation, which could reactivate genes that have been silenced
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What is gene (epigenetic) silencing?
When the epigenome has increased methylation of DNA and decreased acetylation of histones, making a gene inactive hence silenced
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How can epigenetics be used for ealy diagnosis for the early stages of diseases such as cancer, arthiritis and brain disorders?
By identifying the level of methylation and acetylation
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Other cards in this set
Card 2
Front
What theory of evolution is then questioned due to the discovery of epigenetics?
Back
Lamarkism
Card 3
Front
Give three examples of affecting factors
Back
Card 4
Front
What is the name of the chemical which covers DNA and histones?
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