Unit 18: Epigenetics Flashcards
What is epigenetics?
Study of changes in phenotype or gene expression that does not involve changes in the nucleotide sequence.
Given that cytosine can be methylated to 5-methyl cytosine and deaminated to thymine, what does this mean for epigenetics?
This means that epigenetic variation may lead to genetic variation over time.
How does methylation of DNA affect nucleosomes?
Methylation of DNA and histones causes nucleosomes to pack tightly together. Transcription factors cannot bind the DNA, and genes are not expressed.
What is histone acetylation?
Histone acetylation results in loose packing of nucleosomes. Transcription factors can bind the DNA and genes are expressed.
Explain why gene expression of GFP (Green Fluorescent Protein), for
example, decreases when a compound
that contains methyl-donor molecules/co-factors involved in DNA
methylation is added to cells.
- Methyl-donor compounds increase methylation around the GFP gene’s promoter.
- This causes the chromatin to condense.
- Transcription factors and RNA polymerase can’t bind well.
- GFP (Green Fluorescent Protein) expression decreases — the gene is silenced or “turned down”. Fluorescence decreases.
Explain why/how queen bees are different from worker bees.
- Queen bees are genetically
identical to workers. - They develop in “Queen Cups” full of royal jelly.
- Royal jelly silences Dnmt3 which
codes for an enzyme that silences genes genome-wide.
Explain how BPA affects coat color in mice.
BPA is a chemical that can decrease CpG methylation (turn on a gene) in mice that makes their fur yellow and makes them obese.
Explain how methyl-
donor compounds such as folic acid and vitamin B12 can mitigate the effects of BPA.
Choline, folic acid, betaine, and vitamin B12 that are supplements high in methyl-donors negated the effects of BPA
