Question

question 1
how does dna methylation impact gene expression?
increases gene expression
can block or increase gene expression
blocks gene expression
no impact
question 2
how does histone modification change gene expression?
histone modifications decrease transcription
histone modifications increase transcription
histone modifications do not change gene expression
histone modifications can increase or decrease gene expression

Explanation:

1. DNA methylation typically blocks gene expression by preventing transcription factor binding, but in some genomic regions (like certain enhancers), it can also lead to increased gene expression, so it has dual effects.
2. Different histone modifications have opposite impacts: for example, histone acetylation relaxes chromatin to increase transcription, while histone methylation can either increase or decrease expression depending on the specific amino acid modified and the number of methyl groups added.

Answer:

1. Can block or increase gene expression
2. Histone modifications can increase or decrease gene expression