Transcription Regulation and epigenetics

Question 1

What is epigenetics

Answer 1

Epigenetics refers to heritable changes in gene expression that do not involve changes to the underlying DNA sequence.

Question 2

Epigenetics influence gene expression through …

Answer 2

1. DNA methylation: addition of methyl groups to DNA, usually repressing gene expression
2. Histone modifications: changes to histone proteins that can activate or repress genes
3. Chromatin remodeling: changes in the structure of chromatin that can make genes more or less accessible

Question 3

Regulation in bacteria (E.coli)

Answer 3

e.coli (and other cells) perfer glucose over other sugars.

when the lac operon is repressed that means glucose is present (catabolite repression)

• A single gene can be regulated by multiple mechanisms
  
  • In the case of the lac operon lactose needs to be present AND glucose absent

Question 4

Regulation in Eukaryotes

Answer 4

–> have multiple regulatory sequences upstream of the gene
Ex:
1. Enhancers: activity is based on combined action
2. NELF & DSIF (neg reg factors)

Question 5

chromatin and epigenetics

Answer 5

Chromatin- DNA wrapped around histones

–> histone modifications and chromosome condensation impact transcription of genes

Question 6

histone Acetylation

Answer 6

causes chromatin to decondensed, leading to increased transcription

Question 7

Chromatin remoldeling factors

Answer 7

work by moving, removing, or exchanging histones

Question 8

DNA methylation

Answer 8

• Cytosine that precede guanine (CpG dinucleotides) can be methylated
  
  • Corelated with transcriptional repression
• Methylation can also be inherited during replication