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Question 1

PEPCK

Answer 1

• Binding of GR signal leads to chromatin remodeling (turn on gene by displacement of histories by acctyylation of histone tails).
• In the PEPCK example you saw a simple case where the binding of an activator (GR protein) helps recruitment of a chromatin remodelling complex. This is an example of cooperative binding and is typical in eukaryotes

Question 2

Combinatorial control

Answer 2

• Transcription factors can be shared between target genes to be regulated. This is because they act in combination with others to differentially regulate the expression of the targets.
• The activity of a SOX protein is dependent upon the identity of its partner and the context of the DNA sequence to which it binds.

Question 3

SOX partners

Answer 3

• Bind to partners (other sox or other proteins. ).
• Flexibility in DNA motif recognition.
• spacing between DNA binding motifs

Question 4

Epigenetic inheritance

Answer 4

Changes in cellular or physiological state that are not caused by changes in DNA sequence
These non-DNA sequence changes affect gene expression.
•How?
–Acetylation
–Deacetylation
–Methylation

Question 5

Position effect silencing

Answer 5

Genes can be on or off depending on their position in the genome and such position can change due to mutations. chromosome rearrangements can:

1. can place genes in geterchromatoc regions (eg drosophila age variation)
2. place genes user direct regulaoty elements.
   - -drosophila and tissue in thorax.
   - -follicular lymphomas

Question 6

Methylation and imprinting

Answer 6

(sex-specific differences)

Notice that imprinting means only the Igf2 allele inherited from the father is actively expressed in the embryo

Question 7

Methylation and gene expression

Answer 7

1) Methylation affects regulation by modifying chromatin structure
2) Methylationof C (CG islands) in genes can directly silence genes by restricting TFs binding. Similarly lack of methylation promotes gene expression

Question 8

Acetylation histones and chromatin remodeling

Answer 8

facilitates displacement of histoneoctamerexposes DNA to transcription factors.xpression