lecture 4 - genetic disease

Question 1

What is the result of histone methylation?

Answer 1

Histone tails become hydrophobic and attract each other, packing tightly together into heterochromatin.

Question 2

Do methylated histones promote or inhibit gene transcription?

Answer 2

Inhibit - cause packing into heterochromatin

Question 3

Do histone methylation and acetylation have the same or opposite effects on chromatin structure?

Answer 3

Opposite - methylation results in inactive heterochromatin, while acetylation results in active euchromatin

Question 4

How do histone modifications indirectly regulate gene activity?

Answer 4

By recruiting other protein that either activate or inactivate transcription of certain genes by remodelling the chromatin.

Question 5

How do histone modifications directly regulate gene activity?

Answer 5

By physically controlling the accessibility of genes by converting between euchromatin and heterochromatin

Question 6

What is DNA methylation?

Answer 6

The addition of a methyl group to a DNA base

Question 7

What DNA base is typically methylated?

Answer 7

Cytosine (C)

Question 8

What is the result of DNA methylation of bases in the promotor region of a gene?

Answer 8

Inactivated expression of that gene

Question 9

How does DNA methylation of a promotor inhibit the expression of the gene?

Answer 9

Methyl groups are bound to by methyl-binding proteins (MBPs), which physically block transcription factors and RNA polymerase. Or, MBPs recruit enzymes that deacetylate histones creating inactive heterochromatin

Question 10

How does DNA methylation lead to DNA change?

Answer 10

Methylated cytosine bases can be deaminated and then turn into thymine bases - point mutations

Question 11

What are gene networks?

Answer 11

groupings of genes that can enhance or decrease the activity of each other, and are influenced by environmental or lifestyle factors.