Question

1. Fill in the table below concerning chromatin modification.

Name of Enzyme	Function	Writer (W)or Eraser (E)?	Action leads to open (O) or closed (C) chromatin	Effect on transcription (+/-)
	Adds acetyl groups to histones
HMT
HDAC
	Removes methyl groups from histones
DMT

2.Describe how X-chromosome inactivation occurs.

3.Outline the process of RNA interference (RNAi). Note the two types of small RNA molecules typically involved, as well as the three possible outcomes. Be able to define the following: Dicer, RISC, guide strand, passenger strand.

4.Review the three epigenetics case studies we discussed. Briefly discuss one of them here.

Ill rate you HIGH

Topic Genetics

is complete

Answer 1

1.Histone acetyl transferase adds acetyl groups to histones - writer
Histone demethylase (methyl transferase) remove methyl groups from histones - eraser

2. X-chromosome Inactivation occurs when RNA transcribed from the Xist gene on the X chromosome from which it is expressed spreads to coat the whole X chromosome.

3. RNA interference is a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules.
microRNA (miRNA) and small interfering RNA (siRNA) are the two types of RNA molecules involved in RNA interference.
The three possible outcomes of RNAi are:
Degradation of mRNA,
Prevention of translation and
Gene silencing.

Dicer is the enzyme that cleaves double-stranded RNA and pre-microRNA into short double-stranded RNA fragments called small interfering RNA and microRNA, respectively.
RISC refers to "RNA-induced silencing complex". It is a multiprotein complex. It incorporates one strand of a single-stranded RNA fragment, such as microRNA, or double-stranded small interfering RNA.

Passenger strand and guide strand:
Each small interfering RNA (siRNA) is unwound into two single-stranded RNAs (ssRNAs). They are the passenger strand and the guide strand.
The passenger strand is degraded and the guide strand is incorporated into the RNA-induced silencing complex (RISC).

4. There is no data about the epigenetic studies, which is asked as fourth question.