Position-effect variegation (PEV) results when a gene normally in euchromatin is juxtaposed with heterochromatin by rearrangement or transposition. When heterochromatin packaging spreads across the heterochromatin/euchromatin border, it causes transcriptional silencing in a stochastic pattern.

What process is responsible for position effect variegation?

Position-effect variegation (PEV) results when a gene normally in euchromatin is juxtaposed with heterochromatin by rearrangement or transposition. When heterochromatin packaging spreads across the heterochromatin/euchromatin border, it causes transcriptional silencing in a stochastic pattern.

How does position effect influence gene expression?

The position effects are significant, altering the mean protein expression level by up to 15 times and expression noise by up to 20 times. DNA replication timing, 3D chromosomal conformation, and several histone modifications are major covariates of position effects.

How does the location of two genes impact expression?

Position effect is the effect on the expression of a gene when its location in a chromosome is changed, often by translocation. This has been well described in Drosophila with respect to eye color and is known as position effect variegation (PEV).

Does translocation cause variegation?

Transposable element activity generates variegated plants when insertion of a transposon interrupts a nuclear gene required for normal chloroplast biogenesis (white sectors), while element excision (or silencing) reconstitutes WT gene expression (green sectors).

How does translocation happen between 2 chromosomes involve?

Translocations occur when chromosomes become broken during meiosis and the resulting fragment becomes joined to another chromosome. Reciprocal translocations: In a balanced reciprocal translocation (Fig. 2.3), genetic material is exchanged between two chromosomes with no apparent loss.

Which of the following eukaryotic gene expression control take place in the cytoplasm?

protein translation
Eukaryotic gene expression is regulated during transcription and RNA processing, which take place in the nucleus, and during protein translation, which takes place in the cytoplasm. Further regulation may occur through post-translational modifications of proteins.

What do you mean by position effect?

Definition of position effect : a genetic effect in which the expression of a gene is influenced by its interaction with usually adjacent genes and which is modified when the spatial relationships of the genes change (as by translocation)

Which of the following areas of genetics applies mathematical principles to genetic sequences in order to better understand the genetic information?

The use of mathematics to understand the information within genetic sequences is called mathematical genomics.

What is the exact location occupied by a gene along the length of a chromosome?

​Locus. A locus is the specific physical location of a gene or other DNA sequence on a chromosome, like a genetic street address. The plural of locus is “loci”.

How is variegation inherited?

The plants variegation can be inherited (genetic) or occur randomly (chimeric). If genetic, the colour change is stable, this means that if you propagate a green shoot from a plant with colored leaves or sow its seed, the colouring will reappear in the new plant.

How are karyotypes and translocation related?

​Translocation Translocation is a type of chromosomal abnormality in which a chromosome breaks and a portion of it reattaches to a different chromosome. Chromosomal translocations can be detected by analyzing karyotypes of the affected cells.

What event occurs during translocation?

A translocation occurs when a piece of one chromosome breaks off and attaches to another chromosome. This type of rearrangement is described as balanced if no genetic material is gained or lost in the cell. If there is a gain or loss of genetic material, the translocation is described as unbalanced .

What is position effect variegation (PEV)?

Position effect variegation (PEV) is a mechanism for long-range regulation of gene expression whereby genomic rearrangements up to 400 kb away result in local disruption of chromatin structure and thus in access of the transcriptional machinery (reviewed in Bedell et al., 1996; Hendrich and Willard, 1995 ).

What is position effect variegation in genetics?

Position-effect variegation (PEV) was discovered in 1930 in a study of X-ray-induced chromosomal rearrangements. Rearrangements that place euchromatic genes adjacent to a region of centromeric heterochromatin give a variegated phenotype that results from the inactivation of genes by heterochromatin spreading from the breakpoint.

What is the relationship between chromosome rearrangement and variegate in Drosophila?

In Drosophila, virtually every gene that has been examined in an appropriate rearrangement has been shown to variegate, and rearrangements involving the pericentric heterochromatin of any chromosome can lead to PEV ( Girton and Johansen, 2008 ).

What is the Drosophila position effect variegation suppressor gene Su (var) 3-9?

The protein encoded by the Drosophila position effect variegation suppressor gene Su (var)3-9 combines domains of antagonistic regulators of homeotic gene complexes. EMBO J 13: 3822–3831. Tzeng TY, Lee CH, Chan LW, Shen CK. 2007.