which characteristic of DNA allows methylation patterns to b

which characteristic of DNA allows methylation patterns to be maintained through replication and cell division? O topoisomerases O recombination and repair O deoxyribonucleotide synthesis O semiconservative replication O the absence of uracil

Solution

Qs. Which characteristic of DNA allows methylation pattern to be maintained through replication and cell division?

A : Semi-conservative Replication

Qs. What causes the phenotypicdifferences between queen bee and worker bees?

A : Royal jelly suppresses a gene that normally methylates DNA, leading to expression of genes that encode characteristics of the queen. (Explanation : The ingredients in royal jelly inhibit an enzyme called cytosine methyltransferase which methylates cytosine bases in honeybee DNA. Simply lowering the expression levels of this enzyme in recently hatched honeybee larvae causes larvae that are destined to become worker bees to exhibit characteristics of queen bees.)

Qs. Which of the following statements about epigenetic X chromosome inactivation is correct?

A : The active X chromosome produces lncRNAs to silence the inactive X chromosome. (Explanation : In mammals, there are 2 copies of X chromosome genes in females and 1 in males. To balance the expression of X-chromosomes between the sexes, one of the X chromosomes in females is silenced. This is initiated by upregulation of the lncRNA (i.e. long non-coding RNA) Xist.)