Which one of the following statements is NOT correct?

• Together with proteins, rRNA provides a site for polypeptide synthesis

• All DNA molecules are unbranched polymers of nucleotides

• DNA is synthesized in a 5'-3' direction while RNA synthesis occurs in a 3'-5' direction

• A tRNA anticodon may pair with more than one codon 

In a human cell line, large fraction of double-strand DNA breaks are repaired by non-homologous end joining (NHEJ). An inhibitor of FLAP endonuclease will affect.

• recruitment of DNA-dependent kinase

• gap trimming

• DNA unwinding

• pairing of micro-homology regions

Construction of knockout mice may be performed using Cre-LoxP system. Eventually, the Cre recombinase of the bacteriophage P1 mediates site-specific recombination at a 34bp sequence, loxP. From the following statements, choose the INCORRECT event:

• The alteration of the chromosomal copy of the target gene requires a guide RNA.

• The loxP containing mice should not express Cre recombinase prior to mating.

• The Cre recombinase can be expressed by an inducible promoter.

• Induction of the promoter result in the expression of Cre, recombination at loxP sites and excision of the sequence in between.

Which one of the following statements is generally true about RNA polymerase II?

• It is dedicated to transcribing RNA from a single transcription unit, generally a large transcript which is then processed to yield three types of ribosomal RNA.

• It transcribes varities of small non-coding RNAs which are expressed in all cell types.

• It generally synthesizes various types of mRNAs and small non-coding RNAs.

• It is exclusively involved in synthesis of rRNA and tRNA.