Why is MgCl2 included in the PCR buffer If you started a PCR

Why is MgCl_2 included in the PCR buffer? If you started a PCR protocol with 10 double stranded molecules of DNA, how many double stranded molecules of product would you have after 5 cycles of PCR? Where is the initiation and stop codon of the GFPuv gene in the forward and reverse primers, respectively?

Solution

Magnesium between 1-5mm increase the effeciency of Taq polymerase ... without Mg taq polymerase cannot polymerise effeciently ...it acts as cofactor in polymerisation reaction by polymerase ,,,,

comming to question 2

Each cycle of pcr produces 2ⁿ amplicons where n is the cycle number .... this equation is valid when we assume we started with 1 template molecule

if we start with 10 template molecule the equation would be

10 * 2⁵

^{= 10 * 32 = 320}

^{we cannot say where because we never know out of complimentary DNA sequences which one codes for GFP ..... And primers are always complimentary ... so forward primer would be complimentary to 3\'5\'strand hence it might contain complimentary sequence of stop codon ..... and reverse primer is complimentary to 5\'3\' so it might contain complimentary sequence of start codon .... assuming mean to say about direction.... or may be i didnt get your third question ... u can always clarify in comments i will try to answer ....}

^{Hope i answered it correctly Regards GOOD LUCK ...}

^{I WAS THINKING OVER IT.... AND I THINK I GOT IT}

^{SINCE MRNA IS SYNTHESISED IN 5\'3\' DIRECTION so 3\'5\' dna strand would be coding one and if 3\'5\' is coding one .... then forward primer ie which reads 3\'5\' in 5\'3\' direction will have sequence same as mrna and would be sense strand and wold contain initator codon .... but no primer will bind to sense strand in 5\'3\' direction ....so there would be no stop codon in primers}

^{Hope i helped}