1)look into the genetic code: if mRNA UU(U,C)-GG(U,C,A,G)-GG(U,C,A,G)-GC(U,C,A,G)-CC(U,C,A,G)-GU(U,C,A,G)-AA(U,C)-GC(U,C,A,G)
then DNA segment is AA(A,G)-CC(A,G,T,C)-CC(A,G,T,C)-CG(A,G,T,C)-GG(A,G,T,C)-CA(A,G,T,C)-TT(A,G)-CG(A,G,T,C).
just from mRNA to DNA use A becomes T, C becomes G, U becomes A, G becomes C.
2) Don’t agree with you. Why? I mean tRNA also has “origin” from DNA like mRNA or rRNA

PS THIS GENETIC CODE IS FOR NUCLEUS DNA BUT NOT FOR MITOHONDRIAL DNA.Mitohondrial Gen cod is diffgerent in some cases.

The DNA code could be;

AAA, CCT, CCT, CGT, GGT, TTA, CGT or
AAA, CCC, CCC, CGC, GGC, TTG, CGC or
AAA, CCA, CCA, CGA, GGA, TTG, CGA or
AAA, CCG, CCG, CGG, GGG, TTG, CGG or
AAC, CCT, CCT, CGT, GGT, TTA, CGT or
AAC, CCC, CCC, CGC, GGC, TTG, CGC or
AAC, CCA, CCA, CGA, GGA, TTG, CGA or
AAC, CCG, CCG, CGG, GGG, TTG, CGG … I think you get the point 😀
The list could go on…

Some Amino Acids have more than one triplet that will produce them… For example you could have CGA, CGC, CGG, CGT, AGA, or AGG and still get Arginine 😀

I agree with zami’87. on number 2. Every nucleic acid contains a phosphate(of course, not only one, it contains more)