- The base sequence of DNA, a triplet of 3 bases, codes for amino acids that make protein. Protein synthesis takes place in cell organelles called ribosomes.
- A carrier molecule called messenger ribonucleic acid (mRNA) takes the code from DNA in nucleus to ribosomes.
Comparison between DNA and mRNA
Comparison
|
DNA
|
mRNA
|
Sugar
|
deoxyribose
|
ribose
|
|
Nitrogenous base
|
A,T,C,G
|
A,U,C,G
|
|
Pairing rule
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A-T, C-G
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A-U, C-G
|
|
Strands
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Two strands going in opposite directions
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Single strands
|
|
Purpose
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The genetic code
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Transcribed copy of part of the genetic code
|
|
Location
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In nucleus
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Formed in nucleus and used in cytoplasm
|
|
Length
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Very long-can contain millions of nucleotides
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Very short
|
|
Duration
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For the life of the cell
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Constantly formed, used, then broken down
|
- One strand of DNA called the template strand is transcribed (written) to mRNA. The other strand is the non-template (coding) strand.
- The order of bases in mRNA is complementary (have the opposite base) to the template strand and the same as the bases in the non-template strand except the T in DNA is replaced with a U in mRNA.