Understanding DNA/RNA Processes
Quick Answer: DNA contains genetic information. During transcription, a DNA template strand is used to synthesize mRNA. During translation, mRNA codons (triplets) are read by ribosomes to assemble amino acids into proteins.
Key Concepts
Base Pairing Rules: A pairs with T (DNA) or U (RNA), G pairs with C. Central Dogma: DNA → RNA → Protein. Codon: Three-nucleotide sequence on mRNA that codes for one amino acid. The genetic code is universal and degenerate.
Solved Examples
5'-ATGC-3'
3'-TACG-5'
Complementary strand
Antiparallel pairing
DNA: 5'-ATGCGT-3'
mRNA: 5'-AUGCGU-3'
T replaced by U
RNA polymerase
mRNA: AUG CGU
AUG = Met (Start)
CGU = Arg
Met-Arg
FAQs
The template strand (3' to 5') is used by RNA polymerase to synthesize mRNA. The coding strand (5' to 3') has the same sequence as the mRNA (with T instead of U).
Multiple codons can code for the same amino acid (e.g., both GAA and GAG code for Glutamate). This reduces the impact of mutations.
The start codon is AUG (codes for Methionine). Stop codons are UAA, UAG, UGA, which signal the end of translation without coding for any amino acid.