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RNA and protein synthesis
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DNA stays in the nucleus, so a copy of each gene is made as RNA. Ribosomes use it to build proteins.
DNA and RNA
DNA: two strands coiled into a double helix, linked by paired bases: A with T, C with G.
RNA: single-stranded, and it contains uracil (U) instead of thymine (T). So in RNA, A pairs with U.
RNA: single-stranded, and it contains uracil (U) instead of thymine (T). So in RNA, A pairs with U.
Transcription (in the nucleus)
The DNA of a gene unwinds.
One strand is used as a template to make a complementary molecule of mRNA (messenger RNA).
The mRNA leaves the nucleus and goes to a ribosome in the cytoplasm.
One strand is used as a template to make a complementary molecule of mRNA (messenger RNA).
The mRNA leaves the nucleus and goes to a ribosome in the cytoplasm.
Translation (at the ribosome)
The ribosome reads the mRNA in codons: groups of three bases. Each codon codes for one amino acid.
tRNA molecules each carry a specific amino acid. Each tRNA has an anticodon of three bases that pairs with the matching codon.
The amino acids are joined in the order set by the codons, making a chain that folds into a protein.
tRNA molecules each carry a specific amino acid. Each tRNA has an anticodon of three bases that pairs with the matching codon.
The amino acids are joined in the order set by the codons, making a chain that folds into a protein.
A DNA template strand has the bases TAC. What is the mRNA codon, and the tRNA anticodon?
- mRNA is complementary to the template: T to A, A to U, C to G, giving AUG.
- The anticodon is complementary to the codon: A to U, U to A, G to C, giving UAC.
Answer: Codon AUG; anticodon UAC
DNA is a double helix with A-T and C-G pairs. RNA is single-stranded with uracil instead of thymine. Transcription makes mRNA in the nucleus. At the ribosome, codons are read, tRNA anticodons pair with them and bring amino acids, which are joined into a protein.
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